linux-kernel - [RFC PATCH 7/8] perf probe powerpc: Use DWARF info only if necessary

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Message-Id: <50dd0fedb50e3a56ff8f25c44098db3e2a2d6374.1418146300.git.naveen.n.rao@linux.vnet.ibm.com>
Date:	Tue,  9 Dec 2014 23:04:05 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	acme@...nel.org, mpe@...erman.id.au
Cc:	ananth@...ibm.com
Subject: [RFC PATCH 7/8] perf probe powerpc: Use DWARF info only if necessary

Use symbol table lookups by default if DWARF is not necessary, since
powerpc ABIv2 encodes local entry points in the symbol table and the
function entry address in DWARF may not be appropriate for kprobes,
as described here:
https://sourceware.org/bugzilla/show_bug.cgi?id=17638

Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
 tools/perf/util/probe-event.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 174c22e..adcdbd2 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2382,6 +2382,14 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
 		}
 	}
 
+#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
+	if (!perf_probe_event_need_dwarf(pev)) {
+		ret = find_probe_trace_events_from_map(pev, tevs, max_tevs, target);
+		if (ret > 0)
+			return ret;	/* Found in symbol table */
+	}
+#endif
+
 	/* Convert perf_probe_event with debuginfo */
 	ret = try_to_find_probe_trace_events(pev, tevs, max_tevs, target);
 	if (ret != 0)
-- 
2.1.3

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