diff options
Diffstat (limited to 'arch/x86/net/bpf_jit.S')
| -rw-r--r-- | arch/x86/net/bpf_jit.S | 143 |
1 files changed, 81 insertions, 62 deletions
diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S index 66870223f8c..6440221ced0 100644 --- a/arch/x86/net/bpf_jit.S +++ b/arch/x86/net/bpf_jit.S @@ -12,23 +12,26 @@ /* * Calling convention : - * rdi : skb pointer + * rbx : skb pointer (callee saved) * esi : offset of byte(s) to fetch in skb (can be scratched) - * r8 : copy of skb->data + * r10 : 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 +#define SKBDATA %r10 +#define SKF_MAX_NEG_OFF $(-0x200000) /* SKF_LL_OFF from filter.h */ +#define MAX_BPF_STACK (512 /* from filter.h */ + \ + 32 /* space for rbx,r13,r14,r15 */ + \ + 8 /* space for skb_copy_bits */) 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 +40,15 @@ 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 @@ -55,70 +57,45 @@ 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 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 */ \ + mov %rbx, %rdi; /* arg1 == skb */ \ push %r9; \ push SKBDATA; \ /* rsi already has offset */ \ mov $LEN,%ecx; /* len */ \ - lea -12(%rbp),%rdx; \ + lea - MAX_BPF_STACK + 32(%rbp),%rdx; \ call skb_copy_bits; \ test %eax,%eax; \ pop SKBDATA; \ - pop %r9; \ - pop %rdi + pop %r9; bpf_slow_path_word: bpf_slow_path_common(4) js bpf_error - mov -12(%rbp),%eax + mov - MAX_BPF_STACK + 32(%rbp),%eax bswap %eax ret bpf_slow_path_half: bpf_slow_path_common(2) js bpf_error - mov -12(%rbp),%ax + mov - MAX_BPF_STACK + 32(%rbp),%ax rol $8,%ax movzwl %ax,%eax ret @@ -126,15 +103,57 @@ bpf_slow_path_half: bpf_slow_path_byte: bpf_slow_path_common(1) js bpf_error - movzbl -12(%rbp),%eax + movzbl - MAX_BPF_STACK + 32(%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 +#define sk_negative_common(SIZE) \ + mov %rbx, %rdi; /* arg1 == skb */ \ + push %r9; \ + push SKBDATA; \ +/* rsi already has offset */ \ + mov $SIZE,%edx; /* size */ \ + call bpf_internal_load_pointer_neg_helper; \ + test %rax,%rax; \ + pop SKBDATA; \ + pop %r9; \ + 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_error: +# force a return 0 from jit handler + xor %eax,%eax + mov - MAX_BPF_STACK(%rbp),%rbx + mov - MAX_BPF_STACK + 8(%rbp),%r13 + mov - MAX_BPF_STACK + 16(%rbp),%r14 + mov - MAX_BPF_STACK + 24(%rbp),%r15 + leaveq ret |