Re: [PATCH] tools lib traceevent: add checks for returned EVENT_ERROR type

Dean Nelson
2015-08-07T13:02:28Z

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On 08/07/2015 07:16 AM, Namhyung Kim wrote:
> Hi,
>
> On Fri, Aug 7, 2015 at 7:59 PM, Jiri Olsa <jolsa@redhat.com> wrote:
>> On Mon, Aug 03, 2015 at 01:08:05PM -0400, Dean Nelson wrote:
>>> Running the following perf-stat command on an arm64 system produces the
>>> following result...
>>>
>>> [root@aarch64 ~]# perf stat -e kmem:mm_page_alloc -a sleep 1
>>> Warning: [kmem:mm_page_alloc] function sizeof not defined
>>> Warning: Error: expected type 4 but read 0
>>> Segmentation fault
>
> Oops,
>
>
>>> [root@aarch64 ~]#
>>
>> hum, what kernel are you running on? I dont see that warning
>> on my system:
>>
>> [jolsa@krava perf]$ sudo ./perf stat -e kmem:mm_page_alloc -a sleep 1
>>
>> Performance counter stats for 'system wide':
>>
>> 227 kmem:mm_page_alloc
>>
>> 1.000762466 seconds time elapsed
>>
>> Cc-ing Namhyung
>
> Yeah, it seems his kernel has sizeof() somewhere in the event format.
> Anyway, it's not good to see a segfault.
>
> Dean, could you share your event format file?
>
> $ sudo cat /sys/kernel/debug/tracing/events/kmem/mm_page_alloc/format

Sure, I've attached it. See my other email in reply to jirka's question
about what kernel I was running on, for some details about where the
sizeof operator comes from.

>
> Thanks,
> Namhyung
>
>
>>
>>>
>>> The second warning message and SIGSEGV stem from the issue expressed in the
>>> first warning message, and are the result of ignoring the EVENT_ERROR type
>>> returned back through the call chain.
>>>
>>> Dealing with the first warning message is beyond the scope of this patch. But
>>> the second warning is addressed by this patch's first hunk. And the SIGSEGV is
>>> eliminated by its second hunk.
>>>
>>> Signed-off-by: Dean Nelson <dnelson@redhat.com>
>>> ---
>>> tools/lib/traceevent/event-parse.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
>>> index cc25f05..72e2933 100644
>>> --- a/tools/lib/traceevent/event-parse.c
>>> +++ b/tools/lib/traceevent/event-parse.c
>>> @@ -1680,6 +1680,9 @@ process_cond(struct event_format *event, struct print_arg *top, char **tok)
>>> type = process_arg(event, left, &token);
>>>
>>> again:
>>> + if (type == EVENT_ERROR)
>>> + goto out_free;
>>> +
>>> /* Handle other operations in the arguments */
>>> if (type == EVENT_OP && strcmp(token, ":") != 0) {
>>> type = process_op(event, left, &token);
>>> @@ -1940,7 +1943,7 @@ process_op(struct event_format *event, struct print_arg *arg, char **tok)
>>>
>>> type = process_arg_token(event, right, tok, type);
>>>
>>> - if (right->type == PRINT_OP &&
>>> + if (type != EVENT_ERROR && right->type == PRINT_OP &&
>>> get_op_prio(arg->op.op) < get_op_prio(right->op.op)) {
>>> struct print_arg tmp;
>>>
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[-- Attachment #2: kmem-mm_page_alloc-format --]
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name: mm_page_alloc
ID: 360
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;

field:unsigned long pfn; offset:8; size:8; signed:0;
field:unsigned int order; offset:16; size:4; signed:0;
field:gfp_t gfp_flags; offset:20; size:4; signed:0;
field:int migratetype; offset:24; size:4; signed:1;

print fmt: "page=%p pfn=%lu order=%d migratetype=%d gfp_flags=%s", REC->pfn != -1UL ? (((struct page *)((((0xffffffffffffffffUL) << ((42) - 1)) - (1UL << ((16 - 3) * 2 + 3)) - (((((1UL << ((42) - 16)) * sizeof(struct page))) + ((typeof(((1UL << ((42) - 16)) * sizeof(struct page))))(((1UL << ((16 - 3) * 2 + 3)))) - 1)) & ~((typeof(((1UL << ((42) - 16)) * sizeof(struct page))))(((1UL << ((16 - 3) * 2 + 3)))) - 1)) - 0x00010000) + 0x00010000)) + (REC->pfn)) : ((void *)0), REC->pfn != -1UL ? REC->pfn : 0, REC->order, REC->migratetype, (REC->gfp_flags) ? __print_flags(REC->gfp_flags, "|", {(unsigned long)(((((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u) | (( gfp_t)0x20000u)) | (( gfp_t)0x02u)) | (( gfp_t)0x08u)) | (( gfp_t)0x4000u) | (( gfp_t)0x10000u) | (( gfp_t)0x1000u) | (( gfp_t)0x200u) | (( gfp_t)0x400000u)), "GFP_TRANSHUGE"}, {(unsigned long)((((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u) | (( gfp_t)0x20000u)) | (( gfp_t)0x02u)) | (( gfp_t)0x08u)), "GFP_HIGHUSER_MOVABLE"}, {(unsigned long)(((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u) | (( gfp_t)0x20000u)) | (( gfp_t)0x02u)), "GFP_HIGHUSER"}, {(unsigned long)((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u) | (( gfp_t)0x20000u)), "GFP_USER"}, {(unsigned long)((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u) | (( gfp_t)0x80000u)), "GFP_TEMPORARY"}, {(unsigned long)((( gfp_t)0x10u) | (( gfp_t)0x40u) | (( gfp_t)0x80u)), "GFP_KERNEL"}, {(unsigned long)((( gfp_t)0x10u) | (( gfp_t)0x40u)), "GFP_NOFS"}, {(unsigned long)((( gfp_t)0x20u)), "GFP_ATOMIC"}, {(unsigned long)((( gfp_t)0x10u)), "GFP_NOIO"}, {(unsigned long)(( gfp_t)0x20u), "GFP_HIGH"}, {(unsigned long)(( gfp_t)0x10u), "GFP_WAIT"}, {(unsigned long)(( gfp_t)0x40u), "GFP_IO"}, {(unsigned long)(( gfp_t)0x100u), "GFP_COLD"}, {(unsigned long)(( gfp_t)0x200u), "GFP_NOWARN"}, {(unsigned long)(( gfp_t)0x400u), "GFP_REPEAT"}, {(unsigned long)(( gfp_t)0x800u), "GFP_NOFAIL"}, {(unsigned long)(( gfp_t)0x1000u), "GFP_NORETRY"}, {(unsigned long)(( gfp_t)0x4000u), "GFP_COMP"}, {(unsigned long)(( gfp_t)0x8000u), "GFP_ZERO"}, {(unsigned long)(( gfp_t)0x10000u), "GFP_NOMEMALLOC"}, {(unsigned long)(( gfp_t)0x2000u), "GFP_MEMALLOC"}, {(unsigned long)(( gfp_t)0x20000u), "GFP_HARDWALL"}, {(unsigned long)(( gfp_t)0x40000u), "GFP_THISNODE"}, {(unsigned long)(( gfp_t)0x80000u), "GFP_RECLAIMABLE"}, {(unsigned long)(( gfp_t)0x08u), "GFP_MOVABLE"}, {(unsigned long)(( gfp_t)0x200000u), "GFP_NOTRACK"}, {(unsigned long)(( gfp_t)0x400000u), "GFP_NO_KSWAPD"}, {(unsigned long)(( gfp_t)0x800000u), "GFP_OTHER_NODE"} ) : "GFP_NOWAIT"