Merge tag 'compiler-attributes-for-linus-v5.4' of git://github.com/ojeda/linux

Pull asm inline support from Miguel Ojeda:
"Make use of gcc 9's "asm inline()" (Rasmus Villemoes):

gcc 9+ (and gcc 8.3, 7.5) provides a way to override the otherwise
crude heuristic that gcc uses to estimate the size of the code
represented by an asm() statement. From the gcc docs

If you use 'asm inline' instead of just 'asm', then for inlining
purposes the size of the asm is taken as the minimum size, ignoring
how many instructions GCC thinks it is.

For compatibility with older compilers, we obviously want a

#if [understands asm inline]
#define asm_inline asm inline
#else
#define asm_inline asm
#endif

But since we #define the identifier inline to attach some attributes,
we have to use an alternate spelling of that keyword. gcc provides
both __inline__ and __inline, and we currently #define both to inline,
so they all have the same semantics.

We have to free up one of __inline__ and __inline, and the latter is
by far the easiest.

The two x86 changes cause smaller code gen differences than I'd
expect, but I think we do want the asm_inline thing available sooner
or later, so this is just to get the ball rolling"

* tag 'compiler-attributes-for-linus-v5.4' of git://github.com/ojeda/linux:
x86: bug.h: use asm_inline in _BUG_FLAGS definitions
x86: alternative.h: use asm_inline for all alternative variants
compiler-types.h: add asm_inline definition
compiler_types.h: don't #define __inline
lib/zstd/mem.h: replace __inline by inline
staging: rtl8723bs: replace __inline by inline

arch/x86/include/asm/alternative.h

···
  * without volatile and memory clobber.
  */
 #define alternative(oldinstr, newinstr, feature)			\
-	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")
+	asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")
 
 #define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
-	asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")
+	asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")
 
 /*
  * Alternative inline assembly with input.
···
  * Leaving an unused argument 0 to keep API compatibility.
  */
 #define alternative_input(oldinstr, newinstr, feature, input...)	\
-	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature)		\
+	asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature)	\
 		: : "i" (0), ## input)
 
 /*
···
  */
 #define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2,	     \
 			   feature2, input...)				     \
-	asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1,	     \
+	asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1,     \
 		newinstr2, feature2)					     \
 		: : "i" (0), ## input)
 
 /* Like alternative_input, but with a single output argument */
 #define alternative_io(oldinstr, newinstr, feature, output, input...)	\
-	asm volatile (ALTERNATIVE(oldinstr, newinstr, feature)		\
+	asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature)	\
 		: output : "i" (0), ## input)
 
 /* Like alternative_io, but for replacing a direct call with another one. */
 #define alternative_call(oldfunc, newfunc, feature, output, input...)	\
-	asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
+	asm_inline volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
 		: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
 
 /*
···
  */
 #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2,   \
 			   output, input...)				      \
-	asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
+	asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
 		"call %P[new2]", feature2)				      \
 		: output, ASM_CALL_CONSTRAINT				      \
 		: [old] "i" (oldfunc), [new1] "i" (newfunc1),		      \

arch/x86/include/asm/bug.h

···
 
 #define _BUG_FLAGS(ins, flags)						\
 do {									\
-	asm volatile("1:\t" ins "\n"					\
+	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"	\
···
 
 #define _BUG_FLAGS(ins, flags)						\
 do {									\
-	asm volatile("1:\t" ins "\n"					\
+	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"	\

include/linux/compiler_types.h

···
 	__inline_maybe_unused notrace
 #endif
 
+/*
+ * gcc provides both __inline__ and __inline as alternate spellings of
+ * the inline keyword, though the latter is undocumented. New kernel
+ * code should only use the inline spelling, but some existing code
+ * uses __inline__. Since we #define inline above, to ensure
+ * __inline__ has the same semantics, we need this #define.
+ *
+ * However, the spelling __inline is strictly reserved for referring
+ * to the bare keyword.
+ */
 #define __inline__ inline
-#define __inline   inline
 
 /*
  * GCC does not warn about unused static inline functions for -Wunused-function.
···
 
 #ifndef asm_volatile_goto
 #define asm_volatile_goto(x...) asm goto(x)
+#endif
+
+#ifdef CONFIG_CC_HAS_ASM_INLINE
+#define asm_inline asm __inline
+#else
+#define asm_inline asm
 #endif
 
 #ifndef __no_fgcse

init/Kconfig

···
 config TOOLS_SUPPORT_RELR
 	def_bool $(success,env "CC=$(CC)" "LD=$(LD)" "NM=$(NM)" "OBJCOPY=$(OBJCOPY)" $(srctree)/scripts/tools-support-relr.sh)
 
+config CC_HAS_ASM_INLINE
+	def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null)
+
 config CC_HAS_WARN_MAYBE_UNINITIALIZED
 	def_bool $(cc-option,-Wmaybe-uninitialized)
 	help

lib/zstd/mem.h

···
 /*-****************************************
 *  Compiler specifics
 ******************************************/
-#define ZSTD_STATIC static __inline __attribute__((unused))
+#define ZSTD_STATIC static inline
 
 /*-**************************************************************
 *  Basic Types