On Wed, Jan 26, 2022 at 1:08 AM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab@xxxxxxx> wrote: > > Currently on arm64, NT_PRSTATUS notes in dumpfile are not mapped to > online cpus and machine_specific->panic_task_regs correctly. As a > result, the "bt" command can cause a segmentation fault. > > crash> bt -c 0 > PID: 0 TASK: ffff8000117fa240 CPU: 0 COMMAND: "swapper/0" > Segmentation fault (core dumped) > > To fix this, > 1) make map_cpus_to_prstatus_kdump_cmprs() map the notes to > dd->nt_prstatus_percpu also on arm64, and > 2) move arm64_get_crash_notes() to machdep_init(POST_INIT) in order > to apply the mapping to machine_specific->panic_task_regs. > > Resolves: https://github.com/crash-utility/crash/issues/105 > Reported-by: xuchunmei000 <xuchunmei@xxxxxxxxxxxxxxxxx> > Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx> > --- > Note: I suspect that the machine_type("ARM64") in commit 9b41d403b16c might > be placed for debugging and contained in the commit by accident. Because > that segfault could be caused by the uninitialized machdep->process_elf_notes. > > arm64.c | 2 +- > diskdump.c | 3 +-- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/arm64.c b/arm64.c > index 23c3d75d85aa..4f2c2b5104a1 100644 > --- a/arm64.c > +++ b/arm64.c > @@ -472,7 +472,7 @@ arm64_init(int when) > arm64_stackframe_init(); > break; > > - case POST_VM: > + case POST_INIT: > /* > * crash_notes contains machine specific information about the > * crash. In particular, it contains CPU registers at the time > diff --git a/diskdump.c b/diskdump.c > index 3e1cfd548c96..d5674276e1fd 100644 > --- a/diskdump.c > +++ b/diskdump.c > @@ -111,8 +111,7 @@ map_cpus_to_prstatus_kdump_cmprs(void) > if (pc->flags2 & QEMU_MEM_DUMP_COMPRESSED) /* notes exist for all cpus */ > goto resize_note_pointers; > > - if (!(online = get_cpus_online()) || (online == kt->cpus) || > - machine_type("ARM64")) > + if (!(online = get_cpus_online()) || (online == kt->cpus)) > goto resize_note_pointers; > > if (CRASHDEBUG(1)) > -- > 2.27.0 > > You can add Tested-by: Dave Wysochanski <dwysocha@xxxxxxxxxx> Before this patch I had a vmcore that would segfault with 'bt -a', with backtrace as in https://github.com/crash-utility/crash/issues/105#issuecomment-1017176451 After this patch the segfault is gone. FWIW, I saw was some new warnings with the vmcore but may be expected: WARNING: cannot determine starting stack frame for task ffff809920692100 WARNING: cannot determine starting stack frame for task ffff80992068ee00 WARNING: cannot determine starting stack frame for task ffff80992069ed00 WARNING: cpu 4: cannot find NT_PRSTATUS note WARNING: cpu 5: cannot find NT_PRSTATUS note WARNING: cpu 6: cannot find NT_PRSTATUS note WARNING: cpu 7: cannot find NT_PRSTATUS note WARNING: cpu 8: cannot find NT_PRSTATUS note WARNING: cpu 9: cannot find NT_PRSTATUS note WARNING: cpu 10: cannot find NT_PRSTATUS note WARNING: cpu 11: cannot find NT_PRSTATUS note > -- > Crash-utility mailing list > Crash-utility@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/crash-utility > -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/crash-utility
