From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 21 Sep 2019 16:47:19 +0000 (-0700)
Subject: Merge tag 'compiler-attributes-for-linus-v5.4' of git://github.com/ojeda/linux
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=227c3e9eb5cf3552c2cc83225df6d14adb05f8e8;p=linux.git

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
---

227c3e9eb5cf3552c2cc83225df6d14adb05f8e8
diff --cc include/linux/compiler_types.h
index b056a40116da9,2bf316fe0a204..72393a8c1a6c5
--- a/include/linux/compiler_types.h
+++ b/include/linux/compiler_types.h
@@@ -140,27 -144,24 +140,36 @@@ struct ftrace_likely_data 
   */
  #if !defined(CONFIG_OPTIMIZE_INLINING)
  #define inline inline __attribute__((__always_inline__)) __gnu_inline \
 -	__maybe_unused notrace
 +	__inline_maybe_unused notrace
  #else
  #define inline inline                                    __gnu_inline \
 -	__maybe_unused notrace
 +	__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.
 + * Suppress the warning in clang as well by using __maybe_unused, but enable it
 + * for W=1 build. This will allow clang to find unused functions. Remove the
 + * __inline_maybe_unused entirely after fixing most of -Wunused-function warnings.
 + */
 +#ifdef KBUILD_EXTRA_WARN1
 +#define __inline_maybe_unused
 +#else
 +#define __inline_maybe_unused __maybe_unused
 +#endif
 +
  /*
   * Rather then using noinline to prevent stack consumption, use
   * noinline_for_stack instead.  For documentation reasons.
diff --cc init/Kconfig
index f4534c58342d7,7fee5978dd737..7020238fd2638
--- a/init/Kconfig
+++ b/init/Kconfig
@@@ -30,9 -30,9 +30,12 @@@ config CC_CAN_LIN
  config CC_HAS_ASM_GOTO
  	def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
  
 +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