[PATCH -v2 7/7] module: Provide EXPORT_SYMBOL_GPL_FOR() helper

Peter Zijlstra
2024-12-02T15:11:36Z

Requested-by: Masahiro Yamada <masahiroy@kernel.org>
Requested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/export.h | 26 ++++++++++++++++++++------
1 file changed, 20 insertions(+), 6 deletions(-)

--- 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)))
@@ -70,4 +82,6 @@
#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_GPL_FOR(sym, mods) __EXPORT_SYMBOL(sym, "GPL", "MODULE_", mods)
+
#endif /* _LINUX_EXPORT_H */