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| author | Mateusz Guzik <mjguzik@gmail.com> | 2024-06-13 10:26:37 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-06-13 14:40:29 +0200 |
| commit | 501bd734f933f4eb5c080b87936e9d43f471d723 (patch) | |
| tree | 16b37e70d6317bdce9fdd6e8cc3b6e62b8c5e480 /arch/x86/include/asm/processor.h | |
| parent | eb9d3c0bb065e55af6ec88e82a94b57fa1bb6e5d (diff) | |
| download | linux-501bd734f933f4eb5c080b87936e9d43f471d723.tar.gz linux-501bd734f933f4eb5c080b87936e9d43f471d723.tar.bz2 linux-501bd734f933f4eb5c080b87936e9d43f471d723.zip | |
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 <mjguzik@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240613082637.659133-1-mjguzik@gmail.com
Diffstat (limited to 'arch/x86/include/asm/processor.h')
| -rw-r--r-- | arch/x86/include/asm/processor.h | 12 |
1 files changed, 11 insertions, 1 deletions
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; } |