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 /kernel | |
| parent | bpf: Introduce BPF_TRACE_x helper for the tracing tests (diff) | |
| download | linux-dev-b553a6ec570044fc1ae300c6fb24f9ce204c5894.tar.xz linux-dev-b553a6ec570044fc1ae300c6fb24f9ce204c5894.zip | |
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 'kernel')
| -rw-r--r-- | kernel/bpf/arraymap.c | 12 | ||||
| -rw-r--r-- | kernel/bpf/trampoline.c | 8 |
2 files changed, 5 insertions, 15 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 58bdf5fd24cc..f0d19bbb9211 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -746,19 +746,9 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, struct bpf_prog *old, struct bpf_prog *new) { - enum bpf_text_poke_type type; struct prog_poke_elem *elem; struct bpf_array_aux *aux; - if (!old && new) - type = BPF_MOD_NOP_TO_JUMP; - else if (old && !new) - type = BPF_MOD_JUMP_TO_NOP; - else if (old && new) - type = BPF_MOD_JUMP_TO_JUMP; - else - return; - aux = container_of(map, struct bpf_array, map)->aux; WARN_ON_ONCE(!mutex_is_locked(&aux->poke_mutex)); @@ -806,7 +796,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, poke->tail_call.key != key) continue; - ret = bpf_arch_text_poke(poke->ip, type, + ret = bpf_arch_text_poke(poke->ip, BPF_MOD_JUMP, old ? (u8 *)old->bpf_func + poke->adj_off : NULL, new ? (u8 *)new->bpf_func + diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 10ae59d65f13..7e89f1f49d77 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -77,7 +77,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) int err; if (fentry_cnt + fexit_cnt == 0) { - err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL_TO_NOP, + err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL, old_image, NULL); tr->selector = 0; goto out; @@ -105,12 +105,12 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr) if (tr->selector) /* progs already running at this address */ - err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL_TO_CALL, + err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL, old_image, new_image); else /* first time registering */ - err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP_TO_CALL, - NULL, new_image); + err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_CALL, NULL, + new_image); if (err) goto out; tr->selector++; |