diff options
| author | Menglong Dong <menglong8.dong@gmail.com> | 2025-11-18 20:36:33 +0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-11-24 09:47:03 -0800 |
| commit | ae4a3160d19cd16b874737ebc1798c7bc2fe3c9e (patch) | |
| tree | db40355378fbef4f795f47817669d73141eb294f /kernel | |
| parent | 373f2f44c300815c5f170e89560ac361c0053dfe (diff) | |
bpf: specify the old and new poke_type for bpf_arch_text_poke
In the origin logic, the bpf_arch_text_poke() assume that the old and new
instructions have the same opcode. However, they can have different opcode
if we want to replace a "call" insn with a "jmp" insn.
Therefore, add the new function parameter "old_t" along with the "new_t",
which are used to indicate the old and new poke type. Meanwhile, adjust
the implement of bpf_arch_text_poke() for all the archs.
"BPF_MOD_NOP" is added to make the code more readable. In
bpf_arch_text_poke(), we still check if the new and old address is NULL to
determine if nop insn should be used, which I think is more safe.
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20251118123639.688444-6-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/core.c | 5 | ||||
| -rw-r--r-- | kernel/bpf/trampoline.c | 20 |
2 files changed, 17 insertions, 8 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ef4448f18aad..c8ae6ab31651 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -3150,8 +3150,9 @@ int __weak skb_copy_bits(const struct sk_buff *skb, int offset, void *to, return -EFAULT; } -int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, - void *addr1, void *addr2) +int __weak bpf_arch_text_poke(void *ip, enum bpf_text_poke_type old_t, + enum bpf_text_poke_type new_t, void *old_addr, + void *new_addr) { return -ENOTSUPP; } diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 04104397c432..0230ad19533e 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -183,7 +183,8 @@ static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr) if (tr->func.ftrace_managed) ret = unregister_ftrace_direct(tr->fops, (long)old_addr, false); else - ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL); + ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, BPF_MOD_NOP, + old_addr, NULL); return ret; } @@ -200,7 +201,10 @@ static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_ad else ret = modify_ftrace_direct_nolock(tr->fops, (long)new_addr); } else { - ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr); + ret = bpf_arch_text_poke(ip, + old_addr ? BPF_MOD_CALL : BPF_MOD_NOP, + new_addr ? BPF_MOD_CALL : BPF_MOD_NOP, + old_addr, new_addr); } return ret; } @@ -225,7 +229,8 @@ static int register_fentry(struct bpf_trampoline *tr, void *new_addr) return ret; ret = register_ftrace_direct(tr->fops, (long)new_addr); } else { - ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr); + ret = bpf_arch_text_poke(ip, BPF_MOD_NOP, BPF_MOD_CALL, + NULL, new_addr); } return ret; @@ -336,8 +341,9 @@ static void bpf_tramp_image_put(struct bpf_tramp_image *im) * call_rcu_tasks() is not necessary. */ if (im->ip_after_call) { - int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP, - NULL, im->ip_epilogue); + int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_NOP, + BPF_MOD_JUMP, NULL, + im->ip_epilogue); WARN_ON(err); if (IS_ENABLED(CONFIG_TASKS_RCU)) call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks); @@ -570,7 +576,8 @@ static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, if (err) return err; tr->extension_prog = link->link.prog; - return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL, + return bpf_arch_text_poke(tr->func.addr, BPF_MOD_NOP, + BPF_MOD_JUMP, NULL, link->link.prog->bpf_func); } if (cnt >= BPF_MAX_TRAMP_LINKS) @@ -618,6 +625,7 @@ static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, if (kind == BPF_TRAMP_REPLACE) { WARN_ON_ONCE(!tr->extension_prog); err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, + BPF_MOD_NOP, tr->extension_prog->bpf_func, NULL); tr->extension_prog = NULL; guard(mutex)(&tgt_prog->aux->ext_mutex); |