Hi Leo,
My understanding is that when we decode CoreSight trace - be it on the system that generated it, or off target device on a separate host system, we are using the dso files in .debug/ as these represent the memory layout at the time trace was recorded.
If I look into a recent session copied up to my linux box from DB410, is see ~/.debug/[kernel.kallsyms]/ee80c1f3a434469f6174e1cf4bb5583d83a013dc/kallsyms - which seems to me to be the relevant symbol file to use rather than the live one generated by /proc/kallsyms. I don't really want to use the local /proc/kallsyms on my x86 linux box when decoding an ARM trace captured elsewhere.
So perhaps the problem to be solved is not how to use /proc/kallsyms if no vmlinux is supplied to the script, but ensure that the [kernel.kallsyms] is used?
Regards
Mike On Fri, 2 Nov 2018 at 02:55, leo.yan@linaro.org wrote:
Hi all,
Now I found that if use the command 'perf script' for Arm CoreSight trace data, it fails to parse kernel symbols if we don't specify kernel vmlinux file. So when we don't specify kernel symbol files then perf tool will roll back to use /proc/kallsyms for kernel symbols parsing, as result it will run into below flow:
thread__find_addr_map(thread, cpumode, MAP__FUNCTION, address, &al); map__load(al.map); dso__data_read_offset(al.map->dso, machine, offset, buffer, size); `-> data_read_offset()
I can observe the function data_read_offset() returns failure, this is caused by checking the offset sanity "if (offset > dso->data.file_size)" (I pasted the whole function code at below in case you want to get more context for it), but if perf use "/proc/kallsyms" to load kernel symbols, the variable 'dso->data.file_size' will be set to zero thus the sanity checking always thinks the offset is out of the file size bound.
Now I still don't understand how the dso/map support "/proc/kallsyms" and have no idea to fix this issue, though I spent some time to look into it.
Could you give some suggestion for this? Or even better if you have fixing for this, I am glad to test at my side.
static ssize_t data_read_offset(struct dso *dso, struct machine *machine, u64 offset, u8 *data, ssize_t size) { if (data_file_size(dso, machine)) return -1;
/* Check the offset sanity. */ if (offset > dso->data.file_size) return -1; if (offset + size < offset) return -1; return cached_read(dso, machine, offset, data, size);}
Thanks, Leo Yan _______________________________________________ CoreSight mailing list CoreSight@lists.linaro.org https://lists.linaro.org/mailman/listinfo/coresight