Merge tag 'x86-percpu-2024-07-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 percpu updates from Ingo Molnar:

 - Enable the named address spaces based percpu accessors optimization
   on all GCC versions that contain this feature, detected through a
   build-time testcase.

   This effectively enables the feature on GCC 6, GCC 7 and GCC 8
   versions.

 - Fix operand constraint modifier in __raw_cpu_write()

 - Reorganize the per-CPU headers for better readability

 - Misc cleanups and fixes

* tag 'x86-percpu-2024-07-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/percpu: Enable named address spaces for all capable GCC versions
  x86/percpu: Clean up <asm/percpu.h> vertical alignment details
  x86/percpu: Clean up <asm/percpu.h> a bit
  x86/percpu: Move some percpu accessors around to reduce ifdeffery
  x86/percpu: Rename percpu_stable_op() to __raw_cpu_read_stable()
  x86/percpu: Fix operand constraint modifier in __raw_cpu_write()
  x86/percpu: Introduce the __raw_cpu_read_const() macro
  x86/percpu: Unify percpu read-write accessors
  x86/percpu: Move some percpu macros around for readability
  x86/percpu: Introduce the pcpu_binary_op() macro

arch/x86/Kconfig

@@ -2428,7 +2428,8 @@ source "kernel/livepatch/Kconfig"
 endmenu
 
 config CC_HAS_NAMED_AS
-	def_bool CC_IS_GCC && GCC_VERSION >= 90100
+	def_bool $(success,echo 'int __seg_fs fs; int __seg_gs gs;' | $(CC) -x c - -S -o /dev/null)
+	depends on CC_IS_GCC
 
 config CC_HAS_NAMED_AS_FIXED_SANITIZERS
 	def_bool CC_IS_GCC && GCC_VERSION >= 130300