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authorStephane Eranian <eranian@google.com>2020-05-27 15:46:58 -0700
committerIngo Molnar <mingo@kernel.org>2020-05-28 07:58:55 +0200
commit4c953f879460bf65ea3c119354026b126fe8ee57 (patch)
tree12246945deb00e98d9413715cba8e944d66022f9 /arch/x86/events
parent2a3e3f73a23b4ff2c0065d3a42edc18ad94b7851 (diff)
downloadlinux-4c953f879460bf65ea3c119354026b126fe8ee57.tar.gz
perf/x86/rapl: Make perf_probe_msr() more robust and flexible
This patch modifies perf_probe_msr() by allowing passing of struct perf_msr array where some entries are not populated, i.e., they have either an msr address of 0 or no attribute_group pointer. This helps with certain call paths, e.g., RAPL. In case the grp is NULL, the default sysfs visibility rule applies which is to make the group visible. Without the patch, you would get a kernel crash with a NULL group. Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/20200527224659.206129-5-eranian@google.com
Diffstat (limited to 'arch/x86/events')
-rw-r--r--arch/x86/events/probe.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/arch/x86/events/probe.c b/arch/x86/events/probe.c
index c2ede2f3b277..136a1e847254 100644
--- a/arch/x86/events/probe.c
+++ b/arch/x86/events/probe.c
@@ -10,6 +10,11 @@ not_visible(struct kobject *kobj, struct attribute *attr, int i)
return 0;
}
+/*
+ * Accepts msr[] array with non populated entries as long as either
+ * msr[i].msr is 0 or msr[i].grp is NULL. Note that the default sysfs
+ * visibility is visible when group->is_visible callback is set.
+ */
unsigned long
perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
{
@@ -24,8 +29,16 @@ perf_msr_probe(struct perf_msr *msr, int cnt, bool zero, void *data)
if (!msr[bit].no_check) {
struct attribute_group *grp = msr[bit].grp;
+ /* skip entry with no group */
+ if (!grp)
+ continue;
+
grp->is_visible = not_visible;
+ /* skip unpopulated entry */
+ if (!msr[bit].msr)
+ continue;
+
if (msr[bit].test && !msr[bit].test(bit, data))
continue;
/* Virt sucks; you cannot tell if a R/O MSR is present :/ */