@@ -9,10 +9,12 @@
#include <asm/io_bitmap.h>
#include <asm/fpu/api.h>
#include <asm/fred.h>
+#include <asm/ibs.h>
/* 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
@@ -98,6 +100,7 @@ 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
@@ -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 */
@@ -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 */
@@ -15,6 +15,7 @@ bool arch_hw_access_profiling;
static u64 ibs_config __read_mostly;
static u32 ibs_caps;
+#define IBS_SAMPLE_PERIOD 10000
#define IBS_NR_SAMPLES 50
/*
@@ -99,6 +100,36 @@ 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.
*
@@ -305,6 +336,7 @@ 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;
}
Enable IBS memory access data collection for user memory accesses by programming the required MSRs. 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 <bharata@amd.com> --- 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(+)