From b553a6ec570044fc1ae300c6fb24f9ce204c5894 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Sun, 24 Nov 2019 01:39:42 +0100 Subject: 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 Signed-off-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/fcb00a2b0b288d6c73de4ef58116a821c8fe8f2f.1574555798.git.daniel@iogearbox.net --- kernel/bpf/arraymap.c | 12 +----------- kernel/bpf/trampoline.c | 8 ++++---- 2 files changed, 5 insertions(+), 15 deletions(-) (limited to 'kernel') 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++; -- cgit v1.2.3-59-g8ed1b