Messages in this thread | | | Date | Fri, 30 Jan 2015 11:32:20 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH perf/core 1/2] [BUGFIX] perf-probe: Fix to handle optimized not-inlined but has no instance |
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Em Fri, Jan 30, 2015 at 11:21:35AM -0300, Arnaldo Carvalho de Melo escreveu: > Em Fri, Jan 30, 2015 at 06:37:44PM +0900, Masami Hiramatsu escreveu: > > Fix to handle optimized no-inline functions which have > > only function definition but no actual instance at > > that point. To fix this problem, we need to find actual > > instance of the function. > > > > Without this patch: > > ---- > > # perf probe -a __up > > Failed to get entry address of __up. > > Error: Failed to add events. > > # perf probe -L __up > > Specified source line is not found. > > Error: Failed to show lines. > > ---- > > > > With this patch: > > ---- > > # perf probe -a __up > > Added new event: > > probe:__up (on __up) > > > > You can now use it in all perf tools, such as: > > > > perf record -e probe:__up -aR sleep 1 > > > > # perf probe -L __up > > <__up@/home/fedora/ksrc/linux-3/kernel/locking/semaphore.c:0> > > 0 static noinline void __sched __up(struct semaphore *sem) > > { > > struct semaphore_waiter *waiter = list_first_entry(&sem->wait_ > > struct semaphore_waite > > 4 list_del(&waiter->list); > > 5 waiter->up = true; > > 6 wake_up_process(waiter->task); > > 7 } > > ---- > > Since __up here was built in some other way, I looked for another
Nah, I saw you trying to add "perf probe -a __up" and stopped there, hadn't seen that it fails _as well_ for just listing the source code...
Yes, I managed to reproduce the problem and test your fix, it works:
[root@zoo ~]# perf probe --del __up Removed event: probe:__up [root@zoo ~]# perf probe -L __up Specified source line is not found. Error: Failed to show lines.
---->>>>>> APPLY THE PATCH, rebuild and try again:
[root@zoo ~]# [root@zoo ~]# perf probe -L __up <__up@/home/git/linux/kernel/locking/semaphore.c:0> 0 static noinline void __sched __up(struct semaphore *sem) { struct semaphore_waiter *waiter = list_first_entry(&sem->wait_list, struct semaphore_waiter, list); 4 list_del(&waiter->list); 5 waiter->up = true; 6 wake_up_process(waiter->task); 7 } [root@zoo ~]#
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So its just this other case that fails, vmalloc_fault, can you check this one? Does it happen in your machine as well?
Applying your patch, thanks,
- Arnaldo
> 'noinline' function to try, and it failed here: > > [root@zoo ~]# perf probe -L vmalloc_fault | head -5 > <vmalloc_fault@/home/git/linux/arch/x86/mm/fault.c:0> > 0 static noinline int vmalloc_fault(unsigned long address) > 1 { > pgd_t *pgd, *pgd_ref; > pud_t *pud, *pud_ref; > [root@zoo ~]# perf probe vmalloc_fault > Added new event: > Failed to write event: Invalid argument > Error: Failed to add events. > > ---->>>>>> APPLY THE PATCH, rebuild and try again: > > [root@zoo ~]# perf probe vmalloc_fault > Added new event: > Failed to write event: Invalid argument > Error: Failed to add events. > [root@zoo ~]# perf probe -v vmalloc_fault > probe-definition(0): vmalloc_fault > symbol:vmalloc_fault file:(null) line:0 offset:0 return:0 lazy:(null) > 0 arguments > Looking at the vmlinux_path (7 entries long) > Using /lib/modules/3.19.0-rc6+/build/vmlinux for symbols > Open Debuginfo file: /lib/modules/3.19.0-rc6+/build/vmlinux > Try to find probe point from debuginfo. > Probe point found: vmalloc_fault+0 > Found 1 probe_trace_events. > Opening /sys/kernel/debug/tracing/kprobe_events write=1 > Added new event: > Writing event: p:probe/vmalloc_fault _text+289600 > Failed to write event: Invalid argument > Error: Failed to add events. Reason: Invalid argument (Code: -22) > [root@zoo ~]# grep -w vmalloc_fault /proc/kallsyms > ffffffff81046b40 t vmalloc_fault > [root@zoo ~]# grep -w _text /proc/kallsyms > ffffffff81000000 T _text > [root@zoo ~]# python > Python 2.7.5 (default, Nov 3 2014, 14:26:24) > [GCC 4.8.3 20140911 (Red Hat 4.8.3-7)] on linux2 > Type "help", "copyright", "credits" or "license" for more information. > >>> 0xffffffff81046b40 - 0xffffffff81000000 > 289600L > >>> > [root@zoo ~]# readelf -s /lib/modules/3.19.0-rc6+/build/vmlinux | egrep -w _text\|vmalloc_fault > 3499: ffffffff81046b40 410 FUNC LOCAL DEFAULT 1 vmalloc_fault > 48873: ffffffff81000000 0 NOTYPE GLOBAL DEFAULT 1 _text > [root@zoo ~]# > > --------------------------------------------------------------------------- > > So perhaps I need a 'noinline' _and_ '__sched', so that I have a "optimized > no-inline functions which have only function definition but no actual instance > at that point"? > > Looking for one, will post here after objdump -dS finishes... > > - Arnaldo
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