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Fix for the handling of ARM and ARM64 QEMU-generated ELF dumpfiles

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and compressed kdump clones.  The patch utilizes the NT_PRSTATUS
notes in the dumpfile headers instead of reading them from the
kernel's "crash_notes", which are not initialized when QEMU generates
a dumpfile.  Without the patch, these warning messages are displayed
during session initialization:

  WARNING: invalid note (n_type != NT_PRSTATUS)
  WARNING: cannot retrieve registers for active tasks

and running "bt" on an active task causes a segmentation violation.
(drjones@redhat.com)
This commit is contained in:
Dave Anderson 2015-11-23 13:59:18 -05:00
parent 2d8895c36a
commit b2d8f20407
4 changed files with 66 additions and 0 deletions
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22
arm.c
View File

@ -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;

22
arm64.c
View File

@ -1828,6 +1828,28 @@ 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;

1
defs.h
View File

@ -5721,6 +5721,7 @@ 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)

21
netdump.c
View File

@ -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.
*/