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

PATCH New Kim Phillips 3 participants 3 messages Dec 14, 2017 – Dec 28, 2017

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perf events Performance events tooling arm64

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Kim Phillips

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2017-12-14 23:52 UTC #0 lore raw

PATCH 1/1 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 <[email protected]>

---
 tools/perf/arch/arm64/util/Build          |  1 +
 tools/perf/arch/arm64/util/sym-handling.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tools/perf/arch/arm64/util/sym-handling.c

tools/perf/arch/arm64/util/Build +1 -0

index b1ab72d2a42e..e04f6cdd6f32 100644
@@ -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

tools/perf/arch/arm64/util/sym-handling.c new file +22 -0

new file mode 100644
index 000000000000..0051b1ee8450
@@ -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

Signature · 1 line

2.15.1

Arnaldo Carvalho de Melo

maintainer Applied

2017-12-15 13:57 UTC #1 lore raw

PATCH 1/1 perf probe arm64: Fix symbol fixup issues due to ELF type

Em Thu, Dec 14, 2017 at 05:52:42PM -0600, Kim Phillips escreveu:

Quoted 10 lines

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:

Thanks, applied.

- Arnaldo

tip-bot for Kim Phillips

merge bot

2017-12-28 15:38 UTC #2 lore raw

In reply to Kim Phillips

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

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

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

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 <[email protected]>

Cc Alexander Shishkin <[email protected]>

Cc Ganapatrao Kulkarni <[email protected]>

Cc Jiri Olsa <[email protected]>

Cc Namhyung Kim <[email protected]>

Cc Naveen N. Rao <[email protected]>

Cc Peter Zijlstra <[email protected]>

Cc Will Deacon <[email protected]>

Cc [email protected]

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Arnaldo Carvalho de Melo <[email protected]>

---
 tools/perf/arch/arm64/util/Build          |  1 +
 tools/perf/arch/arm64/util/sym-handling.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+)

tools/perf/arch/arm64/util/Build +1 -0

index b1ab72d..e04f6cd 100644
@@ -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

tools/perf/arch/arm64/util/sym-handling.c new file +22 -0

new file mode 100644
index 0000000..0051b1e
@@ -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