Messages in this thread | | | Date | Tue, 12 May 2015 05:42:09 +0900 | From | Masami Hiramatsu <> | Subject | Re: Re: vsprintf: Add support for userspace strings |
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On 2015/05/11 19:57, Richard Weinberger wrote: > Am 11.05.2015 um 10:59 schrieb Richard Weinberger: >> Am 11.05.2015 um 02:24 schrieb Masami Hiramatsu: >>> On 2015/05/11 4:42, Richard Weinberger wrote: >>>> While debugging issues I often add (trace_)printks to strategic positions. >>>> Dealing with user provided string is complicated as an extra buffer a >>>> copy_from_user() is needed. >>>> This adds a new format string to allow direct printing of such strings. >>>> >>>> My initial plan was to use %pU but 'U' is already taken, therefore >>>> I used the next letter which comes in mind when one thinks of userpace, >>>> 'L'. >>>> The %pL format string works exactly like %s. >>> >>> BTW, if you need to do this for debug, you can also use ftrace's kprobe-tracer >>> (and perf probe) which allows you to dump userspace strings :) >> >> Sounds promising! >> >> But I fail to use it: >> $ perf probe -vv -L do_sys_open:0-3 -k /boot/vmlinux-4.1.0-rc2-3.g3541e77-vanilla >> Line range is 0 to 3 >> Use vmlinux: /boot/vmlinux-4.1.0-rc2-3.g3541e77-vanilla >> Failed to find path of kernel module. >> Error: Failed to show lines. Reason: No such file or directory (Code: -2) >> >> Any idea what's the issue? > > Okay, works now as expected. :-) > Had the wrong debuginfo package installed.
Ah, the message is not good... If you give "-vv" (double -v options), you'll see below reason.
symsrc__init: build id mismatch for /boot/vmlinux-4.1.0-rc2-3.g3541e77-vanilla
I'll fix that.
Thank you for reporting!
-- Masami HIRAMATSU Linux Technology Research Center, System Productivity Research Dept. Center for Technology Innovation - Systems Engineering Hitachi, Ltd., Research & Development Group E-mail: masami.hiramatsu.pt@hitachi.com
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