The quilt patch titled
Subject: mm: kmsan: remove runtime checks from kmsan_unpoison_memory()
has been removed from the -mm tree. Its filename was
mm-kmsan-remove-runtime-checks-from-kmsan_unpoison_memory.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: mm: kmsan: remove runtime checks from kmsan_unpoison_memory()
Date: Wed, 24 Jan 2024 18:31:34 +0100
Similarly to what's been done in commit 85716a80c16d ("kmsan: allow using
__msan_instrument_asm_store() inside runtime"), it should be safe to call
kmsan_unpoison_memory() from within the runtime, as it does not allocate
memory or take locks. Remove the redundant runtime checks.
This should fix false positives seen with CONFIG_DEBUG_LIST=y when
the non-instrumented lib/stackdepot.c failed to unpoison the memory
chunks later checked by the instrumented lib/list_debug.c
Also replace the implementation of kmsan_unpoison_entry_regs() with
a call to kmsan_unpoison_memory().
Link: https://lkml.kernel.org/r/20240124173134.1165747-1-glider@xxxxxxxxxx
Fixes: f80be4571b19 ("kmsan: add KMSAN runtime core")
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Tested-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
Cc: Nicholas Miehlbradt <nicholas@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/kmsan/hooks.c | 36 +++++++++++++-----------------------
1 file changed, 13 insertions(+), 23 deletions(-)
--- a/mm/kmsan/hooks.c~mm-kmsan-remove-runtime-checks-from-kmsan_unpoison_memory
+++ a/mm/kmsan/hooks.c
@@ -359,6 +359,12 @@ void kmsan_handle_dma_sg(struct scatterl
}
/* Functions from kmsan-checks.h follow. */
+
+/*
+ * To create an origin, kmsan_poison_memory() unwinds the stacks and stores it
+ * into the stack depot. This may cause deadlocks if done from within KMSAN
+ * runtime, therefore we bail out if kmsan_in_runtime().
+ */
void kmsan_poison_memory(const void *address, size_t size, gfp_t flags)
{
if (!kmsan_enabled || kmsan_in_runtime())
@@ -371,47 +377,31 @@ void kmsan_poison_memory(const void *add
}
EXPORT_SYMBOL(kmsan_poison_memory);
+/*
+ * Unlike kmsan_poison_memory(), this function can be used from within KMSAN
+ * runtime, because it does not trigger allocations or call instrumented code.
+ */
void kmsan_unpoison_memory(const void *address, size_t size)
{
unsigned long ua_flags;
- if (!kmsan_enabled || kmsan_in_runtime())
+ if (!kmsan_enabled)
return;
ua_flags = user_access_save();
- kmsan_enter_runtime();
/* The users may want to poison/unpoison random memory. */
kmsan_internal_unpoison_memory((void *)address, size,
KMSAN_POISON_NOCHECK);
- kmsan_leave_runtime();
user_access_restore(ua_flags);
}
EXPORT_SYMBOL(kmsan_unpoison_memory);
/*
- * Version of kmsan_unpoison_memory() that can be called from within the KMSAN
- * runtime.
- *
- * Non-instrumented IRQ entry functions receive struct pt_regs from assembly
- * code. Those regs need to be unpoisoned, otherwise using them will result in
- * false positives.
- * Using kmsan_unpoison_memory() is not an option in entry code, because the
- * return value of in_task() is inconsistent - as a result, certain calls to
- * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that
- * the registers are unpoisoned even if kmsan_in_runtime() is true in the early
- * entry code.
+ * Version of kmsan_unpoison_memory() called from IRQ entry functions.
*/
void kmsan_unpoison_entry_regs(const struct pt_regs *regs)
{
- unsigned long ua_flags;
-
- if (!kmsan_enabled)
- return;
-
- ua_flags = user_access_save();
- kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs),
- KMSAN_POISON_NOCHECK);
- user_access_restore(ua_flags);
+ kmsan_unpoison_memory((void *)regs, sizeof(*regs));
}
void kmsan_check_memory(const void *addr, size_t size)
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
