From: Ihor Solodrai <ihor.solodrai@linux.dev>
To: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Amery Hung <ameryhung@gmail.com>,
Emil Tsalapatis <emil@etsalapatis.com>,
Nicholas Carlini <npc@anthropic.com>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com
Subject: [PATCH bpf-next v1 2/2] bpf: Rely on callback frame initialization defaults
Date: Fri, 6 Nov 2026 16:21:10 -0700 [thread overview]
Message-ID: <20261106232110.2867412-2-ihor.solodrai@linux.dev> (raw)
In-Reply-To: <20261106232110.2867412-1-ihor.solodrai@linux.dev>
Both callback entry paths call init_func_state(), which initializes all
registers to NOT_INIT and the callback return range to zero.
Callback setters repeat resets for unused registers, and the timer setter
repeats the default return range. Leave those defaults to frame
initialization and set only arguments and callback-specific state in the
setters.
No functional change.
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
kernel/bpf/verifier.c | 31 -------------------------------
1 file changed, 31 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 389488e4e7a7..831a9c0f8c45 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11985,9 +11985,6 @@ int map_set_for_each_callback_args(struct bpf_verifier_env *env,
/* pointer to stack or null */
callee->regs[BPF_REG_4] = caller->regs[BPF_REG_3];
-
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
return 0;
}
@@ -12056,11 +12053,6 @@ static int set_loop_callback_state(struct bpf_verifier_env *env,
callee->regs[BPF_REG_1].type = SCALAR_VALUE;
callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
-
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
@@ -12079,11 +12071,7 @@ static int set_timer_callback_state(struct bpf_verifier_env *env,
mark_map_callback_reg(&callee->regs[BPF_REG_3], &caller->regs[BPF_REG_1], PTR_TO_MAP_VALUE);
callee->regs[BPF_REG_3].id = ++env->id_gen;
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_async_callback_fn = true;
- callee->callback_ret_range = retval_range(0, 0);
return 0;
}
@@ -12106,10 +12094,6 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env,
/* pointer to stack or null */
callee->regs[BPF_REG_3] = caller->regs[BPF_REG_4];
-
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
/* bpf_find_vma() runs the callback under mmap_lock and RCU. */
callee->in_rcu_callback_fn = true;
@@ -12126,15 +12110,9 @@ static int set_user_ringbuf_callback_state(struct bpf_verifier_env *env,
* callback_ctx, u64 flags);
* callback_fn(const struct bpf_dynptr_t* dynptr, void *callback_ctx);
*/
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_0]);
mark_dynptr_cb_reg(env, &callee->regs[BPF_REG_1], BPF_DYNPTR_TYPE_LOCAL);
callee->regs[BPF_REG_2] = caller->regs[BPF_REG_3];
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
-
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
@@ -12165,9 +12143,6 @@ static int set_rbtree_add_callback_state(struct bpf_verifier_env *env,
mark_reg_graph_node(callee->regs, BPF_REG_2, &field->graph_root);
ref_set_non_owning(env, &callee->regs[BPF_REG_2]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_3]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_callback_fn = true;
callee->callback_ret_range = retval_range(0, 1);
return 0;
@@ -12186,9 +12161,6 @@ static int set_task_work_schedule_callback_state(struct bpf_verifier_env *env,
mark_map_callback_reg(&callee->regs[BPF_REG_3], &caller->regs[BPF_REG_3], PTR_TO_MAP_VALUE);
callee->regs[BPF_REG_3].id = ++env->id_gen;
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_async_callback_fn = true;
callee->callback_ret_range = retval_range(S32_MIN, S32_MAX);
return 0;
@@ -12206,9 +12178,6 @@ static int set_rcu_callback_state(struct bpf_verifier_env *env,
mark_map_callback_reg(&callee->regs[BPF_REG_2], &caller->regs[BPF_REG_2], PTR_TO_MAP_KEY);
mark_map_callback_reg(&callee->regs[BPF_REG_3], &caller->regs[BPF_REG_2], PTR_TO_MAP_VALUE);
- /* unused */
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_4]);
- bpf_mark_reg_not_init(env, &callee->regs[BPF_REG_5]);
callee->in_async_callback_fn = true;
callee->callback_ret_range = retval_range(S32_MIN, S32_MAX);
return 0;
--
2.56.0
prev parent reply other threads:[~2026-11-06 23:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-06 23:21 [PATCH bpf-next v1 1/2] bpf: Share map-backed callback register setup Ihor Solodrai
2026-11-06 23:21 ` Ihor Solodrai [this message]
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