linux-kernel - Re: [PATCH 5.4 245/434] perf probe: Fix to list probe event with correct line number

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Message-ID: <20191230113509.GC884080@kroah.com>
Date:   Mon, 30 Dec 2019 12:35:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Thomas Backlund <tmb@...eia.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 5.4 245/434] perf probe: Fix to list probe event with
 correct line number

On Mon, Dec 30, 2019 at 01:00:14AM +0200, Thomas Backlund wrote:
> Den 29-12-2019 kl. 20:42, skrev Thomas Backlund:
> > Den 29-12-2019 kl. 19:24, skrev Greg Kroah-Hartman:
> > > From: Masami Hiramatsu <mhiramat@...nel.org>
> > > 
> > > [ Upstream commit 3895534dd78f0fd4d3f9e05ee52b9cdd444a743e ]
> > > 
> > > Since debuginfo__find_probe_point() uses dwarf_entrypc() for finding the
> > > entry address of the function on which a probe is, it will fail when the
> > > function DIE has only ranges attribute.
> > > 
> > > To fix this issue, use die_entrypc() instead of dwarf_entrypc().
> > > 
> > > Without this fix, perf probe -l shows incorrect offset:
> > > 
> > >    # perf probe -l
> > >      probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579263632@...k/linux/linux/kernel/cpu.c)
> > > 
> > >      probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask+18446744071579263752@...k/linux/linux/kernel/cpu.c)
> > > 
> > > 
> > > With this:
> > > 
> > >    # perf probe -l
> > >      probe:clear_tasks_mm_cpumask (on
> > > clear_tasks_mm_cpumask@...k/linux/linux/kernel/cpu.c)
> > >      probe:clear_tasks_mm_cpumask_1 (on
> > > clear_tasks_mm_cpumask:21@...k/linux/linux/kernel/cpu.c)
> > > 
> > > Committer testing:
> > > 
> > > Before:
> > > 
> > >    [root@...co ~]# perf probe -l
> > >      probe:clear_tasks_mm_cpumask (on
> > > clear_tasks_mm_cpumask+18446744071579765152@...nel/cpu.c)
> > >    [root@...co ~]#
> > > 
> > > After:
> > > 
> > >    [root@...co ~]# perf probe -l
> > >      probe:clear_tasks_mm_cpumask (on
> > > clear_tasks_mm_cpumask@...nel/cpu.c)
> > >    [root@...co ~]#
> > > 
> > > Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number
> > > with inline function")
> > > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > > Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > > Cc: Jiri Olsa <jolsa@...hat.com>
> > > Cc: Namhyung Kim <namhyung@...nel.org>
> > > Link: http://lore.kernel.org/lkml/157199321227.8075.14655572419136993015.stgit@devnote2
> > > 
> > > Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> > > Signed-off-by: Sasha Levin <sashal@...nel.org>
> > > ---
> > >   tools/perf/util/probe-finder.c | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/tools/perf/util/probe-finder.c
> > > b/tools/perf/util/probe-finder.c
> > > index cd9f95e5044e..7c8d30fb2b99 100644
> > > --- a/tools/perf/util/probe-finder.c
> > > +++ b/tools/perf/util/probe-finder.c
> > > @@ -1578,7 +1578,7 @@ int debuginfo__find_probe_point(struct
> > > debuginfo *dbg, unsigned long addr,
> > >           /* Get function entry information */
> > >           func = basefunc = dwarf_diename(&spdie);
> > >           if (!func ||
> > > -            dwarf_entrypc(&spdie, &baseaddr) != 0 ||
> > > +            die_entrypc(&spdie, &baseaddr) != 0 ||
> > >               dwarf_decl_line(&spdie, &baseline) != 0) {
> > >               lineno = 0;
> > >               goto post;
> > > @@ -1595,7 +1595,7 @@ int debuginfo__find_probe_point(struct
> > > debuginfo *dbg, unsigned long addr,
> > >           while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
> > >                           &indie)) {
> > >               /* There is an inline function */
> > > -            if (dwarf_entrypc(&indie, &_addr) == 0 &&
> > > +            if (die_entrypc(&indie, &_addr) == 0 &&
> > >                   _addr == addr) {
> > >                   /*
> > >                    * addr is at an inline function entry.
> > > 
> > 
> > 
> > still broken
> > 
> > /usr/bin/ld: perf-in.o: in function `debuginfo__find_probe_point':
> > /work/rpmbuild/BUILD/kernel-x86_64/linux-5.4/tools/perf/util/probe-finder.c:1616:
> > undefined reference to `die_entrypc'
> > 
> 
> 
> And the fix for the perf build errors I reported against:
> [PATCH 5.4 245/434] perf probe: Fix to list probe event with correct line
> number
> [PATCH 5.4 248/434] perf probe: Fix to probe an inline function which has no
> entry pc
> [PATCH 5.4 249/434] perf probe: Fix to show ranges of variables in functions
> without entry_pc
> [PATCH 5.4 250/434] perf probe: Fix to show inlined function callsite
> without entry_pc
> [PATCH 5.4 252/434] perf probe: Fix to probe a function which has no entry
> pc
> 
> is to add the missing:
> 
> From 91e2f539eeda26ab00bd03fae8dc434c128c85ed Mon Sep 17 00:00:00 2001
> From: Masami Hiramatsu <mhiramat@...nel.org>
> Date: Thu, 24 Oct 2019 18:12:54 +0900
> Subject: [PATCH] perf probe: Fix to show function entry line as probe-able

Thanks for this, now queued up.

greg k-h