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net: filter: Just In Time compiler for x86-64 

In order to speedup packet filtering, here is an implementation of a
JIT compiler for x86_64

It is disabled by default, and must be enabled by the admin.

echo 1 >/proc/sys/net/core/bpf_jit_enable

It uses module_alloc() and module_free() to get memory in the 2GB text
kernel range since we call helpers functions from the generated code.

EAX : BPF A accumulator
EBX : BPF X accumulator
RDI : pointer to skb   (first argument given to JIT function)
RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
r9d : skb->len - skb->data_len (headlen)
r8  : skb->data

To get a trace of generated code, use :

echo 2 >/proc/sys/net/core/bpf_jit_enable

Example of generated code :

# tcpdump -p -n -s 0 -i eth1 host 192.168.20.0/24

flen=18 proglen=147 pass=3 image=ffffffffa00b5000
JIT code: ffffffffa00b5000: 55 48 89 e5 48 83 ec 60 48 89 5d f8 44 8b 4f 60
JIT code: ffffffffa00b5010: 44 2b 4f 64 4c 8b 87 b8 00 00 00 be 0c 00 00 00
JIT code: ffffffffa00b5020: e8 24 7b f7 e0 3d 00 08 00 00 75 28 be 1a 00 00
JIT code: ffffffffa00b5030: 00 e8 fe 7a f7 e0 24 00 3d 00 14 a8 c0 74 49 be
JIT code: ffffffffa00b5040: 1e 00 00 00 e8 eb 7a f7 e0 24 00 3d 00 14 a8 c0
JIT code: ffffffffa00b5050: 74 36 eb 3b 3d 06 08 00 00 74 07 3d 35 80 00 00
JIT code: ffffffffa00b5060: 75 2d be 1c 00 00 00 e8 c8 7a f7 e0 24 00 3d 00
JIT code: ffffffffa00b5070: 14 a8 c0 74 13 be 26 00 00 00 e8 b5 7a f7 e0 24
JIT code: ffffffffa00b5080: 00 3d 00 14 a8 c0 75 07 b8 ff ff 00 00 eb 02 31
JIT code: ffffffffa00b5090: c0 c9 c3

BPF program is 144 bytes long, so native program is almost same size ;)

(000) ldh      [12]
(001) jeq      #0x800           jt 2    jf 8
(002) ld       [26]
(003) and      #0xffffff00
(004) jeq      #0xc0a81400      jt 16   jf 5
(005) ld       [30]
(006) and      #0xffffff00
(007) jeq      #0xc0a81400      jt 16   jf 17
(008) jeq      #0x806           jt 10   jf 9
(009) jeq      #0x8035          jt 10   jf 17
(010) ld       [28]
(011) and      #0xffffff00
(012) jeq      #0xc0a81400      jt 16   jf 13
(013) ld       [38]
(014) and      #0xffffff00
(015) jeq      #0xc0a81400      jt 16   jf 17
(016) ret      #65535
(017) ret      #0

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-04-20 09:27:32 +00:00 committed by David S. Miller
parent b678027cb7
commit 0a14842f5a
14 changed files with 918 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
Documentation/sysctl/net.txt
View File

@ -32,6 +32,17 @@ Table : Subdirectories in /proc/sys/net
1. /proc/sys/net/core - Network core options
-------------------------------------------------------
bpf_jit_enable
--------------
This enables Berkeley Packet Filter Just in Time compiler.
Currently supported on x86_64 architecture, bpf_jit provides a framework
to speed packet filtering, the one used by tcpdump/libpcap for example.
Values :
0 - disable the JIT (default value)
1 - enable the JIT
2 - enable the JIT and ask the compiler to emit traces on kernel log.
rmem_default
------------

1
MAINTAINERS
View File

@ -4372,6 +4372,7 @@ S: Maintained
F: net/ipv4/
F: net/ipv6/
F: include/net/ip*
F: arch/x86/net/*
NETWORKING [LABELED] (NetLabel, CIPSO, Labeled IPsec, SECMARK)
M: Paul Moore <paul.moore@hp.com>

1
arch/x86/Kbuild
View File

@ -15,3 +15,4 @@ obj-y += vdso/
obj-$(CONFIG_IA32_EMULATION) += ia32/
obj-y += platform/
obj-y += net/

1
arch/x86/Kconfig
View File

@ -72,6 +72,7 @@ config X86
select IRQ_FORCED_THREADING
select USE_GENERIC_SMP_HELPERS if SMP
select ARCH_NO_SYSDEV_OPS
select HAVE_BPF_JIT if X86_64
config INSTRUCTION_DECODER
def_bool (KPROBES || PERF_EVENTS)

4
arch/x86/net/Makefile Normal file
View File

@ -0,0 +1,4 @@
#
# Arch-specific network modules
#
obj-$(CONFIG_BPF_JIT) += bpf_jit.o bpf_jit_comp.o

140
arch/x86/net/bpf_jit.S Normal file
View File

@ -0,0 +1,140 @@
/* bpf_jit.S : BPF JIT helper functions
*
* Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <linux/linkage.h>
#include <asm/dwarf2.h>
/*
* Calling convention :
* rdi : skb pointer
* esi : offset of byte(s) to fetch in skb (can be scratched)
* r8 : copy of skb->data
* r9d : hlen = skb->len - skb->data_len
*/
#define SKBDATA %r8
sk_load_word_ind:
.globl sk_load_word_ind
add %ebx,%esi /* offset += X */
# test %esi,%esi /* if (offset < 0) goto bpf_error; */
js bpf_error
sk_load_word:
.globl sk_load_word
mov %r9d,%eax # hlen
sub %esi,%eax # hlen - offset
cmp $3,%eax
jle bpf_slow_path_word
mov (SKBDATA,%rsi),%eax
bswap %eax /* ntohl() */
ret
sk_load_half_ind:
.globl sk_load_half_ind
add %ebx,%esi /* offset += X */
js bpf_error
sk_load_half:
.globl sk_load_half
mov %r9d,%eax
sub %esi,%eax # hlen - offset
cmp $1,%eax
jle bpf_slow_path_half
movzwl (SKBDATA,%rsi),%eax
rol $8,%ax # ntohs()
ret
sk_load_byte_ind:
.globl sk_load_byte_ind
add %ebx,%esi /* offset += X */
js bpf_error
sk_load_byte:
.globl sk_load_byte
cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte */
jle bpf_slow_path_byte
movzbl (SKBDATA,%rsi),%eax
ret
/**
* sk_load_byte_msh - BPF_S_LDX_B_MSH helper
*
* Implements BPF_S_LDX_B_MSH : ldxb 4*([offset]&0xf)
* Must preserve A accumulator (%eax)
* Inputs : %esi is the offset value, already known positive
*/
ENTRY(sk_load_byte_msh)
CFI_STARTPROC
cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte_msh */
jle bpf_slow_path_byte_msh
movzbl (SKBDATA,%rsi),%ebx
and $15,%bl
shl $2,%bl
ret
CFI_ENDPROC
ENDPROC(sk_load_byte_msh)
bpf_error:
# force a return 0 from jit handler
xor %eax,%eax
mov -8(%rbp),%rbx
leaveq
ret
/* rsi contains offset and can be scratched */
#define bpf_slow_path_common(LEN) \
push %rdi; /* save skb */ \
push %r9; \
push SKBDATA; \
/* rsi already has offset */ \
mov $LEN,%ecx; /* len */ \
lea -12(%rbp),%rdx; \
call skb_copy_bits; \
test %eax,%eax; \
pop SKBDATA; \
pop %r9; \
pop %rdi
bpf_slow_path_word:
bpf_slow_path_common(4)
js bpf_error
mov -12(%rbp),%eax
bswap %eax
ret
bpf_slow_path_half:
bpf_slow_path_common(2)
js bpf_error
mov -12(%rbp),%ax
rol $8,%ax
movzwl %ax,%eax
ret
bpf_slow_path_byte:
bpf_slow_path_common(1)
js bpf_error
movzbl -12(%rbp),%eax
ret
bpf_slow_path_byte_msh:
xchg %eax,%ebx /* dont lose A , X is about to be scratched */
bpf_slow_path_common(1)
js bpf_error
movzbl -12(%rbp),%eax
and $15,%al
shl $2,%al
xchg %eax,%ebx
ret

654
arch/x86/net/bpf_jit_comp.c Normal file
View File

@ -0,0 +1,654 @@
/* bpf_jit_comp.c : BPF JIT compiler
*
* Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2
* of the License.
*/
#include <linux/moduleloader.h>
#include <asm/cacheflush.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
/*
* Conventions :
* EAX : BPF A accumulator
* EBX : BPF X accumulator
* RDI : pointer to skb (first argument given to JIT function)
* RBP : frame pointer (even if CONFIG_FRAME_POINTER=n)
* ECX,EDX,ESI : scratch registers
* r9d : skb->len - skb->data_len (headlen)
* r8 : skb->data
* -8(RBP) : saved RBX value
* -16(RBP)..-80(RBP) : BPF_MEMWORDS values
*/
int bpf_jit_enable __read_mostly;
/*
* assembly code in arch/x86/net/bpf_jit.S
*/
extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
{
if (len == 1)
*ptr = bytes;
else if (len == 2)
*(u16 *)ptr = bytes;
else {
*(u32 *)ptr = bytes;
barrier();
}
return ptr + len;
}
#define EMIT(bytes, len) do { prog = emit_code(prog, bytes, len); } while (0)
#define EMIT1(b1) EMIT(b1, 1)
#define EMIT2(b1, b2) EMIT((b1) + ((b2) << 8), 2)
#define EMIT3(b1, b2, b3) EMIT((b1) + ((b2) << 8) + ((b3) << 16), 3)
#define EMIT4(b1, b2, b3, b4) EMIT((b1) + ((b2) << 8) + ((b3) << 16) + ((b4) << 24), 4)
#define EMIT1_off32(b1, off) do { EMIT1(b1); EMIT(off, 4);} while (0)
#define CLEAR_A() EMIT2(0x31, 0xc0) /* xor %eax,%eax */
#define CLEAR_X() EMIT2(0x31, 0xdb) /* xor %ebx,%ebx */
static inline bool is_imm8(int value)
{
return value <= 127 && value >= -128;
}
static inline bool is_near(int offset)
{
return offset <= 127 && offset >= -128;
}
#define EMIT_JMP(offset) \
do { \
if (offset) { \
if (is_near(offset)) \
EMIT2(0xeb, offset); /* jmp .+off8 */ \
else \
EMIT1_off32(0xe9, offset); /* jmp .+off32 */ \
} \
} while (0)
/* list of x86 cond jumps opcodes (. + s8)
* Add 0x10 (and an extra 0x0f) to generate far jumps (. + s32)
*/
#define X86_JB 0x72
#define X86_JAE 0x73
#define X86_JE 0x74
#define X86_JNE 0x75
#define X86_JBE 0x76
#define X86_JA 0x77
#define EMIT_COND_JMP(op, offset) \
do { \
if (is_near(offset)) \
EMIT2(op, offset); /* jxx .+off8 */ \
else { \
EMIT2(0x0f, op + 0x10); \
EMIT(offset, 4); /* jxx .+off32 */ \
} \
} while (0)
#define COND_SEL(CODE, TOP, FOP) \
case CODE: \
t_op = TOP; \
f_op = FOP; \
goto cond_branch
#define SEEN_DATAREF 1 /* might call external helpers */
#define SEEN_XREG 2 /* ebx is used */
#define SEEN_MEM 4 /* use mem[] for temporary storage */
static inline void bpf_flush_icache(void *start, void *end)
{
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
smp_wmb();
flush_icache_range((unsigned long)start, (unsigned long)end);
set_fs(old_fs);
}
void bpf_jit_compile(struct sk_filter *fp)
{
u8 temp[64];
u8 *prog;
unsigned int proglen, oldproglen = 0;
int ilen, i;
int t_offset, f_offset;
u8 t_op, f_op, seen = 0, pass;
u8 *image = NULL;
u8 *func;
int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
unsigned int cleanup_addr; /* epilogue code offset */
unsigned int *addrs;
const struct sock_filter *filter = fp->insns;
int flen = fp->len;
if (!bpf_jit_enable)
return;
addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
if (addrs == NULL)
return;
/* Before first pass, make a rough estimation of addrs[]
* each bpf instruction is translated to less than 64 bytes
*/
for (proglen = 0, i = 0; i < flen; i++) {
proglen += 64;
addrs[i] = proglen;
}
cleanup_addr = proglen; /* epilogue address */
for (pass = 0; pass < 10; pass++) {
/* no prologue/epilogue for trivial filters (RET something) */
proglen = 0;
prog = temp;
if (seen) {
EMIT4(0x55, 0x48, 0x89, 0xe5); /* push %rbp; mov %rsp,%rbp */
EMIT4(0x48, 0x83, 0xec, 96); /* subq $96,%rsp */
/* note : must save %rbx in case bpf_error is hit */
if (seen & (SEEN_XREG | SEEN_DATAREF))
EMIT4(0x48, 0x89, 0x5d, 0xf8); /* mov %rbx, -8(%rbp) */
if (seen & SEEN_XREG)
CLEAR_X(); /* make sure we dont leek kernel memory */
/*
* If this filter needs to access skb data,
* loads r9 and r8 with :
* r9 = skb->len - skb->data_len
* r8 = skb->data
*/
if (seen & SEEN_DATAREF) {
if (offsetof(struct sk_buff, len) <= 127)
/* mov off8(%rdi),%r9d */
EMIT4(0x44, 0x8b, 0x4f, offsetof(struct sk_buff, len));
else {
/* mov off32(%rdi),%r9d */
EMIT3(0x44, 0x8b, 0x8f);
EMIT(offsetof(struct sk_buff, len), 4);
}
if (is_imm8(offsetof(struct sk_buff, data_len)))
/* sub off8(%rdi),%r9d */
EMIT4(0x44, 0x2b, 0x4f, offsetof(struct sk_buff, data_len));
else {
EMIT3(0x44, 0x2b, 0x8f);
EMIT(offsetof(struct sk_buff, data_len), 4);
}
if (is_imm8(offsetof(struct sk_buff, data)))
/* mov off8(%rdi),%r8 */
EMIT4(0x4c, 0x8b, 0x47, offsetof(struct sk_buff, data));
else {
/* mov off32(%rdi),%r8 */
EMIT3(0x4c, 0x8b, 0x87);
EMIT(offsetof(struct sk_buff, data), 4);
}
}
}
switch (filter[0].code) {
case BPF_S_RET_K:
case BPF_S_LD_W_LEN:
case BPF_S_ANC_PROTOCOL:
case BPF_S_ANC_IFINDEX:
case BPF_S_ANC_MARK:
case BPF_S_ANC_RXHASH:
case BPF_S_ANC_CPU:
case BPF_S_ANC_QUEUE:
case BPF_S_LD_W_ABS:
case BPF_S_LD_H_ABS:
case BPF_S_LD_B_ABS:
/* first instruction sets A register (or is RET 'constant') */
break;
default:
/* make sure we dont leak kernel information to user */
CLEAR_A(); /* A = 0 */
}
for (i = 0; i < flen; i++) {
unsigned int K = filter[i].k;
switch (filter[i].code) {
case BPF_S_ALU_ADD_X: /* A += X; */
seen |= SEEN_XREG;
EMIT2(0x01, 0xd8); /* add %ebx,%eax */
break;
case BPF_S_ALU_ADD_K: /* A += K; */
if (!K)
break;
if (is_imm8(K))
EMIT3(0x83, 0xc0, K); /* add imm8,%eax */
else
EMIT1_off32(0x05, K); /* add imm32,%eax */
break;
case BPF_S_ALU_SUB_X: /* A -= X; */
seen |= SEEN_XREG;
EMIT2(0x29, 0xd8); /* sub %ebx,%eax */
break;
case BPF_S_ALU_SUB_K: /* A -= K */
if (!K)
break;
if (is_imm8(K))
EMIT3(0x83, 0xe8, K); /* sub imm8,%eax */
else
EMIT1_off32(0x2d, K); /* sub imm32,%eax */
break;
case BPF_S_ALU_MUL_X: /* A *= X; */
seen |= SEEN_XREG;
EMIT3(0x0f, 0xaf, 0xc3); /* imul %ebx,%eax */
break;
case BPF_S_ALU_MUL_K: /* A *= K */
if (is_imm8(K))
EMIT3(0x6b, 0xc0, K); /* imul imm8,%eax,%eax */
else {
EMIT2(0x69, 0xc0); /* imul imm32,%eax */
EMIT(K, 4);
}
break;
case BPF_S_ALU_DIV_X: /* A /= X; */
seen |= SEEN_XREG;
EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
if (pc_ret0 != -1)
EMIT_COND_JMP(X86_JE, addrs[pc_ret0] - (addrs[i] - 4));
else {
EMIT_COND_JMP(X86_JNE, 2 + 5);
CLEAR_A();
EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 4)); /* jmp .+off32 */
}
EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */
break;
case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */
EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */
EMIT(K, 4);
EMIT4(0x48, 0xc1, 0xe8, 0x20); /* shr $0x20,%rax */
break;
case BPF_S_ALU_AND_X:
seen |= SEEN_XREG;
EMIT2(0x21, 0xd8); /* and %ebx,%eax */
break;
case BPF_S_ALU_AND_K:
if (K >= 0xFFFFFF00) {
EMIT2(0x24, K & 0xFF); /* and imm8,%al */
} else if (K >= 0xFFFF0000) {
EMIT2(0x66, 0x25); /* and imm16,%ax */
EMIT2(K, 2);
} else {
EMIT1_off32(0x25, K); /* and imm32,%eax */
}
break;
case BPF_S_ALU_OR_X:
seen |= SEEN_XREG;
EMIT2(0x09, 0xd8); /* or %ebx,%eax */
break;
case BPF_S_ALU_OR_K:
if (is_imm8(K))
EMIT3(0x83, 0xc8, K); /* or imm8,%eax */
else
EMIT1_off32(0x0d, K); /* or imm32,%eax */
break;
case BPF_S_ALU_LSH_X: /* A <<= X; */
seen |= SEEN_XREG;
EMIT4(0x89, 0xd9, 0xd3, 0xe0); /* mov %ebx,%ecx; shl %cl,%eax */
break;
case BPF_S_ALU_LSH_K:
if (K == 0)
break;
else if (K == 1)
EMIT2(0xd1, 0xe0); /* shl %eax */
else
EMIT3(0xc1, 0xe0, K);
break;
case BPF_S_ALU_RSH_X: /* A >>= X; */
seen |= SEEN_XREG;
EMIT4(0x89, 0xd9, 0xd3, 0xe8); /* mov %ebx,%ecx; shr %cl,%eax */
break;
case BPF_S_ALU_RSH_K: /* A >>= K; */
if (K == 0)
break;
else if (K == 1)
EMIT2(0xd1, 0xe8); /* shr %eax */
else
EMIT3(0xc1, 0xe8, K);
break;
case BPF_S_ALU_NEG:
EMIT2(0xf7, 0xd8); /* neg %eax */
break;
case BPF_S_RET_K:
if (!K) {
if (pc_ret0 == -1)
pc_ret0 = i;
CLEAR_A();
} else {
EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
}
/* fallinto */
case BPF_S_RET_A:
if (seen) {
if (i != flen - 1) {
EMIT_JMP(cleanup_addr - addrs[i]);
break;
}
if (seen & SEEN_XREG)
EMIT4(0x48, 0x8b, 0x5d, 0xf8); /* mov -8(%rbp),%rbx */
EMIT1(0xc9); /* leaveq */
}
EMIT1(0xc3); /* ret */
break;
case BPF_S_MISC_TAX: /* X = A */
seen |= SEEN_XREG;
EMIT2(0x89, 0xc3); /* mov %eax,%ebx */
break;
case BPF_S_MISC_TXA: /* A = X */
seen |= SEEN_XREG;
EMIT2(0x89, 0xd8); /* mov %ebx,%eax */
break;
case BPF_S_LD_IMM: /* A = K */
if (!K)
CLEAR_A();
else
EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
break;
case BPF_S_LDX_IMM: /* X = K */
seen |= SEEN_XREG;
if (!K)
CLEAR_X();
else
EMIT1_off32(0xbb, K); /* mov $imm32,%ebx */
break;
case BPF_S_LD_MEM: /* A = mem[K] : mov off8(%rbp),%eax */
seen |= SEEN_MEM;
EMIT3(0x8b, 0x45, 0xf0 - K*4);
break;
case BPF_S_LDX_MEM: /* X = mem[K] : mov off8(%rbp),%ebx */
seen |= SEEN_XREG | SEEN_MEM;
EMIT3(0x8b, 0x5d, 0xf0 - K*4);
break;
case BPF_S_ST: /* mem[K] = A : mov %eax,off8(%rbp) */
seen |= SEEN_MEM;
EMIT3(0x89, 0x45, 0xf0 - K*4);
break;
case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
seen |= SEEN_XREG | SEEN_MEM;
EMIT3(0x89, 0x5d, 0xf0 - K*4);
break;
case BPF_S_LD_W_LEN: /* A = skb->len; */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
if (is_imm8(offsetof(struct sk_buff, len)))
/* mov off8(%rdi),%eax */
EMIT3(0x8b, 0x47, offsetof(struct sk_buff, len));
else {
EMIT2(0x8b, 0x87);
EMIT(offsetof(struct sk_buff, len), 4);
}
break;
case BPF_S_LDX_W_LEN: /* X = skb->len; */
seen |= SEEN_XREG;
if (is_imm8(offsetof(struct sk_buff, len)))
/* mov off8(%rdi),%ebx */
EMIT3(0x8b, 0x5f, offsetof(struct sk_buff, len));
else {
EMIT2(0x8b, 0x9f);
EMIT(offsetof(struct sk_buff, len), 4);
}
break;
case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
if (is_imm8(offsetof(struct sk_buff, protocol))) {
/* movzwl off8(%rdi),%eax */
EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, protocol));
} else {
EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
EMIT(offsetof(struct sk_buff, protocol), 4);
}
EMIT2(0x86, 0xc4); /* ntohs() : xchg %al,%ah */
break;
case BPF_S_ANC_IFINDEX:
if (is_imm8(offsetof(struct sk_buff, dev))) {
/* movq off8(%rdi),%rax */
EMIT4(0x48, 0x8b, 0x47, offsetof(struct sk_buff, dev));
} else {
EMIT3(0x48, 0x8b, 0x87); /* movq off32(%rdi),%rax */
EMIT(offsetof(struct sk_buff, dev), 4);
}
EMIT3(0x48, 0x85, 0xc0); /* test %rax,%rax */
EMIT_COND_JMP(X86_JE, cleanup_addr - (addrs[i] - 6));
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
EMIT2(0x8b, 0x80); /* mov off32(%rax),%eax */
EMIT(offsetof(struct net_device, ifindex), 4);
break;
case BPF_S_ANC_MARK:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
if (is_imm8(offsetof(struct sk_buff, mark))) {
/* mov off8(%rdi),%eax */
EMIT3(0x8b, 0x47, offsetof(struct sk_buff, mark));
} else {
EMIT2(0x8b, 0x87);
EMIT(offsetof(struct sk_buff, mark), 4);
}
break;
case BPF_S_ANC_RXHASH:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
if (is_imm8(offsetof(struct sk_buff, rxhash))) {
/* mov off8(%rdi),%eax */
EMIT3(0x8b, 0x47, offsetof(struct sk_buff, rxhash));
} else {
EMIT2(0x8b, 0x87);
EMIT(offsetof(struct sk_buff, rxhash), 4);
}
break;
case BPF_S_ANC_QUEUE:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
if (is_imm8(offsetof(struct sk_buff, queue_mapping))) {
/* movzwl off8(%rdi),%eax */
EMIT4(0x0f, 0xb7, 0x47, offsetof(struct sk_buff, queue_mapping));
} else {
EMIT3(0x0f, 0xb7, 0x87); /* movzwl off32(%rdi),%eax */
EMIT(offsetof(struct sk_buff, queue_mapping), 4);
}
break;
case BPF_S_ANC_CPU:
#ifdef CONFIG_SMP
EMIT4(0x65, 0x8b, 0x04, 0x25); /* mov %gs:off32,%eax */
EMIT((u32)(unsigned long)&cpu_number, 4); /* A = smp_processor_id(); */
#else
CLEAR_A();
#endif
break;
case BPF_S_LD_W_ABS:
func = sk_load_word;
common_load: seen |= SEEN_DATAREF;
if ((int)K < 0)
goto out;
t_offset = func - (image + addrs[i]);
EMIT1_off32(0xbe, K); /* mov imm32,%esi */
EMIT1_off32(0xe8, t_offset); /* call */
break;
case BPF_S_LD_H_ABS:
func = sk_load_half;
goto common_load;
case BPF_S_LD_B_ABS:
func = sk_load_byte;
goto common_load;
case BPF_S_LDX_B_MSH:
if ((int)K < 0) {
if (pc_ret0 != -1) {
EMIT_JMP(addrs[pc_ret0] - addrs[i]);
break;
}
CLEAR_A();
EMIT_JMP(cleanup_addr - addrs[i]);
break;
}
seen |= SEEN_DATAREF | SEEN_XREG;
t_offset = sk_load_byte_msh - (image + addrs[i]);
EMIT1_off32(0xbe, K); /* mov imm32,%esi */
EMIT1_off32(0xe8, t_offset); /* call sk_load_byte_msh */
break;
case BPF_S_LD_W_IND:
func = sk_load_word_ind;
common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG;
t_offset = func - (image + addrs[i]);
EMIT1_off32(0xbe, K); /* mov imm32,%esi */
EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */
break;
case BPF_S_LD_H_IND:
func = sk_load_half_ind;
goto common_load_ind;
case BPF_S_LD_B_IND:
func = sk_load_byte_ind;
goto common_load_ind;
case BPF_S_JMP_JA:
t_offset = addrs[i + K] - addrs[i];
EMIT_JMP(t_offset);
break;
COND_SEL(BPF_S_JMP_JGT_K, X86_JA, X86_JBE);
COND_SEL(BPF_S_JMP_JGE_K, X86_JAE, X86_JB);
COND_SEL(BPF_S_JMP_JEQ_K, X86_JE, X86_JNE);
COND_SEL(BPF_S_JMP_JSET_K,X86_JNE, X86_JE);
COND_SEL(BPF_S_JMP_JGT_X, X86_JA, X86_JBE);
COND_SEL(BPF_S_JMP_JGE_X, X86_JAE, X86_JB);
COND_SEL(BPF_S_JMP_JEQ_X, X86_JE, X86_JNE);
COND_SEL(BPF_S_JMP_JSET_X,X86_JNE, X86_JE);
cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
t_offset = addrs[i + filter[i].jt] - addrs[i];
/* same targets, can avoid doing the test :) */
if (filter[i].jt == filter[i].jf) {
EMIT_JMP(t_offset);
break;
}
switch (filter[i].code) {
case BPF_S_JMP_JGT_X:
case BPF_S_JMP_JGE_X:
case BPF_S_JMP_JEQ_X:
seen |= SEEN_XREG;
EMIT2(0x39, 0xd8); /* cmp %ebx,%eax */
break;
case BPF_S_JMP_JSET_X:
seen |= SEEN_XREG;
EMIT2(0x85, 0xd8); /* test %ebx,%eax */
break;
case BPF_S_JMP_JEQ_K:
if (K == 0) {
EMIT2(0x85, 0xc0); /* test %eax,%eax */
break;
}
case BPF_S_JMP_JGT_K:
case BPF_S_JMP_JGE_K:
if (K <= 127)
EMIT3(0x83, 0xf8, K); /* cmp imm8,%eax */
else
EMIT1_off32(0x3d, K); /* cmp imm32,%eax */
break;
case BPF_S_JMP_JSET_K:
if (K <= 0xFF)
EMIT2(0xa8, K); /* test imm8,%al */
else if (!(K & 0xFFFF00FF))
EMIT3(0xf6, 0xc4, K >> 8); /* test imm8,%ah */
else if (K <= 0xFFFF) {
EMIT2(0x66, 0xa9); /* test imm16,%ax */
EMIT(K, 2);
} else {
EMIT1_off32(0xa9, K); /* test imm32,%eax */
}
break;
}
if (filter[i].jt != 0) {
if (filter[i].jf)
t_offset += is_near(f_offset) ? 2 : 6;
EMIT_COND_JMP(t_op, t_offset);
if (filter[i].jf)
EMIT_JMP(f_offset);
break;
}
EMIT_COND_JMP(f_op, f_offset);
break;
default:
/* hmm, too complex filter, give up with jit compiler */
goto out;
}
ilen = prog - temp;
if (image) {
if (unlikely(proglen + ilen > oldproglen)) {
pr_err("bpb_jit_compile fatal error\n");
kfree(addrs);
module_free(NULL, image);
return;
}
memcpy(image + proglen, temp, ilen);
}
proglen += ilen;
addrs[i] = proglen;
prog = temp;
}
/* last bpf instruction is always a RET :
* use it to give the cleanup instruction(s) addr
*/
cleanup_addr = proglen - 1; /* ret */
if (seen)
cleanup_addr -= 1; /* leaveq */
if (seen & SEEN_XREG)
cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
if (image) {
WARN_ON(proglen != oldproglen);
break;
}
if (proglen == oldproglen) {
image = module_alloc(max_t(unsigned int,
proglen,
sizeof(struct work_struct)));
if (!image)
goto out;
}
oldproglen = proglen;
}
if (bpf_jit_enable > 1)
pr_err("flen=%d proglen=%u pass=%d image=%p\n",
flen, proglen, pass, image);
if (image) {
if (bpf_jit_enable > 1)
print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
16, 1, image, proglen, false);
bpf_flush_icache(image, image + proglen);
fp->bpf_func = (void *)image;
}
out:
kfree(addrs);
return;
}
static void jit_free_defer(struct work_struct *arg)
{
module_free(NULL, arg);
}
/* run from softirq, we must use a work_struct to call
* module_free() from process context
*/
void bpf_jit_free(struct sk_filter *fp)
{
if (fp->bpf_func != sk_run_filter) {
struct work_struct *work = (struct work_struct *)fp->bpf_func;
INIT_WORK(work, jit_free_defer);
schedule_work(work);
}
}

76
include/linux/filter.h
View File

@ -135,6 +135,8 @@ struct sk_filter
{
atomic_t refcnt;
unsigned int len; /* Number of filter blocks */
unsigned int (*bpf_func)(const struct sk_buff *skb,
const struct sock_filter *filter);
struct rcu_head rcu;
struct sock_filter insns[0];
};
@ -153,6 +155,80 @@ extern unsigned int sk_run_filter(const struct sk_buff *skb,
extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
extern int sk_detach_filter(struct sock *sk);
extern int sk_chk_filter(struct sock_filter *filter, int flen);
#ifdef CONFIG_BPF_JIT
extern void bpf_jit_compile(struct sk_filter *fp);
extern void bpf_jit_free(struct sk_filter *fp);
#define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns)
#else
static inline void bpf_jit_compile(struct sk_filter *fp)
{
}
static inline void bpf_jit_free(struct sk_filter *fp)
{
}
#define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns)
#endif
enum {
BPF_S_RET_K = 1,
BPF_S_RET_A,
BPF_S_ALU_ADD_K,
BPF_S_ALU_ADD_X,
BPF_S_ALU_SUB_K,
BPF_S_ALU_SUB_X,
BPF_S_ALU_MUL_K,
BPF_S_ALU_MUL_X,
BPF_S_ALU_DIV_X,
BPF_S_ALU_AND_K,
BPF_S_ALU_AND_X,
BPF_S_ALU_OR_K,
BPF_S_ALU_OR_X,
BPF_S_ALU_LSH_K,
BPF_S_ALU_LSH_X,
BPF_S_ALU_RSH_K,
BPF_S_ALU_RSH_X,
BPF_S_ALU_NEG,
BPF_S_LD_W_ABS,
BPF_S_LD_H_ABS,
BPF_S_LD_B_ABS,
BPF_S_LD_W_LEN,
BPF_S_LD_W_IND,
BPF_S_LD_H_IND,
BPF_S_LD_B_IND,
BPF_S_LD_IMM,
BPF_S_LDX_W_LEN,
BPF_S_LDX_B_MSH,
BPF_S_LDX_IMM,
BPF_S_MISC_TAX,
BPF_S_MISC_TXA,
BPF_S_ALU_DIV_K,
BPF_S_LD_MEM,
BPF_S_LDX_MEM,
BPF_S_ST,
BPF_S_STX,
BPF_S_JMP_JA,
BPF_S_JMP_JEQ_K,
BPF_S_JMP_JEQ_X,
BPF_S_JMP_JGE_K,
BPF_S_JMP_JGE_X,
BPF_S_JMP_JGT_K,
BPF_S_JMP_JGT_X,
BPF_S_JMP_JSET_K,
BPF_S_JMP_JSET_X,
/* Ancillary data */
BPF_S_ANC_PROTOCOL,
BPF_S_ANC_PKTTYPE,
BPF_S_ANC_IFINDEX,
BPF_S_ANC_NLATTR,
BPF_S_ANC_NLATTR_NEST,
BPF_S_ANC_MARK,
BPF_S_ANC_QUEUE,
BPF_S_ANC_HATYPE,
BPF_S_ANC_RXHASH,
BPF_S_ANC_CPU,
};
#endif /* __KERNEL__ */
#endif /* __LINUX_FILTER_H__ */

1
include/linux/netdevice.h
View File

@ -2514,6 +2514,7 @@ extern struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
extern int netdev_max_backlog;
extern int netdev_tstamp_prequeue;
extern int weight_p;
extern int bpf_jit_enable;
extern int netdev_set_master(struct net_device *dev, struct net_device *master);
extern int netdev_set_bond_master(struct net_device *dev,
struct net_device *master);

2
include/linux/skbuff.h
View File

@ -391,8 +391,8 @@ struct sk_buff {
__u32 rxhash;
__u16 queue_mapping;
kmemcheck_bitfield_begin(flags2);
__u16 queue_mapping:16;
#ifdef CONFIG_IPV6_NDISC_NODETYPE
__u8 ndisc_nodetype:2;
#endif

13
net/Kconfig
View File

@ -232,6 +232,19 @@ config XPS
depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
default y
config HAVE_BPF_JIT
bool
config BPF_JIT
bool "enable BPF Just In Time compiler"
depends on HAVE_BPF_JIT
---help---
Berkeley Packet Filter filtering capabilities are normally handled
by an interpreter. This option allows kernel to generate a native
code when filter is loaded in memory. This should speedup
packet sniffing (libpcap/tcpdump). Note : Admin should enable
this feature changing /proc/sys/net/core/bpf_jit_enable
menu "Network testing"
config NET_PKTGEN

65
net/core/filter.c
View File

@ -39,65 +39,6 @@
#include <linux/filter.h>
#include <linux/reciprocal_div.h>
enum {
BPF_S_RET_K = 1,
BPF_S_RET_A,
BPF_S_ALU_ADD_K,
BPF_S_ALU_ADD_X,
BPF_S_ALU_SUB_K,
BPF_S_ALU_SUB_X,
BPF_S_ALU_MUL_K,
BPF_S_ALU_MUL_X,
BPF_S_ALU_DIV_X,
BPF_S_ALU_AND_K,
BPF_S_ALU_AND_X,
BPF_S_ALU_OR_K,
BPF_S_ALU_OR_X,
BPF_S_ALU_LSH_K,
BPF_S_ALU_LSH_X,
BPF_S_ALU_RSH_K,
BPF_S_ALU_RSH_X,
BPF_S_ALU_NEG,
BPF_S_LD_W_ABS,
BPF_S_LD_H_ABS,
BPF_S_LD_B_ABS,
BPF_S_LD_W_LEN,
BPF_S_LD_W_IND,
BPF_S_LD_H_IND,
BPF_S_LD_B_IND,
BPF_S_LD_IMM,
BPF_S_LDX_W_LEN,
BPF_S_LDX_B_MSH,
BPF_S_LDX_IMM,
BPF_S_MISC_TAX,
BPF_S_MISC_TXA,
BPF_S_ALU_DIV_K,
BPF_S_LD_MEM,
BPF_S_LDX_MEM,
BPF_S_ST,
BPF_S_STX,
BPF_S_JMP_JA,
BPF_S_JMP_JEQ_K,
BPF_S_JMP_JEQ_X,
BPF_S_JMP_JGE_K,
BPF_S_JMP_JGE_X,
BPF_S_JMP_JGT_K,
BPF_S_JMP_JGT_X,
BPF_S_JMP_JSET_K,
BPF_S_JMP_JSET_X,
/* Ancillary data */
BPF_S_ANC_PROTOCOL,
BPF_S_ANC_PKTTYPE,
BPF_S_ANC_IFINDEX,
BPF_S_ANC_NLATTR,
BPF_S_ANC_NLATTR_NEST,
BPF_S_ANC_MARK,
BPF_S_ANC_QUEUE,
BPF_S_ANC_HATYPE,
BPF_S_ANC_RXHASH,
BPF_S_ANC_CPU,
};
/* No hurry in this branch */
static void *__load_pointer(const struct sk_buff *skb, int k, unsigned int size)
{
@ -145,7 +86,7 @@ int sk_filter(struct sock *sk, struct sk_buff *skb)
rcu_read_lock();
filter = rcu_dereference(sk->sk_filter);
if (filter) {
unsigned int pkt_len = sk_run_filter(skb, filter->insns);
unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
}
@ -638,6 +579,7 @@ void sk_filter_release_rcu(struct rcu_head *rcu)
{
struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
bpf_jit_free(fp);
kfree(fp);
}
EXPORT_SYMBOL(sk_filter_release_rcu);
@ -672,6 +614,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
atomic_set(&fp->refcnt, 1);
fp->len = fprog->len;
fp->bpf_func = sk_run_filter;
err = sk_chk_filter(fp->insns, fp->len);
if (err) {
@ -679,6 +622,8 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
return err;
}
bpf_jit_compile(fp);
old_fp = rcu_dereference_protected(sk->sk_filter,
sock_owned_by_user(sk));
rcu_assign_pointer(sk->sk_filter, fp);

9
net/core/sysctl_net_core.c
View File

@ -122,6 +122,15 @@ static struct ctl_table net_core_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
#ifdef CONFIG_BPF_JIT
{
.procname = "bpf_jit_enable",
.data = &bpf_jit_enable,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = proc_dointvec
},
#endif
{
.procname = "netdev_tstamp_prequeue",
.data = &netdev_tstamp_prequeue,

2
net/packet/af_packet.c
View File

@ -538,7 +538,7 @@ static inline unsigned int run_filter(const struct sk_buff *skb,
rcu_read_lock();
filter = rcu_dereference(sk->sk_filter);
if (filter != NULL)
res = sk_run_filter(skb, filter->insns);
res = SK_RUN_FILTER(filter, skb);
rcu_read_unlock();
return res;