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perf/x86: Improve debug output in check_hw_exists() 

It might be of interest which perfctr msr failed.

Signed-off-by: Robert Richter <robert.richter@amd.com>
[ added hunk to avoid GCC warn ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1340217996-2254-5-git-send-email-robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Robert Richter 2012-06-20 20:46:36 +02:00 committed by Ingo Molnar
parent b1dc3c4820
commit f285f92f7e
1 changed files with 5 additions and 3 deletions
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8
arch/x86/kernel/cpu/perf_event.c
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@ -178,7 +178,7 @@ static void release_pmc_hardware(void) {}
static bool check_hw_exists(void)
{
u64 val, val_new = 0;
u64 val, val_new = ~0;
int i, reg, ret = 0;
/*
@ -211,8 +211,9 @@ static bool check_hw_exists(void)
* that don't trap on the MSR access and always return 0s.
*/
val = 0xabcdUL;
ret = wrmsrl_safe(x86_pmu_event_addr(0), val);
ret |= rdmsrl_safe(x86_pmu_event_addr(0), &val_new);
reg = x86_pmu_event_addr(0);
ret = wrmsrl_safe(reg, val);
ret |= rdmsrl_safe(reg, &val_new);
if (ret || val != val_new)
goto msr_fail;
@ -229,6 +230,7 @@ bios_fail:
msr_fail:
printk(KERN_CONT "Broken PMU hardware detected, using software events only.\n");
printk(KERN_ERR "Failed to access perfctr msr (MSR %x is %Lx)\n", reg, val_new);
return false;
}