Re: [PATCH] perf scripts python arm-cs-trace-disasm.py: Skip disasm if address continuity is broken
From: James Clark
Date: Wed Jul 24 2024 - 10:48:39 EST
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@xxxxxxxxxxxxxxxxxxxxxx>
---
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.
Thanks,
Ganapat