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    SubjectRe: [BUGFIX PATCH] perf probe: Do not depend on dwfl_module_addrsym()
    On Thu, 27 Feb 2020 17:20:39 +0100
    Alexandre Ghiti <alex@ghiti.fr> wrote:

    > On 2/27/20 4:42 PM, Masami Hiramatsu wrote:
    > > Do not depend on dwfl_module_addrsym() because it can fail
    > > on user-space shared libraries.
    > >
    > > Actually, same bug was fixed by commit 664fee3dc379 ("perf
    > > probe: Do not use dwfl_module_addrsym if dwarf_diename finds
    > > symbol name"), but commit 07d369857808 ("perf probe: Fix
    > > wrong address verification) reverted to get actual symbol
    > > address from symtab.
    > >
    > > This fixes it again by getting symbol address from DIE,
    > > and only if the DIE has only address range, it uses
    > > dwfl_module_addrsym().
    > >
    > > Fixes: 07d369857808 ("perf probe: Fix wrong address verification)
    > > Reported-by: Alexandre Ghiti <alex@ghiti.fr>
    > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    > > ---
    > > tools/perf/util/probe-finder.c | 11 ++++++++---
    > > 1 file changed, 8 insertions(+), 3 deletions(-)
    > >
    > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
    > > index 1c817add6ca4..e4cff49384f4 100644
    > > --- a/tools/perf/util/probe-finder.c
    > > +++ b/tools/perf/util/probe-finder.c
    > > @@ -637,14 +637,19 @@ static int convert_to_trace_point(Dwarf_Die *sp_die, Dwfl_Module *mod,
    > > return -EINVAL;
    > > }
    > >
    > > - /* Try to get actual symbol name from symtab */
    > > - symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
    > > + if (dwarf_entrypc(sp_die, &eaddr) == 0) {
    > > + /* If the DIE has entrypc, use it. */
    > > + symbol = dwarf_diename(sp_die);
    > > + } else {
    > > + /* Try to get actual symbol name and address from symtab */
    > > + symbol = dwfl_module_addrsym(mod, paddr, &sym, NULL);
    > > + eaddr = sym.st_value;
    > > + }
    > > if (!symbol) {
    > > pr_warning("Failed to find symbol at 0x%lx\n",
    > > (unsigned long)paddr);
    > > return -ENOENT;
    > > }
    > > - eaddr = sym.st_value;
    > >
    > > tp->offset = (unsigned long)(paddr - eaddr);
    > > tp->address = (unsigned long)paddr;
    > >
    >
    > I have just tested your patch, that fixes the issue, so you can add:
    >
    > Tested-by: Alexandre Ghiti <alex@ghiti.fr>

    Thanks Alexandre,
    Arnaldo, could you also pick this for fix?

    Thank you,

    --
    Masami Hiramatsu <mhiramat@kernel.org>

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