On 05/08/2024 1:22 pm, Ganapatrao Kulkarni wrote:
On 01-08-2024 03:30 pm, James Clark wrote:
On 24/07/2024 3:45 pm, James Clark wrote:
On 24/07/2024 7:38 am, Ganapatrao Kulkarni wrote:
On 23-07-2024 09:16 pm, James Clark wrote:
On 23/07/2024 4:26 pm, Ganapatrao Kulkarni wrote:
On 23-07-2024 06:40 pm, James Clark wrote: > > > On 22/07/2024 11:02 am, Ganapatrao Kulkarni wrote: >> >> Hi James, >> >> On 19-07-2024 08:09 pm, James Clark wrote: >>> >>> >>> On 19/07/2024 10:26 am, Ganapatrao Kulkarni wrote: >>>> To generate the instruction tracing, script uses 2 contiguous >>>> packets >>>> address range. If there a continuity brake due to >>>> discontiguous branch >>>> address, it is required to reset the tracing and start tracing >>>> with the >>>> new set of contiguous packets. >>>> >>>> Adding change to identify the break and complete the remaining >>>> tracing >>>> of current packets and restart tracing from new set of >>>> packets, if >>>> continuity is established. >>>> >>> >>> Hi Ganapatrao, >>> >>> Can you add a before and after example of what's changed to the >>> commit message? It wasn't immediately obvious to me if this is >>> adding missing output, or it was correcting the tail end of the >>> output that was previously wrong. >> >> It is adding tail end of the trace as well avoiding the segfault >> of the perf application. With out this change the perf segfaults >> with as below log >> >> >> ./perf script >> --script=python:./scripts/python/arm-cs-trace-disasm.py -- -d >> objdump -k ../../vmlinux -v $* > dump >> objdump: error: the stop address should be after the start address >> Traceback (most recent call last): >> File "./scripts/python/arm-cs-trace-disasm.py", line 271, in >> process_event >> print_disam(dso_fname, dso_vm_start, start_addr, stop_addr) >> File "./scripts/python/arm-cs-trace-disasm.py", line 105, in >> print_disam >> for line in read_disam(dso_fname, dso_start, start_addr, >> stop_addr): >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> File "./scripts/python/arm-cs-trace-disasm.py", line 99, in >> read_disam >> disasm_output = >> check_output(disasm).decode('utf-8').split('\n') >> ^^^^^^^^^^^^^^^^^^^^ >> File "/usr/lib64/python3.12/subprocess.py", line 466, in >> check_output >> return run(*popenargs, stdout=PIPE, timeout=timeout, >> check=True, >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> File "/usr/lib64/python3.12/subprocess.py", line 571, in run >> raise CalledProcessError(retcode, process.args, >> subprocess.CalledProcessError: Command '['objdump', '-d', '-z', >> '--start-address=0xffff80008125b758', >> '--stop-address=0xffff80008125a934', '../../vmlinux']' returned >> non-zero exit status 1. >> Fatal Python error: handler_call_die: problem in Python trace >> event handler >> Python runtime state: initialized >> >> Current thread 0x0000ffffb05054e0 (most recent call first): >> <no Python frame> >> >> Extension modules: perf_trace_context, systemd._journal, >> systemd._reader, systemd.id128, report._py3report, >> _dbus_bindings, problem._py3abrt (total: 7) >> Aborted (core dumped) >> >>> >>>> Signed-off-by: Ganapatrao Kulkarni >>>> gankulkarni@os.amperecomputing.com >>>> --- >>>> tools/perf/scripts/python/arm-cs-trace-disasm.py | 10 >>>> ++++++++++ >>>> 1 file changed, 10 insertions(+) >>>> >>>> diff --git a/tools/perf/scripts/python/arm-cs-trace-disasm.py >>>> b/tools/perf/scripts/python/arm-cs-trace-disasm.py >>>> index d973c2baed1c..ad10cee2c35e 100755 >>>> --- a/tools/perf/scripts/python/arm-cs-trace-disasm.py >>>> +++ b/tools/perf/scripts/python/arm-cs-trace-disasm.py >>>> @@ -198,6 +198,10 @@ def process_event(param_dict): >>>> cpu_data[str(cpu) + 'addr'] = addr >>>> return >>>> + if (cpu_data.get(str(cpu) + 'ip') == None): >>>> + cpu_data[str(cpu) + 'ip'] = ip >>>> + >>> >>> Do you need to write into the global cpu_data here? Doesn't it >>> get overwritten after you load it back into 'prev_ip' >> >> No, the logic is same as holding the addr of previous packet. >> Saving the previous packet saved ip in to prev_ip before >> overwriting with the current packet. > > It's not exactly the same logic as holding the addr of the > previous sample. For addr, we return on the first None, with your > change we now "pretend" that the second one is also the previous > one: > > if (cpu_data.get(str(cpu) + 'addr') == None): > cpu_data[str(cpu) + 'addr'] = addr > return <----------------------------sample 0 return > > if (cpu_data.get(str(cpu) + 'ip') == None): > cpu_data[str(cpu) + 'ip'] = ip <---- sample 1 save but no > return > > Then for sample 1 'prev_ip' is actually now the 'current' IP:
Yes, it is dummy for first packet. Added anticipating that we wont hit the discontinuity for the first packet itself.
Can this be changed to more intuitive like below?
diff --git a/tools/perf/scripts/python/arm-cs-trace-disasm.py b/tools/perf/scripts/python/arm-cs-trace-disasm.py index d973c2baed1c..d49f5090059f 100755 --- a/tools/perf/scripts/python/arm-cs-trace-disasm.py +++ b/tools/perf/scripts/python/arm-cs-trace-disasm.py @@ -198,6 +198,8 @@ def process_event(param_dict): cpu_data[str(cpu) + 'addr'] = addr return
+ if (cpu_data.get(str(cpu) + 'ip') != None): + prev_ip = cpu_data[str(cpu) + 'ip']
if (options.verbose == True): print("Event type: %s" % name) @@ -243,12 +245,18 @@ def process_event(param_dict):
# Record for previous sample packet cpu_data[str(cpu) + 'addr'] = addr + cpu_data[str(cpu) + 'ip'] = stop_addr
# Handle CS_ETM_TRACE_ON packet if start_addr=0 and stop_addr=4 if (start_addr == 0 and stop_addr == 4): print("CPU%d: CS_ETM_TRACE_ON packet is inserted" % cpu) return
+ if (stop_addr < start_addr and prev_ip != 0): + # Continuity of the Packets broken, set start_addr to previous + # packet ip to complete the remaining tracing of the address range. + start_addr = prev_ip
if (start_addr < int(dso_start) or start_addr > int(dso_end)): print("Start address 0x%x is out of range [ 0x%x .. 0x%x ] for dso %s" % (start_addr, int(dso_start), int(dso_end), dso)) return
Without this patch below is the failure log(with segfault) for reference.
[root@sut01sys-r214 perf]# timeout 4s ./perf record -e cs_etm// -C 1 dd if=/dev/zero of=/dev/null [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.087 MB perf.data ] [root@sut01sys-r214 perf]# ./perf script --script=python:./scripts/python/arm-cs-trace-disasm.py -- -d objdump -k ../../vmlinux -v $* > dump objdump: error: the stop address should be after the start address Traceback (most recent call last): File "./scripts/python/arm-cs-trace-disasm.py", line 271, in process_event print_disam(dso_fname, dso_vm_start, start_addr, stop_addr) File "./scripts/python/arm-cs-trace-disasm.py", line 105, in print_disam for line in read_disam(dso_fname, dso_start, start_addr, stop_addr): ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "./scripts/python/arm-cs-trace-disasm.py", line 99, in read_disam disasm_output = check_output(disasm).decode('utf-8').split('\n') ^^^^^^^^^^^^^^^^^^^^ File "/usr/lib64/python3.12/subprocess.py", line 466, in check_output return run(*popenargs, stdout=PIPE, timeout=timeout, check=True, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/usr/lib64/python3.12/subprocess.py", line 571, in run raise CalledProcessError(retcode, process.args, subprocess.CalledProcessError: Command '['objdump', '-d', '-z', '--start-address=0xffff80008125b758', '--stop-address=0xffff80008125a934', '../../vmlinux']' returned non-zero exit status 1. Fatal Python error: handler_call_die: problem in Python trace event handler Python runtime state: initialized
Current thread 0x0000ffffb90d54e0 (most recent call first): <no Python frame>
Extension modules: perf_trace_context, systemd._journal, systemd._reader, systemd.id128, report._py3report, _dbus_bindings, problem._py3abrt (total: 7) Aborted (core dumped)
dump snippet:
Event type: branches Sample = { cpu: 0001 addr: 0xffff80008030cb00 phys_addr: 0x0000000000000000 ip: 0xffff800080313f0c pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff800080313f04 <__perf_event_header__init_id+0x4c>: ffff800080313f04: 36100094 tbz w20, #2, ffff800080313f14 <__perf_event_header__init_id+0x5c> ffff800080313f08: f941e6a0 ldr x0, [x21, #968] ffff800080313f0c: d63f0000 blr x0 perf 12720/12720 [0001] 5986.372298040 __perf_event_header__init_id+0x54 .../coresight/linux/kernel/events/core.c 586 return event->clock(); Event type: branches Sample = { cpu: 0001 addr: 0xffff8000801bb4a8 phys_addr: 0x0000000000000000 ip: 0xffff80008030cb0c pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff80008030cb00 <local_clock>: ffff80008030cb00: d503233f paciasp ffff80008030cb04: a9bf7bfd stp x29, x30, [sp, #-16]! ffff80008030cb08: 910003fd mov x29, sp ffff80008030cb0c: 97faba67 bl ffff8000801bb4a8 <sched_clock> perf 12720/12720 [0001] 5986.372298040 local_clock+0xc ...t/linux/./include/linux/sched/clock.h 64 return sched_clock(); Event type: branches Sample = { cpu: 0001 addr: 0xffff80008125a8a8 phys_addr: 0x0000000000000000 ip: 0xffff8000801bb4c8 pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff8000801bb4a8 <sched_clock>: ffff8000801bb4a8: d503233f paciasp ffff8000801bb4ac: a9be7bfd stp x29, x30, [sp, #-32]! ffff8000801bb4b0: 910003fd mov x29, sp ffff8000801bb4b4: a90153f3 stp x19, x20, [sp, #16] ffff8000801bb4b8: d5384113 mrs x19, sp_el0 ffff8000801bb4bc: b9401260 ldr w0, [x19, #16] ffff8000801bb4c0: 11000400 add w0, w0, #0x1 ffff8000801bb4c4: b9001260 str w0, [x19, #16] ffff8000801bb4c8: 94427cf8 bl ffff80008125a8a8 <sched_clock_noinstr> perf 12720/12720 [0001] 5986.372298040 sched_clock+0x20 ...sight/linux/kernel/time/sched_clock.c 105 ns = sched_clock_noinstr(); Event type: branches Sample = { cpu: 0001 addr: 0xffff80008125b758 phys_addr: 0x0000000000000000 ip: 0xffff80008125a8e4 pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff80008125a8a8 <sched_clock_noinstr>: ffff80008125a8a8: d503233f paciasp ffff80008125a8ac: a9bc7bfd stp x29, x30, [sp, #-64]! ffff80008125a8b0: 910003fd mov x29, sp ffff80008125a8b4: a90153f3 stp x19, x20, [sp, #16] ffff80008125a8b8: b000e354 adrp x20, ffff800082ec3000 <tick_bc_dev+0x140> ffff80008125a8bc: 910d0294 add x20, x20, #0x340 ffff80008125a8c0: a90363f7 stp x23, x24, [sp, #48] ffff80008125a8c4: 91002297 add x23, x20, #0x8 ffff80008125a8c8: 52800518 mov w24, #0x28 // #40 ffff80008125a8cc: a9025bf5 stp x21, x22, [sp, #32] ffff80008125a8d0: b9400296 ldr w22, [x20] ffff80008125a8d4: 120002d5 and w21, w22, #0x1 ffff80008125a8d8: 9bb87eb5 umull x21, w21, w24 ffff80008125a8dc: 8b1502f3 add x19, x23, x21 ffff80008125a8e0: f9400e60 ldr x0, [x19, #24] ffff80008125a8e4: d63f0000 blr x0 perf 12720/12720 [0001] 5986.372298040 sched_clock_noinstr+0x3c ...sight/linux/kernel/time/sched_clock.c 93 cyc = (rd->read_sched_clock() - rd->epoch_cyc) & Event type: branches Sample = { cpu: 0001 addr: 0xffff8000801bb4cc phys_addr: 0x0000000000000000 ip: 0xffff80008125a930 pid: 12720 tid: 12720 period: 1 time: 5986372298040 }
With fix:
Event type: branches Sample = { cpu: 0001 addr: 0xffff80008030cb00 phys_addr: 0x0000000000000000 ip: 0xffff800080313f0c pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff800080313f04 <__perf_event_header__init_id+0x4c>: ffff800080313f04: 36100094 tbz w20, #2, ffff800080313f14 <__perf_event_header__init_id+0x5c> ffff800080313f08: f941e6a0 ldr x0, [x21, #968] ffff800080313f0c: d63f0000 blr x0 perf 12720/12720 [0001] 5986.372298040 __perf_event_header__init_id+0x54 .../coresight/linux/kernel/events/core.c 586 return event->clock(); Event type: branches Sample = { cpu: 0001 addr: 0xffff8000801bb4a8 phys_addr: 0x0000000000000000 ip: 0xffff80008030cb0c pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff80008030cb00 <local_clock>: ffff80008030cb00: d503233f paciasp ffff80008030cb04: a9bf7bfd stp x29, x30, [sp, #-16]! ffff80008030cb08: 910003fd mov x29, sp ffff80008030cb0c: 97faba67 bl ffff8000801bb4a8 <sched_clock> perf 12720/12720 [0001] 5986.372298040 local_clock+0xc ...t/linux/./include/linux/sched/clock.h 64 return sched_clock(); Event type: branches Sample = { cpu: 0001 addr: 0xffff80008125a8a8 phys_addr: 0x0000000000000000 ip: 0xffff8000801bb4c8 pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff8000801bb4a8 <sched_clock>: ffff8000801bb4a8: d503233f paciasp ffff8000801bb4ac: a9be7bfd stp x29, x30, [sp, #-32]! ffff8000801bb4b0: 910003fd mov x29, sp ffff8000801bb4b4: a90153f3 stp x19, x20, [sp, #16] ffff8000801bb4b8: d5384113 mrs x19, sp_el0 ffff8000801bb4bc: b9401260 ldr w0, [x19, #16] ffff8000801bb4c0: 11000400 add w0, w0, #0x1 ffff8000801bb4c4: b9001260 str w0, [x19, #16] ffff8000801bb4c8: 94427cf8 bl ffff80008125a8a8 <sched_clock_noinstr> perf 12720/12720 [0001] 5986.372298040 sched_clock+0x20 ...sight/linux/kernel/time/sched_clock.c 105 ns = sched_clock_noinstr(); Event type: branches Sample = { cpu: 0001 addr: 0xffff80008125b758 phys_addr: 0x0000000000000000 ip: 0xffff80008125a8e4 pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff80008125a8a8 <sched_clock_noinstr>: ffff80008125a8a8: d503233f paciasp ffff80008125a8ac: a9bc7bfd stp x29, x30, [sp, #-64]! ffff80008125a8b0: 910003fd mov x29, sp ffff80008125a8b4: a90153f3 stp x19, x20, [sp, #16] ffff80008125a8b8: b000e354 adrp x20, ffff800082ec3000 <tick_bc_dev+0x140> ffff80008125a8bc: 910d0294 add x20, x20, #0x340 ffff80008125a8c0: a90363f7 stp x23, x24, [sp, #48] ffff80008125a8c4: 91002297 add x23, x20, #0x8 ffff80008125a8c8: 52800518 mov w24, #0x28 // #40 ffff80008125a8cc: a9025bf5 stp x21, x22, [sp, #32] ffff80008125a8d0: b9400296 ldr w22, [x20] ffff80008125a8d4: 120002d5 and w21, w22, #0x1 ffff80008125a8d8: 9bb87eb5 umull x21, w21, w24 ffff80008125a8dc: 8b1502f3 add x19, x23, x21 ffff80008125a8e0: f9400e60 ldr x0, [x19, #24] ffff80008125a8e4: d63f0000 blr x0
It looks like the disassembly now assumes this BLR wasn't taken. We go from ffff80008125a8e4 straight through to ...
perf 12720/12720 [0001] 5986.372298040 sched_clock_noinstr+0x3c ...sight/linux/kernel/time/sched_clock.c 93 cyc = (rd->read_sched_clock() - rd->epoch_cyc) & Event type: branches Sample = { cpu: 0001 addr: 0xffff8000801bb4cc phys_addr: 0x0000000000000000 ip: 0xffff80008125a930 pid: 12720 tid: 12720 period: 1 time: 5986372298040 } ffff80008125a8e8 <sched_clock_noinstr+0x40>: ffff80008125a8e8: f8756ae3 ldr x3, [x23, x21]
ffff80008125a8e4 which is just the previous one +4. Isn't your issue actually a decode issue in Perf itself? Why is there a discontinuity without branch samples being generated where either the source or destination address is 0?
What are your record options to create this issue? As I mentioned in the previous reply I haven't been able to reproduce it.
I am using below perf record command.
timeout 4s ./perf record -e cs_etm// -C 1 dd if=/dev/zero of=/dev/null
Thanks I managed to reproduce it. I'll take a look to see if I think the issue is somewhere else.
At least for the failures I encountered, the issue is due to the alternatives runtime instruction patching mechanism. vmlinux ends up being the wrong image to decode with because a load of branches are actually turned into nops.
Can you confirm if you use --kcore instead of vmlinux that you still get failures:
sudo perf record -e cs_etm// -C 1 --kcore -o <output-folder.data> -- \ dd if=/dev/zero of=/dev/null
perf script -i <output-folder.data> \ tools/perf/scripts/python/arm-cs-trace-disasm.py -d llvm-objdump \ -k <output-folder.data>/kcore_dir/kcore
With below command combination with kcore also the issue is seen, as reported in this email chain.
timeout 8s ./perf record -e cs_etm// -C 1 --kcore -o kcore \ dd if=/dev/zero of=/dev/null
./perf script -i kcore/data \ --script=python:./scripts/python/arm-cs-trace-disasm.py -- \ -d objdump -k kcore/kcore_dir/kcore
However, with below sequence(same as your command) the issue is *not* seen.
timeout 8s ./perf record -e cs_etm// -C 1 --kcore -o kcore \ dd if=/dev/zero of=/dev/null
./perf script -i kcore/data ./scripts/python/arm-cs-trace-disasm.py \ -- -d objdump -k kcore/kcore_dir/kcore
Do you see any issue with the command, which is showing the problem? Also the output log produced by these both commands is different.
Double check the command I gave. "-i" needs to be the same as "-o" (it's the folder, not the data file). I think this could be causing your issue. Unless you give it the folder it doesn't open kcore along with the data file.
The below diff that you have shared has no effect on the failing case.
But I still think bad decode detection should be moved as much as possible into OpenCSD and Perf rather than this script. Otherwise every tool will have to re-implement it, and OpenCSD has a lot more info to make decisions with.
One change we can make is to desynchronize when an N atom is an unconditional branch:
diff --git a/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp b/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp index c557998..3eefd5d 100644 --- a/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp +++ b/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp @@ -1341,6 +1341,14 @@ ocsd_err_t TrcPktDecodeEtmV4I::processAtom(const ocsd_atm_val atom) // save recorded next instuction address ocsd_vaddr_t nextAddr = m_instr_info.instr_addr;
+ // must have lost sync if an unconditional branch wasn't taken + if (atom == ATOM_N && !m_instr_info.is_conditional) { + m_need_addr = true; + m_out_elem.addElemType(m_index_curr_pkt, OCSD_GEN_TRC_ELEM_NO_SYNC); + // wait for next address + return OCSD_OK; + }
Another one we can spot is when a new address comes that is before the current decode address (basically the backwards check that you added).
There are probably others that can be spotted like an address appearing after a direct branch that doesn't match the branch target.
I think at that point, desynchronising should cause the disassembly script to throw away the last bit, rather than force it to be printed as in this patch. As I mentioned above in the thread, it leads to printing disassembly that's implausible and misleading (where an unconditional branch wasn't taken).
Thanks, Ganapat