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powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

PATCH In review Benjamin Herrenschmidt 3 participants 5 messages Aug 6, 2009 PowerPC

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Benjamin Herrenschmidt

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#0 lore raw

PATCH 1/1 powerpc/perfctr: Check oprofile_cpu_type for NULL before using it

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 <[email protected]>
---
 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(-)
arch/powerpc/kernel/mpc7450-pmu.c +2 -1
index c244133..cc466d0 100644
@@ -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);
arch/powerpc/kernel/power4-pmu.c +2 -1
index db90b0c..3c90a3d 100644
@@ -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);
arch/powerpc/kernel/power5+-pmu.c +3 -2
index f4adca8..31918af 100644
@@ -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);
arch/powerpc/kernel/power5-pmu.c +2 -1
index 29b2c6c..867f6f6 100644
@@ -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);
arch/powerpc/kernel/power6-pmu.c +2 -1
index 09ae5bf..fa21890 100644
@@ -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);
arch/powerpc/kernel/power7-pmu.c +2 -1
index 5a9f5cb..388cf57 100644
@@ -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);
arch/powerpc/kernel/ppc970-pmu.c +3 -2
index 833097a..75dccb7 100644
@@ -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);
Signature · 1 line
1.6.0.4
#1 lore raw
Quoted 4 lines · 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.

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.

Signature · 2 lines
David Woodhouse                            Open Source Technology Centre
[email protected]                              Intel Corporation
author
#2 lore raw
Quoted 8 lines · David Woodhouse
Quoted 4 lines · 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.

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

.... today :-)

Quoted 1 line

Of course, adding the check probably makes sense anyway.

Yup, better safe.

Cheers,
Ben.

#3 lore raw
In reply to Benjamin Herrenschmidt
Quoted 6 lines · 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.

(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

..

Review

Quoted 1 line
(quoted diff) +1 -0
+	if (!cur_cpu_spec->oprofile_cpu_type ||

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

Perhaps:

arch/powerpc/include/asm/cputable.h +5 -0
index 80f315e..956cbc3 100644
@@ -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

author
#4 lore raw
Quoted 2 lines · Michael Ellerman

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.