netdev - [PATCH v3 10/15] parisc: Add support for suppressing warning backtraces

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Message-Id: <20240403131936.787234-11-linux@roeck-us.net>
Date: Wed,  3 Apr 2024 06:19:31 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: linux-kselftest@...r.kernel.org
Cc: David Airlie <airlied@...il.com>,
	Arnd Bergmann <arnd@...db.de>,
	Maíra Canal <mcanal@...lia.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Kees Cook <keescook@...omium.org>,
	Daniel Diaz <daniel.diaz@...aro.org>,
	David Gow <davidgow@...gle.com>,
	Arthur Grillo <arthurgrillo@...eup.net>,
	Brendan Higgins <brendan.higgins@...ux.dev>,
	Naresh Kamboju <naresh.kamboju@...aro.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Maxime Ripard <mripard@...nel.org>,
	Ville Syrjälä <ville.syrjala@...ux.intel.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	dri-devel@...ts.freedesktop.org,
	kunit-dev@...glegroups.com,
	linux-arch@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-riscv@...ts.infradead.org,
	linux-s390@...r.kernel.org,
	linux-sh@...r.kernel.org,
	loongarch@...ts.linux.dev,
	netdev@...r.kernel.org,
	x86@...nel.org,
	Guenter Roeck <linux@...ck-us.net>,
	Linux Kernel Functional Testing <lkft@...aro.org>,
	Helge Deller <deller@....de>
Subject: [PATCH v3 10/15] parisc: 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).

While at it, declare assembler parameters as constants where possible.
Refine .blockz instructions to calculate the necessary padding instead
of using fixed values.

Tested-by: Linux Kernel Functional Testing <lkft@...aro.org>
Acked-by: Dan Carpenter <dan.carpenter@...aro.org>
Acked-by: Helge Deller <deller@....de>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
v2:
- Rebased to v6.9-rc1
- Added Tested-by:, Acked-by:, and Reviewed-by: tags
- Introduced KUNIT_SUPPRESS_BACKTRACE configuration option
v3:
- Rebased to v6.9-rc2

 arch/parisc/include/asm/bug.h | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/parisc/include/asm/bug.h b/arch/parisc/include/asm/bug.h
index 833555f74ffa..b59c3f7380bf 100644
--- a/arch/parisc/include/asm/bug.h
+++ b/arch/parisc/include/asm/bug.h
@@ -23,8 +23,17 @@
 # define __BUG_REL(val) ".word " __stringify(val)
 #endif
 
-
 #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()								\
 	do {								\
 		asm volatile("\n"					\
@@ -33,10 +42,12 @@
 			     "\t.align 4\n"				\
 			     "2:\t" __BUG_REL(1b) "\n"			\
 			     "\t" __BUG_REL(%c0)  "\n"			\
-			     "\t.short %1, %2\n"			\
-			     "\t.blockz %3-2*4-2*2\n"			\
+			     "\t" __BUG_FUNC_PTR  "\n"			\
+			     "\t.short %c2, %c3\n"			\
+			     "\t.blockz %c4-(.-2b)\n"			\
 			     "\t.popsection"				\
-			     : : "i" (__FILE__), "i" (__LINE__),	\
+			     : : "i" (__FILE__), "i" (__BUG_FUNC),	\
+			     "i" (__LINE__),				\
 			     "i" (0), "i" (sizeof(struct bug_entry)) );	\
 		unreachable();						\
 	} while(0)
@@ -58,10 +69,12 @@
 			     "\t.align 4\n"				\
 			     "2:\t" __BUG_REL(1b) "\n"			\
 			     "\t" __BUG_REL(%c0)  "\n"			\
-			     "\t.short %1, %2\n"			\
-			     "\t.blockz %3-2*4-2*2\n"			\
+			     "\t" __BUG_FUNC_PTR  "\n"			\
+			     "\t.short %c2, %3\n"			\
+			     "\t.blockz %c4-(.-2b)\n"			\
 			     "\t.popsection"				\
-			     : : "i" (__FILE__), "i" (__LINE__),	\
+			     : : "i" (__FILE__), "i" (__BUG_FUNC),	\
+			     "i" (__LINE__),				\
 			     "i" (BUGFLAG_WARNING|(flags)),		\
 			     "i" (sizeof(struct bug_entry)) );		\
 	} while(0)
@@ -74,7 +87,7 @@
 			     "\t.align 4\n"				\
 			     "2:\t" __BUG_REL(1b) "\n"			\
 			     "\t.short %0\n"				\
-			     "\t.blockz %1-4-2\n"			\
+			     "\t.blockz %c1-(.-2b)\n"			\
 			     "\t.popsection"				\
 			     : : "i" (BUGFLAG_WARNING|(flags)),		\
 			     "i" (sizeof(struct bug_entry)) );		\
-- 
2.39.2