On 2015/11/26 3:35, Arnaldo Carvalho de Melo wrote:
Em Wed, Nov 25, 2015 at 11:30:59AM +0000, Wang Nan escreveu:
If libelf unable to open debuginfo for an offline module but the ko has
symtab, something unexpected may happen.
# rm -rf ~/.debug/
# mv /usr/lib64/elfutils/libebl_x86_64.so{,.bak}
# ./perf probe -m /home/wangnan/kmodule/mymodule.ko my_func
[mymodule] with build id 326ab42550ef3d24944f53c817533728367effeb not found,
continuing without symbols
Failed to find symbol my_func in /home/wangnan/kmodule/mymodule.ko
Understood, since we are giving the path to that module, we can, if its
build-id matches the one for the online module, use it, is that the
case, i.e. do we check, int his scenario, that the build-id matches?
Please see my test result in v2 patch [1]. In symsrc__init() build-id
would be checked.
[1]
http://lkml.kernel.org/r/1448507949-187812-1-git-send-email-wangn...@huawei.com
# ./perf probe -m ./mymodule.ko my_func
Added new event:
probe:my_func (on my_func in /home/wangnan/kmodule/mymodule.ko)
You can now use it in all perf tools, such as:
perf record -e probe:my_func -aR sleep 1
# ./perf probe -d '*'
Removed event: probe:my_func
# mv ./mymodule.{ko,.bak}
# mv ./moduleb.ko mymodule.ko
# ./perf probe -m ./mymodule.ko my_func
/home/wangnan/kmodule/mymodule.ko with build id
326ab42550ef3d24944f53c817533728367effeb not found, continuing without symbols
Failed to find symbol my_func in /home/wangnan/kmodule/mymodule.ko
Error: Failed to add events.
# ./perf probe -v -m ./mymodule.ko my_func
probe-definition(0): my_func
symbol:my_funcfile:(null) line:0 offset:0 return:0 lazy:(null)
0 arguments
Could not open debuginfo. Try to use symbols.
symsrc__init: build id mismatch for /home/wangnan/kmodule/mymodule.ko.
/home/wangnan/kmodule/mymodule.ko with build id
326ab42550ef3d24944f53c817533728367effeb not found, continuing without symbols
Failed to find symbol my_func in /home/wangnan/kmodule/mymodule.ko
Error: Failed to add events. Reason: No such file or directory (Code: -2)
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