Messages in this thread | | | Date | Sat, 7 Jan 2017 01:22:23 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH perf/core 3/3] perf-probe: Fix to probe on gcc generated functions in modules |
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Hi Arnaldo,
On Thu, 5 Jan 2017 15:47:43 -0300 Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> Em Thu, Jan 05, 2017 at 12:30:37PM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Thu, Jan 05, 2017 at 08:20:19PM +0900, Masami Hiramatsu escreveu: > > > On Wed, 4 Jan 2017 11:48:56 -0300 > > > Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > > > [acme@jouet linux]$ grep e1000_xmit_frame /proc/kallsyms > > > > ffffffffc046fc10 t e1000_xmit_frame [e1000e] > > > > [acme@jouet linux]$ > > > > OK, it sounds reasonable to me too. BTW, how can I get the map for kallsyms? > > > May machine__findnew_module_map(host_machine, ,"[kernel.kallsyms]") > > > include module symbols too? > > > Probably what you want is: > > > symbol = machine__find_kernel_function_by_name(machine, name, &map); > > > Then, if symbol is not NULL, map->dso->name will have your module name, > > map->dso->long_name will have the .ko path, etc. > > Take a look at 'perf kallsyms' a simple toy cmd that exercises the APIs > you need: > > https://git.kernel.org/cgit/linux/kernel/git/acme/linux.git/commit/?h=perf/core&id=25c92235676d2655e3f31ffe02bd4355d838e5e9 > > Basically: > > struct machine *machine = machine__new_kallsyms(); > struct map *map; > struct symbol *symbol = machine__find_kernel_function_by_name(machine, symbol_name, &map); > > Then you have symbol->{addr,end,name,etc} and map->dso->{long,short}_name > > $ perf kallsyms e1000_xmit_frame usb_stor_set_xfer_buf > e1000_xmit_frame: [e1000e] /lib/modules/4.9.0+/kernel/drivers/net/ethernet/intel/e1000e/e1000e.ko 0xffffffffc046fc10-0xffffffffc0470bb0 (0x19c80-0x1ac20) > usb_stor_set_xfer_buf: [usb_storage] /lib/modules/4.9.0+/kernel/drivers/usb/storage/usb-storage.ko 0xffffffffc057aea0-0xffffffffc057af19 (0xf10-0xf89)
I've found an issue on perf kallsyms. Please see below.
When I run kallsyms without root privilege, it works well.
$ ./perf kallsyms -vv drm_malloc_ab Failed to open /proc/kcore. Note /proc/kcore requires CAP_SYS_RAWIO capability to access. drm_malloc_ab: [i915] /lib/modules/4.8.15-300.fc25.x86_64/kernel/drivers/gpu/drm/i915/i915.ko.xz 0xffffffffc0211950-0xffffffffc02119a6 (0x309c0-0x30a16)
However, with root privilege it failed to get correct module name...
$ sudo ./perf kallsyms -vv drm_malloc_ab Using /proc/kcore for kernel object code drm_malloc_ab: [kernel] /proc/kcore 0xffffffffc0211950-0xffffffffc02119b0 (0x7fffc0214950-0x7fffc02149b0)
Thank you,
> > - Arnaldo
-- Masami Hiramatsu <mhiramat@kernel.org>
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