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// 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_HYGON:
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;
}
fallthrough;
case X86_VENDOR_ZHAOXIN:
case X86_VENDOR_CENTAUR:
return msr - MSR_ARCH_PERFMON_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_HYGON:
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;
}
fallthrough;
case X86_VENDOR_ZHAOXIN:
case X86_VENDOR_CENTAUR:
return msr - MSR_ARCH_PERFMON_EVENTSEL0;
}
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);
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