linux-kernel - [PATCHv2 6/8] perf tools powerpc: Fix PPC64 ELF ABIv2 symbol decoding

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Message-Id: <c81364f6bd46c9ab9074fcb107fccf7de63cc56e.1418654436.git.naveen.n.rao@linux.vnet.ibm.com>
Date:	Mon, 15 Dec 2014 20:20:36 +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: [PATCHv2 6/8] perf tools powerpc: Fix PPC64 ELF ABIv2 symbol decoding

PPC64 ELF ABIv2 has a Global Entry Point (GEP) and a Local Entry Point
(LEP). For purposes of probing, we need the LEP. Offset to the LEP is
encoded in st_other.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
Changes from previous patchset:
Simplified logic by adding dependancy on HAVE_ARCH_SYMBOL_HANDLING. Also
generalized arch_elf_sym_decode() to be suitable for other architectures in
future.

 tools/perf/arch/powerpc/util/sym-handling.c | 10 ++++++++++
 tools/perf/util/symbol-elf.c                |  2 ++
 tools/perf/util/symbol.h                    |  6 ++++++
 3 files changed, 18 insertions(+)

diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
index 0a77825..a27bfaf 100644
--- a/tools/perf/arch/powerpc/util/sym-handling.c
+++ b/tools/perf/arch/powerpc/util/sym-handling.c
@@ -1,8 +1,10 @@
 /*
  * Special symbol handling for PowerPC:
  * - Handle dot symbols on ABIv1
+ * - Decode offset from Global entry point to Local entry point on ABIv2
  *
  * Copyright (C) 2014 Naveen N Rao, IBM Corporation.
+ * Copyright (C) 2014 Ananth N Mavinakayanahalli, IBM Corporation.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -26,3 +28,11 @@ int probe_function_filter(struct map *map __maybe_unused, struct symbol *sym)
 	}
 	return 1;
 }
+
+inline void arch_elf_sym_decode(GElf_Sym *sym __maybe_unused)
+{
+#if defined(_CALL_ELF) && _CALL_ELF == 2
+	if (sym && sym->st_other)
+		sym->st_value += PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
+#endif
+}
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 7ac4e4c..557b63b 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -902,6 +902,8 @@ int dso__load_sym(struct dso *dso, struct map *map,
 		    (sym.st_value & 1))
 			--sym.st_value;
 
+		arch_elf_sym_decode(&sym);
+
 		if (dso->kernel || kmodule) {
 			char dso_name[PATH_MAX];
 
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 9d602e9..9e03cdf 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -294,4 +294,10 @@ int compare_proc_modules(const char *from, const char *to);
 int setup_list(struct strlist **list, const char *list_str,
 	       const char *list_name);
 
+#ifdef HAVE_ARCH_SYMBOL_HANDLING
+extern void arch_elf_sym_decode(GElf_Sym *sym __maybe_unused);
+#else
+static inline void arch_elf_sym_decode(GElf_Sym *sym __maybe_unused) { }
+#endif
+
 #endif /* __PERF_SYMBOL */
-- 
2.1.3

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