[ Upstream commit 0dbf66fa7e80024629f816c2ec7a9f3d39637822 ]
In the following patches we will enable LBR capture on AMD CPUs at arbitrary point in time, which means that LBR recording won't be frozen by hardware automatically as part of hardware overflow event. So we need to take care to minimize amount of branches and function calls/returns on the path to freezing LBR, minimizing LBR snapshot altering as much as possible.
amd_pmu_core_disable_all() is one of the functions on this path, and is already marked as __always_inline. But it calls amd_pmu_set_global_ctl() which is marked as just inline. So to guarantee no function call will be generated thoughout mark amd_pmu_set_global_ctl() as __always_inline as well.
Signed-off-by: Andrii Nakryiko andrii@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Reviewed-by: Sandipan Das sandipan.das@amd.com Link: https://lore.kernel.org/r/20240402022118.1046049-2-andrii@kernel.org Signed-off-by: Leon Hwang leon.hwang@linux.dev --- arch/x86/events/amd/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index aa8fc2cf1bde..3b09ec4f2b0d 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -632,7 +632,7 @@ static void amd_pmu_cpu_dead(int cpu) } }
-static inline void amd_pmu_set_global_ctl(u64 ctl) +static __always_inline void amd_pmu_set_global_ctl(u64 ctl) { wrmsrl(MSR_AMD64_PERF_CNTR_GLOBAL_CTL, ctl); }