BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
//===-- BPFISelDAGToDAG.cpp - A dag to dag inst selector for BPF ----------===//
|
|
|
|
//
|
|
|
|
// The LLVM Compiler Infrastructure
|
|
|
|
//
|
|
|
|
// This file is distributed under the University of Illinois Open Source
|
|
|
|
// License. See LICENSE.TXT for details.
|
|
|
|
//
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
//
|
|
|
|
// This file defines a DAG pattern matching instruction selector for BPF,
|
|
|
|
// converting from a legalized dag to a BPF dag.
|
|
|
|
//
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
|
|
|
|
#include "BPF.h"
|
|
|
|
#include "BPFRegisterInfo.h"
|
|
|
|
#include "BPFSubtarget.h"
|
|
|
|
#include "BPFTargetMachine.h"
|
2017-06-29 23:18:54 +08:00
|
|
|
#include "llvm/CodeGen/FunctionLoweringInfo.h"
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
#include "llvm/CodeGen/MachineConstantPool.h"
|
|
|
|
#include "llvm/CodeGen/MachineFrameInfo.h"
|
2015-03-24 03:32:43 +08:00
|
|
|
#include "llvm/CodeGen/MachineFunction.h"
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
#include "llvm/CodeGen/MachineInstrBuilder.h"
|
|
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
|
|
#include "llvm/CodeGen/SelectionDAGISel.h"
|
2017-06-16 23:41:16 +08:00
|
|
|
#include "llvm/IR/Constants.h"
|
2015-03-24 03:32:43 +08:00
|
|
|
#include "llvm/IR/IntrinsicInst.h"
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
#include "llvm/Support/Debug.h"
|
2017-06-16 23:41:16 +08:00
|
|
|
#include "llvm/Support/Endian.h"
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
#include "llvm/Support/ErrorHandling.h"
|
|
|
|
#include "llvm/Support/raw_ostream.h"
|
2015-03-24 03:32:43 +08:00
|
|
|
#include "llvm/Target/TargetMachine.h"
|
2017-06-16 23:41:16 +08:00
|
|
|
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
using namespace llvm;
|
|
|
|
|
|
|
|
#define DEBUG_TYPE "bpf-isel"
|
|
|
|
|
|
|
|
// Instruction Selector Implementation
|
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|
|
namespace {
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|
class BPFDAGToDAGISel : public SelectionDAGISel {
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public:
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explicit BPFDAGToDAGISel(BPFTargetMachine &TM) : SelectionDAGISel(TM) {}
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|
2016-10-01 10:56:57 +08:00
|
|
|
StringRef getPassName() const override {
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
return "BPF DAG->DAG Pattern Instruction Selection";
|
|
|
|
}
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|
2017-06-16 23:41:16 +08:00
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void PreprocessISelDAG() override;
|
|
|
|
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
private:
|
|
|
|
// Include the pieces autogenerated from the target description.
|
|
|
|
#include "BPFGenDAGISel.inc"
|
|
|
|
|
2016-05-13 05:14:47 +08:00
|
|
|
void Select(SDNode *N) override;
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
|
|
|
|
// Complex Pattern for address selection.
|
|
|
|
bool SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
|
2015-10-06 12:00:53 +08:00
|
|
|
bool SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
|
2017-06-16 23:41:16 +08:00
|
|
|
|
2017-06-29 23:18:54 +08:00
|
|
|
// Node preprocessing cases
|
|
|
|
void PreprocessLoad(SDNode *Node, SelectionDAG::allnodes_iterator I);
|
|
|
|
void PreprocessCopyToReg(SDNode *Node);
|
|
|
|
void PreprocessTrunc(SDNode *Node, SelectionDAG::allnodes_iterator I);
|
|
|
|
|
2017-06-16 23:41:16 +08:00
|
|
|
// Find constants from a constant structure
|
|
|
|
typedef std::vector<unsigned char> val_vec_type;
|
|
|
|
bool fillGenericConstant(const DataLayout &DL, const Constant *CV,
|
|
|
|
val_vec_type &Vals, uint64_t Offset);
|
|
|
|
bool fillConstantDataArray(const DataLayout &DL, const ConstantDataArray *CDA,
|
|
|
|
val_vec_type &Vals, int Offset);
|
|
|
|
bool fillConstantArray(const DataLayout &DL, const ConstantArray *CA,
|
|
|
|
val_vec_type &Vals, int Offset);
|
|
|
|
bool fillConstantStruct(const DataLayout &DL, const ConstantStruct *CS,
|
|
|
|
val_vec_type &Vals, int Offset);
|
|
|
|
bool getConstantFieldValue(const GlobalAddressSDNode *Node, uint64_t Offset,
|
|
|
|
uint64_t Size, unsigned char *ByteSeq);
|
2017-06-29 23:18:54 +08:00
|
|
|
bool checkLoadDef(unsigned DefReg, unsigned match_load_op);
|
2017-06-16 23:41:16 +08:00
|
|
|
|
|
|
|
// Mapping from ConstantStruct global value to corresponding byte-list values
|
|
|
|
std::map<const void *, val_vec_type> cs_vals_;
|
2017-06-29 23:18:54 +08:00
|
|
|
// Mapping from vreg to load memory opcode
|
|
|
|
std::map<unsigned, unsigned> load_to_vreg_;
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
};
|
2017-06-16 23:41:16 +08:00
|
|
|
} // namespace
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
|
|
|
|
// ComplexPattern used on BPF Load/Store instructions
|
|
|
|
bool BPFDAGToDAGISel::SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset) {
|
|
|
|
// if Address is FI, get the TargetFrameIndex.
|
2015-04-29 04:38:56 +08:00
|
|
|
SDLoc DL(Addr);
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
|
2017-06-16 23:41:16 +08:00
|
|
|
Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
|
2015-04-29 04:38:56 +08:00
|
|
|
Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (Addr.getOpcode() == ISD::TargetExternalSymbol ||
|
|
|
|
Addr.getOpcode() == ISD::TargetGlobalAddress)
|
|
|
|
return false;
|
|
|
|
|
2015-10-06 12:00:53 +08:00
|
|
|
// Addresses of the form Addr+const or Addr|const
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
if (CurDAG->isBaseWithConstantOffset(Addr)) {
|
|
|
|
ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
|
2017-04-14 06:24:13 +08:00
|
|
|
if (isInt<16>(CN->getSExtValue())) {
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
|
|
|
|
// If the first operand is a FI, get the TargetFI Node
|
|
|
|
if (FrameIndexSDNode *FIN =
|
|
|
|
dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
|
|
|
|
Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
|
|
|
|
else
|
|
|
|
Base = Addr.getOperand(0);
|
|
|
|
|
2015-04-29 04:38:56 +08:00
|
|
|
Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64);
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2017-06-16 23:41:16 +08:00
|
|
|
Base = Addr;
|
2015-04-29 04:38:56 +08:00
|
|
|
Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
2015-10-06 12:00:53 +08:00
|
|
|
// ComplexPattern used on BPF FI instruction
|
2017-06-16 23:41:16 +08:00
|
|
|
bool BPFDAGToDAGISel::SelectFIAddr(SDValue Addr, SDValue &Base,
|
|
|
|
SDValue &Offset) {
|
2015-10-06 12:00:53 +08:00
|
|
|
SDLoc DL(Addr);
|
|
|
|
|
|
|
|
if (!CurDAG->isBaseWithConstantOffset(Addr))
|
|
|
|
return false;
|
|
|
|
|
|
|
|
// Addresses of the form Addr+const or Addr|const
|
|
|
|
ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
|
2017-04-14 06:24:13 +08:00
|
|
|
if (isInt<16>(CN->getSExtValue())) {
|
2015-10-06 12:00:53 +08:00
|
|
|
|
|
|
|
// If the first operand is a FI, get the TargetFI Node
|
2017-06-16 23:41:16 +08:00
|
|
|
if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
|
2015-10-06 12:00:53 +08:00
|
|
|
Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
|
|
|
|
else
|
|
|
|
return false;
|
|
|
|
|
|
|
|
Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64);
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
2016-05-13 05:14:47 +08:00
|
|
|
void BPFDAGToDAGISel::Select(SDNode *Node) {
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
unsigned Opcode = Node->getOpcode();
|
|
|
|
|
|
|
|
// Dump information about the Node being selected
|
|
|
|
DEBUG(dbgs() << "Selecting: "; Node->dump(CurDAG); dbgs() << '\n');
|
|
|
|
|
|
|
|
// If we have a custom node, we already have selected!
|
|
|
|
if (Node->isMachineOpcode()) {
|
|
|
|
DEBUG(dbgs() << "== "; Node->dump(CurDAG); dbgs() << '\n');
|
2016-05-13 05:14:47 +08:00
|
|
|
return;
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
// tablegen selection should be handled here.
|
|
|
|
switch (Opcode) {
|
2017-06-16 23:41:16 +08:00
|
|
|
default:
|
|
|
|
break;
|
2016-03-19 06:02:47 +08:00
|
|
|
case ISD::SDIV: {
|
|
|
|
DebugLoc Empty;
|
|
|
|
const DebugLoc &DL = Node->getDebugLoc();
|
|
|
|
if (DL != Empty)
|
|
|
|
errs() << "Error at line " << DL.getLine() << ": ";
|
|
|
|
else
|
|
|
|
errs() << "Error: ";
|
|
|
|
errs() << "Unsupport signed division for DAG: ";
|
2017-01-28 10:02:38 +08:00
|
|
|
Node->print(errs(), CurDAG);
|
2016-03-19 06:02:47 +08:00
|
|
|
errs() << "Please convert to unsigned div/mod.\n";
|
|
|
|
break;
|
|
|
|
}
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
case ISD::INTRINSIC_W_CHAIN: {
|
|
|
|
unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
|
|
|
|
switch (IntNo) {
|
|
|
|
case Intrinsic::bpf_load_byte:
|
|
|
|
case Intrinsic::bpf_load_half:
|
|
|
|
case Intrinsic::bpf_load_word: {
|
|
|
|
SDLoc DL(Node);
|
|
|
|
SDValue Chain = Node->getOperand(0);
|
|
|
|
SDValue N1 = Node->getOperand(1);
|
|
|
|
SDValue Skb = Node->getOperand(2);
|
|
|
|
SDValue N3 = Node->getOperand(3);
|
|
|
|
|
|
|
|
SDValue R6Reg = CurDAG->getRegister(BPF::R6, MVT::i64);
|
|
|
|
Chain = CurDAG->getCopyToReg(Chain, DL, R6Reg, Skb, SDValue());
|
|
|
|
Node = CurDAG->UpdateNodeOperands(Node, Chain, N1, R6Reg, N3);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
case ISD::FrameIndex: {
|
2015-04-10 19:24:51 +08:00
|
|
|
int FI = cast<FrameIndexSDNode>(Node)->getIndex();
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
EVT VT = Node->getValueType(0);
|
|
|
|
SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
|
|
|
|
unsigned Opc = BPF::MOV_rr;
|
2016-05-13 05:14:47 +08:00
|
|
|
if (Node->hasOneUse()) {
|
|
|
|
CurDAG->SelectNodeTo(Node, Opc, VT, TFI);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
ReplaceNode(Node, CurDAG->getMachineNode(Opc, SDLoc(Node), VT, TFI));
|
|
|
|
return;
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// Select the default instruction
|
2016-05-13 05:14:47 +08:00
|
|
|
SelectCode(Node);
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
}
|
|
|
|
|
2017-06-29 23:18:54 +08:00
|
|
|
void BPFDAGToDAGISel::PreprocessLoad(SDNode *Node,
|
|
|
|
SelectionDAG::allnodes_iterator I) {
|
|
|
|
union {
|
|
|
|
uint8_t c[8];
|
|
|
|
uint16_t s;
|
|
|
|
uint32_t i;
|
|
|
|
uint64_t d;
|
|
|
|
} new_val; // hold up the constant values replacing loads.
|
|
|
|
bool to_replace = false;
|
|
|
|
SDLoc DL(Node);
|
|
|
|
const LoadSDNode *LD = cast<LoadSDNode>(Node);
|
|
|
|
uint64_t size = LD->getMemOperand()->getSize();
|
|
|
|
|
|
|
|
if (!size || size > 8 || (size & (size - 1)))
|
|
|
|
return;
|
|
|
|
|
|
|
|
SDNode *LDAddrNode = LD->getOperand(1).getNode();
|
|
|
|
// Match LDAddr against either global_addr or (global_addr + offset)
|
|
|
|
unsigned opcode = LDAddrNode->getOpcode();
|
|
|
|
if (opcode == ISD::ADD) {
|
|
|
|
SDValue OP1 = LDAddrNode->getOperand(0);
|
|
|
|
SDValue OP2 = LDAddrNode->getOperand(1);
|
|
|
|
|
|
|
|
// We want to find the pattern global_addr + offset
|
|
|
|
SDNode *OP1N = OP1.getNode();
|
|
|
|
if (OP1N->getOpcode() <= ISD::BUILTIN_OP_END || OP1N->getNumOperands() == 0)
|
|
|
|
return;
|
|
|
|
|
|
|
|
DEBUG(dbgs() << "Check candidate load: "; LD->dump(); dbgs() << '\n');
|
|
|
|
|
|
|
|
const GlobalAddressSDNode *GADN =
|
|
|
|
dyn_cast<GlobalAddressSDNode>(OP1N->getOperand(0).getNode());
|
|
|
|
const ConstantSDNode *CDN = dyn_cast<ConstantSDNode>(OP2.getNode());
|
|
|
|
if (GADN && CDN)
|
|
|
|
to_replace =
|
|
|
|
getConstantFieldValue(GADN, CDN->getZExtValue(), size, new_val.c);
|
|
|
|
} else if (LDAddrNode->getOpcode() > ISD::BUILTIN_OP_END &&
|
|
|
|
LDAddrNode->getNumOperands() > 0) {
|
|
|
|
DEBUG(dbgs() << "Check candidate load: "; LD->dump(); dbgs() << '\n');
|
|
|
|
|
|
|
|
SDValue OP1 = LDAddrNode->getOperand(0);
|
|
|
|
if (const GlobalAddressSDNode *GADN =
|
|
|
|
dyn_cast<GlobalAddressSDNode>(OP1.getNode()))
|
|
|
|
to_replace = getConstantFieldValue(GADN, 0, size, new_val.c);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (!to_replace)
|
|
|
|
return;
|
|
|
|
|
|
|
|
// replacing the old with a new value
|
|
|
|
uint64_t val;
|
|
|
|
if (size == 1)
|
|
|
|
val = new_val.c[0];
|
|
|
|
else if (size == 2)
|
|
|
|
val = new_val.s;
|
|
|
|
else if (size == 4)
|
|
|
|
val = new_val.i;
|
|
|
|
else {
|
|
|
|
val = new_val.d;
|
|
|
|
}
|
|
|
|
|
|
|
|
DEBUG(dbgs() << "Replacing load of size " << size << " with constant " << val
|
|
|
|
<< '\n');
|
|
|
|
SDValue NVal = CurDAG->getConstant(val, DL, MVT::i64);
|
|
|
|
|
|
|
|
// After replacement, the current node is dead, we need to
|
|
|
|
// go backward one step to make iterator still work
|
|
|
|
I--;
|
|
|
|
SDValue From[] = {SDValue(Node, 0), SDValue(Node, 1)};
|
|
|
|
SDValue To[] = {NVal, NVal};
|
|
|
|
CurDAG->ReplaceAllUsesOfValuesWith(From, To, 2);
|
|
|
|
I++;
|
|
|
|
// It is safe to delete node now
|
|
|
|
CurDAG->DeleteNode(Node);
|
|
|
|
}
|
|
|
|
|
2017-06-16 23:41:16 +08:00
|
|
|
void BPFDAGToDAGISel::PreprocessISelDAG() {
|
2017-06-29 23:18:54 +08:00
|
|
|
// Iterate through all nodes, interested in the following cases:
|
|
|
|
//
|
|
|
|
// . loads from ConstantStruct or ConstantArray of constructs
|
|
|
|
// which can be turns into constant itself, with this we can
|
|
|
|
// avoid reading from read-only section at runtime.
|
|
|
|
//
|
|
|
|
// . reg truncating is often the result of 8/16/32bit->64bit or
|
|
|
|
// 8/16bit->32bit conversion. If the reg value is loaded with
|
|
|
|
// masked byte width, the AND operation can be removed since
|
|
|
|
// BPF LOAD already has zero extension.
|
|
|
|
//
|
|
|
|
// This also solved a correctness issue.
|
|
|
|
// In BPF socket-related program, e.g., __sk_buff->{data, data_end}
|
|
|
|
// are 32-bit registers, but later on, kernel verifier will rewrite
|
|
|
|
// it with 64-bit value. Therefore, truncating the value after the
|
|
|
|
// load will result in incorrect code.
|
2017-06-16 23:41:16 +08:00
|
|
|
for (SelectionDAG::allnodes_iterator I = CurDAG->allnodes_begin(),
|
|
|
|
E = CurDAG->allnodes_end();
|
|
|
|
I != E;) {
|
|
|
|
SDNode *Node = &*I++;
|
|
|
|
unsigned Opcode = Node->getOpcode();
|
2017-06-29 23:18:54 +08:00
|
|
|
if (Opcode == ISD::LOAD)
|
|
|
|
PreprocessLoad(Node, I);
|
|
|
|
else if (Opcode == ISD::CopyToReg)
|
|
|
|
PreprocessCopyToReg(Node);
|
|
|
|
else if (Opcode == ISD::AND)
|
|
|
|
PreprocessTrunc(Node, I);
|
2017-06-16 23:41:16 +08:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::getConstantFieldValue(const GlobalAddressSDNode *Node,
|
|
|
|
uint64_t Offset, uint64_t Size,
|
|
|
|
unsigned char *ByteSeq) {
|
|
|
|
const GlobalVariable *V = dyn_cast<GlobalVariable>(Node->getGlobal());
|
|
|
|
|
|
|
|
if (!V || !V->hasInitializer())
|
|
|
|
return false;
|
|
|
|
|
|
|
|
const Constant *Init = V->getInitializer();
|
|
|
|
const DataLayout &DL = CurDAG->getDataLayout();
|
|
|
|
val_vec_type TmpVal;
|
|
|
|
|
|
|
|
auto it = cs_vals_.find(static_cast<const void *>(Init));
|
|
|
|
if (it != cs_vals_.end()) {
|
|
|
|
TmpVal = it->second;
|
|
|
|
} else {
|
|
|
|
uint64_t total_size = 0;
|
|
|
|
if (const ConstantStruct *CS = dyn_cast<ConstantStruct>(Init))
|
|
|
|
total_size =
|
|
|
|
DL.getStructLayout(cast<StructType>(CS->getType()))->getSizeInBytes();
|
|
|
|
else if (const ConstantArray *CA = dyn_cast<ConstantArray>(Init))
|
|
|
|
total_size = DL.getTypeAllocSize(CA->getType()->getElementType()) *
|
|
|
|
CA->getNumOperands();
|
|
|
|
else
|
|
|
|
return false;
|
|
|
|
|
|
|
|
val_vec_type Vals(total_size, 0);
|
|
|
|
if (fillGenericConstant(DL, Init, Vals, 0) == false)
|
|
|
|
return false;
|
|
|
|
cs_vals_[static_cast<const void *>(Init)] = Vals;
|
|
|
|
TmpVal = std::move(Vals);
|
|
|
|
}
|
|
|
|
|
|
|
|
// test whether host endianness matches target
|
2017-06-17 07:28:04 +08:00
|
|
|
union {
|
|
|
|
uint8_t c[2];
|
|
|
|
uint16_t s;
|
|
|
|
} test_buf;
|
2017-06-16 23:41:16 +08:00
|
|
|
uint16_t test_val = 0x2345;
|
|
|
|
if (DL.isLittleEndian())
|
2017-06-17 07:28:04 +08:00
|
|
|
support::endian::write16le(test_buf.c, test_val);
|
2017-06-16 23:41:16 +08:00
|
|
|
else
|
2017-06-17 07:28:04 +08:00
|
|
|
support::endian::write16be(test_buf.c, test_val);
|
2017-06-16 23:41:16 +08:00
|
|
|
|
2017-06-17 07:28:04 +08:00
|
|
|
bool endian_match = test_buf.s == test_val;
|
2017-06-16 23:41:16 +08:00
|
|
|
for (uint64_t i = Offset, j = 0; i < Offset + Size; i++, j++)
|
|
|
|
ByteSeq[j] = endian_match ? TmpVal[i] : TmpVal[Offset + Size - 1 - j];
|
|
|
|
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::fillGenericConstant(const DataLayout &DL,
|
|
|
|
const Constant *CV,
|
|
|
|
val_vec_type &Vals, uint64_t Offset) {
|
|
|
|
uint64_t Size = DL.getTypeAllocSize(CV->getType());
|
|
|
|
|
|
|
|
if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
|
|
|
|
return true; // already done
|
|
|
|
|
|
|
|
if (const ConstantInt *CI = dyn_cast<ConstantInt>(CV)) {
|
|
|
|
uint64_t val = CI->getZExtValue();
|
|
|
|
DEBUG(dbgs() << "Byte array at offset " << Offset << " with value " << val
|
|
|
|
<< '\n');
|
|
|
|
|
|
|
|
if (Size > 8 || (Size & (Size - 1)))
|
|
|
|
return false;
|
|
|
|
|
|
|
|
// Store based on target endian
|
|
|
|
for (uint64_t i = 0; i < Size; ++i) {
|
|
|
|
Vals[Offset + i] = DL.isLittleEndian()
|
|
|
|
? ((val >> (i * 8)) & 0xFF)
|
|
|
|
: ((val >> ((Size - i - 1) * 8)) & 0xFF);
|
|
|
|
}
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (const ConstantDataArray *CDA = dyn_cast<ConstantDataArray>(CV))
|
|
|
|
return fillConstantDataArray(DL, CDA, Vals, Offset);
|
|
|
|
|
|
|
|
if (const ConstantArray *CA = dyn_cast<ConstantArray>(CV))
|
|
|
|
return fillConstantArray(DL, CA, Vals, Offset);
|
|
|
|
|
|
|
|
if (const ConstantStruct *CVS = dyn_cast<ConstantStruct>(CV))
|
|
|
|
return fillConstantStruct(DL, CVS, Vals, Offset);
|
|
|
|
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::fillConstantDataArray(const DataLayout &DL,
|
|
|
|
const ConstantDataArray *CDA,
|
|
|
|
val_vec_type &Vals, int Offset) {
|
|
|
|
for (unsigned i = 0, e = CDA->getNumElements(); i != e; ++i) {
|
|
|
|
if (fillGenericConstant(DL, CDA->getElementAsConstant(i), Vals, Offset) ==
|
|
|
|
false)
|
|
|
|
return false;
|
|
|
|
Offset += DL.getTypeAllocSize(CDA->getElementAsConstant(i)->getType());
|
|
|
|
}
|
|
|
|
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::fillConstantArray(const DataLayout &DL,
|
|
|
|
const ConstantArray *CA,
|
|
|
|
val_vec_type &Vals, int Offset) {
|
|
|
|
for (unsigned i = 0, e = CA->getNumOperands(); i != e; ++i) {
|
|
|
|
if (fillGenericConstant(DL, CA->getOperand(i), Vals, Offset) == false)
|
|
|
|
return false;
|
|
|
|
Offset += DL.getTypeAllocSize(CA->getOperand(i)->getType());
|
|
|
|
}
|
|
|
|
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::fillConstantStruct(const DataLayout &DL,
|
|
|
|
const ConstantStruct *CS,
|
|
|
|
val_vec_type &Vals, int Offset) {
|
|
|
|
const StructLayout *Layout = DL.getStructLayout(CS->getType());
|
|
|
|
for (unsigned i = 0, e = CS->getNumOperands(); i != e; ++i) {
|
|
|
|
const Constant *Field = CS->getOperand(i);
|
|
|
|
uint64_t SizeSoFar = Layout->getElementOffset(i);
|
|
|
|
if (fillGenericConstant(DL, Field, Vals, Offset + SizeSoFar) == false)
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
return true;
|
|
|
|
}
|
|
|
|
|
2017-06-29 23:18:54 +08:00
|
|
|
void BPFDAGToDAGISel::PreprocessCopyToReg(SDNode *Node) {
|
|
|
|
const RegisterSDNode *RegN = dyn_cast<RegisterSDNode>(Node->getOperand(1));
|
|
|
|
if (!RegN || !TargetRegisterInfo::isVirtualRegister(RegN->getReg()))
|
|
|
|
return;
|
|
|
|
|
|
|
|
const LoadSDNode *LD = dyn_cast<LoadSDNode>(Node->getOperand(2));
|
|
|
|
if (!LD)
|
|
|
|
return;
|
|
|
|
|
|
|
|
// Assign a load value to a virtual register. record its load width
|
|
|
|
unsigned mem_load_op = 0;
|
|
|
|
switch (LD->getMemOperand()->getSize()) {
|
|
|
|
default:
|
|
|
|
return;
|
|
|
|
case 4:
|
|
|
|
mem_load_op = BPF::LDW;
|
|
|
|
break;
|
|
|
|
case 2:
|
|
|
|
mem_load_op = BPF::LDH;
|
|
|
|
break;
|
|
|
|
case 1:
|
|
|
|
mem_load_op = BPF::LDB;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
DEBUG(dbgs() << "Find Load Value to VReg "
|
|
|
|
<< TargetRegisterInfo::virtReg2Index(RegN->getReg()) << '\n');
|
|
|
|
load_to_vreg_[RegN->getReg()] = mem_load_op;
|
|
|
|
}
|
|
|
|
|
|
|
|
void BPFDAGToDAGISel::PreprocessTrunc(SDNode *Node,
|
|
|
|
SelectionDAG::allnodes_iterator I) {
|
|
|
|
ConstantSDNode *MaskN = dyn_cast<ConstantSDNode>(Node->getOperand(1));
|
|
|
|
if (!MaskN)
|
|
|
|
return;
|
|
|
|
|
|
|
|
unsigned match_load_op = 0;
|
|
|
|
switch (MaskN->getZExtValue()) {
|
|
|
|
default:
|
|
|
|
return;
|
|
|
|
case 0xFFFFFFFF:
|
|
|
|
match_load_op = BPF::LDW;
|
|
|
|
break;
|
|
|
|
case 0xFFFF:
|
|
|
|
match_load_op = BPF::LDH;
|
|
|
|
break;
|
|
|
|
case 0xFF:
|
|
|
|
match_load_op = BPF::LDB;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
// The Reg operand should be a virtual register, which is defined
|
|
|
|
// outside the current basic block. DAG combiner has done a pretty
|
|
|
|
// good job in removing truncating inside a single basic block.
|
|
|
|
SDValue BaseV = Node->getOperand(0);
|
|
|
|
if (BaseV.getOpcode() != ISD::CopyFromReg)
|
|
|
|
return;
|
|
|
|
|
|
|
|
const RegisterSDNode *RegN =
|
|
|
|
dyn_cast<RegisterSDNode>(BaseV.getNode()->getOperand(1));
|
|
|
|
if (!RegN || !TargetRegisterInfo::isVirtualRegister(RegN->getReg()))
|
|
|
|
return;
|
|
|
|
unsigned AndOpReg = RegN->getReg();
|
|
|
|
DEBUG(dbgs() << "Examine %vreg" << TargetRegisterInfo::virtReg2Index(AndOpReg)
|
|
|
|
<< '\n');
|
|
|
|
|
|
|
|
// Examine the PHI insns in the MachineBasicBlock to found out the
|
|
|
|
// definitions of this virtual register. At this stage (DAG2DAG
|
|
|
|
// transformation), only PHI machine insns are available in the machine basic
|
|
|
|
// block.
|
|
|
|
MachineBasicBlock *MBB = FuncInfo->MBB;
|
|
|
|
MachineInstr *MII = nullptr;
|
|
|
|
for (auto &MI : *MBB) {
|
|
|
|
for (unsigned i = 0; i < MI.getNumOperands(); ++i) {
|
|
|
|
const MachineOperand &MOP = MI.getOperand(i);
|
|
|
|
if (!MOP.isReg() || !MOP.isDef())
|
|
|
|
continue;
|
|
|
|
unsigned Reg = MOP.getReg();
|
|
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg) && Reg == AndOpReg) {
|
|
|
|
MII = &MI;
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
if (MII == nullptr) {
|
|
|
|
// No phi definition in this block.
|
|
|
|
if (!checkLoadDef(AndOpReg, match_load_op))
|
|
|
|
return;
|
|
|
|
} else {
|
|
|
|
// The PHI node looks like:
|
|
|
|
// %vreg2<def> = PHI %vreg0, <BB#1>, %vreg1, <BB#3>
|
|
|
|
// Trace each incoming definition, e.g., (%vreg0, BB#1) and (%vreg1, BB#3)
|
|
|
|
// The AND operation can be removed if both %vreg0 in BB#1 and %vreg1 in
|
|
|
|
// BB#3 are defined with with a load matching the MaskN.
|
|
|
|
DEBUG(dbgs() << "Check PHI Insn: "; MII->dump(); dbgs() << '\n');
|
|
|
|
unsigned PrevReg = -1;
|
|
|
|
for (unsigned i = 0; i < MII->getNumOperands(); ++i) {
|
|
|
|
const MachineOperand &MOP = MII->getOperand(i);
|
|
|
|
if (MOP.isReg()) {
|
|
|
|
if (MOP.isDef())
|
|
|
|
continue;
|
|
|
|
PrevReg = MOP.getReg();
|
|
|
|
if (!TargetRegisterInfo::isVirtualRegister(PrevReg))
|
|
|
|
return;
|
|
|
|
if (!checkLoadDef(PrevReg, match_load_op))
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
DEBUG(dbgs() << "Remove the redundant AND operation in: "; Node->dump();
|
|
|
|
dbgs() << '\n');
|
|
|
|
|
|
|
|
I--;
|
|
|
|
CurDAG->ReplaceAllUsesWith(SDValue(Node, 0), BaseV);
|
|
|
|
I++;
|
|
|
|
CurDAG->DeleteNode(Node);
|
|
|
|
}
|
|
|
|
|
|
|
|
bool BPFDAGToDAGISel::checkLoadDef(unsigned DefReg, unsigned match_load_op) {
|
|
|
|
auto it = load_to_vreg_.find(DefReg);
|
|
|
|
if (it == load_to_vreg_.end())
|
|
|
|
return false; // The definition of register is not exported yet.
|
|
|
|
|
|
|
|
return it->second == match_load_op;
|
|
|
|
}
|
|
|
|
|
BPF backend
Summary:
V8->V9:
- cleanup tests
V7->V8:
- addressed feedback from David:
- switched to range-based 'for' loops
- fixed formatting of tests
V6->V7:
- rebased and adjusted AsmPrinter args
- CamelCased .td, fixed formatting, cleaned up names, removed unused patterns
- diffstat: 3 files changed, 203 insertions(+), 227 deletions(-)
V5->V6:
- addressed feedback from Chandler:
- reinstated full verbose standard banner in all files
- fixed variables that were not in CamelCase
- fixed names of #ifdef in header files
- removed redundant braces in if/else chains with single statements
- fixed comments
- removed trailing empty line
- dropped debug annotations from tests
- diffstat of these changes:
46 files changed, 456 insertions(+), 469 deletions(-)
V4->V5:
- fix setLoadExtAction() interface
- clang-formated all where it made sense
V3->V4:
- added CODE_OWNERS entry for BPF backend
V2->V3:
- fix metadata in tests
V1->V2:
- addressed feedback from Tom and Matt
- removed top level change to configure (now everything via 'experimental-backend')
- reworked error reporting via DiagnosticInfo (similar to R600)
- added few more tests
- added cmake build
- added Triple::bpf
- tested on linux and darwin
V1 cover letter:
---------------------
recently linux gained "universal in-kernel virtual machine" which is called
eBPF or extended BPF. The name comes from "Berkeley Packet Filter", since
new instruction set is based on it.
This patch adds a new backend that emits extended BPF instruction set.
The concept and development are covered by the following articles:
http://lwn.net/Articles/599755/
http://lwn.net/Articles/575531/
http://lwn.net/Articles/603983/
http://lwn.net/Articles/606089/
http://lwn.net/Articles/612878/
One of use cases: dtrace/systemtap alternative.
bpf syscall manpage:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b4fc1a460f3017e958e6a8ea560ea0afd91bf6fe
instruction set description and differences vs classic BPF:
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/networking/filter.txt
Short summary of instruction set:
- 64-bit registers
R0 - return value from in-kernel function, and exit value for BPF program
R1 - R5 - arguments from BPF program to in-kernel function
R6 - R9 - callee saved registers that in-kernel function will preserve
R10 - read-only frame pointer to access stack
- two-operand instructions like +, -, *, mov, load/store
- implicit prologue/epilogue (invisible stack pointer)
- no floating point, no simd
Short history of extended BPF in kernel:
interpreter in 3.15, x64 JIT in 3.16, arm64 JIT, verifier, bpf syscall in 3.18, more to come in the future.
It's a very small and simple backend.
There is no support for global variables, arbitrary function calls, floating point, varargs,
exceptions, indirect jumps, arbitrary pointer arithmetic, alloca, etc.
From C front-end point of view it's very restricted. It's done on purpose, since kernel
rejects all programs that it cannot prove safe. It rejects programs with loops
and with memory accesses via arbitrary pointers. When kernel accepts the program it is
guaranteed that program will terminate and will not crash the kernel.
This patch implements all 'must have' bits. There are several things on TODO list,
so this is not the end of development.
Most of the code is a boiler plate code, copy-pasted from other backends.
Only odd things are lack or < and <= instructions, specialized load_byte intrinsics
and 'compare and goto' as single instruction.
Current instruction set is fixed, but more instructions can be added in the future.
Signed-off-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subscribers: majnemer, chandlerc, echristo, joerg, pete, rengolin, kristof.beyls, arsenm, t.p.northover, tstellarAMD, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D6494
llvm-svn: 227008
2015-01-25 01:51:26 +08:00
|
|
|
FunctionPass *llvm::createBPFISelDag(BPFTargetMachine &TM) {
|
|
|
|
return new BPFDAGToDAGISel(TM);
|
|
|
|
}
|