diff options
Diffstat (limited to 'arch/x86/net/bpf_jit.S')
| -rw-r--r-- | arch/x86/net/bpf_jit.S | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S new file mode 100644 index 0000000..6687022 --- /dev/null +++ b/arch/x86/net/bpf_jit.S @@ -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 |
