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Message-Id: <20210715135821.c58ca2ff97b0c1db449db0b4@kernel.org>
Date: Thu, 15 Jul 2021 13:58:21 +0900
From: Masami Hiramatsu <mhiramat@...nel.org>
To: Yang Jihong <yangjihong1@...wei.com>
Cc: <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
<mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
<jolsa@...hat.com>, <namhyung@...nel.org>, <irogers@...gle.com>,
<fche@...hat.com>, <ravi.bangoria@...ux.ibm.com>,
<yao.jin@...ux.intel.com>, <srikar@...ux.vnet.ibm.com>,
<Jianlin.Lv@....com>, <lihuafei1@...wei.com>,
<linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf probe: Fix add event failed when 32-bit perf
running in 64-bit kernel
On Thu, 15 Jul 2021 09:20:01 +0800
Yang Jihong <yangjihong1@...wei.com> wrote:
> Hello Hiramatsu,
>
> On 2021/7/14 16:35, Masami Hiramatsu wrote:
> > Hi Yang,
> >
> > On Wed, 14 Jul 2021 14:54:32 +0800
> > Yang Jihong <yangjihong1@...wei.com> wrote:
> >
> >> The "address" member of "struct probe_trace_point" uses long data type.
> >> If kernel is 64-bit and perf program is 32-bit, size of "address" variable is
> >> 32 bits. As a result, upper 32 bits of address read from kernel are truncated,
> >> An error occurs during address comparison in kprobe_warn_out_range function.
> >
> > Good catch!
> > I didn't imagine that such a use case. But that is important because perf
> > probe can be used for cross-arch probe definition too.
> >
> >>
> >> Before:
> >>
> >> # perf probe -a schedule
> >> schedule is out of .text, skip it.
> >> Error: Failed to add events.
> >>
> >> Solution:
> >> Change data type of "address" variable to u64 and change corresponding
> >> address printing and value assignment.
> >
> > OK, as far as I can see, the other parts of the perf also uses u64 for
> > "address" storing variables. (e.g. symbols, maps etc.)
> >
> >>
> >> After:
> >>
> >> # perf.new.new probe -a schedule
> >> Added new event:
> >> probe:schedule (on schedule)
> >>
> >> You can now use it in all perf tools, such as:
> >>
> >> perf record -e probe:schedule -aR sleep 1
> >>
> >> # perf probe -l
> >> probe:schedule (on schedule)
> >
> > I think you missed one thing here.
> > Usually, this shows the filename and line number of schedule().
> Yes, I tried the following diff and now it can show the filename (as is
> function entry, relative line number is 0), thank you very much :)
>
> The test result in my environment is as follows:
>
> # perf probe -a schedule
> Added new event:
> probe:schedule (on schedule)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe:schedule -aR sleep 1
>
> # perf probe -l schedule -k vmlinux.debug
> probe:schedule (on schedule@...nel/sched/core.c)
>
OK, good!
>
> Can I put the following diff together and submit a v2 patch?
Yes, please include this fix in your patch, because it is what your patch
has to do :)
Thank you!
> >
> > Could you try below diff?
> >
> > diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> > index 7d2ba8419b0c..609ca1671501 100644
> > --- a/tools/perf/util/dwarf-aux.c
> > +++ b/tools/perf/util/dwarf-aux.c
> > @@ -113,14 +113,14 @@ static Dwarf_Line *cu_getsrc_die(Dwarf_Die *cu_die, Dwarf_Addr addr)
> > *
> > * Find a line number and file name for @addr in @cu_die.
> > */
> > -int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr,
> > - const char **fname, int *lineno)
> > +int cu_find_lineinfo(Dwarf_Die *cu_die, Dwarf_Addr addr,
> > + const char **fname, int *lineno)
> > {
> > Dwarf_Line *line;
> > Dwarf_Die die_mem;
> > Dwarf_Addr faddr;
> >
> > - if (die_find_realfunc(cu_die, (Dwarf_Addr)addr, &die_mem)
> > + if (die_find_realfunc(cu_die, addr, &die_mem)
> > && die_entrypc(&die_mem, &faddr) == 0 &&
> > faddr == addr) {
> > *fname = dwarf_decl_file(&die_mem);
> > @@ -128,7 +128,7 @@ int cu_find_lineinfo(Dwarf_Die *cu_die, unsigned long addr,
> > goto out;
> > }
> >
> > - line = cu_getsrc_die(cu_die, (Dwarf_Addr)addr);
> > + line = cu_getsrc_die(cu_die, addr);
> > if (line && dwarf_lineno(line, lineno) == 0) {
> > *fname = dwarf_linesrc(line, NULL, NULL);
> > if (!*fname)
> > diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
> > index cb99646843a9..7ee0fa19b5c4 100644
> > --- a/tools/perf/util/dwarf-aux.h
> > +++ b/tools/perf/util/dwarf-aux.h
> > @@ -19,7 +19,7 @@ const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname);
> > const char *cu_get_comp_dir(Dwarf_Die *cu_die);
> >
> > /* Get a line number and file name for given address */
> > -int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr,
> > +int cu_find_lineinfo(Dwarf_Die *cudie, Dwarf_Addr addr,
> > const char **fname, int *lineno);
> >
> > /* Walk on functions at given address */
> > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> > index 8ba01bbdf05c..50d861a80f57 100644
> > --- a/tools/perf/util/probe-finder.c
> > +++ b/tools/perf/util/probe-finder.c
> > @@ -1727,7 +1727,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, u64 addr,
> > }
> >
> > /* Find a corresponding line (filename and lineno) */
> > - cu_find_lineinfo(&cudie, addr, &fname, &lineno);
> > + cu_find_lineinfo(&cudie, (Dwarf_Addr)addr, &fname, &lineno);
> > /* Don't care whether it failed or not */
> >
> > /* Find a corresponding function (name, baseline and baseaddr) */
> > @@ -1828,8 +1828,7 @@ static int line_range_add_line(const char *src, unsigned int lineno,
> > }
> >
> > static int line_range_walk_cb(const char *fname, int lineno,
> > - Dwarf_Addr addr __maybe_unused,
> > - void *data)
> > + Dwarf_Addr addr, void *data)
> > {
> > struct line_finder *lf = data;
> > const char *__fname;
> >
> >
--
Masami Hiramatsu <mhiramat@...nel.org>
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