Messages in this thread Patch in this message | | | Date | Wed, 4 Dec 2019 16:06:56 +0100 | From | Peter Zijlstra <> | Subject | Re: UBSAN: Undefined behaviour in arch/x86/events/intel/p6.c:116:29 |
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On Wed, Dec 04, 2019 at 01:15:40PM +0100, Jiri Olsa wrote: > On Tue, Dec 03, 2019 at 03:39:49PM +0200, Meelis Roos wrote: > > > Does something like so fix it? > > > > Unfortunately not (tested on top of todays git): > > hi, > which p6 model are you seeing this on? > how do you trigger that?
Triggers on any p6 model. I hacked up perf and used "qemu-system-x86_64 -cpu pentium2".
The below seems to cure things.
--- diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 9a89d98c55bd..f17417644665 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -1642,9 +1643,12 @@ static struct attribute_group x86_pmu_format_group __ro_after_init = { ssize_t events_sysfs_show(struct device *dev, struct device_attribute *attr, char *page) { - struct perf_pmu_events_attr *pmu_attr = \ + struct perf_pmu_events_attr *pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr); - u64 config = x86_pmu.event_map(pmu_attr->id); + u64 config = 0; + + if (pmu_attr->id < x86_pmu.max_events) + x86_pmu.event_map(pmu_attr->id); /* string trumps id */ if (pmu_attr->event_str) @@ -1713,6 +1717,9 @@ is_visible(struct kobject *kobj, struct attribute *attr, int idx) { struct perf_pmu_events_attr *pmu_attr; + if (idx >= x86_pmu.max_events) + return 0; + pmu_attr = container_of(attr, struct perf_pmu_events_attr, attr.attr); /* str trumps id */ return pmu_attr->event_str || x86_pmu.event_map(idx) ? attr->mode : 0;
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