11:08 a.m.
----- Original Message -----
On Thu, Nov 19, 2015 at 11:50:22AM -0500, Dave Anderson wrote:
>
>
> ----- Original Message -----
> > QEMU can generate both non-makedumpfile (just elf) and makedumpfile
> > formatted kdumps. In neither case will crash_notes have prstatus, as
> > crash_kexec doesn't run in the kernel, however the elf notes will
> > contain the prstatus, and we can dig them out of there.
>
> Hi Andrew,
>
> Refresh my memory -- without the patch, what does "bt" do when run
> against the active tasks from QEMU generated dumps?
On initial loading a couple warnings are output
WARNING: invalid note (n_type != NT_PRSTATUS)
WARNING: cannot retrieve registers for active tasks
When attempting 'bt', crash segfaults
PID: 2424 TASK: ffffffc057a46e00 CPU: 1 COMMAND: "bash"
bt: WARNING: cannot determine starting stack frame for task
ffffffc057a46e00
Segmentation fault
Wow, it's worse than I thought! Thanks for addressing it.
So anyway, I'll just wait for you to post an updated v2 patch set.
Thanks,
Dave
Thanks,
drew
>
> Dave
>
>
> > ---
> > arm.c | 22 ++++++++++++++++++++++
> > arm64.c | 22 ++++++++++++++++++++++
> > defs.h | 1 +
> > netdump.c | 21 +++++++++++++++++++++
> > 4 files changed, 66 insertions(+)
> >
> > diff --git a/arm.c b/arm.c
> > index ffc7c06d0f42c..8fc3d48a8ac89 100644
> > --- a/arm.c
> > +++ b/arm.c
> > @@ -597,6 +597,28 @@ arm_get_crash_notes(void)
> > note = (Elf32_Nhdr *)buf;
> > p = buf + sizeof(Elf32_Nhdr);
> >
> > + /*
> > + * dumpfiles created with qemu won't have crash_notes, but there will
> > + * be elf notes.
> > + */
> > + if (note->n_namesz == 0 && (DISKDUMP_DUMPFILE() ||
KDUMP_DUMPFILE()))
> > {
> > + if (DISKDUMP_DUMPFILE())
> > + note = diskdump_get_prstatus_percpu(i);
> > + else if (KDUMP_DUMPFILE())
> > + note = netdump_get_prstatus_percpu(i);
> > + if (note) {
> > + /*
> > + * SIZE(note_buf) accounts for a "final note", which is a
> > + * trailing empty elf note header.
> > + */
> > + long notesz = SIZE(note_buf) - sizeof(Elf32_Nhdr);
> > +
> > + if (sizeof(Elf32_Nhdr) + roundup(note->n_namesz, 4) +
> > + note->n_descsz == notesz)
> > + BCOPY((char *)note, buf, notesz);
> > + }
> > + }
> > +
> > if (note->n_type != NT_PRSTATUS) {
> > error(WARNING, "invalid note (n_type != NT_PRSTATUS)\n");
> > goto fail;
> > diff --git a/arm64.c b/arm64.c
> > index 6187b96d25a4d..91b35787e6942 100644
> > --- a/arm64.c
> > +++ b/arm64.c
> > @@ -1827,6 +1827,28 @@ arm64_get_crash_notes(void)
> > note = (Elf64_Nhdr *)buf;
> > p = buf + sizeof(Elf64_Nhdr);
> >
> > + /*
> > + * dumpfiles created with qemu won't have crash_notes, but there will
> > + * be elf notes.
> > + */
> > + if (note->n_namesz == 0 && (DISKDUMP_DUMPFILE() ||
KDUMP_DUMPFILE()))
> > {
> > + if (DISKDUMP_DUMPFILE())
> > + note = diskdump_get_prstatus_percpu(i);
> > + else if (KDUMP_DUMPFILE())
> > + note = netdump_get_prstatus_percpu(i);
> > + if (note) {
> > + /*
> > + * SIZE(note_buf) accounts for a "final note", which is a
> > + * trailing empty elf note header.
> > + */
> > + long notesz = SIZE(note_buf) - sizeof(Elf64_Nhdr);
> > +
> > + if (sizeof(Elf64_Nhdr) + roundup(note->n_namesz, 4) +
> > + note->n_descsz == notesz)
> > + BCOPY((char *)note, buf, notesz);
> > + }
> > + }
> > +
> > if (note->n_type != NT_PRSTATUS) {
> > error(WARNING, "invalid note (n_type != NT_PRSTATUS)\n");
> > goto fail;
> > diff --git a/defs.h b/defs.h
> > index 1bcd1b3b177db..981b030cc6688 100644
> > --- a/defs.h
> > +++ b/defs.h
> > @@ -5722,6 +5722,7 @@ void dump_registers_for_qemu_mem_dump(void);
> > void kdump_backup_region_init(void);
> > void display_regs_from_elf_notes(int, FILE *);
> > void display_ELF_note(int, int, void *, FILE *);
> > +void *netdump_get_prstatus_percpu(int);
> > #define PRSTATUS_NOTE (1)
> > #define QEMU_NOTE (2)
> >
> > diff --git a/netdump.c b/netdump.c
> > index bfa818fdef8e1..3ff49f0577c23 100644
> > --- a/netdump.c
> > +++ b/netdump.c
> > @@ -2345,6 +2345,27 @@ dump_Elf64_Nhdr(Elf64_Off offset, int store)
> > return len;
> > }
> >
> > +void *
> > +netdump_get_prstatus_percpu(int cpu)
> > +{
> > + int online;
> > +
> > + if ((cpu < 0) || (cpu >= nd->num_prstatus_notes))
> > + return NULL;
> > +
> > + /*
> > + * If no cpu mapping was done, then there must be
> > + * a one-to-one relationship between the number
> > + * of online cpus and the number of notes.
> > + */
> > + if ((online = get_cpus_online()) &&
> > + (online == kt->cpus) &&
> > + (online != nd->num_prstatus_notes))
> > + return NULL;
> > +
> > + return nd->nt_prstatus_percpu[cpu];
> > +}
> > +
> > /*
> > * Send the request to the proper architecture hander.
> > */
> > --
> > 2.4.3
> >
> >