Commit 92d1b3d5 authored by Viktor Prutyanov's avatar Viktor Prutyanov Committed by Paolo Bonzini
Browse files

dump: use system context in Windows dump 



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: default avatarViktor Prutyanov <viktor.prutyanov@virtuozzo.com>
Message-Id: <20180517162342.4330-3-viktor.prutyanov@virtuozzo.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2da91b54

win_dump.c

+17 −9
Original line number Diff line number Diff line
@@ -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;

}