[PATCHv2 8/8] perf probe powerpc: Fixup function entry if using kallsyms lookup

From: Naveen N. Rao
Date: Mon Dec 15 2014 - 09:51:28 EST


On powerpc ABIv2, if no debug-info is found and we use kallsyms, we need
to fixup the function entry to point to the local entry point. Use
offset of 8 since current toolchains always generate 2 instructions (8
bytes).

Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
---
Changes:
Generalize and introduce helper to post-process trace point.

tools/perf/arch/powerpc/util/sym-handling.c | 17 +++++++++++++++++
tools/perf/util/probe-event.c | 1 +
tools/perf/util/probe-event.h | 10 ++++++++++
3 files changed, 28 insertions(+)

diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
index 22fc2e6..30c8797 100644
--- a/tools/perf/arch/powerpc/util/sym-handling.c
+++ b/tools/perf/arch/powerpc/util/sym-handling.c
@@ -45,3 +45,20 @@ inline bool prefer_symtab(void)
return false;
#endif
}
+
+void arch_fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused,
+ struct probe_trace_event *tev __maybe_unused,
+ struct map *map __maybe_unused)
+{
+#if defined(_CALL_ELF) && _CALL_ELF == 2
+ /*
+ * If we used kallsyms, we should fixup the function entry address here.
+ * ppc64 ABIv2 local entry point is currently always 2 instructions (8 bytes)
+ * after the global entry point. Fix this if it ever changes.
+ */
+ if (!pev->uprobes && map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
+ tev->point.address += 8;
+ tev->point.offset += 8;
+ }
+#endif
+}
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index dfc3151..85f37a4 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2340,6 +2340,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
strdup_or_goto(pev->args[i].type,
nomem_out);
}
+ arch_fix_tev_from_maps(pev, tev, map);
}

out:
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 5f92906..335a6a4 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -147,6 +147,16 @@ extern bool prefer_symtab(void);
static inline bool prefer_symtab(void) { return false; };
#endif

+#ifdef HAVE_ARCH_SYMBOL_HANDLING
+extern void arch_fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused,
+ struct probe_trace_event *tev __maybe_unused,
+ struct map *map __maybe_unused);
+#else
+static inline void arch_fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused,
+ struct probe_trace_event *tev __maybe_unused,
+ struct map *map __maybe_unused) { }
+#endif
+
/* Maximum index number of event-name postfix */
#define MAX_EVENT_INDEX 1024

--
2.1.3

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