Messages in this thread | | | Subject | Re: [RFC][PATCH 0/3] ftrace: Add dynamically allocated trampolines | From | Namhyung Kim <> | Date | Mon, 14 Jul 2014 23:18:41 +0900 |
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2014-07-14 (월), 17:18 +0900, Masami Hiramatsu: > (2014/07/14 16:16), Namhyung Kim wrote: > > Hi Masami, > > > > On Mon, 14 Jul 2014 10:35:21 +0900, Masami Hiramatsu wrote: > >> (2014/07/11 23:29), Josh Poimboeuf wrote: > >>> Here's the same stack trace with this patch: > >>> > >>> [ 1314.612287] [<ffffffff81700312>] dump_stack+0x45/0x56 > >>> [ 1314.612290] [<ffffffff8125f5b0>] ? meminfo_proc_open+0x30/0x30 > >>> [ 1314.612293] [<ffffffffa080a494>] kpatch_ftrace_handler+0x14/0xf0 [kpatch] > >>> [ 1314.612306] [<ffffffffa00160c4>] 0xffffffffa00160c3 > >> > >> Here, this still has a wrong entry. Maybe the trampline doesn't setup > >> frame pointer (bp) correctly. > > > > Hmm.. are you saying about the hex address above? I guess it's a valid > > entry in the (dynamic) trampoline, but has no symbol.. > > Ah, indeed. (BTW, why is it one less than the address ...? printk's spec?)
Argh, it seems like a bug in printk's %pB format processing.. :-/
It subtract 1 from the address for stacktrace. Please see the commit 0f77a8d37825 ("vsprintf: Introduce %pB format specifier") and 71f9e59800e5 ("x86, dumpstack: Use %pB format specifier for stack trace") for details. But it should restore the original address when it failed to find a symbol for that address.
I'll send a fix soon.
Thanks, Namhyung
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