linux-kernel - [PATCH v3 2/3] kcsan: mark !__SANITIZE_THREAD__ stubs __always

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251216-gcov-inline-noinstr-v3-2-10244d154451@google.com>
Date: Tue, 16 Dec 2025 10:16:35 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Andrey Ryabinin <ryabinin.a.a@...il.com>, Alexander Potapenko <glider@...gle.com>, 
	Andrey Konovalov <andreyknvl@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>, 
	Vincenzo Frascino <vincenzo.frascino@....com>, Marco Elver <elver@...gle.com>, 
	Ard Biesheuvel <ardb@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Nathan Chancellor <nathan@...nel.org>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>
Cc: kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev, Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH v3 2/3] kcsan: mark !__SANITIZE_THREAD__ stubs __always_inline

The x86 instrumented bitops in
include/asm-generic/bitops/instrumented-non-atomic.h are
KCSAN-instrumented via explicit calls to instrument_* functions from
include/linux/instrumented.h.

This bitops are used from noinstr code in __sev_es_nmi_complete(). This
code avoids noinstr violations by disabling __SANITIZE_THREAD__ etc for
the compilation unit.

However, when GCOV is enabled, there can still be violations caused by
the stub versions of these functions, since coverage instrumentation is
injected that causes them to be out-of-lined.

Fix this by just applying __always_inline.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 include/linux/kcsan-checks.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/kcsan-checks.h b/include/linux/kcsan-checks.h
index 92f3843d9ebb8177432bb4eccc151ea66d3dcbb7..c4c8e03e53459f5030ca33f9103a9bde49fd3820 100644
--- a/include/linux/kcsan-checks.h
+++ b/include/linux/kcsan-checks.h
@@ -226,10 +226,10 @@ static inline void kcsan_end_scoped_access(struct kcsan_scoped_access *sa) { }
 #define __kcsan_disable_current kcsan_disable_current
 #define __kcsan_enable_current kcsan_enable_current_nowarn
 #else /* __SANITIZE_THREAD__ */
-static inline void kcsan_check_access(const volatile void *ptr, size_t size,
-				      int type) { }
-static inline void __kcsan_enable_current(void)  { }
-static inline void __kcsan_disable_current(void) { }
+static __always_inline void kcsan_check_access(const volatile void *ptr,
+					       size_t size, int type) { }
+static __always_inline void __kcsan_enable_current(void)  { }
+static __always_inline void __kcsan_disable_current(void) { }
 #endif /* __SANITIZE_THREAD__ */
 
 #if defined(CONFIG_KCSAN_WEAK_MEMORY) && defined(__SANITIZE_THREAD__)

-- 
2.50.1