The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: 501bd734f933f4eb5c080b87936e9d43f471d723
Gitweb: https://git.kernel.org/tip/501bd734f933f4eb5c080b87936e9d43f471d723
Author: Mateusz Guzik <mjguzik@xxxxxxxxx>
AuthorDate: Thu, 13 Jun 2024 10:26:37 +02:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Thu, 13 Jun 2024 14:40:29 +02:00
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@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240613082637.659133-1-mjguzik@xxxxxxxxx
---
arch/x86/include/asm/processor.h | 12 +++++++++++-
arch/x86/kernel/cpu/amd.c | 11 -----------
2 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index cb4f6c5..a75a07f 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; }
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 44df3f1..be5889b 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -1220,14 +1220,3 @@ void amd_check_microcode(void)
on_each_cpu(zenbleed_check_cpu, NULL, 1);
}
-
-/*
- * Issue a DIV 0/1 insn to clear any division data from previous DIV
- * operations.
- */
-void noinstr amd_clear_divider(void)
-{
- asm volatile(ALTERNATIVE("", "div %2\n\t", X86_BUG_DIV0)
- :: "a" (0), "d" (0), "r" (1));
-}
-EXPORT_SYMBOL_GPL(amd_clear_divider);
|