linux-kernel - [tip: perf/urgent] perf probe: Do not depend on dwfl_module

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Date:   Thu, 19 Mar 2020 14:04:43 -0000
From:   "tip-bot2 for Masami Hiramatsu" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Alexandre Ghiti <alex@...ti.fr>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Sasha Levin <sashal@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: perf/urgent] perf probe: Do not depend on dwfl_module_addrsym()

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     1efde2754275dbd9d11c6e0132a4f09facf297ab
Gitweb:        https://git.kernel.org/tip/1efde2754275dbd9d11c6e0132a4f09facf297ab
Author:        Masami Hiramatsu <mhiramat@...nel.org>
AuthorDate:    Fri, 28 Feb 2020 00:42:01 +09:00
Committer:     Arnaldo Carvalho de Melo <acme@...hat.com>
CommitterDate: Mon, 09 Mar 2020 10:43:53 -03:00

perf probe: Do not depend on dwfl_module_addrsym()

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@...ti.fr>
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Tested-by: Alexandre Ghiti <alex@...ti.fr>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Sasha Levin <sashal@...nel.org>
Link: http://lore.kernel.org/lkml/158281812176.476.14164573830975116234.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 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 1c817ad..e4cff49 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;