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[Qemu-devel] [RFC] dump memory when host pci device is used by guest
From: |
Wen Congyang |
Subject: |
[Qemu-devel] [RFC] dump memory when host pci device is used by guest |
Date: |
Wed, 16 Nov 2011 16:27:36 +0800 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 |
Hi, all
'virsh dump' can not work when host pci device is used by guest. We have
discussed this issue here:
http://lists.nongnu.org/archive/html/qemu-devel/2011-10/msg00736.html
We have determined to introduce a new command dump to dump memory. The core
file's format can be elf.
I created a kdump-elf vmcore, and found that it can be used by both crash and
gdb:
# gdb /usr/lib/debug/lib/modules/2.6.32-71.el6.x86_64/vmlinux /work/core/vmcore
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-48.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from
/usr/lib/debug/lib/modules/2.6.32-71.el6.x86_64/vmlinux...done.
[New Thread 1691]
[New <main task>]
#0 sysrq_handle_crash (key=99, tty=0x0) at drivers/char/sysrq.c:130
130 drivers/char/sysrq.c: No such file or directory.
in drivers/char/sysrq.c
(gdb) bt
#0 sysrq_handle_crash (key=99, tty=0x0) at drivers/char/sysrq.c:130
#1 0xffffffff8130d822 in __handle_sysrq (key=99, tty=0x0, check_mask=<value
optimized out>) at drivers/char/sysrq.c:521
#2 0xffffffff8130d8de in write_sysrq_trigger (file=<value optimized out>,
buf=<value optimized out>, count=2, ppos=<value optimized out>) at
drivers/char/sysrq.c:599
#3 0xffffffff811cf31e in proc_reg_write (file=<value optimized out>,
buf=0x7fdabafea000 <Address 0x7fdabafea000 out of bounds>, count=2, ppos=<value
optimized out>)
at fs/proc/inode.c:207
#4 0xffffffff8116c818 in vfs_write (file=0xffff88003c7bb740,
buf=0x7fdabafea000 <Address 0x7fdabafea000 out of bounds>, count=<value
optimized out>, pos=0xffff88003767ff48)
at fs/read_write.c:347
#5 0xffffffff8116d251 in sys_write (fd=<value optimized out>,
buf=0x7fdabafea000 <Address 0x7fdabafea000 out of bounds>, count=2) at
fs/read_write.c:399
#6 0xffffffff81013172 in ?? () at arch/x86/kernel/entry_64.S:487
#7 0x0000000000000246 in ?? ()
#8 0x00000000ffffffff in ?? ()
#9 0x00007fdabafde700 in ?? ()
#10 0x000000000000000a in ?? ()
#11 0x0000000000000001 in ?? ()
#12 0x0000000000000002 in ?? ()
#13 0x0000000000000001 in ?? ()
#14 0x00000030f80d4230 in ?? ()
#15 0x0000000000000033 in ?? ()
#16 0x0000000000010206 in ?? ()
#17 0x00007fff8a126470 in ?? ()
#18 0x000000000000002b in ?? ()
#19 0xffff8800374f5000 in ?? ()
#20 0xffff88003c6f9000 in ?? ()
#21 0x0000000000000080 in ?? ()
#22 0xffff880037680080 in ?? ()
#23 0xffffffff00000014 in ?? ()
#24 0x0000000000000000 in ?? ()
(gdb) q
# crash -s /usr/lib/debug/lib/modules/2.6.32-71.el6.x86_64/vmlinux
/work/core/vmcore
crash> bt
PID: 1691 TASK: ffff88003711d520 CPU: 0 COMMAND: "bash"
#0 [ffff88003767fae0] machine_kexec at ffffffff8103695b
#1 [ffff88003767fb40] crash_kexec at ffffffff810b8f08
#2 [ffff88003767fc10] oops_end at ffffffff814cbbd0
#3 [ffff88003767fc40] no_context at ffffffff8104651b
#4 [ffff88003767fc90] __bad_area_nosemaphore at ffffffff810467a5
#5 [ffff88003767fce0] bad_area at ffffffff810468ce
#6 [ffff88003767fd10] do_page_fault at ffffffff814cd740
#7 [ffff88003767fd60] page_fault at ffffffff814caf45
[exception RIP: sysrq_handle_crash+22]
RIP: ffffffff8130d566 RSP: ffff88003767fe18 RFLAGS: 00010096
RAX: 0000000000000010 RBX: 0000000000000063 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000063
RBP: ffff88003767fe18 R8: 0000000000000000 R9: ffffffff815106c0
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff8179e6c0 R14: 0000000000000286 R15: 0000000000000007
ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018
#8 [ffff88003767fe20] __handle_sysrq at ffffffff8130d822
#9 [ffff88003767fe70] write_sysrq_trigger at ffffffff8130d8de
#10 [ffff88003767fea0] proc_reg_write at ffffffff811cf31e
#11 [ffff88003767fef0] vfs_write at ffffffff8116c818
#12 [ffff88003767ff30] sys_write at ffffffff8116d251
#13 [ffff88003767ff80] system_call_fastpath at ffffffff81013172
RIP: 00000030f80d4230 RSP: 00007fff8a126470 RFLAGS: 00010206
RAX: 0000000000000001 RBX: ffffffff81013172 RCX: 0000000000000400
RDX: 0000000000000002 RSI: 00007fdabafea000 RDI: 0000000000000001
RBP: 00007fdabafea000 R8: 000000000000000a R9: 00007fdabafde700
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000002
R13: 00000030f8379780 R14: 0000000000000002 R15: 00000030f8379780
ORIG_RAX: 0000000000000001 CS: 0033 SS: 002b
crash>
I wrote a sample(not finished). It only can works on x86_64(both host and guest)
I use it to create a core file:
# readelf -h /tmp/vm2.save
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: CORE (Core file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x0
Start of program headers: 64 (bytes into file)
Start of section headers: 0 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 9
Size of section headers: 0 (bytes)
Number of section headers: 0
Section header string table index: 0
# readelf -l /tmp/vm2.save
Elf file type is CORE (Core file)
Entry point 0x0
There are 9 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
NOTE 0x0000000000000238 0x0000000000000000 0x0000000000000000
0x00000000000002c8 0x00000000000002c8 0
LOAD 0x0000000000000500 0xffffffff81000000 0x0000000001000000
0x000000001f000000 0x000000001f000000 0
LOAD 0x000000001f000500 0x0000000000000000 0x0000000000000000
0x0000000001000000 0x0000000001000000 0
LOAD 0x0000000020000500 0x0000000000000000 0x0000000020000000
0x0000000000020000 0x0000000000020000 0
LOAD 0x0000000020020500 0x0000000000000000 0x0000000020870000
0x0000000000010000 0x0000000000010000 0
LOAD 0x0000000020030500 0x0000000000000000 0x0000000020850000
0x0000000000020000 0x0000000000020000 0
LOAD 0x0000000020050500 0x0000000000000000 0x0000000020840000
0x0000000000010000 0x0000000000010000 0
LOAD 0x0000000020060500 0x0000000000000000 0x0000000020040000
0x0000000000800000 0x0000000000800000 0
LOAD 0x0000000020860500 0x0000000000000000 0x0000000020020000
0x0000000000020000 0x0000000000020000 0
I can use crash to anaylze the file, but I can not use gdb to anaylze it.
# gdb /usr/lib/debug/lib/modules/2.6.32-71.el6.x86_64/vmlinux /tmp/vm2.save
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-48.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from
/usr/lib/debug/lib/modules/2.6.32-71.el6.x86_64/vmlinux...done.
[New <main task>]
[New <main task>]
#0 0x8103be8b00000000 in ?? ()
(gdb) bt
#0 0x8103be8b00000000 in ?? ()
Cannot access memory at address 0x8170dec800000000
(gdb) q
My first and the most important question is that: Is there necessary to
continue this work?
The attachment is the sample patch.
Thanks
Wen Congyang
0001-dump-sample.patch
Description: Text Data
- [Qemu-devel] [RFC] dump memory when host pci device is used by guest,
Wen Congyang <=
[Qemu-devel] [RFC][PATCH] introduce a new monitor command 'dump' to dump guest's memory, Wen Congyang, 2011/11/29