Re: exercising current aarch64 kprobe support with systemtap

[Pratyush Anand <panand at redhat dot com>]

On 13/07/2016:02:25:57 PM, David Long wrote:
> On 07/12/2016 10:33 AM, William Cohen wrote:
> > On 06/10/2016 01:49 AM, David Long wrote:
> > > Attached are incremental diffs I hope will fix the latest systemtap failures, without abandoning atomic sequence checking.  I'm trying to avoid the hex constants but I don't think the insn.c functions help in this case.
> > > 
> > > -dl
> > > 
> > 
> > Hi Dave,
> > 
> > Is this heuristic to limit the search to not go past the prologue going to be included in the arm64 kprobe patches?  I ran the current v15 patches and saw that some of the tests were failing becuase some of the problems were unseccussful in registering as seen below in the output of systemtap.log.  -Will
> > 
> > spawn stap /root/systemtap_write/systemtap/testsuite/systemtap.base/bz1027459.stp
> > 
> > WARNING: probe kernel.function("SyS_set_tid_address@kernel/fork.c:1236").call (address 0xfffffc00080c5f00) registration error (rc -22)
> > 
> > WARNING: probe kernel.function("SyS_sched_setaffinity@kernel/sched/core.c:4706").call (address 0xfffffc00081010e8) registration error (rc -22)
> > 
> > WARNING: probe kernel.function("SyS_sched_get_priority_min@kernel/sched/core.c:5029").call (address 0xfffffc00081015e8) registration error (rc -22)
> > 
> > WARNING: probe kernel.function("SyS_sched_get_priority_max@kernel/sched/core.c:5002").call (address 0xfffffc0008101580) registration error (rc -22)
> > 
> > hi
> > 
> > FAIL: bz1027459 -p5 (0)
> > 
> > spawn stap -v /root/systemtap_write/systemtap/testsuite/systemtap.base/equal.stp
> > 
> > Pass 1: parsed user script and 115 library scripts using 51968virt/38784res/6976shr/32576data kb, in 190usr/0sys/202real ms.
> > 
> > Pass 2: analyzed script: 4 probes, 1 function, 0 embeds, 2 globals using 91776virt/82176res/7744shr/72384data kb, in 1230usr/10sys/1241real ms.
> > 
> > Pass 3: translated to C into "/tmp/stapK5F1ze/stap_5a080310fa71fdec33340dcee0389f80_1969_src.c" using 91776virt/82432res/8000shr/72384data kb, in 0usr/0sys/11real ms.
> > 
> > Pass 4: compiled C into "stap_5a080310fa71fdec33340dcee0389f80_1969.ko" in 3190usr/640sys/3803real ms.
> > 
> > Pass 5: starting run.
> > 
> > WARNING: probe kernel.function("schedule@kernel/sched/core.c:3369") (address 0xfffffc00088f65c0) registration error (rc -22)
> > 
> > systemtap starting probe
> > 
> > FAIL: systemtap.base/equal.stp startup (timeout)
> > 
> > spawn stap -v /root/systemtap_write/systemtap/testsuite/systemtap.base/finloop2.stp
> > 
> > Pass 1: parsed user script and 115 library scripts using 52032virt/38848res/6976shr/32640data kb, in 200usr/0sys/204real ms.
> > 
> > Pass 2: analyzed script: 4 probes, 1 function, 0 embeds, 2 globals using 91840virt/82240res/7744shr/72448data kb, in 1230usr/10sys/1246real ms.
> > 
> > Pass 3: translated to C into "/tmp/stapfwr7Sg/stap_177624071ced2b52cbbfd6b4ea09dd28_1964_src.c" using 91840virt/82496res/8000shr/72448data kb, in 10usr/10sys/11real ms.
> > 
> > Pass 4: compiled C into "stap_177624071ced2b52cbbfd6b4ea09dd28_1964.ko" in 3230usr/620sys/3812real ms.
> > 
> > Pass 5: starting run.
> > 
> > WARNING: probe kernel.function("schedule@kernel/sched/core.c:3369") (address 0xfffffc00088f65c0) registration error (rc -22)
> > 
> > systemtap starting probe
> > 
> > FAIL: systemtap.base/finloop2.stp startup (timeout)
> > 
> > spawn stap -v /root/systemtap_write/systemtap/testsuite/systemtap.base/kfunct.stp
> > 
> > Pass 1: parsed user script and 115 library scripts using 52032virt/38848res/6976shr/32640data kb, in 190usr/10sys/201real ms.
> > 
> > Pass 2: analyzed script: 4 probes, 1 function, 0 embeds, 1 global using 91840virt/82240res/7744shr/72448data kb, in 1240usr/10sys/1245real ms.
> > 
> > Pass 3: translated to C into "/tmp/stap8zsRzS/stap_2fa61ae7aa177442cb013709494408e9_1680_src.c" using 91840virt/82496res/8000shr/72448data kb, in 10usr/0sys/11real ms.
> > 
> > Pass 4: compiled C into "stap_2fa61ae7aa177442cb013709494408e9_1680.ko" in 3210usr/620sys/3789real ms.
> > 
> > Pass 5: starting run.
> > 
> > WARNING: probe kernel.function("schedule@kernel/sched/core.c:3369") (address 0xfffffc00088f65c0) registration error (rc -22)
> > 
> > systemtap starting probe
> > 
> > FAIL: systemtap.base/kfunct.stp startup (timeout)
> > 
> > 
> 
> I don't think we ever closed the loop on whether this was a good idea or

I think, we should go with that improvement of recognising "stp
x29,x30,[sp,...]" until we have something from compiler to recognize .word
instructions.

> not.  This code is not present in v15.

So, please take that in next revision.

~Pratyush