[PATCH 07/14] x86: Add support for suppressing warning backtraces

From: Guenter Roeck <linux@roeck-us.net>
To: linux-kselftest@vger.kernel.org
Cc: loongarch@lists.linux.dev, linux-doc@vger.kernel.org,
	dri-devel@lists.freedesktop.org,
	"Brendan Higgins" <brendan.higgins@linux.dev>,
	linux-riscv@lists.infradead.org,
	"David Airlie" <airlied@gmail.com>,
	"Arthur Grillo" <arthurgrillo@riseup.net>,
	"Ville Syrjälä" <ville.syrjala@linux.intel.com>,
	linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
	"Daniel Diaz" <daniel.diaz@linaro.org>,
	linux-sh@vger.kernel.org,
	"Naresh Kamboju" <naresh.kamboju@linaro.org>,
	"Maíra Canal" <mcanal@igalia.com>,
	"Dan Carpenter" <dan.carpenter@linaro.org>,
	"Guenter Roeck" <linux@roeck-us.net>,
	netdev@lists.linux.dev, "Kees Cook" <keescook@chromium.org>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"David Gow" <davidgow@google.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	linux-arm-kernel@lists.infradead.org, kunit-dev@googlegroups.com,
	linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Thomas Zimmerman n" <tzimmermann@suse.de>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 07/14] x86: Add support for suppressing warning backtraces
Date: Tue, 12 Mar 2024 10:03:02 -0700	[thread overview]
Message-ID: <20240312170309.2546362-8-linux@roeck-us.net> (raw)
In-Reply-To: <20240312170309.2546362-1-linux@roeck-us.net>

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 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).

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 arch/x86/include/asm/bug.h | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index a3ec87d198ac..d87bf8bab238 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -23,18 +23,28 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
+#if IS_ENABLED(CONFIG_KUNIT)
+# 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 /* IS_ENABLED(CONFIG_KUNIT) */
+
 #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)
@@ -80,7 +90,8 @@ do {								\
 do {								\
 	__auto_type __flags = BUGFLAG_WARNING|(flags);		\
 	instrumentation_begin();				\
-	_BUG_FLAGS(ASM_UD2, __flags, ASM_REACHABLE);		\
+	if (!IS_SUPPRESSED_WARNING(__func__))			\
+		_BUG_FLAGS(ASM_UD2, __flags, ASM_REACHABLE);	\
 	instrumentation_end();					\
 } while (0)
 
-- 
2.39.2

