> You could use the command 'nm' to get your symbols and look them up. I
> am sure Babeltrace can do this from a python level. You could also use
> a GUI based trace viewer to get the information.
nm only shows the linked address, but the traced address are the
loaded address in memory. So, they're different.
For example:
trace@trace:~/cc$ nm instrument | grep 'add3\|main'
00000000000011a9 T add3
00000000000011ee T main
@Christophe:
Do you mean that babeltrace2 can help get the function name and call site
offset?
B.R.
Changcheng
On 12:52 Tue 23 Jun, Christophe Bédard wrote:
> Hi,
>
> Babeltrace is doing exactly what it should as far as I know.
>
> yes, but babeltrace can provide the information if:
> * ip and vpid contexts are enabled (for userspace), e.g.
>
> $ lttng add-context --userspace --type=ip --type=vpid
>
> * LTTng state dump events are enabled, e.g.
>
> $ lttng enable-event --userspace 'lttng_ust_statedump:*'
>
> see this (from bt2 but it also applies to
> bt1): [1]https://babeltrace.org/docs/v2.0/man7/babeltrace2-filter.lttng
> -utils.debug-info.7/#doc-lttng-prereq
> Note that the Python bindings for babeltrace don't provide/expose this
> debug info.
> Christophe
> On Tue, 23 Jun 2020 at 11:12, Matthew Khouzam via lttng-dev
> <[2]lttng-dev@lists.lttng.org> wrote:
>
> Hi,
> You have the pointers that are traced. Babeltrace is doing exactly what
> it should as far as I know.
> You could use the command 'nm' to get your symbols and look them up. I
> am sure Babeltrace can do this from a python level. You could also use
> a GUI based trace viewer to get the information.
> Hope that helps.
> Matthew
> __________________________________________________________________
>
> From: lttng-dev <[3]lttng-dev-boun...@lists.lttng.org> on behalf of
> Liu, Changcheng via lttng-dev <[4]lttng-dev@lists.lttng.org>
> Sent: Tuesday, June 23, 2020 10:37 AM
> To: [5]lttng-dev@lists.lttng.org <[6]lttng-dev@lists.lttng.org>
> Cc: [7]changcheng....@intel.com <[8]changcheng....@intel.com>
> Subject: [lttng-dev] get function names with lttng-ust-cyg-profile
>
> Hi all,
> I'm trying to use lttng-ust-cyg-profile to trace program.
> Does anyone know how to get function names and offset through
> lttng-ust-cyg-profile?
> In below example, the babeltrace could only get the function
> entry/exit value.
> 1. Source program: instrument.c
> 1 #include <stdio.h>
> 2
> 3 int add3(int val) {
> 4 return val + 3;
> 5 }
> 6
> 7 int main(int argc, char **argv) {
> 8 int x = 4;
> 9
> 10 puts("Press Enter to continue...");
> 11 getchar();
> 12
> 13 x = add3(x);
> 14
> 15 return 0;
> 16 }
> 2. build source code:
> $ gcc -g -finstrument-functions instrument.c -o instrument
> 3. run program:
> $
> LD_PRELOAD=/usr/lib/x86_64-linux-gnu/liblttng-ust-cyg-profile.so
> ./instrument
> 4. start trace process:
> trace@trace:~/cc$ sudo lttng create instrument
> Session instrument created.
> Traces will be output to
> /root/lttng-traces/instrument-20200623-222917
> trace@trace:~/cc$ sudo lttng enable-channel user_func_trace
> --userspace
> UST channel user_func_trace enabled for session instrument
> trace@trace:~/cc$ sudo lttng enable-event --userspace
> lttng_ust_cyg_profile:func_entry --channel user_func_trace
> UST event lttng_ust_cyg_profile:func_entry created in channel
> user_func_trace
> trace@trace:~/cc$ sudo lttng enable-event --userspace
> lttng_ust_cyg_profile:func_exit --channel user_func_trace
> UST event lttng_ust_cyg_profile:func_exit created in channel
> user_func_trace
> trace@trace:~/cc$ sudo lttng start
> Tracing started for session instrument
> trace@trace:~/cc$ sudo lttng destroy
> Destroying session instrument..
> Session instrument destroyed
> trace@trace:~/cc$ sudo babeltrace
> /root/lttng-traces/instrument-20200623-222917
> [22:29:55.388607059] (+?.?????????) trace
> lttng_ust_cyg_profile:func_entry: { cpu_id = 2 }, { addr =
> 0x5625C88B01A9, call_site = 0x5625C88B0237 }
> [22:29:55.388612293] (+0.000005234) trace
> lttng_ust_cyg_profile:func_exit: { cpu_id = 2 }, { addr =
> 0x5625C88B01A9, call_site = 0x5625C88B0237 }
> [22:29:55.388613215] (+0.000000922) trace
> lttng_ust_cyg_profile:func_exit: { cpu_id = 2 }, { addr =
> 0x5625C88B01EE, call_site = 0x7FE40BD5C0B3 }
> B.R.
> Changcheng
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