Re: linux-2.6.28-rc2 regression : oprofile doesnt work anymore ?

Andi Kleen
2008-11-07T12:54:19Z

Can you please test this patch and see if it solves the problem?

Thanks,
-Andi

---

oprofile: Fix p6 counter overflow check

Fix the counter overflow check for CPUs with counter width > 32

I had a similar change in a different patch that I didn't submit
and I didn't notice the problem earlier because it was always
tested together.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
arch/x86/oprofile/op_model_ppro.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

Index: linux-2.6.28-rc3-test/arch/x86/oprofile/op_model_ppro.c
===================================================================
--- linux-2.6.28-rc3-test.orig/arch/x86/oprofile/op_model_ppro.c 2008-11-07 13:46:23.000000000 +0100
+++ linux-2.6.28-rc3-test/arch/x86/oprofile/op_model_ppro.c 2008-11-07 13:50:57.000000000 +0100
@@ -27,8 +27,7 @@
static int counter_width = 32;

#define CTR_IS_RESERVED(msrs, c) (msrs->counters[(c)].addr ? 1 : 0)
-#define CTR_READ(l, h, msrs, c) do {rdmsr(msrs->counters[(c)].addr, (l), (h)); } while (0)
-#define CTR_OVERFLOWED(n) (!((n) & (1U<<(counter_width-1))))
+#define CTR_OVERFLOWED(n) (!((n) & (1ULL<<(counter_width-1))))

#define CTRL_IS_RESERVED(msrs, c) (msrs->controls[(c)].addr ? 1 : 0)
#define CTRL_READ(l, h, msrs, c) do {rdmsr((msrs->controls[(c)].addr), (l), (h)); } while (0)
@@ -124,14 +123,14 @@
static int ppro_check_ctrs(struct pt_regs * const regs,
struct op_msrs const * const msrs)
{
- unsigned int low, high;
+ u64 val;
int i;

for (i = 0 ; i < num_counters; ++i) {
if (!reset_value[i])
continue;
- CTR_READ(low, high, msrs, i);
- if (CTR_OVERFLOWED(low)) {
+ rdmsrl(msrs->counters[i].addr, val);
+ if (CTR_OVERFLOWED(val)) {
oprofile_add_sample(regs, i);
wrmsrl(msrs->counters[i].addr, -reset_value[i]);
}

--
ak@linux.intel.com