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[Qemu-devel] [PATCH 2/4] dump: use system context in Windows dump
From: |
Viktor Prutyanov |
Subject: |
[Qemu-devel] [PATCH 2/4] dump: use system context in Windows dump |
Date: |
Thu, 17 May 2018 19:23:40 +0300 |
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 <address@hidden>
---
win_dump.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/win_dump.c b/win_dump.c
index 58255c12ee..7d956ca996 100644
--- a/win_dump.c
+++ b/win_dump.c
@@ -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;
}
--
2.14.3
- [Qemu-devel] [PATCH 0/4] dump: add Windows crashdump format, Viktor Prutyanov, 2018/05/17
- [Qemu-devel] [PATCH 3/4] dump: add fallback KDBG using in Windows dump, Viktor Prutyanov, 2018/05/17
- [Qemu-devel] [PATCH 2/4] dump: use system context in Windows dump,
Viktor Prutyanov <=
- [Qemu-devel] [PATCH 4/4] dump: add Windows live system dump, Viktor Prutyanov, 2018/05/17
- [Qemu-devel] [PATCH 1/4] dump: add Windows dump format to dump-guest-memory, Viktor Prutyanov, 2018/05/17
- Re: [Qemu-devel] [PATCH 0/4] dump: add Windows crashdump format, no-reply, 2018/05/17
- Re: [Qemu-devel] [PATCH 0/4] dump: add Windows crashdump format, no-reply, 2018/05/17