From: Jeremy Linton <jeremy.linton@arm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, acme@redhat.com,
namhyung@kernel.org, kapileshwar.singh@arm.com,
scottwood@freescale.com, hekuang@huawei.com
Subject: Re: [RFC/PATCH] perf: Add sizeof operator support
Date: Fri, 17 Jun 2016 11:32:08 -0500 [thread overview]
Message-ID: <57642608.9070504@arm.com> (raw)
In-Reply-To: <20160617121736.023f009f@gandalf.local.home>
Hi Steven,
On 06/17/2016 11:17 AM, Steven Rostedt wrote:
> On Tue, 14 Jun 2016 11:38:32 -0500
> Jeremy Linton <jeremy.linton@arm.com> wrote:
>
>> There are a fair number of tracepoints in the kernel making
>> use of the sizeof operator. Allow perf to understand some of
>> those cases, and report a more informative error message for
>> the ones it cannot understand.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
>> ---
>>
>> So this is as much a RFC as a patch because the use of sizeof
>> seems to extend to structures, pointers, etc that aren't easy
>> to deduce from userspace. I'm not sure what the correct solution
>> should be in those cases.
>>
>> tools/lib/traceevent/event-parse.c | 46 ++++++++++++++++++++++++++++++++++++++
(trimming)
>> +
>> + if (strcmp(token, "__u64") == 0) {
>> + if (asprintf(&arg->atom.atom, "%zd", sizeof(__u64)) < 0)
>> + goto out_free_atom;
>> + } else if (strcmp(token, "__u32") == 0) {
>> + if (asprintf(&arg->atom.atom, "%zd", sizeof(__u32)) < 0)
>> + goto out_free_atom;
>
> What events are doing sizeof(__u64) and sizeof(__u32)?
>
> First, that's useless, as sizeof(__u64) will always be 8, and
> sizeof(__u32) will always be 4.
>
> What exactly is this fixing?
It starts to fix things like:
kmem:mm_page_alloc
Warning: [kmem:mm_page_alloc] function sizeof not defined
or:
# perf stat -e kvm:kvm_arm_set_regset -- true
Warning: [kvm:kvm_arm_set_regset] function sizeof not defined
Warning: Error: expected type 5 but read 0
*** Error in `perf': double free or corruption (fasttop):
0x00000000303f5930 ***
There is a RH bug about it (and the "~" operator, which has been fixed)
here: https://bugzilla.redhat.com/show_bug.cgi?id=1298229
Thanks for taking a look at this,
next prev parent reply other threads:[~2016-06-17 16:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 16:38 [RFC/PATCH] perf: Add sizeof operator support Jeremy Linton
2016-06-17 16:17 ` Steven Rostedt
2016-06-17 16:32 ` Jeremy Linton [this message]
2016-06-17 16:50 ` Steven Rostedt
2016-06-17 18:57 ` Jeremy Linton
2016-06-17 19:08 ` Steven Rostedt
2016-06-20 0:29 ` Namhyung Kim
2017-04-30 22:06 ` Jon Masters
2017-05-02 11:47 ` Jeremy Linton
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