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[RFC PATCH V2]s390/perf:fix 'start' address of module's map

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  [RFC PATCH V2]s390/perf:fix 'start' address of module's map Song Shan Gong <gongss@linux.vnet.ibm.com> - 2016-07-15 12:20 +0200
    [RFC PATCH V2] s390/perf: fix 'start' address of module's map Song Shan Gong <gongss@linux.vnet.ibm.com> - 2016-07-15 12:20 +0200
      Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map Songshan Gong <gongss@linux.vnet.ibm.com> - 2016-07-18 04:00 +0200
      Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map Jiri Olsa <jolsa@redhat.com> - 2016-07-18 16:10 +0200
        Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map Songshan Gong <gongss@linux.vnet.ibm.com> - 2016-07-19 04:00 +0200
          Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map Songshan Gong <gongss@linux.vnet.ibm.com> - 2016-07-19 05:40 +0200

#1444148 — [RFC PATCH V2]s390/perf:fix 'start' address of module's map

Change log:

From V1:
1.change func name from 'fix__arch_module_baseaddr' to
'fix__arch_module_text_start';
2.Parse '.text' start addr from 'sys' through 'sysfs__read_ull', not
'hex2u64()';
2.Perfect code: check return value and allocated pointer by 'strdup'.

Song Shan Gong (1):
  s390/perf: fix 'start' address of module's map

 tools/perf/arch/s390/util/Build          |  2 ++
 tools/perf/arch/s390/util/sym-handling.c | 27 +++++++++++++++++++++++++++
 tools/perf/util/machine.c                |  8 ++++++++
 tools/perf/util/machine.h                |  1 +
 4 files changed, 38 insertions(+)
 create mode 100644 tools/perf/arch/s390/util/sym-handling.c

-- 
2.3.0

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#1444153 — [RFC PATCH V2] s390/perf: fix 'start' address of module's map

At preset, when creating module's map, perf gets 'start' address by parsing
'/proc/modules', but it's module base address, isn't the start address of
'.text' section. In most archs, 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>
---
 tools/perf/arch/s390/util/Build          |  2 ++
 tools/perf/arch/s390/util/sym-handling.c | 27 +++++++++++++++++++++++++++
 tools/perf/util/machine.c                |  8 ++++++++
 tools/perf/util/machine.h                |  1 +
 4 files changed, 38 insertions(+)
 create mode 100644 tools/perf/arch/s390/util/sym-handling.c

diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build
index 8a61372..5e322ed 100644
--- a/tools/perf/arch/s390/util/Build
+++ b/tools/perf/arch/s390/util/Build
@@ -2,3 +2,5 @@ libperf-y += header.o
 libperf-y += kvm-stat.o
 
 libperf-$(CONFIG_DWARF) += dwarf-regs.o
+
+libperf-y += sym-handling.o
diff --git a/tools/perf/arch/s390/util/sym-handling.c b/tools/perf/arch/s390/util/sym-handling.c
new file mode 100644
index 0000000..ff51336
--- /dev/null
+++ b/tools/perf/arch/s390/util/sym-handling.c
@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.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];
+	char *module_name = NULL;
+	int len;
+
+	if (!(module_name = strdup(name)))
+		return -1;
+
+	len = strlen(module_name);
+	module_name[len - 1] = '\0';
+	snprintf(path, PATH_MAX, "module/%s/sections/.text",
+				module_name + 1);
+
+	if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
+		free(module_name);
+		return -1;
+	}
+	return 0;
+}
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index b177218..97cc9f0 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1091,12 +1091,20 @@ 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;
diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
index 41ac9cf..20739f7 100644
--- a/tools/perf/util/machine.h
+++ b/tools/perf/util/machine.h
@@ -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);
-- 
2.3.0

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#1445153 — Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map

在 7/15/2016 6:15 PM, Song Shan Gong 写道:
> At preset, when creating module's map, perf gets 'start' address by parsing
> '/proc/modules', but it's module base address, isn't the start address of
> '.text' section. In most archs, 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>
> ---
>  tools/perf/arch/s390/util/Build          |  2 ++
>  tools/perf/arch/s390/util/sym-handling.c | 27 +++++++++++++++++++++++++++
>  tools/perf/util/machine.c                |  8 ++++++++
>  tools/perf/util/machine.h                |  1 +
>  4 files changed, 38 insertions(+)
>  create mode 100644 tools/perf/arch/s390/util/sym-handling.c
>
> diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build
> index 8a61372..5e322ed 100644
> --- a/tools/perf/arch/s390/util/Build
> +++ b/tools/perf/arch/s390/util/Build
> @@ -2,3 +2,5 @@ libperf-y += header.o
>  libperf-y += kvm-stat.o
>
>  libperf-$(CONFIG_DWARF) += dwarf-regs.o
> +
> +libperf-y += sym-handling.o
> diff --git a/tools/perf/arch/s390/util/sym-handling.c b/tools/perf/arch/s390/util/sym-handling.c
> new file mode 100644
> index 0000000..ff51336
> --- /dev/null
> +++ b/tools/perf/arch/s390/util/sym-handling.c
> @@ -0,0 +1,27 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.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];
> +	char *module_name = NULL;
> +	int len;
> +
> +	if (!(module_name = strdup(name)))
> +		return -1;
'checkpatch.pl' don't allow to use assignment in if condition.I'll split 
this sentence then.

Sorry for careless. And others is OK for 'checkpatch.pl'.

> +
> +	len = strlen(module_name);
> +	module_name[len - 1] = '\0';
> +	snprintf(path, PATH_MAX, "module/%s/sections/.text",
> +				module_name + 1);
> +
> +	if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
> +		free(module_name);
> +		return -1;
> +	}
> +	return 0;
> +}
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index b177218..97cc9f0 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1091,12 +1091,20 @@ 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;
> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> index 41ac9cf..20739f7 100644
> --- a/tools/perf/util/machine.h
> +++ b/tools/perf/util/machine.h
> @@ -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);
>

-- 
SongShan Gong

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#1445504 — Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map

On Fri, Jul 15, 2016 at 06:15:11PM +0800, Song Shan Gong wrote:
> At preset, when creating module's map, perf gets 'start' address by parsing
> '/proc/modules', but it's module base address, isn't the start address of
> '.text' section. In most archs, 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>
> ---
>  tools/perf/arch/s390/util/Build          |  2 ++
>  tools/perf/arch/s390/util/sym-handling.c | 27 +++++++++++++++++++++++++++
>  tools/perf/util/machine.c                |  8 ++++++++
>  tools/perf/util/machine.h                |  1 +
>  4 files changed, 38 insertions(+)
>  create mode 100644 tools/perf/arch/s390/util/sym-handling.c
> 
> diff --git a/tools/perf/arch/s390/util/Build b/tools/perf/arch/s390/util/Build
> index 8a61372..5e322ed 100644
> --- a/tools/perf/arch/s390/util/Build
> +++ b/tools/perf/arch/s390/util/Build
> @@ -2,3 +2,5 @@ libperf-y += header.o
>  libperf-y += kvm-stat.o
>  
>  libperf-$(CONFIG_DWARF) += dwarf-regs.o
> +
> +libperf-y += sym-handling.o
> diff --git a/tools/perf/arch/s390/util/sym-handling.c b/tools/perf/arch/s390/util/sym-handling.c
> new file mode 100644
> index 0000000..ff51336
> --- /dev/null
> +++ b/tools/perf/arch/s390/util/sym-handling.c
> @@ -0,0 +1,27 @@
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.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];
> +	char *module_name = NULL;
> +	int len;
> +
> +	if (!(module_name = strdup(name)))
> +		return -1;
> +
> +	len = strlen(module_name);
> +	module_name[len - 1] = '\0';
> +	snprintf(path, PATH_MAX, "module/%s/sections/.text",
> +				module_name + 1);

why can't you use 'name' in here? I can't see the reason
you allocated module_name..

> +
> +	if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
> +		free(module_name);
> +		return -1;
> +	}

leaking module_name in here

> +	return 0;
> +}

SNIP

thanks,
jirka

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#1445988 — Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map

在 7/19/2016 9:37 AM, Songshan Gong 写道:
>
>
> 在 7/18/2016 10:07 PM, Jiri Olsa 写道:
>> On Fri, Jul 15, 2016 at 06:15:11PM +0800, Song Shan Gong wrote:
>>> At preset, when creating module's map, perf gets 'start' address by
>>> parsing
>>> '/proc/modules', but it's module base address, isn't the start
>>> address of
>>> '.text' section. In most archs, 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>
>>> ---
>>>  tools/perf/arch/s390/util/Build          |  2 ++
>>>  tools/perf/arch/s390/util/sym-handling.c | 27
>>> +++++++++++++++++++++++++++
>>>  tools/perf/util/machine.c                |  8 ++++++++
>>>  tools/perf/util/machine.h                |  1 +
>>>  4 files changed, 38 insertions(+)
>>>  create mode 100644 tools/perf/arch/s390/util/sym-handling.c
>>>
>>> diff --git a/tools/perf/arch/s390/util/Build
>>> b/tools/perf/arch/s390/util/Build
>>> index 8a61372..5e322ed 100644
>>> --- a/tools/perf/arch/s390/util/Build
>>> +++ b/tools/perf/arch/s390/util/Build
>>> @@ -2,3 +2,5 @@ libperf-y += header.o
>>>  libperf-y += kvm-stat.o
>>>
>>>  libperf-$(CONFIG_DWARF) += dwarf-regs.o
>>> +
>>> +libperf-y += sym-handling.o
>>> diff --git a/tools/perf/arch/s390/util/sym-handling.c
>>> b/tools/perf/arch/s390/util/sym-handling.c
>>> new file mode 100644
>>> index 0000000..ff51336
>>> --- /dev/null
>>> +++ b/tools/perf/arch/s390/util/sym-handling.c
>>> @@ -0,0 +1,27 @@
>>> +#include <stdio.h>
>>> +#include <stdlib.h>
>>> +#include <unistd.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];
>>> +    char *module_name = NULL;
>>> +    int len;
>>> +
>>> +    if (!(module_name = strdup(name)))
>>> +        return -1;
>>> +
>>> +    len = strlen(module_name);
>>> +    module_name[len - 1] = '\0';
>>> +    snprintf(path, PATH_MAX, "module/%s/sections/.text",
>>> +                module_name + 1);
>>
>> why can't you use 'name' in here? I can't see the reason
>> you allocated module_name..
>
> Oh, yes.
>
Sorry, just ignore the upper reply.

I use the 'module_name' here instead of 'name', because 'name' is 
something like '[module_name]', I need strip the '[' and ']', so I have 
to set the tail ']' to '\0' to indicate the string end, which will need 
change the constant variable 'name'.


>
>>> +
>>> +    if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
>>> +        free(module_name);
>>> +        return -1;
>>> +    }
>>
>> leaking module_name in here
>
> yes, thanks.
>>
>>> +    return 0;
>>> +}
>>
>> SNIP
>>
>> thanks,
>> jirka
>>
>

-- 
SongShan Gong

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#1446004 — Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map

在 7/19/2016 9:50 AM, Songshan Gong 写道:
>
>
> 在 7/19/2016 9:37 AM, Songshan Gong 写道:
>>
>>
>> 在 7/18/2016 10:07 PM, Jiri Olsa 写道:
>>> On Fri, Jul 15, 2016 at 06:15:11PM +0800, Song Shan Gong wrote:
>>>> At preset, when creating module's map, perf gets 'start' address by
>>>> parsing
>>>> '/proc/modules', but it's module base address, isn't the start
>>>> address of
>>>> '.text' section. In most archs, 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>
>>>> ---
>>>>  tools/perf/arch/s390/util/Build          |  2 ++
>>>>  tools/perf/arch/s390/util/sym-handling.c | 27
>>>> +++++++++++++++++++++++++++
>>>>  tools/perf/util/machine.c                |  8 ++++++++
>>>>  tools/perf/util/machine.h                |  1 +
>>>>  4 files changed, 38 insertions(+)
>>>>  create mode 100644 tools/perf/arch/s390/util/sym-handling.c
>>>>
>>>> diff --git a/tools/perf/arch/s390/util/Build
>>>> b/tools/perf/arch/s390/util/Build
>>>> index 8a61372..5e322ed 100644
>>>> --- a/tools/perf/arch/s390/util/Build
>>>> +++ b/tools/perf/arch/s390/util/Build
>>>> @@ -2,3 +2,5 @@ libperf-y += header.o
>>>>  libperf-y += kvm-stat.o
>>>>
>>>>  libperf-$(CONFIG_DWARF) += dwarf-regs.o
>>>> +
>>>> +libperf-y += sym-handling.o
>>>> diff --git a/tools/perf/arch/s390/util/sym-handling.c
>>>> b/tools/perf/arch/s390/util/sym-handling.c
>>>> new file mode 100644
>>>> index 0000000..ff51336
>>>> --- /dev/null
>>>> +++ b/tools/perf/arch/s390/util/sym-handling.c
>>>> @@ -0,0 +1,27 @@
>>>> +#include <stdio.h>
>>>> +#include <stdlib.h>
>>>> +#include <unistd.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];
>>>> +    char *module_name = NULL;
>>>> +    int len;
>>>> +
>>>> +    if (!(module_name = strdup(name)))
>>>> +        return -1;
>>>> +
>>>> +    len = strlen(module_name);
>>>> +    module_name[len - 1] = '\0';
>>>> +    snprintf(path, PATH_MAX, "module/%s/sections/.text",
>>>> +                module_name + 1);
>>>
>>> why can't you use 'name' in here? I can't see the reason
>>> you allocated module_name..
>>
>> Oh, yes.
>>
> Sorry, just ignore the upper reply.
>
> I use the 'module_name' here instead of 'name', because 'name' is
> something like '[module_name]', I need strip the '[' and ']', so I have
> to set the tail ']' to '\0' to indicate the string end, which will need
> change the constant variable 'name'.
>
eeee, I found a new way to implement it.

I could use '%.*s' to format the 'path', 'name' is enough indeed.

It's so concise now. Appreciate.
>
>>
>>>> +
>>>> +    if (sysfs__read_ull(path, (unsigned long long *)start) < 0) {
>>>> +        free(module_name);
>>>> +        return -1;
>>>> +    }
>>>
>>> leaking module_name in here
>>
>> yes, thanks.
>>>
>>>> +    return 0;
>>>> +}
>>>
>>> SNIP
>>>
>>> thanks,
>>> jirka
>>>
>>
>

-- 
SongShan Gong

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