From: Changbin Du <[email protected]>
The terminal character '\0' should take into account as size of the string
buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
'--trace-funcs' options didn't work as expected when the <func> doesn't
exist.
I didn't dive into kernel ftrace fops, but strace shows that if usersapce
writes a non-terminated string, the kernel side will return success but
no filter applied. After this fix in userspace, the kernel will return an
error.
$ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
0) 0.140 us | rcu_all_qs();
3) 0.304 us | mutex_unlock();
0) 0.153 us | find_vma();
3) 0.088 us | __fsnotify_parent();
0) 6.145 us | handle_mm_fault();
3) 0.089 us | fsnotify();
3) 0.161 us | __sb_end_write();
3) 0.710 us | SyS_close();
3) 7.848 us | exit_to_usermode_loop();
On above example, I specified function filter 'abcdefg' but all functions
are enabled.
Signed-off-by: Changbin Du <[email protected]>
---
tools/perf/builtin-ftrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 25a42ac..2604a64 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append)
{
char *file;
int fd, ret = -1;
- ssize_t size = strlen(val);
+ ssize_t size = strlen(val) + 1;
int flags = O_WRONLY;
char errbuf[512];
--
2.7.4
Hi Olsa,
What about this fix now? Thanks!
On Tue, Dec 26, 2017 at 05:26:56PM +0800, [email protected] wrote:
> From: Changbin Du <[email protected]>
>
> The terminal character '\0' should take into account as size of the string
> buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
> '--trace-funcs' options didn't work as expected when the <func> doesn't
> exist.
>
> I didn't dive into kernel ftrace fops, but strace shows that if usersapce
> writes a non-terminated string, the kernel side will return success but
> no filter applied. After this fix in userspace, the kernel will return an
> error.
>
> $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
> 0) 0.140 us | rcu_all_qs();
> 3) 0.304 us | mutex_unlock();
> 0) 0.153 us | find_vma();
> 3) 0.088 us | __fsnotify_parent();
> 0) 6.145 us | handle_mm_fault();
> 3) 0.089 us | fsnotify();
> 3) 0.161 us | __sb_end_write();
> 3) 0.710 us | SyS_close();
> 3) 7.848 us | exit_to_usermode_loop();
>
> On above example, I specified function filter 'abcdefg' but all functions
> are enabled.
>
> Signed-off-by: Changbin Du <[email protected]>
> ---
> tools/perf/builtin-ftrace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 25a42ac..2604a64 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append)
> {
> char *file;
> int fd, ret = -1;
> - ssize_t size = strlen(val);
> + ssize_t size = strlen(val) + 1;
> int flags = O_WRONLY;
> char errbuf[512];
>
> --
> 2.7.4
>
--
Thanks,
Changbin Du
On Mon, Jan 08, 2018 at 11:05:12AM +0800, Du, Changbin wrote:
> Hi Olsa,
> What about this fix now? Thanks!
>
> On Tue, Dec 26, 2017 at 05:26:56PM +0800, [email protected] wrote:
> > From: Changbin Du <[email protected]>
> >
> > The terminal character '\0' should take into account as size of the string
> > buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
> > '--trace-funcs' options didn't work as expected when the <func> doesn't
> > exist.
> >
> > I didn't dive into kernel ftrace fops, but strace shows that if usersapce
> > writes a non-terminated string, the kernel side will return success but
> > no filter applied. After this fix in userspace, the kernel will return an
> > error.
> >
> > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
> > 0) 0.140 us | rcu_all_qs();
> > 3) 0.304 us | mutex_unlock();
> > 0) 0.153 us | find_vma();
> > 3) 0.088 us | __fsnotify_parent();
> > 0) 6.145 us | handle_mm_fault();
> > 3) 0.089 us | fsnotify();
> > 3) 0.161 us | __sb_end_write();
> > 3) 0.710 us | SyS_close();
> > 3) 7.848 us | exit_to_usermode_loop();
> >
> > On above example, I specified function filter 'abcdefg' but all functions
> > are enabled.
hum, haven't checked, but looks like the filter is not working at all now:
[root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs proc_sys_read
write ' ' to tracing/set_ftrace_pid failed: Invalid argument
[root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs SyS_read
write ' ' to tracing/set_ftrace_pid failed: Invalid argument
[root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs fsnotify
write ' ' to tracing/set_ftrace_pid failed: Invalid argument
jirka
> >
> > Signed-off-by: Changbin Du <[email protected]>
> > ---
> > tools/perf/builtin-ftrace.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 25a42ac..2604a64 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -69,7 +69,7 @@ static int __write_tracing_file(const char *name, const char *val, bool append)
> > {
> > char *file;
> > int fd, ret = -1;
> > - ssize_t size = strlen(val);
> > + ssize_t size = strlen(val) + 1;
> > int flags = O_WRONLY;
> > char errbuf[512];
> >
> > --
> > 2.7.4
> >
>
> --
> Thanks,
> Changbin Du
On Mon, Jan 08, 2018 at 03:34:57PM +0100, Jiri Olsa wrote:
> On Mon, Jan 08, 2018 at 11:05:12AM +0800, Du, Changbin wrote:
> > Hi Olsa,
> > What about this fix now? Thanks!
> >
> > On Tue, Dec 26, 2017 at 05:26:56PM +0800, [email protected] wrote:
> > > From: Changbin Du <[email protected]>
> > >
> > > The terminal character '\0' should take into account as size of the string
> > > buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
> > > '--trace-funcs' options didn't work as expected when the <func> doesn't
> > > exist.
> > >
> > > I didn't dive into kernel ftrace fops, but strace shows that if usersapce
> > > writes a non-terminated string, the kernel side will return success but
> > > no filter applied. After this fix in userspace, the kernel will return an
> > > error.
> > >
> > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
> > > 0) 0.140 us | rcu_all_qs();
> > > 3) 0.304 us | mutex_unlock();
> > > 0) 0.153 us | find_vma();
> > > 3) 0.088 us | __fsnotify_parent();
> > > 0) 6.145 us | handle_mm_fault();
> > > 3) 0.089 us | fsnotify();
> > > 3) 0.161 us | __sb_end_write();
> > > 3) 0.710 us | SyS_close();
> > > 3) 7.848 us | exit_to_usermode_loop();
> > >
> > > On above example, I specified function filter 'abcdefg' but all functions
> > > are enabled.
>
> hum, haven't checked, but looks like the filter is not working at all now:
>
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs proc_sys_read
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs SyS_read
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs fsnotify
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
>
Thanks for your test. I forgot to test normal case and thought the err is expected...
This time I dived into kernel side, and found 3 issues (if I am all right) at the
kernel function trace_get_user(). This function has problems to process both complete
C string or not.
I will send the kernel patches and Cc you guys. And I still think it is better
let perf write a complete C string.
Thanks!
Changbin Du
> jirka
>
[...]
Hi,
On Mon, Jan 08, 2018 at 03:34:57PM +0100, Jiri Olsa wrote:
> On Mon, Jan 08, 2018 at 11:05:12AM +0800, Du, Changbin wrote:
> > Hi Olsa,
> > What about this fix now? Thanks!
> >
> > On Tue, Dec 26, 2017 at 05:26:56PM +0800, [email protected] wrote:
> > > From: Changbin Du <[email protected]>
> > >
> > > The terminal character '\0' should take into account as size of the string
> > > buffer. Without this fix, the '--graph-funcs', '--nograph-funcs' and
> > > '--trace-funcs' options didn't work as expected when the <func> doesn't
> > > exist.
> > >
> > > I didn't dive into kernel ftrace fops, but strace shows that if usersapce
> > > writes a non-terminated string, the kernel side will return success but
> > > no filter applied. After this fix in userspace, the kernel will return an
> > > error.
> > >
> > > $ sudo ./perf ftrace -a --graph-depth 1 --graph-funcs abcdefg
> > > 0) 0.140 us | rcu_all_qs();
> > > 3) 0.304 us | mutex_unlock();
> > > 0) 0.153 us | find_vma();
> > > 3) 0.088 us | __fsnotify_parent();
> > > 0) 6.145 us | handle_mm_fault();
> > > 3) 0.089 us | fsnotify();
> > > 3) 0.161 us | __sb_end_write();
> > > 3) 0.710 us | SyS_close();
> > > 3) 7.848 us | exit_to_usermode_loop();
> > >
> > > On above example, I specified function filter 'abcdefg' but all functions
> > > are enabled.
>
> hum, haven't checked, but looks like the filter is not working at all now:
>
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs proc_sys_read
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs SyS_read
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
> [root@krava perf]# ./perf ftrace -vv -a --graph-depth 1 --graph-funcs fsnotify
> write ' ' to tracing/set_ftrace_pid failed: Invalid argument
Hmm.. it seems writing a whitespace alone caused the failure.
The filter files are handled little bit different in that they process
the given string when it find a whitespace or at the close() if not.
But the thing is that it's gonna lose the return value if handled at
close().
Anyway adding a NUL character at the end won't make different IMHO
since it's not a whitespace. And I think it needs a separate function
to set filters with a whitespace. But this will change the program
behavior on invalid filter inputs.
Thanks,
Namhyung