Usage of libv4l causes a crash during rr record

[georgewsinger]

libv4l2 found.
[FATAL /build/source/src/record_syscall.cc:5817:rec_process_syscall_arch()] 
 (task 36247 (rec:36247) at time 11843)
 -> Assertion `t->regs().syscall_result_signed() == -syscall_state.expect_errno' failed to hold. Expected EINVAL for 'ioctl' but got result 0 (errno SUCCESS); Unknown ioctl(0x80045626): type:0x56 nr:0x26 dir:0x2 size:4 addr:0x7ffc5be5f1f0
Tail of trace dump:
{
  real_time:48306.157920 global_time:11823, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405443
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xc r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.157979 global_time:11824, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405508
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xd r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158027 global_time:11825, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405508
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xd r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158086 global_time:11826, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405577
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xe r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158134 global_time:11827, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405577
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xe r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158193 global_time:11828, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405650
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xf r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158241 global_time:11829, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405650
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0xf r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158300 global_time:11830, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405727
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x10 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158353 global_time:11831, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405727
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x10 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158412 global_time:11832, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405808
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x11 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158461 global_time:11833, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405808
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x11 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158521 global_time:11834, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405893
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x12 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158569 global_time:11835, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405893
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x12 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158628 global_time:11836, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405982
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158677 global_time:11837, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405982
rax:0xffffffffffffffea rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60140 rsi:0xc02c564a rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0xffffffff r9:0x7ffc5be60390 r10:0x13 r11:0x246 r12:0x1 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60140, length:0x2c }
}
{
  real_time:48306.158735 global_time:11838, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532405996
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60170 rsi:0xc0405602 rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0x7ffc5be60390 r9:0x7ffc5be60390 r10:0xffffffff r11:0x246 r12:0x2 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158784 global_time:11839, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532405996
rax:0xffffffffffffffea rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60170 rsi:0xc0405602 rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0x7ffc5be60390 r9:0x7ffc5be60390 r10:0xffffffff r11:0x246 r12:0x2 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60170, length:0x40 }
}
{
  real_time:48306.158843 global_time:11840, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532406009
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60170 rsi:0x80685600 rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0x7ffc5be60390 r9:0x7ffc5be60390 r10:0x7ffc5be60390 r11:0x246 r12:0x2 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
{
  real_time:48306.158892 global_time:11841, event:`SYSCALL: ioctl' (state:EXITING_SYSCALL) tid:36247, ticks:532406009
rax:0x0 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be60170 rsi:0x80685600 rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0x7ffc5be60390 r9:0x7ffc5be60390 r10:0x7ffc5be60390 r11:0x246 r12:0x2 r13:0x13 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
  { tid:36247, addr:0x7ffc5be60170, length:0x68 }
}
{
  real_time:48306.158954 global_time:11842, event:`SYSCALL: ioctl' (state:ENTERING_SYSCALL) tid:36247, ticks:532406113
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x7ffc5be5f1f0 rsi:0x80045626 rdi:0x7 rbp:0x681ffea0 rsp:0x681ffe50 r8:0x1 r9:0x13 r10:0x7ec7ec0 r11:0x246 r12:0x7ec7ec0 r13:0x7ffc5be5f1f0 r14:0x7ffc5be60170 r15:0x7ec84c0 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x10 fs_base:0x7f062423ba80 gs_base:0x0
}
=== Start rr backtrace:
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr13dump_rr_stackEv+0x44)[0x68eed8]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr9GdbServer15emergency_debugEPNS_4TaskE+0x1a2)[0x4ce81e]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr[0x4fda7c]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr21EmergencyDebugOstreamD1Ev+0x62)[0x4fdcd6]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr[0x577ce3]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr[0x560ac8]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr19rec_process_syscallEPNS_10RecordTaskE+0xe8)[0x560c45]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession21syscall_state_changedEPNS_10RecordTaskEPNS0_9StepStateE+0xd00)[0x541be4]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession11record_stepEv+0x404)[0x547754]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr[0x539817]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordCommand3runERSt6vectorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS7_EE+0x3dd)[0x53a447]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(main+0x227)[0x6aa46f]
/nix/store/hp8wcylqr14hrrpqap4wdrwzq092wfln-glibc-2.32-37/lib/libc.so.6(__libc_start_main+0xed)[0x7fbf87134ded]
/nix/store/hjbjqsbv32y440c6vqp3kz1hrf1s2vzl-rr-unstable-2020-10-10/bin/rr(_start+0x2a)[0x43056a]
=== End rr backtrace
Launch gdb with
  gdb '-l' '10000' '-ex' 'set sysroot /' '-ex' 'target extended-remote 127.0.0.1:36247' /home/george/Simula/submodules/godot/bin/godot.x11.tools.64

[khuey]

That looks like VIDIOC_G_INPUT.

[khuey]

Try again with the latest tip?

[georgewsinger]

We now get

[FATAL /build/source/src/RecordSession.cc:345:handle_seccomp_traced_syscall()] 
 (task 78878 (rec:78878) at time 91107)
 -> Assertion `patch_ok' failed to hold. The tracee issues a vsyscall, but we failed to moneypatch the
caller. Recording will not succeed. Exiting.
Tail of trace dump:
{
  real_time:66044.530806 global_time:91087, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408613
rax:0x7fb6266ae000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x210808 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb6266ae000, length:0x211000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x211000 }
}
{
  real_time:66044.530863 global_time:91088, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408695
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x20000 rdi:0x7fb64e2ff000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.530915 global_time:91089, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408695
rax:0x7fb64e2ff000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x20000 rdi:0x7fb64e2ff000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb64e2ff000, length:0x20000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x20000 }
}
{
  real_time:66044.530967 global_time:91090, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408730
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64d13f000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531022 global_time:91091, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408730
rax:0x7fb64d13f000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64d13f000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb64d13f000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:66044.531074 global_time:91092, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408765
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64ccc5000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531130 global_time:91093, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408765
rax:0x7fb64ccc5000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64ccc5000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb64ccc5000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:66044.531181 global_time:91094, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408800
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64a8ef000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531236 global_time:91095, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408800
rax:0x7fb64a8ef000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb64a8ef000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb64a8ef000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:66044.531287 global_time:91096, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408835
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb638a3f000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531342 global_time:91097, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408835
rax:0x7fb638a3f000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fb638a3f000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb638a3f000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:66044.531394 global_time:91098, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2408882
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x100000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531445 global_time:91099, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2408882
rax:0x7fb6265ae000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x100000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb6265ae000, length:0x100000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x100000 }
}
{
  real_time:66044.531518 global_time:91100, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2409503
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x55de8eb5dca0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531569 global_time:91101, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2409503
rax:0x7fb62659e000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x55de8eb5dca0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb62659e000, length:0x10000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x10000 }
}
{
  real_time:66044.531627 global_time:91102, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:78878, ticks:2409567
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531679 global_time:91103, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:78878, ticks:2409567
rax:0x7fb62658e000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fb64d2ffa80 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fb62658e000, length:0x10000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x10000 }
}
{
  real_time:66044.531756 global_time:91104, event:`INSTRUCTION_TRAP' tid:78878, ticks:2412555
rax:0xd rbx:0x756e6547 rcx:0x6c65746e rdx:0x49656e69 rsi:0x55de8e63f6c0 rdi:0xc00000c1e0 rbp:0x7ffe0426d088 rsp:0x7ffe0426d050 r8:0x7fb6266ae60e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x55de8e4299c8 r15:0x0 rip:0x55de8db35f5a eflags:0x10246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531804 global_time:91105, event:`INSTRUCTION_TRAP' tid:78878, ticks:2412556
rax:0x306c3 rbx:0x100800 rcx:0x3ffafbbf rdx:0xbfebfbff rsi:0x55de8e63f6c0 rdi:0xc00000c1e0 rbp:0x7ffe0426d088 rsp:0x7ffe0426d050 r8:0x7fb6266ae60e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x55de8e4299c8 r15:0x0 rip:0x55de8db35f5a eflags:0x10206 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fb64d2ffa80 gs_base:0x0
}
{
  real_time:66044.531852 global_time:91106, event:`INSTRUCTION_TRAP' tid:78878, ticks:2412559
rax:0x0 rbx:0x27ab rcx:0x0 rdx:0x9c000600 rsi:0x55de8e63f6c0 rdi:0xc00000c1e0 rbp:0x7ffe0426d088 rsp:0x7ffe0426d050 r8:0x7fb6266ae60e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x55de8e4299c8 r15:0x0 rip:0x55de8db35f5a eflags:0x10206 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fb64d2ffa80 gs_base:0x0
}
=== Start rr backtrace:
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr13dump_rr_stackEv+0x44)[0x69e873]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr9GdbServer15emergency_debugEPNS_4TaskE+0x1a2)[0x4d0896]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr[0x500834]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr21EmergencyDebugOstreamD1Ev+0x62)[0x500a8e]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession29handle_seccomp_traced_syscallEPNS_10RecordTaskEPNS0_9StepStateEPNS0_12RecordResultEPb+0x479)[0x5414b7]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession19handle_ptrace_eventEPPNS_10RecordTaskEPNS0_9StepStateEPNS0_12RecordResultEPb+0x31a)[0x54262a]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession11record_stepEv+0x31f)[0x54a97b]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr[0x53c807]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordCommand3runERSt6vectorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS7_EE+0x3dd)[0x53d44b]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(main+0x227)[0x6b9e1f]
/nix/store/hp8wcylqr14hrrpqap4wdrwzq092wfln-glibc-2.32-37/lib/libc.so.6(__libc_start_main+0xed)[0x7fe5a0353ded]
/nix/store/6cglxyfwblnb1jpiqa2j008sm8j80q7z-rr-unstable-2020-10-10/bin/rr(_start+0x2a)[0x43056a]
=== End rr backtrace
Launch gdb with
  gdb '-l' '10000' '-ex' 'set sysroot /' '-ex' 'target extended-remote 127.0.0.1:13342' /usr/bin/snap

[khuey]

Attach gdb to the tracee following the instructions at the bottom and get a backtrace?

[georgewsinger]

When I run

gdb '-l' '10000' '-ex' 'set sysroot /' '-ex' 'target extended-remote 127.0.0.1:30174' /usr/bin/snap

I get taken to

Reading symbols from /usr/lib/debug//lib/x86_64-linux-gnu/ld-2.32.so...
0x000056040c49c20c in _start () from /lib64/ld-linux-x86-64.so.2
(gdb) bt
#0  0x000056040c49c20c in _start () from /lib64/ld-linux-x86-64.so.2
#1  0x000056040cdcee20 in ?? ()
#2  0x000000c000002001 in ?? ()
#3  0x000000c00000c000 in ?? ()
#4  0x000056040cb95ea0 in ?? ()
#5  0x00007ffe52a173a8 in ?? ()
#6  0x000056040c47b039 in ?? ()
#7  0x0000000000010000 in ?? ()
#8  0x000056040cb95ea0 in ?? ()
#9  0x0000000000000004 in ?? ()
#10 0x000056040d4cd3ab in ?? ()
#11 0x0000000000000010 in ?? ()
#12 0x00007ffe52a173f0 in ?? ()
#13 0x000056040c466cac in ?? ()
#14 0x000056040d4cd240 in ?? ()
#15 0x0000000000000080 in ?? ()
#16 0x0000000000000080 in ?? ()
#17 0x0000000000000010 in ?? ()
#18 0x0000000000000000 in ?? ()

Pressing c just results in termination of the program:

(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) n
Program not restarted.
(gdb) c
Continuing.
Warning:
Cannot insert breakpoint -2: Remote connection closed
Command aborted.

[rocallahan]

If you rerun that recording and attach the emergency debugger again, what's the value of $rip, what's the return address on the stack at [$rsp], and what's the disassembly of the code at that address?

[georgewsinger]

Some output from gdb:

(gdb) p $rip
$1 = (void (*)()) 0x55e0662bf20c <_start>
(gdb) p $rsp
$2 = (void *) 0x7ffe96ad7210
(gdb) x/10i $rsp
   0x7ffe96ad7210:	and    %bl,(%rsi)
   0x7ffe96ad7212:	mov    $0x55e066,%edi
   0x7ffe96ad7217:	add    %al,(%rcx)
   0x7ffe96ad7219:	and    %al,(%rax)
   0x7ffe96ad721b:	add    %al,%al
   0x7ffe96ad721d:	add    %al,(%rax)
   0x7ffe96ad721f:	add    %al,(%rax)
   0x7ffe96ad7221:	rolb   $0x0,(%rax)
   0x7ffe96ad7224:	rolb   $0x0,(%rax)
   0x7ffe96ad7227:	add    %ah,-0x1f996472(%rax)
(gdb) x/10i $rip
=> 0x55e0662bf20c <_start>:	mov    (%rsp),%eax
   0x55e0662bf20f <_start+3>:	mov    0x8(%rsp),%edx
   0x55e0662bf213 <_start+7>:	mov    %rbp,%rsp
   0x55e0662bf216 <_dl_start_user+2>:	movq   $0x0,0x328(%rbx)
   0x55e0662bf221 <_dl_start_user+13>:	imul   $0x3e8,%rdx,%rdx
   0x55e0662bf228 <_dl_start_user+20>:	imul   $0x3b9aca00,%rax,%rax
   0x55e0662bf22f <_dl_start_user+27>:	add    %rdx,%rax
   0x55e0662bf232 <_dl_start_user+30>:	mov    %rax,0x18(%rsp)
   0x55e0662bf237 <_dl_start_user+35>:	mov    0x8(%rsp),%rbp
   0x55e0662bf23c <_dl_start_user+40>:	add    $0x10,%rsp

[rocallahan]

779040e adds some more debug logging, can you pull it and rerun your failing test?

[rocallahan]

It seems deeply wrong that the return address should be _start here...

[georgewsinger]

Here's the updated log:

[FATAL /build/source/src/RecordSession.cc:347:handle_seccomp_traced_syscall()] 
 (task 30031 (rec:30031) at time 87012)
 -> Assertion `patch_ok' failed to hold. The tracee issues a vsyscall to 0xffffffffff600000 but we failed to moneypatch the caller (return address 0x5618f2a7920b, sp=0x7ffdf2fe34e8). Recording will not succeed. Exiting.
Tail of trace dump:
{
  real_time:6140.719522 global_time:86992, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629286
rax:0x7fa5d33e1000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x210808 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5d33e1000, length:0x211000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x211000 }
}
{
  real_time:6140.719591 global_time:86993, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629368
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x20000 rdi:0x7fa5fa246000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.719656 global_time:86994, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629368
rax:0x7fa5fa246000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x20000 rdi:0x7fa5fa246000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5fa246000, length:0x20000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x20000 }
}
{
  real_time:6140.719719 global_time:86995, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629403
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f9e72000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.719787 global_time:86996, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629403
rax:0x7fa5f9e72000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f9e72000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5f9e72000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:6140.719851 global_time:86997, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629438
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f99f8000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.719919 global_time:86998, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629438
rax:0x7fa5f99f8000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f99f8000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5f99f8000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:6140.719983 global_time:86999, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629473
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f7622000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720051 global_time:87000, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629473
rax:0x7fa5f7622000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5f7622000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5f7622000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:6140.720115 global_time:87001, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629508
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5e5772000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720183 global_time:87002, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629508
rax:0x7fa5e5772000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x1000 rdi:0x7fa5e5772000 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x32 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5e5772000, length:0x1000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x1000 }
}
{
  real_time:6140.720247 global_time:87003, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:629555
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x100000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720310 global_time:87004, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:629555
rax:0x7fa5d32e1000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x100000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x40 r13:0x40 r14:0x1 r15:0x6e43a318 rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5d32e1000, length:0x100000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x100000 }
}
{
  real_time:6140.720399 global_time:87005, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:630176
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x5618f3a3bca0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720462 global_time:87006, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:630176
rax:0x7fa5d32d1000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x5618f3a3bca0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5d32d1000, length:0x10000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x10000 }
}
{
  real_time:6140.720533 global_time:87007, event:`SYSCALL: mmap' (state:ENTERING_SYSCALL) tid:30031, ticks:630240
rax:0xffffffffffffffda rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720596 global_time:87008, event:`SYSCALL: mmap' (state:EXITING_SYSCALL) tid:30031, ticks:630240
rax:0x7fa5d32c1000 rbx:0x681fffa0 rcx:0xffffffffffffffff rdx:0x3 rsi:0x10000 rdi:0x0 rbp:0x681ffec0 rsp:0x681ffe70 r8:0xffffffff r9:0x0 r10:0x22 r11:0x246 r12:0x0 r13:0x12 r14:0x80c000000000 r15:0x80c000001fff rip:0x70000002 eflags:0x246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0x9 fs_base:0x7fa5fa033080 gs_base:0x0
  { map_file:"<ZERO>", addr:0x7fa5d32c1000, length:0x10000, prot_flags:"rw-p", file_offset:0x0, device:0, inode:0, data_file:"", data_offset:0x0, file_size:0x10000 }
}
{
  real_time:6140.720686 global_time:87009, event:`INSTRUCTION_TRAP' tid:30031, ticks:633222
rax:0xd rbx:0x756e6547 rcx:0x6c65746e rdx:0x49656e69 rsi:0x5618f351d6c0 rdi:0xc00000c1e0 rbp:0x7ffdf2fe3548 rsp:0x7ffdf2fe3510 r8:0x7fa5d33e160e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x5618f33079c8 r15:0x0 rip:0x5618f2a13f5a eflags:0x10246 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720745 global_time:87010, event:`INSTRUCTION_TRAP' tid:30031, ticks:633223
rax:0x306c3 rbx:0x100800 rcx:0x3ffafbbf rdx:0xbfebfbff rsi:0x5618f351d6c0 rdi:0xc00000c1e0 rbp:0x7ffdf2fe3548 rsp:0x7ffdf2fe3510 r8:0x7fa5d33e160e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x5618f33079c8 r15:0x0 rip:0x5618f2a13f5a eflags:0x10206 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fa5fa033080 gs_base:0x0
}
{
  real_time:6140.720803 global_time:87011, event:`INSTRUCTION_TRAP' tid:30031, ticks:633226
rax:0x0 rbx:0x27ab rcx:0x0 rdx:0x9c000600 rsi:0x5618f351d6c0 rdi:0xc00000c1e0 rbp:0x7ffdf2fe3548 rsp:0x7ffdf2fe3510 r8:0x7fa5d33e160e r9:0x203000 r10:0x8 r11:0x75 r12:0xf5 r13:0x0 r14:0x5618f33079c8 r15:0x0 rip:0x5618f2a13f5a eflags:0x10206 cs:0x33 ss:0x2b ds:0x0 es:0x0 fs:0x0 gs:0x0 orig_rax:0xffffffffffffffff fs_base:0x7fa5fa033080 gs_base:0x0
}
=== Start rr backtrace:
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr13dump_rr_stackEv+0x44)[0x69d39d]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr9GdbServer15emergency_debugEPNS_4TaskE+0x1a2)[0x4d080a]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr[0x50088c]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr21EmergencyDebugOstreamD1Ev+0x62)[0x500ae6]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession29handle_seccomp_traced_syscallEPNS_10RecordTaskEPNS0_9StepStateEPNS0_12RecordResultEPb+0x4d6)[0x5415c2]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession19handle_ptrace_eventEPPNS_10RecordTaskEPNS0_9StepStateEPNS0_12RecordResultEPb+0x31a)[0x542734]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordSession11record_stepEv+0x377)[0x54aa8b]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr[0x53c88e]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_ZN2rr13RecordCommand3runERSt6vectorINSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESaIS7_EE+0x3dd)[0x53d4f9]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(main+0x227)[0x6b894f]
/nix/store/hp8wcylqr14hrrpqap4wdrwzq092wfln-glibc-2.32-37/lib/libc.so.6(__libc_start_main+0xed)[0x7ff962546ded]
/nix/store/r4riwfhnx9is1809kwwywgkjzhkpr1q3-rr-unstable-2020-10-10/bin/rr(_start+0x2a)[0x43056a]
=== End rr backtrace
Launch gdb with
  gdb '-l' '10000' '-ex' 'set sysroot /' '-ex' 'target extended-remote 127.0.0.1:30031' /usr/bin/snap

[khuey]

Can you disassemble the code at 0xffffffffff600000?

[georgewsinger]

@khuey Re-running the trace I get

[FATAL /build/source/src/RecordSession.cc:347:handle_seccomp_traced_syscall()] 
 (task 4805 (rec:4805) at time 94687)
 -> Assertion `patch_ok' failed to hold. The tracee issues a vsyscall to 0xffffffffff600000 but we failed to moneypatch the caller (return address 0x55dc68b6020b, sp=0x7fffd94b0cc8). Recording will not succeed. Exiting.
# ...

and then

(gdb) x/10i 0xffffffffff600000
   0xffffffffff600000:	Cannot access memory at address 0xffffffffff600000

[khuey]

Hmm, ok. The vsyscall page should be there ...

You could try booting your kernel with the parameter vsyscall=none and see if this goes away.

[georgewsinger]

✔️ This worked. Thank you.

Testing now to see if Pernosco accepts the trace.