On 2015/4/7 23:13, Arnaldo Carvalho de Melo wrote:
> Em Tue, Apr 07, 2015 at 08:22:46AM +0000, Wang Nan escreveu:
>> perf report and perf annotate are easy to trigger segfault if trace data
>> contain kernel module information like this:
>>
>> # perf report -D -i ./perf.data
>> ...
>> 0 0 0x188 [0x50]: PERF_RECORD_MMAP -1/0: [0xffffffbff1018000(0xf068000) @
>> 0]: x [test_module]
>> ...
>>
>> # perf report -i ./perf.data --objdump=/path/to/objdump
>> --kallsyms=/path/to/kallsyms
>>
>> perf: Segmentation fault
>> -------- backtrace --------
>> /path/to/perf[0x503478]
>> /lib64/libc.so.6(+0x3545f)[0x7fb201f3745f]
>> /path/to/perf[0x499b56]
>
> So, with this patch applied I am seeing this:
>
> [root@ssdandy ~]# perf sched record -a
> Kmod (modules.order) and cpumode (0) inconsistent
> Kmod (modules.builtin) and cpumode (0) inconsistent
> Kmod (modules.dep) and cpumode (0) inconsistent
> Kmod (modules.dep.bin) and cpumode (0) inconsistent
> Kmod (modules.alias) and cpumode (0) inconsistent
> Kmod (modules.alias.bin) and cpumode (0) inconsistent
> Kmod (modules.softdep) and cpumode (0) inconsistent
> Kmod (modules.symbols) and cpumode (0) inconsistent
> Kmod (modules.symbols.bin) and cpumode (0) inconsistent
> Kmod (modules.builtin.bin) and cpumode (0) inconsistent
> Kmod (modules.devname) and cpumode (0) inconsistent
> ^C[ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.465 MB perf.data (1595 samples) ]
>
> [root@ssdandy ~]#o
>
> Can you please check this?
>
> Why do we get these warning for these files?
>
This is because in map_groups__set_modules_path_dir() we enumerate over each
file
in /lib/modules/`uname -a`/ and use kmod_path__parse_name() to parse their
names.
In this v3 patch, I update __kmod_path__parse() to check consistency between
m.kmod and
cpumode. It will warn if one passes a kernel module name with user
space cpumode, or passes kernel space cpumode with a non-kmodule name.
I'll post a patch v4 to avoid such warning if passed cpumode is not explicitly
set to
user or kernel.
Difference from v3:
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index fb1ed7d..875f7c9 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -215,7 +215,7 @@ int __kmod_path__parse(struct kmod_path *m, const char
*path,
const char *name = strrchr(path, '/');
const char *ext = strrchr(path, '.');
bool is_simple_name = false;
- bool cpu_mode_kernel, is_kernel = false;
+ bool cpu_mode_kernel, cpu_mode_unknown = false, is_kernel = false;
/* treat PERF_RECORD_MISC_CPUMODE_UNKNOWN as kernel. */
switch (cpumode & PERF_RECORD_MISC_CPUMODE_MASK) {
@@ -224,6 +224,9 @@ int __kmod_path__parse(struct kmod_path *m, const char
*path,
case PERF_RECORD_MISC_GUEST_USER:
cpu_mode_kernel = false;
break;
+ case PERF_RECORD_MISC_CPUMODE_UNKNOWN:
+ cpu_mode_unknown = true;
+ /* fall through */
default:
cpu_mode_kernel = true;
}
@@ -288,10 +291,12 @@ int __kmod_path__parse(struct kmod_path *m, const char
*path,
}
}
out:
- if ((m->kmod && !cpu_mode_kernel) ||
- (cpu_mode_kernel && !m->kmod && !is_kernel))
- pr_warning("Kmod (%s) and cpumode (%d) inconsistent\n",
- path, cpumode);
+ if (!cpu_mode_unknown) {
+ if ((m->kmod && !cpu_mode_kernel) ||
+ (cpu_mode_kernel && !m->kmod && !is_kernel))
+ pr_warning("Kmod (%s) and cpumode (%d) inconsistent\n",
+ path, cpumode);
+ }
return 0;
}
>
> Applied the other patch:
>
> -> 28 T 04/07 Wang Nan (8,8K) [PATCH v3 1/2] perf: kmaps: enforce usage of
> kmaps to protect futher bugs.
>
>
> - Arnaldo
>
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