diff options
author | Daniel Borkmann <daniel@iogearbox.net> | 2019-11-24 01:39:42 +0100 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2019-11-24 17:12:11 -0800 |
commit | b553a6ec570044fc1ae300c6fb24f9ce204c5894 (patch) | |
tree | 6121de7c1e38050fd9d4d46480ae6fddf9d585b2 /arch | |
parent | f9a7cf6eb17cd0110c8c47d9e7969fc2716e5772 (diff) | |
download | linux-b553a6ec570044fc1ae300c6fb24f9ce204c5894.tar.bz2 |
bpf: Simplify __bpf_arch_text_poke poke type handling
Given that we have BPF_MOD_NOP_TO_{CALL,JUMP}, BPF_MOD_{CALL,JUMP}_TO_NOP
and BPF_MOD_{CALL,JUMP}_TO_{CALL,JUMP} poke types and that we also pass in
old_addr as well as new_addr, it's a bit redundant and unnecessarily
complicates __bpf_arch_text_poke() itself since we can derive the same from
the *_addr that were passed in. Hence simplify and use BPF_MOD_{CALL,JUMP}
as types which also allows to clean up call-sites.
In addition to that, __bpf_arch_text_poke() currently verifies that text
matches expected old_insn before we invoke text_poke_bp(). Also add a check
on new_insn and skip rewrite if it already matches. Reason why this is rather
useful is that it avoids making any special casing in prog_array_map_poke_run()
when old and new prog were NULL and has the benefit that also for this case
we perform a check on text whether it really matches our expectations.
Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/fcb00a2b0b288d6c73de4ef58116a821c8fe8f2f.1574555798.git.daniel@iogearbox.net
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 85 |
1 files changed, 25 insertions, 60 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 15615c94804f..b8be18427277 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -269,76 +269,42 @@ static int __bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *old_addr, void *new_addr, const bool text_live) { - int (*emit_patch_fn)(u8 **pprog, void *func, void *ip); const u8 *nop_insn = ideal_nops[NOP_ATOMIC5]; - u8 old_insn[X86_PATCH_SIZE] = {}; - u8 new_insn[X86_PATCH_SIZE] = {}; + u8 old_insn[X86_PATCH_SIZE]; + u8 new_insn[X86_PATCH_SIZE]; u8 *prog; int ret; - switch (t) { - case BPF_MOD_NOP_TO_CALL ... BPF_MOD_CALL_TO_NOP: - emit_patch_fn = emit_call; - break; - case BPF_MOD_NOP_TO_JUMP ... BPF_MOD_JUMP_TO_NOP: - emit_patch_fn = emit_jump; - break; - default: - return -ENOTSUPP; + memcpy(old_insn, nop_insn, X86_PATCH_SIZE); + if (old_addr) { + prog = old_insn; + ret = t == BPF_MOD_CALL ? + emit_call(&prog, old_addr, ip) : + emit_jump(&prog, old_addr, ip); + if (ret) + return ret; } - switch (t) { - case BPF_MOD_NOP_TO_CALL: - case BPF_MOD_NOP_TO_JUMP: - if (!old_addr && new_addr) { - memcpy(old_insn, nop_insn, X86_PATCH_SIZE); - - prog = new_insn; - ret = emit_patch_fn(&prog, new_addr, ip); - if (ret) - return ret; - break; - } - return -ENXIO; - case BPF_MOD_CALL_TO_CALL: - case BPF_MOD_JUMP_TO_JUMP: - if (old_addr && new_addr) { - prog = old_insn; - ret = emit_patch_fn(&prog, old_addr, ip); - if (ret) - return ret; - - prog = new_insn; - ret = emit_patch_fn(&prog, new_addr, ip); - if (ret) - return ret; - break; - } - return -ENXIO; - case BPF_MOD_CALL_TO_NOP: - case BPF_MOD_JUMP_TO_NOP: - if (old_addr && !new_addr) { - memcpy(new_insn, nop_insn, X86_PATCH_SIZE); - - prog = old_insn; - ret = emit_patch_fn(&prog, old_addr, ip); - if (ret) - return ret; - break; - } - return -ENXIO; - default: - return -ENOTSUPP; + memcpy(new_insn, nop_insn, X86_PATCH_SIZE); + if (new_addr) { + prog = new_insn; + ret = t == BPF_MOD_CALL ? + emit_call(&prog, new_addr, ip) : + emit_jump(&prog, new_addr, ip); + if (ret) + return ret; } ret = -EBUSY; mutex_lock(&text_mutex); if (memcmp(ip, old_insn, X86_PATCH_SIZE)) goto out; - if (text_live) - text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL); - else - memcpy(ip, new_insn, X86_PATCH_SIZE); + if (memcmp(ip, new_insn, X86_PATCH_SIZE)) { + if (text_live) + text_poke_bp(ip, new_insn, X86_PATCH_SIZE, NULL); + else + memcpy(ip, new_insn, X86_PATCH_SIZE); + } ret = 0; out: mutex_unlock(&text_mutex); @@ -465,7 +431,6 @@ static void emit_bpf_tail_call_direct(struct bpf_jit_poke_descriptor *poke, static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) { - static const enum bpf_text_poke_type type = BPF_MOD_NOP_TO_JUMP; struct bpf_jit_poke_descriptor *poke; struct bpf_array *array; struct bpf_prog *target; @@ -490,7 +455,7 @@ static void bpf_tail_call_direct_fixup(struct bpf_prog *prog) * read-only. Both modifications on the given image * are under text_mutex to avoid interference. */ - ret = __bpf_arch_text_poke(poke->ip, type, NULL, + ret = __bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, NULL, (u8 *)target->bpf_func + poke->adj_off, false); BUG_ON(ret < 0); |