[PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[Benjamin Herrenschmidt]

If the current CPU doesn't support performance counters,
cur_cpu_spec->oprofile_cpu_type can be NULL. The current
perfctr modules don't test for that case and would thus
crash.

Bug reported by David Woodhouse

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
 arch/powerpc/kernel/mpc7450-pmu.c |    3 ++-
 arch/powerpc/kernel/power4-pmu.c  |    3 ++-
 arch/powerpc/kernel/power5+-pmu.c |    5 +++--
 arch/powerpc/kernel/power5-pmu.c  |    3 ++-
 arch/powerpc/kernel/power6-pmu.c  |    3 ++-
 arch/powerpc/kernel/power7-pmu.c  |    3 ++-
 arch/powerpc/kernel/ppc970-pmu.c  |    5 +++--
 7 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/kernel/mpc7450-pmu.c b/arch/powerpc/kernel/mpc7450-pmu.c
index c244133..cc466d0 100644
--- a/arch/powerpc/kernel/mpc7450-pmu.c
+++ b/arch/powerpc/kernel/mpc7450-pmu.c
@@ -407,7 +407,8 @@ struct power_pmu mpc7450_pmu = {
 
 static int init_mpc7450_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc/7450"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc/7450"))
 		return -ENODEV;
 
 	return register_power_pmu(&mpc7450_pmu);
diff --git a/arch/powerpc/kernel/power4-pmu.c b/arch/powerpc/kernel/power4-pmu.c
index db90b0c..3c90a3d 100644
--- a/arch/powerpc/kernel/power4-pmu.c
+++ b/arch/powerpc/kernel/power4-pmu.c
@@ -606,7 +606,8 @@ static struct power_pmu power4_pmu = {
 
 static int init_power4_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power4"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power4"))
 		return -ENODEV;
 
 	return register_power_pmu(&power4_pmu);
diff --git a/arch/powerpc/kernel/power5+-pmu.c b/arch/powerpc/kernel/power5+-pmu.c
index f4adca8..31918af 100644
--- a/arch/powerpc/kernel/power5+-pmu.c
+++ b/arch/powerpc/kernel/power5+-pmu.c
@@ -678,8 +678,9 @@ static struct power_pmu power5p_pmu = {
 
 static int init_power5p_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5+")
-	    && strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5++"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5+")
+	     && strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5++")))
 		return -ENODEV;
 
 	return register_power_pmu(&power5p_pmu);
diff --git a/arch/powerpc/kernel/power5-pmu.c b/arch/powerpc/kernel/power5-pmu.c
index 29b2c6c..867f6f6 100644
--- a/arch/powerpc/kernel/power5-pmu.c
+++ b/arch/powerpc/kernel/power5-pmu.c
@@ -618,7 +618,8 @@ static struct power_pmu power5_pmu = {
 
 static int init_power5_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power5"))
 		return -ENODEV;
 
 	return register_power_pmu(&power5_pmu);
diff --git a/arch/powerpc/kernel/power6-pmu.c b/arch/powerpc/kernel/power6-pmu.c
index 09ae5bf..fa21890 100644
--- a/arch/powerpc/kernel/power6-pmu.c
+++ b/arch/powerpc/kernel/power6-pmu.c
@@ -537,7 +537,8 @@ static struct power_pmu power6_pmu = {
 
 static int init_power6_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power6"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power6"))
 		return -ENODEV;
 
 	return register_power_pmu(&power6_pmu);
diff --git a/arch/powerpc/kernel/power7-pmu.c b/arch/powerpc/kernel/power7-pmu.c
index 5a9f5cb..388cf57 100644
--- a/arch/powerpc/kernel/power7-pmu.c
+++ b/arch/powerpc/kernel/power7-pmu.c
@@ -366,7 +366,8 @@ static struct power_pmu power7_pmu = {
 
 static int init_power7_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power7"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power7"))
 		return -ENODEV;
 
 	return register_power_pmu(&power7_pmu);
diff --git a/arch/powerpc/kernel/ppc970-pmu.c b/arch/powerpc/kernel/ppc970-pmu.c
index 833097a..75dccb7 100644
--- a/arch/powerpc/kernel/ppc970-pmu.c
+++ b/arch/powerpc/kernel/ppc970-pmu.c
@@ -488,8 +488,9 @@ static struct power_pmu ppc970_pmu = {
 
 static int init_ppc970_pmu(void)
 {
-	if (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/970")
-	    && strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/970MP"))
+	if (!cur_cpu_spec->oprofile_cpu_type ||
+	    (strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/970")
+	     && strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/970MP")))
 		return -ENODEV;
 
 	return register_power_pmu(&ppc970_pmu);
-- 
1.6.0.4

Re: [PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[David Woodhouse]

On Thu, 2009-08-06 at 14:02 +1000, Benjamin Herrenschmidt wrote:
> If the current CPU doesn't support performance counters,
> cur_cpu_spec->oprofile_cpu_type can be NULL. The current
> perfctr modules don't test for that case and would thus
> crash.

It can't actually be NULL on a 64-bit CPU; all 64-bit CPUs in the table
have ->oprofile_cpu_type set.

Of course, adding the check probably makes sense anyway.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation

Re: [PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[Benjamin Herrenschmidt]

On Thu, 2009-08-06 at 07:41 +0100, David Woodhouse wrote:
> On Thu, 2009-08-06 at 14:02 +1000, Benjamin Herrenschmidt wrote:
> > If the current CPU doesn't support performance counters,
> > cur_cpu_spec->oprofile_cpu_type can be NULL. The current
> > perfctr modules don't test for that case and would thus
> > crash.
> 
> It can't actually be NULL on a 64-bit CPU; all 64-bit CPUs in the table
> have ->oprofile_cpu_type set.

 .... today :-)

> Of course, adding the check probably makes sense anyway.

Yup, better safe.

Cheers,
Ben.

Re: [PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[Michael Ellerman]

On Thu, 2009-08-06 at 14:02 +1000, Benjamin Herrenschmidt wrote:
> If the current CPU doesn't support performance counters,
> cur_cpu_spec->oprofile_cpu_type can be NULL. The current
> perfctr modules don't test for that case and would thus
> crash.

> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||
..
> +	if (!cur_cpu_spec->oprofile_cpu_type ||

Typing it seven times didn't make you think "how about a helper?" :)

Perhaps:

diff --git a/arch/powerpc/include/asm/cputable.h b/arch/powerpc/include/asm/cput
index 80f315e..956cbc3 100644
--- a/arch/powerpc/include/asm/cputable.h
+++ b/arch/powerpc/include/asm/cputable.h
@@ -123,6 +123,11 @@ struct cpu_spec {
 
 extern struct cpu_spec         *cur_cpu_spec;
 
+static inline int oprofile_cpu_type_matches(const char *s)
+{
+       return s && (strcmp(cur_cpu_spec->oprofile_cpu_type, s) == 0);
+}
+
 extern unsigned int __start___ftr_fixup, __stop___ftr_fixup;
 
 extern struct cpu_spec *identify_cpu(unsigned long offset, unsigned int pvr);


And then callsites become:

 static int init_mpc7450_pmu(void)
 {
        if (!oprofile_cpu_type_matches("ppc/7450"))
                return -ENODEV;


cheers

Re: [PATCH] powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

[Benjamin Herrenschmidt]

On Thu, 2009-08-06 at 21:03 +1000, Michael Ellerman wrote:
> 
> Typing it seven times didn't make you think "how about a helper?" :)

Copy/paste works fine :-) Seriously, I did think about it, but a couple
of cases test more than one string so a totally trivial helper wouldn't
do and I couldn't be bothered doing anything more complicated while
under influenza :-) You are welcome to do something nicer for .32.

BTW. While at it, I think we should move that stuff to a separate
subdir too.

Cheers,
Ben.