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[bpf] error when unknown bpf helper is called 

Emit error when BPF backend sees a call to a global function or to an external symbol.
The kernel verifier only allows calls to predefined helpers from bpf.h
which are defined in 'enum bpf_func_id'. Such calls in assembler must
look like 'call [1-9]+' where number matches bpf_func_id.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
llvm-svn: 292204
This commit is contained in:
Alexei Starovoitov 2017-01-17 07:26:17 +00:00
parent c0857a40e7
commit e4975487f5
14 changed files with 107 additions and 21 deletions
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18
llvm/lib/Target/BPF/BPFISelLowering.cpp
View File

@ -33,7 +33,7 @@ using namespace llvm;
#define DEBUG_TYPE "bpf-lower"
static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *Msg) {
static void fail(const SDLoc &DL, SelectionDAG &DAG, const Twine &Msg) {
MachineFunction &MF = DAG.getMachineFunction();
DAG.getContext()->diagnose(
DiagnosticInfoUnsupported(*MF.getFunction(), Msg, DL.getDebugLoc()));
@ -306,11 +306,23 @@ SDValue BPFTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
// If the callee is a GlobalAddress node (quite common, every direct call is)
// turn it into a TargetGlobalAddress node so that legalize doesn't hack it.
// Likewise ExternalSymbol -> TargetExternalSymbol.
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee))
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
auto GV = G->getGlobal();
Twine Msg("A call to global function '" + StringRef(GV->getName())
+ "' is not supported. "
+ (GV->isDeclaration() ?
"Only calls to predefined BPF helpers are allowed." :
"Please use __attribute__((always_inline) to make sure"
" this function is inlined."));
fail(CLI.DL, DAG, Msg);
Callee = DAG.getTargetGlobalAddress(G->getGlobal(), CLI.DL, PtrVT,
G->getOffset(), 0);
else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee))
} else if (ExternalSymbolSDNode *E = dyn_cast<ExternalSymbolSDNode>(Callee)) {
Callee = DAG.getTargetExternalSymbol(E->getSymbol(), PtrVT, 0);
fail(CLI.DL, DAG, Twine("A call to built-in function '"
+ StringRef(E->getSymbol())
+ "' is not supported."));
}
// Returns a chain & a flag for retval copy to use.
SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);

1
llvm/lib/Target/BPF/BPFInstrInfo.td
View File

@ -470,6 +470,7 @@ def : Pat<(i64 (and (i64 GPR:$src), 0xffffFFFF)),
// Calls
def : Pat<(BPFcall tglobaladdr:$dst), (JAL tglobaladdr:$dst)>;
def : Pat<(BPFcall texternalsym:$dst), (JAL texternalsym:$dst)>;
def : Pat<(BPFcall imm:$dst), (JAL imm:$dst)>;
// Loads

8
llvm/lib/Target/BPF/BPFMCInstLower.cpp
View File

@ -29,6 +29,11 @@ BPFMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
return Printer.getSymbol(MO.getGlobal());
}
MCSymbol *
BPFMCInstLower::GetExternalSymbolSymbol(const MachineOperand &MO) const {
return Printer.GetExternalSymbolSymbol(MO.getSymbolName());
}
MCOperand BPFMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
MCSymbol *Sym) const {
@ -66,6 +71,9 @@ void BPFMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
break;
case MachineOperand::MO_RegisterMask:
continue;
case MachineOperand::MO_ExternalSymbol:
MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
break;
case MachineOperand::MO_GlobalAddress:
MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
break;

1
llvm/lib/Target/BPF/BPFMCInstLower.h
View File

@ -37,6 +37,7 @@ public:
MCOperand LowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym) const;
MCSymbol *GetGlobalAddressSymbol(const MachineOperand &MO) const;
MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
};
}

2
llvm/test/CodeGen/BPF/cc_args.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpfel -show-mc-encoding | FileCheck %s
; RUN: not llc < %s -march=bpfel -show-mc-encoding | FileCheck %s
define void @test() #0 {
entry:

2
llvm/test/CodeGen/BPF/cc_args_be.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpfeb -show-mc-encoding | FileCheck %s
; RUN: not llc < %s -march=bpfeb -show-mc-encoding | FileCheck %s
; test big endian
define void @test() #0 {

2
llvm/test/CodeGen/BPF/cc_ret.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpfel | FileCheck %s
; RUN: not llc < %s -march=bpfel | FileCheck %s
define void @test() #0 {
entry:

2
llvm/test/CodeGen/BPF/fi_ri.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpf | FileCheck %s
; RUN: not llc < %s -march=bpf | FileCheck %s
%struct.key_t = type { i32, [16 x i8] }

4
llvm/test/CodeGen/BPF/intrinsics.ll
View File

@ -52,14 +52,12 @@ declare i64 @llvm.bpf.load.word(i8*, i64) #1
define i32 @ld_pseudo() #0 {
entry:
%call = tail call i64 @llvm.bpf.pseudo(i64 2, i64 3)
tail call void @bar(i64 %call, i32 4) #2
tail call void inttoptr (i64 4 to void (i64, i32)*)(i64 %call, i32 4) #2
ret i32 0
; CHECK-LABEL: ld_pseudo:
; CHECK: ld_pseudo r1, 2, 3 # encoding: [0x18,0x21,0x00,0x00,0x03,0x00
}
declare void @bar(i64, i32) #1
declare i64 @llvm.bpf.pseudo(i64, i64) #2
define i32 @bswap(i64 %a, i64 %b, i64 %c) #0 {

4
llvm/test/CodeGen/BPF/objdump_intrinsics.ll
View File

@ -52,14 +52,12 @@ declare i64 @llvm.bpf.load.word(i8*, i64) #1
define i32 @ld_pseudo() #0 {
entry:
%call = tail call i64 @llvm.bpf.pseudo(i64 2, i64 3)
tail call void @bar(i64 %call, i32 4) #2
tail call void inttoptr (i64 4 to void (i64, i32)*)(i64 %call, i32 4) #2
ret i32 0
; CHECK-LABEL: ld_pseudo:
; CHECK: ld_pseudo r1, 2, 3
}
declare void @bar(i64, i32) #1
declare i64 @llvm.bpf.pseudo(i64, i64) #2
define i32 @bswap(i64 %a, i64 %b, i64 %c) #0 {

11
llvm/test/CodeGen/BPF/objdump_trivial.ll
View File

@ -1,19 +1,18 @@
; RUN: llc -march=bpfel -filetype=obj -o - %s | llvm-objdump -d - | FileCheck %s
; CHECK: if r2 s> r1 goto
; CHECK: call
; CHECK: call 1
; CHECK: exit
; CHECK: call 2
; CHECK: exit
declare void @a()
declare void @b()
define void @foo(i32 %a) {
%b = icmp sgt i32 %a, -1
br i1 %b, label %x, label %y
x:
call void @a()
call void inttoptr (i64 1 to void ()*)()
ret void
y:
call void @b()
call void inttoptr (i64 2 to void ()*)()
ret void
}

2
llvm/test/CodeGen/BPF/sanity.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpfel | FileCheck %s
; RUN: not llc < %s -march=bpfel | FileCheck %s
@foo_printf.fmt = private unnamed_addr constant [9 x i8] c"hello \0A\00", align 1

2
llvm/test/CodeGen/BPF/undef.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -march=bpf | FileCheck %s
; RUN: not llc < %s -march=bpf | FileCheck %s
%struct.bpf_map_def = type { i32, i32, i32, i32 }
%struct.__sk_buff = type opaque

69
llvm/test/CodeGen/BPF/warn-call.ll Normal file
View File

@ -0,0 +1,69 @@
; RUN: not llc -march=bpfel < %s 2>&1 >/dev/null | FileCheck %s
; CHECK: error: warn_call.c
; CHECK: built-in function 'memcpy'
; CHECK: error: warn_call.c
; CHECK: global function 'foo'
; CHECK: global function 'bar'
define i8* @warn(i8* returned, i8*, i64) local_unnamed_addr #0 !dbg !6 {
tail call void @llvm.dbg.value(metadata i8* %0, i64 0, metadata !14, metadata !17), !dbg !18
tail call void @llvm.dbg.value(metadata i8* %1, i64 0, metadata !15, metadata !17), !dbg !19
tail call void @llvm.dbg.value(metadata i64 %2, i64 0, metadata !16, metadata !17), !dbg !20
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %0, i8* %1, i64 %2, i32 1, i1 false), !dbg !21
%4 = tail call i8* @foo(i8* %0, i8* %1, i64 %2) #5, !dbg !22
%5 = tail call fastcc i8* @bar(i8* %0), !dbg !23
ret i8* %5, !dbg !24
}
; Function Attrs: argmemonly nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1) #1
declare i8* @foo(i8*, i8*, i64) local_unnamed_addr #2
; Function Attrs: noinline nounwind readnone
define internal fastcc i8* @bar(i8* readnone returned) unnamed_addr #3 !dbg !25 {
tail call void @llvm.dbg.value(metadata i8* null, i64 0, metadata !28, metadata !17), !dbg !30
tail call void @llvm.dbg.value(metadata i64 0, i64 0, metadata !29, metadata !17), !dbg !31
ret i8* %0, !dbg !32
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #4
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!llvm.ident = !{!5}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 5.0.0 (trunk 292174) (llvm/trunk 292179)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "warn_call.c", directory: "/w/llvm/bld")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{!"clang version 5.0.0 (trunk 292174) (llvm/trunk 292179)"}
!6 = distinct !DISubprogram(name: "warn", scope: !1, file: !1, line: 4, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !13)
!7 = !DISubroutineType(types: !8)
!8 = !{!9, !9, !10, !12}
!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
!11 = !DIDerivedType(tag: DW_TAG_const_type, baseType: null)
!12 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned)
!13 = !{!14, !15, !16}
!14 = !DILocalVariable(name: "dst", arg: 1, scope: !6, file: !1, line: 4, type: !9)
!15 = !DILocalVariable(name: "src", arg: 2, scope: !6, file: !1, line: 4, type: !10)
!16 = !DILocalVariable(name: "len", arg: 3, scope: !6, file: !1, line: 4, type: !12)
!17 = !DIExpression()
!18 = !DILocation(line: 4, column: 18, scope: !6)
!19 = !DILocation(line: 4, column: 35, scope: !6)
!20 = !DILocation(line: 4, column: 54, scope: !6)
!21 = !DILocation(line: 6, column: 2, scope: !6)
!22 = !DILocation(line: 7, column: 2, scope: !6)
!23 = !DILocation(line: 8, column: 9, scope: !6)
!24 = !DILocation(line: 8, column: 2, scope: !6)
!25 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 2, type: !7, isLocal: true, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !26)
!26 = !{!27, !28, !29}
!27 = !DILocalVariable(name: "dst", arg: 1, scope: !25, file: !1, line: 2, type: !9)
!28 = !DILocalVariable(name: "src", arg: 2, scope: !25, file: !1, line: 2, type: !10)
!29 = !DILocalVariable(name: "len", arg: 3, scope: !25, file: !1, line: 2, type: !12)
!30 = !DILocation(line: 2, column: 67, scope: !25)
!31 = !DILocation(line: 2, column: 86, scope: !25)
!32 = !DILocation(line: 2, column: 93, scope: !25)