From 9297e602adf8d5587d83941c48e4dbae46c8df5f Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 2 Nov 2020 11:54:02 -0800 Subject: [PATCH] selftests/x86: Use __builtin_ia32_read/writeeflags The asm to read and write EFLAGS from userspace is horrible. The compiler builtins are now available on all supported compilers, so use them instead. (The compiler builtins are also unnecessarily ugly, but that's a more manageable level of ugliness.) Signed-off-by: Andy Lutomirski Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/aee4b1cdfc56083eb779ce927b7d3459aad2af76.1604346818.git.luto@kernel.org --- tools/testing/selftests/x86/helpers.h | 24 ++++-------------------- 1 file changed, 4 insertions(+), 20 deletions(-) diff --git a/tools/testing/selftests/x86/helpers.h b/tools/testing/selftests/x86/helpers.h index f5ff2a2615df..4ef42c4559a9 100644 --- a/tools/testing/selftests/x86/helpers.h +++ b/tools/testing/selftests/x86/helpers.h @@ -6,36 +6,20 @@ static inline unsigned long get_eflags(void) { - unsigned long eflags; - - asm volatile ( #ifdef __x86_64__ - "subq $128, %%rsp\n\t" - "pushfq\n\t" - "popq %0\n\t" - "addq $128, %%rsp" + return __builtin_ia32_readeflags_u64(); #else - "pushfl\n\t" - "popl %0" + return __builtin_ia32_readeflags_u32(); #endif - : "=r" (eflags) :: "memory"); - - return eflags; } static inline void set_eflags(unsigned long eflags) { - asm volatile ( #ifdef __x86_64__ - "subq $128, %%rsp\n\t" - "pushq %0\n\t" - "popfq\n\t" - "addq $128, %%rsp" + __builtin_ia32_writeeflags_u64(eflags); #else - "pushl %0\n\t" - "popfl" + __builtin_ia32_writeeflags_u32(eflags); #endif - :: "r" (eflags) : "flags", "memory"); } #endif /* __SELFTESTS_X86_HELPERS_H */