Re: [peterz-queue:module/namespace 8/8] <inline asm>:1191:93: error: unexpected token

[Peter Zijlstra <peterz@infradead.org>]

On Sun, Nov 17, 2024 at 12:32:12PM +0100, Peter Zijlstra wrote:
> On Sun, Nov 17, 2024 at 06:49:12AM +0800, kernel test robot wrote:
> 
> >     1191 | .section ".export_symbol","a" ; __export_symbol_kvm_caps: ; .asciz "GPL" ; .asciz "MODULE_" "kvm,kvm-intel,kvm-amd" ; .balign 8 ; .quad kvm_caps ; .previous
> >          |                                                                                             ^
> 
> Urgh.. so GCC does the expected string concatenation here, while LLVM is
> having a wobble because it expects a single string constant, and not
> two.
> 
> I've tried the whole CONCATENATE() trick, but that doesn't work right
> for strings.
> 
> And I'm not sure what else to try.. The whole of C is build on the
> expectation that two string constants are merged into one, but LLVM
> integrated assembler clearly disagrees :-/
> 
> Anybody?

Made it work like so.

diff --git a/include/linux/export.h b/include/linux/export.h
index 176671624420..2bf1eb80c86b 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -24,11 +24,23 @@
 	.long sym
 #endif
 
-#define ___EXPORT_SYMBOL(sym, license, ns)		\
+/*
+ * LLVM intregrated assembler refuses to merge adjacent string literals (like
+ * C and GNU-as) and chokes on:
+ *
+ *   .asciz "MODULE_" "kvm" ;
+ *
+ * As would be generated when using EXPORT_SYMBOL_GPL_FOR(foo, "kvm"), use
+ * varargs to assemble it like so:
+ *
+ *   .ascii "MODULE_", "kvm", "\0" ;
+ *
+ */
+#define ___EXPORT_SYMBOL(sym, license, ns...)		\
 	.section ".export_symbol","a"		ASM_NL	\
 	__export_symbol_##sym:			ASM_NL	\
 		.asciz license			ASM_NL	\
-		.asciz ns			ASM_NL	\
+		.ascii ns, "\0"			ASM_NL	\
 		__EXPORT_SYMBOL_REF(sym)	ASM_NL	\
 	.previous
 
@@ -39,20 +51,20 @@
  * be reused in other execution contexts such as the UEFI stub or the
  * decompressor.
  */
-#define __EXPORT_SYMBOL(sym, license, ns)
+#define __EXPORT_SYMBOL(sym, license, ns...)
 
 #elif defined(__GENKSYMS__)
 
-#define __EXPORT_SYMBOL(sym, license, ns)	__GENKSYMS_EXPORT_SYMBOL(sym)
+#define __EXPORT_SYMBOL(sym, license, ns...)	__GENKSYMS_EXPORT_SYMBOL(sym)
 
 #elif defined(__ASSEMBLY__)
 
-#define __EXPORT_SYMBOL(sym, license, ns) \
+#define __EXPORT_SYMBOL(sym, license, ns...) \
 	___EXPORT_SYMBOL(sym, license, ns)
 
 #else
 
-#define __EXPORT_SYMBOL(sym, license, ns)			\
+#define __EXPORT_SYMBOL(sym, license, ns...)			\
 	extern typeof(sym) sym;					\
 	__ADDRESSABLE(sym)					\
 	asm(__stringify(___EXPORT_SYMBOL(sym, license, ns)))
@@ -68,9 +80,8 @@
 #define EXPORT_SYMBOL(sym)		_EXPORT_SYMBOL(sym, "")
 #define EXPORT_SYMBOL_GPL(sym)		_EXPORT_SYMBOL(sym, "GPL")
 #define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL(sym, "", ns)
-#define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL(sym, "GPL", ns)
+#define EXPORT_SYMBOL_NS_GPL(sym, ns...)	__EXPORT_SYMBOL(sym, "GPL", ns)
 
-#define EXPORT_SYMBOL_FOR(sym, mods)	EXPORT_SYMBOL_NS(sym, "MODULE_" mods)
-#define EXPORT_SYMBOL_GPL_FOR(sym, mods) EXPORT_SYMBOL_NS_GPL(sym, "MODULE_" mods)
+#define EXPORT_SYMBOL_GPL_FOR(sym, mods) EXPORT_SYMBOL_NS_GPL(sym, "MODULE_", mods)
 
 #endif /* _LINUX_EXPORT_H */