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Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kernel/cpu/perfctr-watchdog.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perfctr-watchdog.c b/arch/x86/kernel/cpu/perfctr-watchdog.c new file mode 100644 index 000000000..d38908333 --- /dev/null +++ b/arch/x86/kernel/cpu/perfctr-watchdog.c @@ -0,0 +1,161 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * local apic based NMI watchdog for various CPUs. + * + * This file also handles reservation of performance counters for coordination + * with other users (like oprofile). + * + * Note that these events normally don't tick when the CPU idles. This means + * the frequency varies with CPU load. + * + * Original code for K7/P6 written by Keith Owens + * + */ + +#include <linux/percpu.h> +#include <linux/export.h> +#include <linux/kernel.h> +#include <linux/bitops.h> +#include <linux/smp.h> +#include <asm/nmi.h> +#include <linux/kprobes.h> + +#include <asm/apic.h> +#include <asm/perf_event.h> + +/* + * this number is calculated from Intel's MSR_P4_CRU_ESCR5 register and it's + * offset from MSR_P4_BSU_ESCR0. + * + * It will be the max for all platforms (for now) + */ +#define NMI_MAX_COUNTER_BITS 66 + +/* + * perfctr_nmi_owner tracks the ownership of the perfctr registers: + * evtsel_nmi_owner tracks the ownership of the event selection + * - different performance counters/ event selection may be reserved for + * different subsystems this reservation system just tries to coordinate + * things a little + */ +static DECLARE_BITMAP(perfctr_nmi_owner, NMI_MAX_COUNTER_BITS); +static DECLARE_BITMAP(evntsel_nmi_owner, NMI_MAX_COUNTER_BITS); + +/* converts an msr to an appropriate reservation bit */ +static inline unsigned int nmi_perfctr_msr_to_bit(unsigned int msr) +{ + /* returns the bit offset of the performance counter register */ + switch (boot_cpu_data.x86_vendor) { + case X86_VENDOR_AMD: + if (msr >= MSR_F15H_PERF_CTR) + return (msr - MSR_F15H_PERF_CTR) >> 1; + return msr - MSR_K7_PERFCTR0; + case X86_VENDOR_INTEL: + if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) + return msr - MSR_ARCH_PERFMON_PERFCTR0; + + switch (boot_cpu_data.x86) { + case 6: + return msr - MSR_P6_PERFCTR0; + case 11: + return msr - MSR_KNC_PERFCTR0; + case 15: + return msr - MSR_P4_BPU_PERFCTR0; + } + } + return 0; +} + +/* + * converts an msr to an appropriate reservation bit + * returns the bit offset of the event selection register + */ +static inline unsigned int nmi_evntsel_msr_to_bit(unsigned int msr) +{ + /* returns the bit offset of the event selection register */ + switch (boot_cpu_data.x86_vendor) { + case X86_VENDOR_AMD: + if (msr >= MSR_F15H_PERF_CTL) + return (msr - MSR_F15H_PERF_CTL) >> 1; + return msr - MSR_K7_EVNTSEL0; + case X86_VENDOR_INTEL: + if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) + return msr - MSR_ARCH_PERFMON_EVENTSEL0; + + switch (boot_cpu_data.x86) { + case 6: + return msr - MSR_P6_EVNTSEL0; + case 11: + return msr - MSR_KNC_EVNTSEL0; + case 15: + return msr - MSR_P4_BSU_ESCR0; + } + } + return 0; + +} + +/* checks for a bit availability (hack for oprofile) */ +int avail_to_resrv_perfctr_nmi_bit(unsigned int counter) +{ + BUG_ON(counter > NMI_MAX_COUNTER_BITS); + + return !test_bit(counter, perfctr_nmi_owner); +} +EXPORT_SYMBOL(avail_to_resrv_perfctr_nmi_bit); + +int reserve_perfctr_nmi(unsigned int msr) +{ + unsigned int counter; + + counter = nmi_perfctr_msr_to_bit(msr); + /* register not managed by the allocator? */ + if (counter > NMI_MAX_COUNTER_BITS) + return 1; + + if (!test_and_set_bit(counter, perfctr_nmi_owner)) + return 1; + return 0; +} +EXPORT_SYMBOL(reserve_perfctr_nmi); + +void release_perfctr_nmi(unsigned int msr) +{ + unsigned int counter; + + counter = nmi_perfctr_msr_to_bit(msr); + /* register not managed by the allocator? */ + if (counter > NMI_MAX_COUNTER_BITS) + return; + + clear_bit(counter, perfctr_nmi_owner); +} +EXPORT_SYMBOL(release_perfctr_nmi); + +int reserve_evntsel_nmi(unsigned int msr) +{ + unsigned int counter; + + counter = nmi_evntsel_msr_to_bit(msr); + /* register not managed by the allocator? */ + if (counter > NMI_MAX_COUNTER_BITS) + return 1; + + if (!test_and_set_bit(counter, evntsel_nmi_owner)) + return 1; + return 0; +} +EXPORT_SYMBOL(reserve_evntsel_nmi); + +void release_evntsel_nmi(unsigned int msr) +{ + unsigned int counter; + + counter = nmi_evntsel_msr_to_bit(msr); + /* register not managed by the allocator? */ + if (counter > NMI_MAX_COUNTER_BITS) + return; + + clear_bit(counter, evntsel_nmi_owner); +} +EXPORT_SYMBOL(release_evntsel_nmi); |