Messages in this thread | | | Date | Tue, 14 Jun 2016 14:05:04 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | perf probe issues |
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Hi Masami,
While investigating a problem in the annotation code reported by Linus, with "kaslr" on the kernel command line and this in .config:
[root@jouet ~]# egrep 'CONFIG_(RANDOMIZE_BASE|DEBUG_INFO)' ~acme/git/build/v4.7.0-rc3/.config CONFIG_RANDOMIZE_BASE=y # CONFIG_DEBUG_INFO is not set [root@jouet ~]#
[root@jouet ~]# grep -w vfs_write /proc/kallsyms ffffffffac2404c0 T vfs_write [root@jouet ~]# perf probe vfs_write vfs_write is out of .text, skip it. Error: Failed to add events. [root@jouet ~]# perf probe -v vfs_write probe-definition(0): vfs_write symbol:vfs_write file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (8 entries long) Using /lib/modules/4.7.0-rc3/build/vmlinux for symbols Could not open debuginfo. Try to use symbols. vfs_write is out of .text, skip it. Error: Failed to add events. Reason: No such file or directory (Code: -2) [root@jouet ~]#
Can you try to test with this config to investigate this problem?
We need to improve the error messages, for instance:
"Could not open debuginfo. Try to use symbols."
I think should be rewritten as: "Trying to use kallsyms", no? I.e. if it doesn't manage to find a vmlinux file, it will try to use kallsyms as a fallback, is that what is happening here?
- Arnaldo
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