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 v2 06/11] bpf: Rely on callback frame initialization defaults
Date: Fri, 9 Oct 2026 13:27:53 -0700 [thread overview]
Message-ID: <20261009202759.50520-7-ihor.solodrai@linux.dev> (raw)
In-Reply-To: <20261009202759.50520-1-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 8f2125c6e348..67a61570a9ab 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -11295,9 +11295,6 @@ 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;
}
@@ -11341,11 +11338,6 @@ 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;
@@ -11365,11 +11357,7 @@ 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;
}
@@ -11393,10 +11381,6 @@ 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;
callee->callback_ret_range = retval_range(0, 1);
return 0;
@@ -11412,15 +11396,9 @@ 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;
@@ -11452,9 +11430,6 @@ 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;
@@ -11474,9 +11449,6 @@ 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;
@@ -11495,9 +11467,6 @@ 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
next prev parent reply other threads:[~2026-10-09 20:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-09 20:27 [PATCH bpf-next v2 00/11] bpf: Scope callback arguments to their frame Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 01/11] bpf: Set up callee state outside of setup_func_entry() Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 02/11] bpf: Pass the owning verifier state to callback setters Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 03/11] bpf: Append complete reference states Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 04/11] bpf: Separate reference removal from descendant invalidation Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 05/11] bpf: Share map-backed callback register setup Ihor Solodrai
2026-10-09 20:27 ` Ihor Solodrai [this message]
2026-10-09 20:27 ` [PATCH bpf-next v2 07/11] bpf: Introduce REF_TYPE_FRAME in the verifier Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 08/11] bpf: Scope the bpf_user_ringbuf_drain() dynptr to its callback frame Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 09/11] selftests/bpf: Cover the user ringbuf callback dynptr lifetime Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 10/11] bpf: Scope the bpf_for_each_map_elem() array key to the callback frame Ihor Solodrai
2026-10-09 20:27 ` [PATCH bpf-next v2 11/11] selftests/bpf: Cover callback-frame map key lifetime Ihor Solodrai
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