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dump: use system context in Windows dump

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We use CPU #0 to access guest virtual memory, but it can execute user
thread at that moment. So, switch CR3 to PageDirectoryBase from header
and restore original value at the end.

Signed-off-by: Viktor Prutyanov <viktor.prutyanov@virtuozzo.com>
Message-Id: <20180517162342.4330-3-viktor.prutyanov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Viktor Prutyanov 2018-05-17 19:23:40 +03:00 committed by Paolo Bonzini
parent 2da91b54fe
commit 92d1b3d508
1 changed files with 17 additions and 9 deletions
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26
win_dump.c
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@ -111,12 +111,6 @@ static void patch_header(WinDumpHeader64 *h)
h->PhysicalMemoryBlock.unused = 0;
h->unused1 = 0;
/*
* We assume h->DirectoryBase and current CR3 are the same when we access
* memory by virtual address. In other words, we suppose current context
* is system context. It is definetely true in case of BSOD.
*/
patch_mm_pfn_database(h, &local_err);
if (local_err) {
warn_report_err(local_err);
@ -171,6 +165,8 @@ void create_win_dump(DumpState *s, Error **errp)
{
WinDumpHeader64 *h = (WinDumpHeader64 *)(s->guest_note +
VMCOREINFO_ELF_NOTE_HDR_SIZE);
X86CPU *first_x86_cpu = X86_CPU(first_cpu);
uint64_t saved_cr3 = first_x86_cpu->env.cr[3];
Error *local_err = NULL;
if (s->guest_note_size != sizeof(WinDumpHeader64) +
@ -185,10 +181,17 @@ void create_win_dump(DumpState *s, Error **errp)
return;
}
/*
* Further access to kernel structures by virtual addresses
* should be made from system context.
*/
first_x86_cpu->env.cr[3] = h->DirectoryTableBase;
check_kdbg(h, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
goto out_cr3;
}
patch_header(h);
@ -198,12 +201,17 @@ void create_win_dump(DumpState *s, Error **errp)
s->written_size = qemu_write_full(s->fd, h, sizeof(*h));
if (s->written_size != sizeof(*h)) {
error_setg(errp, QERR_IO_ERROR);
return;
goto out_cr3;
}
write_runs(s, h, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
goto out_cr3;
}
out_cr3:
first_x86_cpu->env.cr[3] = saved_cr3;
return;
}