Messages in this thread | | | Subject | Re: [RFC PATCH V2] s390/perf: fix 'start' address of module's map | From | Songshan Gong <> | Date | Tue, 19 Jul 2016 11:35:13 +0800 |
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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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