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The profiling is turned ON only for user mode execution and turned OFF for kernel mode execution. Profiling is explicitly disabled for NMI handler too. TODOs: - IBS sampling rate is kept fixed for now. - Arch/vendor separation/isolation of the code needs relook. Signed-off-by: Bharata B Rao --- arch/x86/include/asm/entry-common.h | 3 +++ arch/x86/include/asm/hardirq.h | 2 ++ arch/x86/include/asm/ibs.h | 2 ++ arch/x86/mm/ibs.c | 32 +++++++++++++++++++++++++++++ 4 files changed, 39 insertions(+) diff --git a/arch/x86/include/asm/entry-common.h b/arch/x86/include/asm/entry-common.h index d535a97c7284..7144b57d209b 100644 --- a/arch/x86/include/asm/entry-common.h +++ b/arch/x86/include/asm/entry-common.h @@ -9,10 +9,12 @@ #include #include #include +#include /* Check that the stack and regs on entry from user mode are sane. */ static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) { + hw_access_profiling_stop(); if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) { /* * Make sure that the entry code gave us a sensible EFLAGS @@ -99,6 +101,7 @@ static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, static __always_inline void arch_exit_to_user_mode(void) { amd_clear_divider(); + hw_access_profiling_start(); } #define arch_exit_to_user_mode arch_exit_to_user_mode diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h index f00c09ffe6a9..0752cb6ebd7a 100644 --- a/arch/x86/include/asm/hardirq.h +++ b/arch/x86/include/asm/hardirq.h @@ -91,4 +91,6 @@ static __always_inline bool kvm_get_cpu_l1tf_flush_l1d(void) static __always_inline void kvm_set_cpu_l1tf_flush_l1d(void) { } #endif /* IS_ENABLED(CONFIG_KVM_INTEL) */ +#define arch_nmi_enter() hw_access_profiling_stop() +#define arch_nmi_exit() hw_access_profiling_start() #endif /* _ASM_X86_HARDIRQ_H */ diff --git a/arch/x86/include/asm/ibs.h b/arch/x86/include/asm/ibs.h index b5a4f2ca6330..6b480958534e 100644 --- a/arch/x86/include/asm/ibs.h +++ b/arch/x86/include/asm/ibs.h @@ -2,6 +2,8 @@ #ifndef _ASM_X86_IBS_H #define _ASM_X86_IBS_H +void hw_access_profiling_start(void); +void hw_access_profiling_stop(void); extern bool arch_hw_access_profiling; #endif /* _ASM_X86_IBS_H */ diff --git a/arch/x86/mm/ibs.c b/arch/x86/mm/ibs.c index 6669710dd35b..3128e8fa5f39 100644 --- a/arch/x86/mm/ibs.c +++ b/arch/x86/mm/ibs.c @@ -16,6 +16,7 @@ static u64 ibs_config __read_mostly; static u32 ibs_caps; #define IBS_NR_SAMPLES 150 +#define IBS_SAMPLE_PERIOD 10000 /* * Basic access info captured for each memory access. @@ -98,6 +99,36 @@ static void ibs_irq_handler(struct irq_work *i) schedule_work_on(smp_processor_id(), &ibs_work); } +void hw_access_profiling_stop(void) +{ + u64 ops_ctl; + + if (!arch_hw_access_profiling) + return; + + rdmsrl(MSR_AMD64_IBSOPCTL, ops_ctl); + wrmsrl(MSR_AMD64_IBSOPCTL, ops_ctl & ~IBS_OP_ENABLE); +} + +void hw_access_profiling_start(void) +{ + u64 config = 0; + unsigned int period = IBS_SAMPLE_PERIOD; + + if (!arch_hw_access_profiling) + return; + + /* Disable IBS for kernel thread */ + if (!current->mm) + goto out; + + config = (period >> 4) & IBS_OP_MAX_CNT; + config |= (period & IBS_OP_MAX_CNT_EXT_MASK); + config |= ibs_config; +out: + wrmsrl(MSR_AMD64_IBSOPCTL, config); +} + /* * IBS NMI handler: Process the memory access info reported by IBS. * @@ -304,6 +335,7 @@ static int __init ibs_access_profiling_init(void) x86_amd_ibs_access_profile_startup, x86_amd_ibs_access_profile_teardown); + arch_hw_access_profiling = true; pr_info("IBS setup for memory access profiling\n"); return 0; } -- 2.34.1