From: Arnaldo Carvalho de Melo <acme@kernel•org>
To: Ravi Bangoria <ravi.bangoria@linux•vnet.ibm.com>
Cc: linux-kernel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
peterz@infradead•org, mingo@redhat•com,
alexander.shishkin@linux•intel.com, treeze.taeung@gmail•com,
naveen.n.rao@linux•vnet.ibm.com, markus@trippelsdorf•de,
chris.ryder@arm•com, pawel.moll@arm•com, mhiramat@kernel•org,
rmk+kernel@arm•linux.org.uk, jolsa@kernel•org,
mpe@ellerman•id.au, hemant@linux•vnet.ibm.com,
namhyung@kernel•org
Subject: Re: [PATCH v6 4/7] perf annotate: Do not ignore call instruction with indirect target
Date: Tue, 20 Sep 2016 11:56:00 -0300 [thread overview]
Message-ID: <20160920145600.GD4973@kernel.org> (raw)
In-Reply-To: <57E14917.5070100@linux.vnet.ibm.com>
Em Tue, Sep 20, 2016 at 08:05:03PM +0530, Ravi Bangoria escreveu:
> On Monday 19 September 2016 09:14 PM, Arnaldo Carvalho de Melo wrote:
> > Em Fri, Aug 19, 2016 at 06:29:35PM +0530, Ravi Bangoria escreveu:
> >> Do not ignore call instruction with indirect target when its already
> >> identified as a call. This is an extension of commit e8ea1561952b
> >> ("perf annotate: Use raw form for register indirect call instructions")
> >> to generalize annotation for all instructions with indirect calls.
> >> This is needed for certain powerpc call instructions that use address
> >> in a register (such as bctrl, btarl, ...).
> >>
> >> Apart from that, when kcore is used to disassemble function, all call
> >> instructions were ignored. This patch will fix it as a side effect by
> >> not ignoring them. For example,
> >>
> >> Before (with kcore):
> >> mov %r13,%rdi
> >> callq 0xffffffff811a7e70
> >> ^ jmpq 64
> >> mov %gs:0x7ef41a6e(%rip),%al
> >>
> >> After (with kcore):
> >> mov %r13,%rdi
> >> > callq 0xffffffff811a7e70
> >> ^ jmpq 64
> >> mov %gs:0x7ef41a6e(%rip),%al
> > Ok, makes sense, but then now I have the -> and can't press enter to go
> > to that function, in fact for the case I'm using as a test, the
> > vsnprintf kernel function, I get:
> >
> > │ 56: test %al,%al
> > │ ↓ je 81
> > │ lea -0x38(%rbp),%rsi
> > │ mov %r15,%rdi
> > │ → callq 0xffffffff993e3230
> >
> > That 0xffffffff993e3230 should've been resolved to:
> >
> > [root@jouet ~]# grep ffffffff993e3230 /proc/kallsyms
> > ffffffff993e3230 t format_decode
> >
> > Trying to investigate why it doesn't...
>
> I investigated this.
>
> If this example is with kcore, then it's expected. Because, perf annotate does
> not inspect kallsyms when it can't find symbol name from disassembly itself.
>
> For example, disassembly of finish_task_switch,
Yeah, that was the case, up to yesterday, please take a look at my
perf/core branch, specifically this patch:
https://git.kernel.org/cgit/linux/kernel/git/acme/linux.git/commit/?id=4de86ebeb433aa59764a13ce851cba08d747e0e1
I'll do that for other instructions as well, like with 'mov
$0xabcdef,%rax' that will try to resolve that address to a variable.
Will try to continue processing your (and others) patches first tho :-)
- Arnaldo
> with kcore:
>
> ffffffff810cf1b0: mov $0x1,%esi
> ffffffff810cf1b5: mov $0x4,%edi
> ffffffff810cf1ba: callq 0xffffffff811aced0
> ffffffff810cf1bf: andb $0xfb,0x4c4(%rbx)
> ffffffff810cf1c6: jmpq 0xffffffff810cf0e9
> ffffffff810cf1cb: mov %rbx,%rsi
> ffffffff810cf1ce: mov %r13,%rdi
> ffffffff810cf1d1: callq 0xffffffff811a7e70
> ffffffff810cf1d6: jmpq 0xffffffff810cf0e4
>
> with debuginfo:
> ffffffff810cf1b0: mov $0x1,%esi
> ffffffff810cf1b5: mov $0x4,%edi
> ffffffff810cf1ba: callq ffffffff811aced0 <___perf_sw_event>
> ffffffff810cf1bf: andb $0xfb,0x4c4(%rbx)
> ffffffff810cf1c6: jmpq ffffffff810cf0e9 <finish_task_switch+0x69>
> ffffffff810cf1cb: mov %rbx,%rsi
> ffffffff810cf1ce: mov %r13,%rdi
> ffffffff810cf1d1: callq ffffffff811a7e70 <__perf_event_task_sched_in>
> ffffffff810cf1d6: jmpq ffffffff810cf0e4 <finish_task_switch+0x64>
>
> call__parse tries to find symbol from angle brackets which is not present
> in case of kcore.
>
> -Ravi
>
>
> > - Arnaldo
> >
> >> Suggested-by: Michael Ellerman <mpe@ellerman•id.au>
> >> [Suggested about 'bctrl' instruction]
> >> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux•vnet.ibm.com>
> >> ---
> >> Changes in v6:
> >> - No change
> >>
> >> tools/perf/util/annotate.c | 8 ++------
> >> 1 file changed, 2 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
> >> index ea07588..a05423b 100644
> >> --- a/tools/perf/util/annotate.c
> >> +++ b/tools/perf/util/annotate.c
> >> @@ -81,16 +81,12 @@ static int call__parse(struct ins_operands *ops, const char *norm_arch)
> >> return ops->target.name == NULL ? -1 : 0;
> >>
> >> indirect_call:
> >> - tok = strchr(endptr, '(');
> >> - if (tok != NULL) {
> >> + tok = strchr(endptr, '*');
> >> + if (tok == NULL) {
> >> ops->target.addr = 0;
> >> return 0;
> >> }
> >>
> >> - tok = strchr(endptr, '*');
> >> - if (tok == NULL)
> >> - return -1;
> >> -
> >> ops->target.addr = strtoull(tok + 1, NULL, 16);
> >> return 0;
> >> }
> >> --
> >> 2.5.5
next prev parent reply other threads:[~2016-09-20 14:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-19 12:59 [PATCH v6 0/7] perf: Cross arch annotate + few miscellaneous fixes Ravi Bangoria
2016-08-19 12:59 ` [PATCH v6 1/7] perf: Define macro for normalized arch names Ravi Bangoria
2016-08-19 12:59 ` [PATCH v6 2/7] perf annotate: Add cross arch annotate support Ravi Bangoria
2016-08-22 23:01 ` Kim Phillips
2016-08-23 2:17 ` Namhyung Kim
2016-08-23 20:36 ` Kim Phillips
2016-08-26 6:21 ` Namhyung Kim
2016-08-26 7:26 ` Ravi Bangoria
2016-08-27 0:40 ` [PATCH] perf annotate: cross arch annotate support fixes for ARM Kim Phillips
2016-08-19 12:59 ` [PATCH v6 3/7] perf annotate: Add support for powerpc Ravi Bangoria
2016-09-19 15:26 ` Arnaldo Carvalho de Melo
2016-08-19 12:59 ` [PATCH v6 4/7] perf annotate: Do not ignore call instruction with indirect target Ravi Bangoria
2016-09-19 15:44 ` Arnaldo Carvalho de Melo
2016-09-20 14:35 ` Ravi Bangoria
2016-09-20 14:56 ` Arnaldo Carvalho de Melo [this message]
2016-08-19 12:59 ` [PATCH v6 5/7] perf annotate: Show raw form for jump " Ravi Bangoria
2016-08-19 12:59 ` [PATCH v6 6/7] perf annotate: Support jump instruction with target as second operand Ravi Bangoria
2016-08-19 12:59 ` [PATCH v6 7/7] perf annotate: Fix jump target outside of function address range Ravi Bangoria
2016-09-07 15:39 ` [PATCH v6 0/7] perf: Cross arch annotate + few miscellaneous fixes Ravi Bangoria
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