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

Pekka J Enberg
2008-11-04T19:19:59Z

Hi Robert,

On Tue, 4 Nov 2008, Robert Richter wrote:
> your patchset breaks oprofile on Intel Core 2 cpus. I could bisect the
> bug for c493756..5951290. Please take a look at this and send me a fix.

Unfortunately I don't have my machine with me right now so I can't test
this, but don't we want something like this? Andi?

Pekka

>From 37d362c0262006be6a5d6a72b5993834afa776d7 Mon Sep 17 00:00:00 2001
From: Pekka Enberg <penberg@cs.helsinki.fi>
Date: Tue, 4 Nov 2008 21:17:47 +0200
Subject: [PATCH] oprofile: make perfmon nethalem only

Commit b99170288421c79f0c2efa8b33e26e65f4bb7fb8 ("oprofile: Implement Intel
architectural perfmon support") added perfmon support to newer Intel CPUs
(Core1+). The problem there is that it requires a patched oprofile userland to
work properly.

Fix that up by making oprofile perfmon support nethalem only.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---
arch/x86/oprofile/nmi_int.c | 7 +++++++
arch/x86/oprofile/op_model_ppro.c | 4 +++-
2 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
index 022cd41..1f4448e 100644
--- a/arch/x86/oprofile/nmi_int.c
+++ b/arch/x86/oprofile/nmi_int.c
@@ -426,8 +426,15 @@ static int __init ppro_init(char **cpu_type)

static int __init arch_perfmon_init(char **cpu_type)
{
+ __u8 cpu_model = boot_cpu_data.x86_model;
+
if (!cpu_has_arch_perfmon)
return 0;
+
+ /* Nethalem only */
+ if (cpu_model != 26)
+ return 0;
+
*cpu_type = "i386/arch_perfmon";
model = &op_arch_perfmon_spec;
arch_perfmon_setup_counters();
diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
index 0620d6d..1c91ba2 100644
--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -66,6 +66,7 @@ static void ppro_fill_in_addresses(struct op_msrs * const msrs)

static void ppro_setup_ctrs(struct op_msrs const * const msrs)
{
+ __u8 cpu_model = boot_cpu_data.x86_model;
unsigned int low, high;
int i;

@@ -76,7 +77,8 @@ static void ppro_setup_ctrs(struct op_msrs const * const msrs)
return;
}

- if (cpu_has_arch_perfmon) {
+ /* Nethalem only */
+ if (cpu_has_arch_perfmon && cpu_model == 26) {
union cpuid10_eax eax;
eax.full = cpuid_eax(0xa);
if (counter_width < eax.split.bit_width)
--
1.5.3.7