Re: perf segmentation fault from NULL dereference
From: John Garry
Date: Tue Oct 02 2018 - 06:21:07 EST
On 27/09/2018 04:00, Andi Kleen wrote:
Please me let me know if a valid issue so we can get a fix in.
If it crashes it must be a valid issue of course.
But I'm not sure about your bisect. Hard to see how my patch
could cause this. Sometimes bisects go wrong.
You verified by just reverting the patch?
It no longer reverts cleanly. And the previous patch - 4ca69ca9db3a -
did not have this crash:
root@localhost:~# ./perf_debug_ record -e armv8_pmuv3_0/br_mis_pred/ sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.001 MB perf.data (6 samples) ]
root@localhost:~#
First thing I would also try is to run with valgrind or ASan and see if it
reports anything.
Here's the valgrind output:
root@localhost:~#valgrind --leak-check=yes ./perf_debug_ record -e
armv8_pmuv3_0/br_mis_pred/ sleep 1
==16025== Memcheck, a memory error detector
==16025== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==16025== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==16025== Command: ./perf_debug_ record -e armv8_pmuv3_0/br_mis_pred/
sleep 1
==16025==
--16025-- WARNING: unhandled arm64-linux syscall: 168
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error
38 (Function not implemented)
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
perf_event_open(..., 0) failed unexpectedly with error 38 (Function not
implemented)
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
--16025-- WARNING: unhandled arm64-linux syscall: 241
--16025-- You may be able to write your own handler.
--16025-- Read the file README_MISSING_SYSCALL_OR_IOCTL.
--16025-- Nevertheless we consider this a bug. Please report
--16025-- it at http://valgrind.org/support/bug_reports.html.
Error:
The sys_perf_event_open() syscall returned with 38 (Function not
implemented) for event (armv8_pmuv3_0/br_mis_pred/).
/bin/dmesg | grep -i perf may provide additional information.
==16059==
==16059== Process terminating with default action of signal 15 (SIGTERM)
==16059== at 0x486F974: __read_nocancel (syscall-template.S:84)
==16059== by 0x48D02F: read (unistd.h:44)
==16059== by 0x48D02F: perf_evlist__prepare_workload (evlist.c:1471)
==16059== by 0x41AB0F: __cmd_record (builtin-record.c:898)
==16059== by 0x41AB0F: cmd_record (builtin-record.c:1873)
==16059== by 0x476C7F: run_builtin (perf.c:302)
==16059== by 0x476F37: handle_internal_command (perf.c:354)
==16059== by 0x407093: run_argv (perf.c:398)
==16059== by 0x407093: main (perf.c:520)
==16059==
==16059== HEAP SUMMARY:
==16059== in use at exit: 56,239 bytes in 226 blocks
==16059== total heap usage: 1,164 allocs, 938 frees, 2,238,979 bytes
allocated
==16059==
==16059== 12 bytes in 1 blocks are definitely lost in loss record 1 of 6
==16059== at 0x4844B88: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16059==
==16059== 344 bytes in 5 blocks are possibly lost in loss record 3 of 6
==16059== at 0x4846CFC: calloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16059==
==16059== 5,736 bytes in 125 blocks are possibly lost in loss record 4 of 6
==16059== at 0x4844B88: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16059==
==16059== LEAK SUMMARY:
==16059== definitely lost: 12 bytes in 1 blocks
==16059== indirectly lost: 0 bytes in 0 blocks
==16059== possibly lost: 6,080 bytes in 130 blocks
==16059== still reachable: 50,147 bytes in 95 blocks
==16059== suppressed: 0 bytes in 0 blocks
==16059== Reachable blocks (those to which a pointer was found) are not
shown.
==16059== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==16059==
==16059== For counts of detected and suppressed errors, rerun with: -v
==16059== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0)
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025== Warning: invalid file descriptor -1 in syscall close()
==16025==
==16025== HEAP SUMMARY:
==16025== in use at exit: 26,640 bytes in 209 blocks
==16025== total heap usage: 1,202 allocs, 993 frees, 2,455,112 bytes
allocated
==16025==
==16025== 328 bytes in 7 blocks are definitely lost in loss record 2 of 6
==16025== at 0x4844B88: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16025==
==16025== 344 bytes in 5 blocks are possibly lost in loss record 3 of 6
==16025== at 0x4846CFC: calloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16025==
==16025== 6,000 bytes in 126 blocks are possibly lost in loss record 5 of 6
==16025== at 0x4844B88: malloc (in
/usr/lib/valgrind/vgpreload_memcheck-arm64-linux.so)
==16025==
==16025== LEAK SUMMARY:
==16025== definitely lost: 328 bytes in 7 blocks
==16025== indirectly lost: 0 bytes in 0 blocks
==16025== possibly lost: 6,344 bytes in 131 blocks
==16025== still reachable: 19,968 bytes in 71 blocks
==16025== suppressed: 0 bytes in 0 blocks
==16025== Reachable blocks (those to which a pointer was found) are not
shown.
==16025== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==16025==
==16025== For counts of detected and suppressed errors, rerun with: -v
==16025== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 0 from 0)
root@localhost:~#
(pretty much the same as previous patch)
Cheers,
John
-Andi
.