diff options
| -rw-r--r-- | arch/x86/net/bpf_jit.S | 122 | ||||
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 41 |
2 files changed, 115 insertions, 48 deletions
diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S index 6687022..877b9a1 100644 --- a/arch/x86/net/bpf_jit.S +++ b/arch/x86/net/bpf_jit.S @@ -18,17 +18,17 @@ * 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 +#define SKF_MAX_NEG_OFF $(-0x200000) /* SKF_LL_OFF from filter.h */ sk_load_word: .globl sk_load_word + test %esi,%esi + js bpf_slow_path_word_neg + +sk_load_word_positive_offset: + .globl sk_load_word_positive_offset + mov %r9d,%eax # hlen sub %esi,%eax # hlen - offset cmp $3,%eax @@ -37,16 +37,15 @@ sk_load_word: 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 + test %esi,%esi + js bpf_slow_path_half_neg + +sk_load_half_positive_offset: + .globl sk_load_half_positive_offset + mov %r9d,%eax sub %esi,%eax # hlen - offset cmp $1,%eax @@ -55,14 +54,15 @@ sk_load_half: 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 + test %esi,%esi + js bpf_slow_path_byte_neg + +sk_load_byte_positive_offset: + .globl sk_load_byte_positive_offset + cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte */ jle bpf_slow_path_byte movzbl (SKBDATA,%rsi),%eax @@ -73,25 +73,21 @@ sk_load_byte: * * Implements BPF_S_LDX_B_MSH : ldxb 4*([offset]&0xf) * Must preserve A accumulator (%eax) - * Inputs : %esi is the offset value, already known positive + * Inputs : %esi is the offset value */ -ENTRY(sk_load_byte_msh) - CFI_STARTPROC +sk_load_byte_msh: + .globl sk_load_byte_msh + test %esi,%esi + js bpf_slow_path_byte_msh_neg + +sk_load_byte_msh_positive_offset: + .globl sk_load_byte_msh_positive_offset 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) \ @@ -138,3 +134,67 @@ bpf_slow_path_byte_msh: shl $2,%al xchg %eax,%ebx ret + +#define sk_negative_common(SIZE) \ + push %rdi; /* save skb */ \ + push %r9; \ + push SKBDATA; \ +/* rsi already has offset */ \ + mov $SIZE,%ecx; /* size */ \ + call bpf_internal_load_pointer_neg_helper; \ + test %rax,%rax; \ + pop SKBDATA; \ + pop %r9; \ + pop %rdi; \ + jz bpf_error + + +bpf_slow_path_word_neg: + cmp SKF_MAX_NEG_OFF, %esi /* test range */ + jl bpf_error /* offset lower -> error */ +sk_load_word_negative_offset: + .globl sk_load_word_negative_offset + sk_negative_common(4) + mov (%rax), %eax + bswap %eax + ret + +bpf_slow_path_half_neg: + cmp SKF_MAX_NEG_OFF, %esi + jl bpf_error +sk_load_half_negative_offset: + .globl sk_load_half_negative_offset + sk_negative_common(2) + mov (%rax),%ax + rol $8,%ax + movzwl %ax,%eax + ret + +bpf_slow_path_byte_neg: + cmp SKF_MAX_NEG_OFF, %esi + jl bpf_error +sk_load_byte_negative_offset: + .globl sk_load_byte_negative_offset + sk_negative_common(1) + movzbl (%rax), %eax + ret + +bpf_slow_path_byte_msh_neg: + cmp SKF_MAX_NEG_OFF, %esi + jl bpf_error +sk_load_byte_msh_negative_offset: + .globl sk_load_byte_msh_negative_offset + xchg %eax,%ebx /* dont lose A , X is about to be scratched */ + sk_negative_common(1) + movzbl (%rax),%eax + and $15,%al + shl $2,%al + xchg %eax,%ebx + ret + +bpf_error: +# force a return 0 from jit handler + xor %eax,%eax + mov -8(%rbp),%rbx + leaveq + ret diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 5a5b6e4..0597f95 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -30,7 +30,10 @@ 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[]; +extern u8 sk_load_word_positive_offset[], sk_load_half_positive_offset[]; +extern u8 sk_load_byte_positive_offset[], sk_load_byte_msh_positive_offset[]; +extern u8 sk_load_word_negative_offset[], sk_load_half_negative_offset[]; +extern u8 sk_load_byte_negative_offset[], sk_load_byte_msh_negative_offset[]; static inline u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len) { @@ -117,6 +120,8 @@ static inline void bpf_flush_icache(void *start, void *end) set_fs(old_fs); } +#define CHOOSE_LOAD_FUNC(K, func) \ + ((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset) void bpf_jit_compile(struct sk_filter *fp) { @@ -473,44 +478,46 @@ void bpf_jit_compile(struct sk_filter *fp) #endif break; case BPF_S_LD_W_ABS: - func = sk_load_word; + func = CHOOSE_LOAD_FUNC(K, sk_load_word); common_load: seen |= SEEN_DATAREF; - if ((int)K < 0) { - /* Abort the JIT because __load_pointer() is needed. */ - 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; + func = CHOOSE_LOAD_FUNC(K, sk_load_half); goto common_load; case BPF_S_LD_B_ABS: - func = sk_load_byte; + func = CHOOSE_LOAD_FUNC(K, sk_load_byte); goto common_load; case BPF_S_LDX_B_MSH: - if ((int)K < 0) { - /* Abort the JIT because __load_pointer() is needed. */ - goto out; - } + func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh); seen |= SEEN_DATAREF | SEEN_XREG; - t_offset = sk_load_byte_msh - (image + addrs[i]); + t_offset = func - (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; + func = sk_load_word; common_load_ind: seen |= SEEN_DATAREF | SEEN_XREG; t_offset = func - (image + addrs[i]); - EMIT1_off32(0xbe, K); /* mov imm32,%esi */ + if (K) { + if (is_imm8(K)) { + EMIT3(0x8d, 0x73, K); /* lea imm8(%rbx), %esi */ + } else { + EMIT2(0x8d, 0xb3); /* lea imm32(%rbx),%esi */ + EMIT(K, 4); + } + } else { + EMIT2(0x89,0xde); /* mov %ebx,%esi */ + } EMIT1_off32(0xe8, t_offset); /* call sk_load_xxx_ind */ break; case BPF_S_LD_H_IND: - func = sk_load_half_ind; + func = sk_load_half; goto common_load_ind; case BPF_S_LD_B_IND: - func = sk_load_byte_ind; + func = sk_load_byte; goto common_load_ind; case BPF_S_JMP_JA: t_offset = addrs[i + K] - addrs[i]; |
