From: Guenter Roeck <linux@roeck-us.net>
Date: Thu, 13 Mar 2025 11:43:25 +0000 (+0000)
Subject: s390: add support for suppressing warning backtraces
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=8bb4e7edef06cda1ea32227c749c29fbf46d9acf;p=users%2Fwilly%2Fpagecache.git

s390: add support for suppressing warning backtraces

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/20250313114329.284104-11-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: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Arthur Grillo <arthurgrillo@riseup.net>
Cc: Borislav Petkov <bp@alien8.de>
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: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Gow <davidgow@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
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 Gleixner <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
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>
---

diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h
index c500d45fb465c..44d4e9f24ae0e 100644
--- a/arch/s390/include/asm/bug.h
+++ b/arch/s390/include/asm/bug.h
@@ -8,6 +8,15 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+# define HAVE_BUG_FUNCTION
+# define __BUG_FUNC_PTR	"	.long	%0-.\n"
+# define __BUG_FUNC	__func__
+#else
+# define __BUG_FUNC_PTR
+# define __BUG_FUNC	NULL
+#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+
 #define __EMIT_BUG(x) do {					\
 	asm_inline volatile(					\
 		"0:	mc	0,0\n"				\
@@ -17,10 +26,12 @@
 		".section __bug_table,\"aw\"\n"			\
 		"2:	.long	0b-.\n"				\
 		"	.long	1b-.\n"				\
-		"	.short	%0,%1\n"			\
-		"	.org	2b+%2\n"			\
+		__BUG_FUNC_PTR					\
+		"	.short	%1,%2\n"			\
+		"	.org	2b+%3\n"			\
 		".previous\n"					\
-		: : "i" (__LINE__),				\
+		: : "i" (__BUG_FUNC),				\
+		    "i" (__LINE__),				\
 		    "i" (x),					\
 		    "i" (sizeof(struct bug_entry)));		\
 } while (0)