From 501bd734f933f4eb5c080b87936e9d43f471d723 Mon Sep 17 00:00:00 2001 From: Mateusz Guzik Date: Thu, 13 Jun 2024 10:26:37 +0200 Subject: x86/CPU/AMD: Always inline amd_clear_divider() The routine is used on syscall exit and on non-AMD CPUs is guaranteed to be empty. It probably does not need to be a function call even on CPUs which do need the mitigation. [ bp: Make sure it is always inlined so that noinstr marking works. ] Signed-off-by: Mateusz Guzik Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240613082637.659133-1-mjguzik@gmail.com --- arch/x86/include/asm/processor.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'arch/x86/include/asm/processor.h') diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index cb4f6c513c48..a75a07f4931f 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -692,7 +692,17 @@ static inline u32 per_cpu_l2c_id(unsigned int cpu) #ifdef CONFIG_CPU_SUP_AMD extern u32 amd_get_highest_perf(void); -extern void amd_clear_divider(void); + +/* + * Issue a DIV 0/1 insn to clear any division data from previous DIV + * operations. + */ +static __always_inline void amd_clear_divider(void) +{ + asm volatile(ALTERNATIVE("", "div %2\n\t", X86_BUG_DIV0) + :: "a" (0), "d" (0), "r" (1)); +} + extern void amd_check_microcode(void); #else static inline u32 amd_get_highest_perf(void) { return 0; } -- cgit v1.2.3