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perf_counter: fix crash on perfmon v1 systems

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Impact: fix boot crash on Intel Perfmon Version 1 systems

Intel Perfmon v1 does not support the global MSRs, nor does
it offer the generalized MSR ranges. So support v2 and later
CPUs only.

Also mark pmc_ops as read-mostly - to avoid false cacheline
sharing.

Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Ingo Molnar 2009-03-18 08:59:21 +01:00
parent 4e193bd4df
commit 7bb497bd88
1 changed files with 12 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
arch/x86/kernel/cpu/perf_counter.c
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@ -57,12 +57,14 @@ struct pmc_x86_ops {
int max_events;
};
static struct pmc_x86_ops *pmc_ops;
static struct pmc_x86_ops *pmc_ops __read_mostly;
static DEFINE_PER_CPU(struct cpu_hw_counters, cpu_hw_counters) = {
.enabled = 1,
};
static __read_mostly int intel_perfmon_version;
/*
* Intel PerfMon v3. Used on Core2 and later.
*/
@ -613,7 +615,7 @@ void perf_counter_print_debug(void)
cpu = smp_processor_id();
cpuc = &per_cpu(cpu_hw_counters, cpu);
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) {
if (intel_perfmon_version >= 2) {
rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl);
rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status);
rdmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, overflow);
@ -930,10 +932,10 @@ static struct pmc_x86_ops pmc_amd_ops = {
static struct pmc_x86_ops *pmc_intel_init(void)
{
union cpuid10_eax eax;
unsigned int ebx;
unsigned int unused;
union cpuid10_edx edx;
union cpuid10_eax eax;
unsigned int unused;
unsigned int ebx;
/*
* Check whether the Architectural PerfMon supports
@ -943,8 +945,12 @@ static struct pmc_x86_ops *pmc_intel_init(void)
if (eax.split.mask_length <= ARCH_PERFMON_BRANCH_MISSES_RETIRED)
return NULL;
intel_perfmon_version = eax.split.version_id;
if (intel_perfmon_version < 2)
return NULL;
pr_info("Intel Performance Monitoring support detected.\n");
pr_info("... version: %d\n", eax.split.version_id);
pr_info("... version: %d\n", intel_perfmon_version);
pr_info("... bit width: %d\n", eax.split.bit_width);
pr_info("... mask length: %d\n", eax.split.mask_length);