Messages in this thread Patch in this message | | | Date | Fri, 19 Aug 2016 12:56:34 +0200 | From | Peter Zijlstra <> | Subject | Re: perf: fuzzer crashes immediately on AMD system |
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On Fri, Aug 19, 2016 at 12:01:30PM +0200, Peter Zijlstra wrote: > On Thu, Aug 18, 2016 at 10:46:31AM -0400, Vince Weaver wrote: > > On Thu, 18 Aug 2016, Vince Weaver wrote: > > > > > Tried the perf_fuzzer on my A10 fam15h/model13h system with 4.8-rc2 and it > > > falls over more or less immediately. > > > > > > This maps to variable_test_bit() > > > called by ctx = find_get_context(pmu, task, event); > > > in kernel/events/core.c:9467 > > > > > > It happens quickly enough I can probably track down the exact event that > > > causes this, if needed. > > > > I have a one line reproducer: > > > > perf stat -a -e amd_nb/config=0x37,config1=0x20/ /bin/ls > > OK, cannot reproduce on my fam15h/model1h. I'll go dig through the > various manuals to see if I can spot the fail. > > Huang could you either prod someone at AMD or do yourself, audit the AMD > perf code for all the various new models?
So this should obviously help a little in that it will limit the events you can program into the hardware.
Not at all sure that is what you're hitting though, because I cannot for the life of me figure how that would end up exploding in generic code.
--- arch/x86/events/amd/uncore.c | 47 +++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-)
diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c index e6131d4..8c314d7 100644 --- a/arch/x86/events/amd/uncore.c +++ b/arch/x86/events/amd/uncore.c @@ -174,8 +174,8 @@ static void amd_uncore_del(struct perf_event *event, int flags) static int amd_uncore_event_init(struct perf_event *event) { - struct amd_uncore *uncore; struct hw_perf_event *hwc = &event->hw; + struct amd_uncore *uncore; if (event->attr.type != event->pmu->type) return -ENOENT; @@ -215,6 +215,47 @@ static int amd_uncore_event_init(struct perf_event *event) return 0; } +static inline unsigned int amd_get_event_code(struct hw_perf_event *hwc) +{ + return ((hwc->config >> 24) & 0x0f00) | (hwc->config & 0x00ff); +} + +static int amd_uncore_l2_event_init(struct perf_event *event) +{ + int ret = amd_uncore_event_init(event); + unsigned int event_code; + + if (ret) + return ret; + + /* + * Fam16h L2I performance counter events are in the range: 0x060 - 0x07F + */ + event_code = amd_get_event_code(&event->hw); + if (event_code < 0x060 || event_code > 0x07F) + return -EINVAL; + + return 0; +} + +static int amd_uncore_nb_event_init(struct perf_event *event) +{ + int ret = amd_uncore_event_init(event); + unsigned int event_code; + + if (ret) + return ret; + + /* + * AMD NB events will have bits 0x0E0 set. + */ + event_code = amd_get_event_code(&event->hw); + if ((event_code & 0x0E0) != 0x0E0) + return -EINVAL; + + return 0; +} + static ssize_t amd_uncore_attr_show_cpumask(struct device *dev, struct device_attribute *attr, char *buf) @@ -266,7 +307,7 @@ static struct pmu amd_nb_pmu = { .task_ctx_nr = perf_invalid_context, .attr_groups = amd_uncore_attr_groups, .name = "amd_nb", - .event_init = amd_uncore_event_init, + .event_init = amd_uncore_nb_event_init, .add = amd_uncore_add, .del = amd_uncore_del, .start = amd_uncore_start, @@ -278,7 +319,7 @@ static struct pmu amd_l2_pmu = { .task_ctx_nr = perf_invalid_context, .attr_groups = amd_uncore_attr_groups, .name = "amd_l2", - .event_init = amd_uncore_event_init, + .event_init = amd_uncore_l2_event_init, .add = amd_uncore_add, .del = amd_uncore_del, .start = amd_uncore_start,
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