[PATCH 5/5] kmsan: rework kmsan_in_runtime() handling in kmsan_report()

Alexander Potapenko
2025-05-07T16:00:28Z

kmsan_report() calls used to require entering/leaving the runtime around
them. To simplify the things, drop this requirement and move calls to
kmsan_enter_runtime()/kmsan_leave_runtime() into kmsan_report().

Cc: Marco Elver <elver@google.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Alexander Potapenko <glider@google.com>
---
mm/kmsan/core.c | 8 --------
mm/kmsan/instrumentation.c | 4 ----
mm/kmsan/report.c | 6 +++---
3 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c
index a97dc90fa6a93..1ea711786c522 100644
--- a/mm/kmsan/core.c
+++ b/mm/kmsan/core.c
@@ -274,11 +274,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
* bytes before, report them.
*/
if (cur_origin) {
- kmsan_enter_runtime();
kmsan_report(cur_origin, addr, size,
cur_off_start, pos - 1, user_addr,
reason);
- kmsan_leave_runtime();
}
cur_origin = 0;
cur_off_start = -1;
@@ -292,11 +290,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
* poisoned bytes before, report them.
*/
if (cur_origin) {
- kmsan_enter_runtime();
kmsan_report(cur_origin, addr, size,
cur_off_start, pos + i - 1,
user_addr, reason);
- kmsan_leave_runtime();
}
cur_origin = 0;
cur_off_start = -1;
@@ -312,11 +308,9 @@ void kmsan_internal_check_memory(void *addr, size_t size,
*/
if (cur_origin != new_origin) {
if (cur_origin) {
- kmsan_enter_runtime();
kmsan_report(cur_origin, addr, size,
cur_off_start, pos + i - 1,
user_addr, reason);
- kmsan_leave_runtime();
}
cur_origin = new_origin;
cur_off_start = pos + i;
@@ -326,10 +320,8 @@ void kmsan_internal_check_memory(void *addr, size_t size,
}
KMSAN_WARN_ON(pos != size);
if (cur_origin) {
- kmsan_enter_runtime();
kmsan_report(cur_origin, addr, size, cur_off_start, pos - 1,
user_addr, reason);
- kmsan_leave_runtime();
}
}

diff --git a/mm/kmsan/instrumentation.c b/mm/kmsan/instrumentation.c
index 02a405e55d6ca..69f0a57a401c4 100644
--- a/mm/kmsan/instrumentation.c
+++ b/mm/kmsan/instrumentation.c
@@ -312,13 +312,9 @@ EXPORT_SYMBOL(__msan_unpoison_alloca);
void __msan_warning(u32 origin);
void __msan_warning(u32 origin)
{
- if (!kmsan_enabled || kmsan_in_runtime())
- return;
- kmsan_enter_runtime();
kmsan_report(origin, /*address*/ NULL, /*size*/ 0,
/*off_first*/ 0, /*off_last*/ 0, /*user_addr*/ NULL,
REASON_ANY);
- kmsan_leave_runtime();
}
EXPORT_SYMBOL(__msan_warning);

diff --git a/mm/kmsan/report.c b/mm/kmsan/report.c
index 94a3303fb65e0..d6853ce089541 100644
--- a/mm/kmsan/report.c
+++ b/mm/kmsan/report.c
@@ -157,14 +157,14 @@ void kmsan_report(depot_stack_handle_t origin, void *address, int size,
unsigned long ua_flags;
bool is_uaf;

- if (!kmsan_enabled)
+ if (!kmsan_enabled || kmsan_in_runtime())
return;
if (current->kmsan_ctx.depth)
return;
if (!origin)
return;

- kmsan_disable_current();
+ kmsan_enter_runtime();
ua_flags = user_access_save();
raw_spin_lock(&kmsan_report_lock);
pr_err("=====================================================\n");
@@ -217,5 +217,5 @@ void kmsan_report(depot_stack_handle_t origin, void *address, int size,
if (panic_on_kmsan)
panic("kmsan.panic set ...\n");
user_access_restore(ua_flags);
- kmsan_enable_current();
+ kmsan_leave_runtime();
}
--
2.49.0.967.g6a0df3ecc3-goog