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perf s390: Fix 'start' address of module's map

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At present, when creating module's map, perf gets 'start' address by
parsing '/proc/modules', but it's the module base address, it isn't the
start address of the '.text' section.

In most arches, it's OK. But for s390, it places 'GOT' and 'PLT'
relocations before '.text' section. So there exists an offset between
module base address and '.text' section, which will incur wrong symbol
resolution for modules.

Fix this bug by getting 'start' address of module's map from parsing
'/sys/module/[module name]/sections/.text', not from '/proc/modules'.

Signed-off-by: Song Shan Gong <gongss@linux.vnet.ibm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1469070651-6447-2-git-send-email-gongss@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Song Shan Gong 2016-07-21 11:10:51 +08:00 committed by Arnaldo Carvalho de Melo
parent 9b16137ab0
commit 203d8a4aa6
4 changed files with 30 additions and 0 deletions
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2
tools/perf/arch/s390/util/Build
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@ -2,3 +2,5 @@ libperf-y += header.o
libperf-y += kvm-stat.o
libperf-$(CONFIG_DWARF) += dwarf-regs.o
libperf-y += machine.o

19
tools/perf/arch/s390/util/machine.c Normal file
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@ -0,0 +1,19 @@
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include "util.h"
#include "machine.h"
#include "api/fs/fs.h"
int arch__fix_module_text_start(u64 *start, const char *name)
{
char path[PATH_MAX];
snprintf(path, PATH_MAX, "module/%.*s/sections/.text",
(int)strlen(name) - 2, name + 1);
if (sysfs__read_ull(path, (unsigned long long *)start) < 0)
return -1;
return 0;
}

8
tools/perf/util/machine.c
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@ -1093,12 +1093,20 @@ static int machine__set_modules_path(struct machine *machine)
return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
}
int __weak arch__fix_module_text_start(u64 *start __maybe_unused,
const char *name __maybe_unused)
{
return 0;
}
static int machine__create_module(void *arg, const char *name, u64 start)
{
struct machine *machine = arg;
struct map *map;
if (arch__fix_module_text_start(&start, name) < 0)
return -1;
map = machine__findnew_module_map(machine, start, name);
if (map == NULL)
return -1;

1
tools/perf/util/machine.h
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@ -216,6 +216,7 @@ struct symbol *machine__find_kernel_function_by_name(struct machine *machine,
struct map *machine__findnew_module_map(struct machine *machine, u64 start,
const char *filename);
int arch__fix_module_text_start(u64 *start, const char *name);
int __machine__load_kallsyms(struct machine *machine, const char *filename,
enum map_type type, bool no_kcore, symbol_filter_t filter);