From 699b1c4a66084049531bc59a392052b4251da1e0 Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Sat, 30 Sep 2023 15:12:17 +0200 Subject: x86/include/arch/cpuid.h: Fix inline assembly In the cpuid helper functions eax is always written to by the cpuid instruction, so add it to the output clobbered list. This prevents GCC from generating code with undefined behaviour when the function is inlined. Test: Verified that the generated assembly is sane and runtime tests showed no "strange" behaviour when calling cpuid functions. Change-Id: I5dc0bb620184a355716b9c8d4206d55554b41ab9 Signed-off-by: Patrick Rudolph Reviewed-on: https://review.coreboot.org/c/coreboot/+/78192 Reviewed-by: Felix Held Tested-by: build bot (Jenkins) Reviewed-by: Krystian Hebel Reviewed-by: Paul Menzel --- src/arch/x86/include/arch/cpuid.h | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) (limited to 'src/arch') diff --git a/src/arch/x86/include/arch/cpuid.h b/src/arch/x86/include/arch/cpuid.h index 70a5beb9b9b8..b2780bec472c 100644 --- a/src/arch/x86/include/arch/cpuid.h +++ b/src/arch/x86/include/arch/cpuid.h @@ -56,39 +56,36 @@ static inline uint32_t cpuid_eax(uint32_t eax) return eax; } -static inline uint32_t cpuid_ebx(const uint32_t eax) +static inline uint32_t cpuid_ebx(uint32_t eax) { uint32_t ebx; asm volatile( "cpuid;" - : "=b" (ebx) - : "a" (eax) - : "ecx", "edx"); + : "=b" (ebx), "+a" (eax) + :: "ecx", "edx"); return ebx; } -static inline uint32_t cpuid_ecx(const uint32_t eax) +static inline uint32_t cpuid_ecx(uint32_t eax) { uint32_t ecx; asm volatile( "cpuid;" - : "=c" (ecx) - : "a" (eax) - : "ebx", "edx"); + : "=c" (ecx), "+a" (eax) + :: "ebx", "edx"); return ecx; } -static inline uint32_t cpuid_edx(const uint32_t eax) +static inline uint32_t cpuid_edx(uint32_t eax) { uint32_t edx; asm volatile( "cpuid;" - : "=d" (edx) - : "a" (eax) - : "ebx", "ecx"); + : "=d" (edx), "+a" (eax) + :: "ebx", "ecx"); return edx; } -- cgit v1.2.3