linux-kernel - [PATCH 07/11] x86_64/bug: Add BUG

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Message-ID: <20250607095618.822433827@infradead.org>
Date: Sat, 07 Jun 2025 11:42:31 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org,
 kees@...nel.org,
 acarmina@...hat.com,
 jpoimboe@...nel.org,
 mark.rutland@....com,
 torvalds@...uxfoundation.org
Subject: [PATCH 07/11] x86_64/bug: Add BUG_FORMAT basics

Opt-in to BUG_FORMAT for x86_64, adjust the BUGTABLE helper and for
now, just store NULL pointers.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/include/asm/bug.h |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -47,22 +47,35 @@
 #define ASM_BUGTABLE_VERBOSE_SIZE	0
 #endif
 
+#ifdef CONFIG_X86_64
+#define HAVE_ARCH_BUG_FORMAT
+#define ASM_BUGTABLE_FORMAT(format)					\
+	ASM_BUG_REL(format)
+#define ASM_BUGTABLE_FORMAT_SIZE	4 /* sizeof(format) */
+#else
+#define ASM_BUGTABLE_FORMAT(format)
+#define ASM_BUGTABLE_FORMAT_SIZE	0
+#endif
+
 #define ASM_BUGTABLE_BASE_SIZE		6 /* sizeof(bug_addr) + sizeof(flags) */
 
-#define ASM_BUGTABLE_FLAGS(at, file, line, flags)			\
+#define ASM_BUGTABLE_FLAGS(at, format, file, line, flags)		\
 	.pushsection __bug_table, "aw" ;				\
 	123:	ASM_BUG_REL(at) ;					\
+	ASM_BUGTABLE_FORMAT(format) ;					\
 	ASM_BUGTABLE_VERBOSE(file, line) ;				\
 	.word	flags ;							\
-	.org 123b + ASM_BUGTABLE_BASE_SIZE + ASM_BUGTABLE_VERBOSE_SIZE ;\
+	.org 123b + ASM_BUGTABLE_BASE_SIZE + ASM_BUGTABLE_FORMAT_SIZE + ASM_BUGTABLE_VERBOSE_SIZE ; \
 	.popsection
 
 #define _BUG_FLAGS(insn, flags, extra)					\
 do {									\
 	asm_inline volatile("1:\t" insn "\n"				\
-	    __stringify(ASM_BUGTABLE_FLAGS(1b, %c[file], %c[line], %c[fl])) "\n" \
+	    __stringify(ASM_BUGTABLE_FLAGS(1b, %c[fmt], %c[file], %c[line], %c[fl])) "\n" \
 			    extra					\
-		     : : [file] "i" (__FILE__), [line] "i" (__LINE__),	\
+		     : : [fmt] "i" (NULL),				\
+		         [file] "i" (__FILE__),				\
+			 [line] "i" (__LINE__),				\
 			 [fl] "i" (flags));				\
 } while (0)