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authorAlexei Starovoitov <ast@plumgrid.com>2014-11-30 01:46:13 +0300
committerDavid S. Miller <davem@davemloft.net>2014-12-06 08:23:54 +0300
commit769e0de6475e5512f88bfb4dbf6d6323fd23514f (patch)
treed6a8648b1dcc509a47e47f995159f70bcb0572c6 /arch/x86/net
parent6fb2a756739aa507c1fd5b8126f0bfc2f070dc46 (diff)
downloadlinux-769e0de6475e5512f88bfb4dbf6d6323fd23514f.tar.xz
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.c6
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 3f627345d51c..7e90244c84e3 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] */