x86: 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/20250313114329.284104-7-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>

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index e85ac0c7c039ea95272a5525e2099ccadf386c1f..f6e13fc675abcc23e6a41055ecf45a3d17fc69ad 100644 (file)
--- a/arch/x86/include/asm/bug.h
+++ b/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)