diff options
Diffstat (limited to 'include/linux/compiler-gcc.h')
| -rw-r--r-- | include/linux/compiler-gcc.h | 23 |
1 files changed, 5 insertions, 18 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index 3ebee1ce6f98..a80d6de3c8ad 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -12,26 +12,13 @@ #if GCC_VERSION < 40600 # error Sorry, your compiler is too old - please upgrade it. -#endif - -/* Optimization barrier */ - -/* The "volatile" is due to gcc bugs */ -#define barrier() __asm__ __volatile__("": : :"memory") +#elif defined(CONFIG_ARM64) && GCC_VERSION < 50100 /* - * This version is i.e. to prevent dead stores elimination on @ptr - * where gcc and llvm may behave differently when otherwise using - * normal barrier(): while gcc behavior gets along with a normal - * barrier(), llvm needs an explicit input variable to be assumed - * clobbered. The issue is as follows: while the inline asm might - * access any memory it wants, the compiler could have fit all of - * @ptr into memory registers instead, and since @ptr never escaped - * from that, it proved that the inline asm wasn't touching any of - * it. This version works well with both compilers, i.e. we're telling - * the compiler that the inline asm absolutely may see the contents - * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63293 + * https://lore.kernel.org/r/20210107111841.GN1551@shell.armlinux.org.uk */ -#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") +# error Sorry, your version of GCC is too old - please use 5.1 or newer. +#endif /* * This macro obfuscates arithmetic on a variable address so that gcc |