+ x86-add-support-for-suppressing-warning-backtraces.patch added to mm-nonmm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

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The patch titled
     Subject: x86: add support for suppressing warning backtraces
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     x86-add-support-for-suppressing-warning-backtraces.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-add-support-for-suppressing-warning-backtraces.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Guenter Roeck <linux@roeck-us.net>
Subject: x86: add support for suppressing warning backtraces
Date: Thu, 13 Mar 2025 11:43:21 +0000

Add name of functions triggering warning backtraces to the __bug_table
object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added
to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and
CONFIG_DEBUG_BUGVERBOSE are enabled.  Otherwise, the __func__ assembly
parameter is replaced with a (dummy) NULL parameter to avoid an image size
increase due to unused __func__ entries (this is necessary because
__func__ is not a define but a virtual variable).

Link: https://lkml.kernel.org/r/20250313114329.284104-7-acarmina@redhat.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Alessandro Carminati <acarmina@redhat.com>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Acked-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Arthur Grillo <arthurgrillo@riseup.net>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Charlie Jenkins <charlie@rivosinc.com>
Cc: Daniel Diaz <daniel.diaz@linaro.org>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Dave Airlie <airlied@gmail.com>
Cc: David Gow <davidgow@google.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maíra Canal <mcanal@igalia.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Rae Moar <rmoar@google.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Simon Horman <horms@kernel.org>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/include/asm/bug.h |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/arch/x86/include/asm/bug.h~x86-add-support-for-suppressing-warning-backtraces
+++ a/arch/x86/include/asm/bug.h
@@ -35,18 +35,28 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR	__BUG_REL(%c1)
+# define __BUG_FUNC	__func__
+#else
+# define __BUG_FUNC_PTR
+# define __BUG_FUNC	NULL
+#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+
 #define _BUG_FLAGS(ins, flags, extra)					\
 do {									\
 	asm_inline volatile("1:\t" ins "\n"				\
 		     ".pushsection __bug_table,\"aw\"\n"		\
 		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
 		     "\t"  __BUG_REL(%c0) "\t# bug_entry::file\n"	\
-		     "\t.word %c1"        "\t# bug_entry::line\n"	\
-		     "\t.word %c2"        "\t# bug_entry::flags\n"	\
-		     "\t.org 2b+%c3\n"					\
+		     "\t"  __BUG_FUNC_PTR "\t# bug_entry::function\n"	\
+		     "\t.word %c2"        "\t# bug_entry::line\n"	\
+		     "\t.word %c3"        "\t# bug_entry::flags\n"	\
+		     "\t.org 2b+%c4\n"					\
 		     ".popsection\n"					\
 		     extra						\
-		     : : "i" (__FILE__), "i" (__LINE__),		\
+		     : : "i" (__FILE__), "i" (__BUG_FUNC), "i" (__LINE__),\
 			 "i" (flags),					\
 			 "i" (sizeof(struct bug_entry)));		\
 } while (0)
@@ -92,7 +102,8 @@ do {								\
 do {								\
 	__auto_type __flags = BUGFLAG_WARNING|(flags);		\
 	instrumentation_begin();				\
-	_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b));	\
+	if (!KUNIT_IS_SUPPRESSED_WARNING(__func__))			\
+		_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b));	\
 	instrumentation_end();					\
 } while (0)
 
_

Patches currently in -mm which might be from linux@roeck-us.net are

bug-kunit-core-support-for-suppressing-warning-backtraces.patch
kunit-bug-count-suppressed-warning-backtraces.patch
kunit-add-test-cases-for-backtrace-warning-suppression.patch
kunit-add-documentation-for-warning-backtrace-suppression-api.patch
drm-suppress-intentional-warning-backtraces-in-scaling-unit-tests.patch
x86-add-support-for-suppressing-warning-backtraces.patch
arm64-add-support-for-suppressing-warning-backtraces.patch
loongarch-add-support-for-suppressing-warning-backtraces.patch
parisc-add-support-for-suppressing-warning-backtraces.patch
s390-add-support-for-suppressing-warning-backtraces.patch
sh-add-support-for-suppressing-warning-backtraces.patch
sh-move-defines-needed-for-suppressing-warning-backtraces.patch
riscv-add-support-for-suppressing-warning-backtraces.patch
powerpc-add-support-for-suppressing-warning-backtraces.patch