linux-kernel - [tip:perf/core] perf probe arm64: Fix symbol fixup issues due to ELF type

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Message-ID: <tip-f1031c8d33a8c40d4cac26e58c37d9fba0e31a8a@git.kernel.org>
Date:   Thu, 28 Dec 2017 07:35:40 -0800
From:   tip-bot for Kim Phillips <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     kim.phillips@....com, namhyung@...nel.org, jolsa@...hat.com,
        hpa@...or.com, will.deacon@....com, acme@...hat.com,
        linux-kernel@...r.kernel.org, tglx@...utronix.de,
        ganapatrao.kulkarni@...ium.com, naveen.n.rao@...ux.vnet.ibm.com,
        alexander.shishkin@...ux.intel.com, mingo@...nel.org,
        peterz@...radead.org
Subject: [tip:perf/core] perf probe arm64: Fix symbol fixup issues due to
 ELF type

Commit-ID:  f1031c8d33a8c40d4cac26e58c37d9fba0e31a8a
Gitweb:     https://git.kernel.org/tip/f1031c8d33a8c40d4cac26e58c37d9fba0e31a8a
Author:     Kim Phillips <kim.phillips@....com>
AuthorDate: Thu, 14 Dec 2017 17:52:42 -0600
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Wed, 27 Dec 2017 12:15:58 -0300

perf probe arm64: Fix symbol fixup issues due to ELF type

On an arm64 machine running a CONFIG_RANDOMIZE_BASE=y kernel, perf
kernel symbol resolution fails.  Debugging saw symsrc_init calling the
default elf__needs_adjust_symbols() where checks for an ET_DYN (3)
ehdr.e_type failed when they should have succeeded.

Fix by adopting powerpc version of the weak elf__needs_adjust_symbols()
function, as done in commit d2332098331f ("perf probe ppc: Fix symbol
fixup issues due to ELF type").

Prior to this patch, perf test 1 would fail:

  $ sudo oldperf test -v 1 |& head
   1: vmlinux symtab matches kallsyms                       :
  test child forked, pid 33374
  Looking at the vmlinux_path (8 entries long)
  Using /usr/lib/debug/boot/vmlinux for symbols
  ERR : 0xfffe0000100f1000: do_undefinstr not on kallsyms
  ERR : 0xfffe0000100f1320: do_sysinstr not on kallsyms
  ERR : 0xfffe0000100f13b0: do_debug_exception not on kallsyms
  ERR : 0xfffe0000100f1498: do_mem_abort not on kallsyms
  ERR : 0xfffe0000100f1580: do_sp_pc_abort not on kallsyms
  ...

After applying this patch, perf test 1 now succeeds:

  $ sudo ./newperf test -v 1 |& head
   1: vmlinux symtab matches kallsyms                       :
  test child forked, pid 33378
  Looking at the vmlinux_path (8 entries long)
  Using /usr/lib/debug/boot/vmlinux for symbols
  WARN: 0xffff000008081000: diff name v: do_undefinstr k: __exception_text_start
  WARN: 0xffff0000080819e8: diff name v: __irqentry_text_end k: __softirqentry_text_start
  WARN: 0xffff000008081d08: diff name v: __entry_text_start k: __softirqentry_text_end
  WARN: 0xffff00000809db5c: diff name v: flush_icache_range k: __flush_cache_user_range
  WARN: 0xffff000008101908: diff name v: sys_ni_syscall k: sys_vm86old
  ...

Signed-off-by: Kim Phillips <kim.phillips@....com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Will Deacon <will.deacon@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Link: http://lkml.kernel.org/r/20171214175242.e30450f17f93ad675d968fa3@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/arch/arm64/util/Build          |  1 +
 tools/perf/arch/arm64/util/sym-handling.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/tools/perf/arch/arm64/util/Build b/tools/perf/arch/arm64/util/Build
index b1ab72d..e04f6cd 100644
--- a/tools/perf/arch/arm64/util/Build
+++ b/tools/perf/arch/arm64/util/Build
@@ -1,4 +1,5 @@
 libperf-y += header.o
+libperf-y += sym-handling.o
 libperf-$(CONFIG_DWARF)     += dwarf-regs.o
 libperf-$(CONFIG_LOCAL_LIBUNWIND) += unwind-libunwind.o
 
diff --git a/tools/perf/arch/arm64/util/sym-handling.c b/tools/perf/arch/arm64/util/sym-handling.c
new file mode 100644
index 0000000..0051b1e
--- /dev/null
+++ b/tools/perf/arch/arm64/util/sym-handling.c
@@ -0,0 +1,22 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * Copyright (C) 2015 Naveen N. Rao, IBM Corporation
+ */
+
+#include "debug.h"
+#include "symbol.h"
+#include "map.h"
+#include "probe-event.h"
+#include "probe-file.h"
+
+#ifdef HAVE_LIBELF_SUPPORT
+bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
+{
+	return ehdr.e_type == ET_EXEC ||
+	       ehdr.e_type == ET_REL ||
+	       ehdr.e_type == ET_DYN;
+}
+#endif