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| author | Alexei Starovoitov <ast@plumgrid.com> | 2014-11-29 14:46:13 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-12-05 21:23:54 -0800 |
| commit | 769e0de6475e5512f88bfb4dbf6d6323fd23514f (patch) | |
| tree | d6a8648b1dcc509a47e47f995159f70bcb0572c6 /arch/x86/net | |
| parent | 6fb2a756739aa507c1fd5b8126f0bfc2f070dc46 (diff) | |
| download | op-kernel-dev-769e0de6475e5512f88bfb4dbf6d6323fd23514f.zip op-kernel-dev-769e0de6475e5512f88bfb4dbf6d6323fd23514f.tar.gz | |
bpf: x86: fix epilogue generation for eBPF programs
classic BPF has a restriction that last insn is always BPF_RET.
eBPF doesn't have BPF_RET instruction and this restriction.
It has BPF_EXIT insn which can appear anywhere in the program
one or more times and it doesn't have to be last insn.
Fix eBPF JIT to emit epilogue when first BPF_EXIT is seen
and all other BPF_EXIT instructions will be emitted as jump.
Since jump offset to epilogue is computed as:
jmp_offset = ctx->cleanup_addr - addrs[i]
we need to change type of cleanup_addr to signed to compute the offset as:
(long long) ((int)20 - (int)30)
instead of:
(long long) ((unsigned int)20 - (int)30)
Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/x86/net')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 3f62734..7e90244 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -178,7 +178,7 @@ static void jit_fill_hole(void *area, unsigned int size) } struct jit_context { - unsigned int cleanup_addr; /* epilogue code offset */ + int cleanup_addr; /* epilogue code offset */ bool seen_ld_abs; }; @@ -192,6 +192,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, struct bpf_insn *insn = bpf_prog->insnsi; int insn_cnt = bpf_prog->len; bool seen_ld_abs = ctx->seen_ld_abs | (oldproglen == 0); + bool seen_exit = false; u8 temp[BPF_MAX_INSN_SIZE + BPF_INSN_SAFETY]; int i; int proglen = 0; @@ -854,10 +855,11 @@ common_load: goto common_load; case BPF_JMP | BPF_EXIT: - if (i != insn_cnt - 1) { + if (seen_exit) { jmp_offset = ctx->cleanup_addr - addrs[i]; goto emit_jmp; } + seen_exit = true; /* update cleanup_addr */ ctx->cleanup_addr = proglen; /* mov rbx, qword ptr [rbp-X] */ |
