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

1 files changed, 16 insertions, 1 deletions

diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index b056a40116da..72393a8c1a6c 100644
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@ -146,8 +146,17 @@ struct ftrace_likely_data {
 	__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.
@@ -197,6 +206,12 @@ struct ftrace_likely_data {
 #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
 # define __no_fgcse
 #endif