From: Eduard Zingerman <eddyz87@gmail.com>
To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org
Cc: daniel@iogearbox.net, martin.lau@linux.dev, kernel-team@fb.com,
yonghong.song@linux.dev, eddyz87@gmail.com
Subject: [PATCH bpf-next v3 06/13] bpf: prepare bpf_liveness api for use by static analysis pass
Date: Fri, 10 Apr 2026 02:29:10 -0700 [thread overview]
Message-ID: <20260410-patch-set-v3-6-1f5826dc0ef2@gmail.com> (raw)
In-Reply-To: <20260410-patch-set-v3-0-1f5826dc0ef2@gmail.com>
bpf: prepare liveness internal API for static analysis pass
Move the `updated` check and reset from bpf_update_live_stack() into
update_instance() itself, so callers outside the main loop can reuse
it. Similarly, move write_insn_idx assignment out of
reset_stack_write_marks() into its public caller, and thread insn_idx
as a parameter to commit_stack_write_marks() instead of reading it
from liveness->write_insn_idx. Drop the unused `env` parameter from
alloc_frame_masks() and mark_stack_read().
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
kernel/bpf/liveness.c | 48 +++++++++++++++++++++++-------------------------
1 file changed, 23 insertions(+), 25 deletions(-)
diff --git a/kernel/bpf/liveness.c b/kernel/bpf/liveness.c
index e2697cd9ae27..a3af5972520f 100644
--- a/kernel/bpf/liveness.c
+++ b/kernel/bpf/liveness.c
@@ -259,8 +259,7 @@ static struct per_frame_masks *get_frame_masks(struct func_instance *instance,
return &instance->frames[frame][relative_idx(instance, insn_idx)];
}
-static struct per_frame_masks *alloc_frame_masks(struct bpf_verifier_env *env,
- struct func_instance *instance,
+static struct per_frame_masks *alloc_frame_masks(struct func_instance *instance,
u32 frame, u32 insn_idx)
{
struct per_frame_masks *arr;
@@ -298,13 +297,12 @@ static int ensure_cur_instance(struct bpf_verifier_env *env)
}
/* Accumulate may_read masks for @frame at @insn_idx */
-static int mark_stack_read(struct bpf_verifier_env *env,
- struct func_instance *instance, u32 frame, u32 insn_idx, spis_t mask)
+static int mark_stack_read(struct func_instance *instance, u32 frame, u32 insn_idx, spis_t mask)
{
struct per_frame_masks *masks;
spis_t new_may_read;
- masks = alloc_frame_masks(env, instance, frame, insn_idx);
+ masks = alloc_frame_masks(instance, frame, insn_idx);
if (IS_ERR(masks))
return PTR_ERR(masks);
new_may_read = spis_or(masks->may_read, mask);
@@ -321,17 +319,15 @@ int bpf_mark_stack_read(struct bpf_verifier_env *env, u32 frame, u32 insn_idx, s
int err;
err = ensure_cur_instance(env);
- err = err ?: mark_stack_read(env, env->liveness->cur_instance, frame, insn_idx, mask);
+ err = err ?: mark_stack_read(env->liveness->cur_instance, frame, insn_idx, mask);
return err;
}
-static void reset_stack_write_marks(struct bpf_verifier_env *env,
- struct func_instance *instance, u32 insn_idx)
+static void reset_stack_write_marks(struct bpf_verifier_env *env, struct func_instance *instance)
{
struct bpf_liveness *liveness = env->liveness;
int i;
- liveness->write_insn_idx = insn_idx;
for (i = 0; i <= instance->callchain.curframe; i++)
liveness->write_masks_acc[i] = SPIS_ZERO;
}
@@ -345,7 +341,8 @@ int bpf_reset_stack_write_marks(struct bpf_verifier_env *env, u32 insn_idx)
if (err)
return err;
- reset_stack_write_marks(env, liveness->cur_instance, insn_idx);
+ liveness->write_insn_idx = insn_idx;
+ reset_stack_write_marks(env, liveness->cur_instance);
return 0;
}
@@ -355,7 +352,8 @@ void bpf_mark_stack_write(struct bpf_verifier_env *env, u32 frame, spis_t mask)
}
static int commit_stack_write_marks(struct bpf_verifier_env *env,
- struct func_instance *instance)
+ struct func_instance *instance,
+ u32 insn_idx)
{
struct bpf_liveness *liveness = env->liveness;
u32 idx, frame, curframe;
@@ -366,13 +364,13 @@ static int commit_stack_write_marks(struct bpf_verifier_env *env,
return 0;
curframe = instance->callchain.curframe;
- idx = relative_idx(instance, liveness->write_insn_idx);
+ idx = relative_idx(instance, insn_idx);
for (frame = 0; frame <= curframe; frame++) {
mask = liveness->write_masks_acc[frame];
/* avoid allocating frames for zero masks */
if (spis_is_zero(mask) && !instance->must_write_set[idx])
continue;
- masks = alloc_frame_masks(env, instance, frame, liveness->write_insn_idx);
+ masks = alloc_frame_masks(instance, frame, insn_idx);
if (IS_ERR(masks))
return PTR_ERR(masks);
old_must_write = masks->must_write;
@@ -402,7 +400,7 @@ static int commit_stack_write_marks(struct bpf_verifier_env *env,
*/
int bpf_commit_stack_write_marks(struct bpf_verifier_env *env)
{
- return commit_stack_write_marks(env, env->liveness->cur_instance);
+ return commit_stack_write_marks(env, env->liveness->cur_instance, env->liveness->write_insn_idx);
}
static char *fmt_callchain(struct bpf_verifier_env *env, struct callchain *callchain)
@@ -576,18 +574,17 @@ static int propagate_to_outer_instance(struct bpf_verifier_env *env,
if (IS_ERR(outer_instance))
return PTR_ERR(outer_instance);
callsite = callchain->callsites[callchain->curframe - 1];
-
- reset_stack_write_marks(env, outer_instance, callsite);
+ reset_stack_write_marks(env, outer_instance);
for (frame = 0; frame < callchain->curframe; frame++) {
insn = get_frame_masks(instance, frame, this_subprog_start);
if (!insn)
continue;
bpf_mark_stack_write(env, frame, insn->must_write_acc);
- err = mark_stack_read(env, outer_instance, frame, callsite, insn->live_before);
+ err = mark_stack_read(outer_instance, frame, callsite, insn->live_before);
if (err)
return err;
}
- commit_stack_write_marks(env, outer_instance);
+ commit_stack_write_marks(env, outer_instance, callsite);
return 0;
}
@@ -654,6 +651,9 @@ static int update_instance(struct bpf_verifier_env *env, struct func_instance *i
bool changed;
int err;
+ if (!instance->updated)
+ return 0;
+
this_subprog_start = callchain_subprog_start(callchain);
/*
* If must_write marks were updated must_write_acc needs to be reset
@@ -699,6 +699,8 @@ static int update_instance(struct bpf_verifier_env *env, struct func_instance *i
return err;
}
+ instance->updated = false;
+ instance->must_write_dropped = false;
return 0;
}
@@ -721,13 +723,9 @@ int bpf_update_live_stack(struct bpf_verifier_env *env)
if (IS_ERR(instance))
return PTR_ERR(instance);
- if (instance->updated) {
- err = update_instance(env, instance);
- if (err)
- return err;
- instance->updated = false;
- instance->must_write_dropped = false;
- }
+ err = update_instance(env, instance);
+ if (err)
+ return err;
}
return 0;
}
--
2.53.0
next prev parent reply other threads:[~2026-04-10 9:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-10 9:29 [PATCH bpf-next v3 00/13] bpf: static stack liveness data flow analysis Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 01/13] bpf: share several utility functions as internal API Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 02/13] bpf: save subprogram name in bpf_subprog_info Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 03/13] bpf: Add spis_*() helpers for 4-byte stack slot bitmasks Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 04/13] bpf: make liveness.c track stack with 4-byte granularity Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 05/13] bpf: 4-byte precise clean_verifier_state Eduard Zingerman
2026-04-10 9:29 ` Eduard Zingerman [this message]
2026-04-10 9:57 ` [PATCH bpf-next v3 06/13] bpf: prepare bpf_liveness api for use by static analysis pass bot+bpf-ci
2026-04-10 9:29 ` [PATCH bpf-next v3 07/13] bpf: introduce forward arg-tracking dataflow analysis Eduard Zingerman
2026-04-10 10:10 ` bot+bpf-ci
2026-04-10 9:29 ` [PATCH bpf-next v3 08/13] bpf: simplify liveness to use (callsite, depth) keyed func_instances Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 09/13] bpf: change logging scheme for live stack analysis Eduard Zingerman
2026-04-10 9:57 ` bot+bpf-ci
2026-04-10 9:29 ` [PATCH bpf-next v3 10/13] selftests/bpf: update existing tests due to liveness changes Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 11/13] selftests/bpf: adjust verifier_log buffers Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 12/13] selftests/bpf: add new tests for static stack liveness analysis Eduard Zingerman
2026-04-10 9:29 ` [PATCH bpf-next v3 13/13] bpf: poison dead stack slots Eduard Zingerman
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