linux-kernel - [PATCH v2 3/3] x86/sev: Disable GCOV on noinstr object

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Message-ID: <20251215-gcov-inline-noinstr-v2-3-6f100b94fa99@google.com>
Date: Mon, 15 Dec 2025 10:12:41 +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>
Cc: kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org, 
	Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH v2 3/3] x86/sev: Disable GCOV on noinstr object

With Debian clang version 19.1.7 (3+build5) there are calls to
kasan_check_write() from __sev_es_nmi_complete, which violates noinstr.
Fix it by disabling GCOV for the noinstr object, as has been done for
previous such instrumentation issues.

Note that this file already disables __SANITIZE_ADDRESS__ and
__SANITIZE_THREAD__, thus calls like kasan_check_write() ought to be
nops regardless of GCOV. This has been fixed in other patches. However,
to avoid any other accidental instrumentation showing up, (and since, in
principle GCOV is instrumentation and hence should be disabled for
noinstr code anyway), disable GCOV overall as well.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 arch/x86/coco/sev/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/coco/sev/Makefile b/arch/x86/coco/sev/Makefile
index 3b8ae214a6a64de6bb208eb3b7c8bf12007ccc2c..b2e9ec2f69014fa3507d40c6c266f1b74d634fcb 100644
--- a/arch/x86/coco/sev/Makefile
+++ b/arch/x86/coco/sev/Makefile
@@ -8,3 +8,5 @@ UBSAN_SANITIZE_noinstr.o	:= n
 # GCC may fail to respect __no_sanitize_address or __no_kcsan when inlining
 KASAN_SANITIZE_noinstr.o	:= n
 KCSAN_SANITIZE_noinstr.o	:= n
+
+GCOV_PROFILE_noinstr.o		:= n

-- 
2.50.1