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Subject: Re: perf: fuzzer causes crash in new XMM code
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     Vince Weaver <vincent.weaver@maine.edu>,
        Andi Kleen <ak@linux.intel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Stephane Eranian <eranian@google.com>,
        Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org
References: <alpine.DEB.2.21.1905221154300.22830@macbook-air>
 <a7cde307-8c53-14b5-2272-03dd3a8985c6@linux.intel.com>
 <20190522225006.GD11325@krava>
From:   "Liang, Kan" <kan.liang@linux.intel.com>
Message-ID: <cecf84af-d79e-2134-8443-e934609d13b5@linux.intel.com>
Date:   Thu, 23 May 2019 08:48:30 -0400
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On 5/22/2019 6:50 PM, Jiri Olsa wrote:
> On Wed, May 22, 2019 at 05:54:58PM -0400, Liang, Kan wrote:
> 
> SNIP
> 
>>> [ 9680.197779] RSP: 002b:00007fff595603a8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13
>>> [ 9680.205489] RAX: 0000000000004985 RBX: 000000000000000c RCX: 00000000000365ca
>>> [ 9680.212748] RDX: 00001e15d36cec84 RSI: 0000000000000000 RDI: 0000000000000001
>>> [ 9680.220059] RBP: 00007fff595603c0 R08: 0000000000000000 R09: 00007fccbb62e540
>>> [ 9680.227362] R10: fffffffffffffd4e R11: 0000000000000246 R12: 000055dad779a4c0
>>> [ 9680.234630] R13: 00007fff595627b0 R14: 0000000000000000 R15: 0000000000000000
>>> [ 9680.310017] ---[ end trace 511b9368cf14c65a ]---
>>>
>>
>> Hi Vince,
>>
>> Thanks for the test.
>>
>> XMM registers can only collected by hardware PEBS events. We should disable
>> it for all software/probe events.
> 
> I think you should also include HW non-PEBS events
> in those checks below

The HW non-PEBS events have been checked in x86_pmu_hw_config().
Only the software/probe events are missed.

Thanks,
Kan

> 
> jirka
> 
>>
>> Could you please try the patch as below?
>>
>> Thanks,
>> Kan
>>
>>  From 0136d8374c2db65b125c8d92b661c96e8d21adb0 Mon Sep 17 00:00:00 2001
>> From: Kan Liang <kan.liang@linux.intel.com>
>> Date: Wed, 22 May 2019 12:14:16 -0700
>> Subject: [PATCH] perf/x86: Disable non generic regs for software/probe
>> events
>>
>> The perf fuzzer caused skylake machine to crash.
>>
>> [ 9680.085831] Call Trace:
>> [ 9680.088301]  <IRQ>
>> [ 9680.090363]  perf_output_sample_regs+0x43/0xa0
>> [ 9680.094928]  perf_output_sample+0x3aa/0x7a0
>> [ 9680.099181]  perf_event_output_forward+0x53/0x80
>> [ 9680.103917]  __perf_event_overflow+0x52/0xf0
>> [ 9680.108266]  ? perf_trace_run_bpf_submit+0xc0/0xc0
>> [ 9680.113108]  perf_swevent_hrtimer+0xe2/0x150
>> [ 9680.117475]  ? check_preempt_wakeup+0x181/0x230
>> [ 9680.122091]  ? check_preempt_curr+0x62/0x90
>> [ 9680.126361]  ? ttwu_do_wakeup+0x19/0x140
>> [ 9680.130355]  ? try_to_wake_up+0x54/0x460
>> [ 9680.134366]  ? reweight_entity+0x15b/0x1a0
>> [ 9680.138559]  ? __queue_work+0x103/0x3f0
>> [ 9680.142472]  ? update_dl_rq_load_avg+0x1cd/0x270
>> [ 9680.147194]  ? timerqueue_del+0x1e/0x40
>> [ 9680.151092]  ? __remove_hrtimer+0x35/0x70
>> [ 9680.155191]  __hrtimer_run_queues+0x100/0x280
>> [ 9680.159658]  hrtimer_interrupt+0x100/0x220
>> [ 9680.163835]  smp_apic_timer_interrupt+0x6a/0x140
>> [ 9680.168555]  apic_timer_interrupt+0xf/0x20
>> [ 9680.172756]  </IRQ>
>>
>> The XMM registers can only be collected by hardware PEBS events, not
>> software/probe events.
>>
>> Add has_non_generic_regs() to check if non-generic regs, e.g. XMM on
>> X86, are applied for software/probe events. If yes, return -EOPNOTSUPP.
>>
>> Add __weak function non_generic_regs_mask() to return the mask of
>> non-generic regs. For X86, the mask of non-generic regs equals to the
>> mask of XMM registers.
>>
>> Fixes: 878068ea270e ("perf/x86: Support outputting XMM registers")
>> Reported-by: Vince Weaver <vincent.weaver@maine.edu>
>> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>> ---
>>   arch/x86/kernel/perf_regs.c |  5 +++++
>>   include/linux/perf_regs.h   |  2 ++
>>   kernel/events/core.c        | 37 +++++++++++++++++++++++++++++++++++++
>>   3 files changed, 44 insertions(+)
>>
>> diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
>> index 07c30ee..86ffe5a 100644
>> --- a/arch/x86/kernel/perf_regs.c
>> +++ b/arch/x86/kernel/perf_regs.c
>> @@ -57,6 +57,11 @@ static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = {
>>   #endif
>>   };
>>
>> +u64 non_generic_regs_mask(void)
>> +{
>> +	return (~((1ULL << PERF_REG_X86_XMM0) - 1));
>> +}
>> +
>>   u64 perf_reg_value(struct pt_regs *regs, int idx)
>>   {
>>   	struct x86_perf_regs *perf_regs;
>> diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
>> index 4767474..c1c3454 100644
>> --- a/include/linux/perf_regs.h
>> +++ b/include/linux/perf_regs.h
>> @@ -9,6 +9,8 @@ struct perf_regs {
>>   	struct pt_regs	*regs;
>>   };
>>
>> +u64 non_generic_regs_mask(void);
>> +
>>   #ifdef CONFIG_HAVE_PERF_REGS
>>   #include <asm/perf_regs.h>
>>   u64 perf_reg_value(struct pt_regs *regs, int idx);
>> diff --git a/kernel/events/core.c b/kernel/events/core.c
>> index abbd4b3..14da1d9 100644
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -8457,6 +8457,19 @@ static void sw_perf_event_destroy(struct perf_event
>> *event)
>>   	swevent_hlist_put();
>>   }
>>
>> +u64 __weak non_generic_regs_mask(void)
>> +{
>> +	return 0;
>> +}
>> +
>> +static inline bool has_non_generic_regs(struct perf_event *event)
>> +{
>> +	u64 mask = non_generic_regs_mask();
>> +
>> +	return ((event->attr.sample_regs_user & mask) ||
>> +		(event->attr.sample_regs_intr & mask));
>> +}
>> +
>>   static int perf_swevent_init(struct perf_event *event)
>>   {
>>   	u64 event_id = event->attr.config;
>> @@ -8470,6 +8483,10 @@ static int perf_swevent_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	switch (event_id) {
>>   	case PERF_COUNT_SW_CPU_CLOCK:
>>   	case PERF_COUNT_SW_TASK_CLOCK:
>> @@ -8633,6 +8650,10 @@ static int perf_tp_event_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	err = perf_trace_init(event);
>>   	if (err)
>>   		return err;
>> @@ -8722,6 +8743,10 @@ static int perf_kprobe_event_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
>>   	err = perf_kprobe_init(event, is_retprobe);
>>   	if (err)
>> @@ -8782,6 +8807,10 @@ static int perf_uprobe_event_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	is_retprobe = event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE;
>>   	ref_ctr_offset = event->attr.config >> PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
>>   	err = perf_uprobe_init(event, ref_ctr_offset, is_retprobe);
>> @@ -9562,6 +9591,10 @@ static int cpu_clock_event_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	perf_swevent_init_hrtimer(event);
>>
>>   	return 0;
>> @@ -9643,6 +9676,10 @@ static int task_clock_event_init(struct perf_event
>> *event)
>>   	if (has_branch_stack(event))
>>   		return -EOPNOTSUPP;
>>
>> +	/* only support generic regs */
>> +	if (has_non_generic_regs(event))
>> +		return -EOPNOTSUPP;
>> +
>>   	perf_swevent_init_hrtimer(event);
>>
>>   	return 0;
>> -- 
>> 2.7.4
>>
>>
>>