Rework the __bug_table helpers such that usage from assembly becomes
possible.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/include/asm/bug.h |   50 ++++++++++++++++++---------------------------
 1 file changed, 21 insertions(+), 29 deletions(-)

--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -28,46 +28,38 @@
 #ifdef CONFIG_GENERIC_BUG
 
 #ifdef CONFIG_X86_32
-# define __BUG_REL(val)	".long " __stringify(val)
+#define ASM_BUG_REL(val)	.long val
 #else
-# define __BUG_REL(val)	".long " __stringify(val) " - ."
+#define ASM_BUG_REL(val)	.long val - .
 #endif
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
+#define ASM_BUGTABLE_VERBOSE(file, line)				\
+	ASM_BUG_REL(file) ;						\
+	.word line
+#define ASM_BUGTABLE_VERBOSE_SIZE	6
+#else
+#define ASM_BUGTABLE_VERBOSE(file, line)
+#define ASM_BUGTABLE_VERBOSE_SIZE	0
+#endif
 
-#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"					\
-		     ".popsection\n"					\
-		     extra						\
-		     : : "i" (__FILE__), "i" (__LINE__),		\
-			 "i" (flags),					\
-			 "i" (sizeof(struct bug_entry)));		\
-} while (0)
-
-#else /* !CONFIG_DEBUG_BUGVERBOSE */
+#define ASM_BUGTABLE_FLAGS(at, file, line, flags)			\
+	.pushsection __bug_table, "aw" ;				\
+	123:	ASM_BUG_REL(at) ;					\
+	ASM_BUGTABLE_VERBOSE(file, line) ;				\
+	.word	flags ;							\
+	.org 123b + 6 + ASM_BUGTABLE_VERBOSE_SIZE ;			\
+	.popsection
 
 #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.word %c0"        "\t# bug_entry::flags\n"	\
-		     "\t.org 2b+%c1\n"					\
-		     ".popsection\n"					\
-		     extra						\
-		     : : "i" (flags),					\
-			 "i" (sizeof(struct bug_entry)));		\
+	    __stringify(ASM_BUGTABLE_FLAGS(1b, %c0, %c1, %c2)) "\n"	\
+			    extra					\
+		     : : "i" (__FILE__), "i" (__LINE__),		\
+			 "i" (flags));					\
 } while (0)
 
-#endif /* CONFIG_DEBUG_BUGVERBOSE */
-
 #else
 
 #define _BUG_FLAGS(ins, flags, extra)  asm volatile(ins)

On Mon, Oct 07, 2024 at 10:32:11AM +0200, Peter Zijlstra wrote:
> +#define ASM_BUGTABLE_FLAGS(at, file, line, flags)			\
> +	.pushsection __bug_table, "aw" ;				\
> +	123:	ASM_BUG_REL(at) ;					\
> +	ASM_BUGTABLE_VERBOSE(file, line) ;				\
> +	.word	flags ;							\
> +	.org 123b + 6 + ASM_BUGTABLE_VERBOSE_SIZE ;			\

I'm guessing this second 6 is the sizeof(long + word) of the second two?

I.e., in here:

asm __inline volatile("1:\t" ".byte 0x0f, 0x0b" "\n"
		      ".pushsection __bug_table, \"aw\" ;
		       123:
		       		.long 1b - . ;
				.long %c0 - . ;
				^^^^^^^^^^^^^
				.word %c1 ;
				.word %c2 ;
				^^^^^^^^^^


				.org 123b + 6 + 6 ;
			.popsection" "\n" ""

Can we add a define for it too instead of a naked 6?

> +	.popsection
>  
>  #define _BUG_FLAGS(ins, flags, extra)					\
>  do {									\
>  	asm_inline volatile("1:\t" ins "\n"				\

s/ins/insn/ while at it.

The usual abbreviation for an "instruction".

> -		     ".pushsection __bug_table,\"aw\"\n"		\
> -		     "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n"	\
> -		     "\t.word %c0"        "\t# bug_entry::flags\n"	\
> -		     "\t.org 2b+%c1\n"					\
> -		     ".popsection\n"					\
> -		     extra						\
> -		     : : "i" (flags),					\
> -			 "i" (sizeof(struct bug_entry)));		\
> +	    __stringify(ASM_BUGTABLE_FLAGS(1b, %c0, %c1, %c2)) "\n"	\
> +			    extra					\
> +		     : : "i" (__FILE__), "i" (__LINE__),		\
> +			 "i" (flags));					\
>  } while (0)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

On Mon, Oct 07, 2024 at 10:32:11AM +0200, Peter Zijlstra wrote:
> +#define ASM_BUGTABLE_FLAGS(at, file, line, flags)			\
> +	.pushsection __bug_table, "aw" ;				\
> +	123:	ASM_BUG_REL(at) ;					\
> +	ASM_BUGTABLE_VERBOSE(file, line) ;				\
> +	.word	flags ;							\
> +	.org 123b + 6 + ASM_BUGTABLE_VERBOSE_SIZE ;			\
	    ^
should be a tab?

Nice cleanup!

Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>

-- 
Josh