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authorDaniel Borkmann <daniel@iogearbox.net>2019-11-24 03:39:42 +0300
committerAlexei Starovoitov <ast@kernel.org>2019-11-25 04:12:11 +0300
commitb553a6ec570044fc1ae300c6fb24f9ce204c5894 (patch)
tree6121de7c1e38050fd9d4d46480ae6fddf9d585b2 /kernel
parentf9a7cf6eb17cd0110c8c47d9e7969fc2716e5772 (diff)
downloadlinux-b553a6ec570044fc1ae300c6fb24f9ce204c5894.tar.xz
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.c12
-rw-r--r--kernel/bpf/trampoline.c8
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++;