From: Milton Miller <[EMAIL PROTECTED]>
Bcc: Milton Miller <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Subject: [Fastboot} X86 Segmentation Violation due to /proc/iomem
I tried to run kboot (version 10) on my 486 laptop, and was
getting a Segmentation Violation. The stack trace below
shows that malloc is getting corrupted. The strace showed
a successful brk change from 0x8068000 to 0x806f000, just
the same as running in the chroot on my development machine.
I finally copied /proc/iomem to my chroot and was able to
replicate the fail. I then determinted that add a reserved
entry ending at 0x9ffff and would prevent the core dump.
I copied the modified iomem to the 486 and was able to run
kexec -l without segfaulting, and then was able to successfully
kexec -e into the loaded kernel.
To recreate, build kboot-10 (kexec-tools-1.101 plus
kexec-tools-1.101-fix-real-mode-entry-vivek.patch built against
uClibc). You can copy the below to proc/iomem and a bzImage into
the build root, and chroot into it. I am using a 2.6.18-rc1
bzImage to load, I can supply the config if needed.
milton
The failing /proc/iomem
00000000-0009efff : System RAM
000a0000-000bffff : Video RAM area
000e0000-000effff : Extension ROM
000f0000-000fffff : System ROM
00100000-01c2ffff : System RAM
00100000-00227710 : Kernel code
00227711-00285053 : Kernel data
I added this line as the second line to make it work:
0009f000-0009ffff : reserved
Here is some info from the core dump:
gdb ../kexec-tools-1.101/objdir-i686/build/sbin/kexec /tmp/core
GNU gdb 6.3-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and
you are
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Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for
details.
This GDB was configured as "i386-linux"...Using host libthread_db
library "/lib/tls/libthread_db.so.1".
Core was generated by `kexec -l
/mnt/tmp/b358eff335ec33c12e76e78381c44ceb/linux'.
Program terminated with signal 11, Segmentation fault.
Reading symbols from /UNIONFS/lib/libc.so.0...done.
Loaded symbols for /lib/libc.so.0
Reading symbols from /UNIONFS/lib/ld-uClibc.so.0...done.
Loaded symbols for /lib/ld-uClibc.so.0
#0 0xb7f34490 in malloc () from /lib/libc.so.0
(gdb) where
#0 0xb7f34490 in malloc () from /lib/libc.so.0
#1 0x08048c12 in xmalloc (size=5632) at kexec/kexec.c:59
#2 0x0804e792 in do_bzImage_load (info=0xbfab2c90, kernel=0xb7e3a008
"fÍ\b",
kernel_len=871864, command_line=0x0, command_line_len=0, initrd=0x0,
initrd_len=0, real_mode_entry=0, debug=0)
at kexec/arch/i386/kexec-bzImage.c:140
#3 0x0804ed37 in bzImage_load (argc=3, argv=0xbfab2e64,
buf=0xb7e3a008 "fÍ\b", len=871864, info=0xbfab2c90)
at kexec/arch/i386/kexec-bzImage.c:289
#4 0x08049ded in my_load (type=0x0, fileind=2, argc=3, argv=0xbfab2e64,
kexec_flags=0) at kexec/kexec.c:562
#5 0x0804a53d in main (argc=3, argv=0xbfab2e64) at kexec/kexec.c:791
(gdb) up 2
#2 0x0804e792 in do_bzImage_load (info=0xbfab2c90, kernel=0xb7e3a008
"fÍ\b",
kernel_len=871864, command_line=0x0, command_line_len=0, initrd=0x0,
initrd_len=0, real_mode_entry=0, debug=0)
at kexec/arch/i386/kexec-bzImage.c:140
140 real_mode = xmalloc(setup_size);
(gdb) print *info
$1 = {segment = 0x806e5d8, nr_segments = 1, entry = 0x95498, rhdr = {
ei_class = 1, ei_data = 1, e_type = 1, e_machine = 3, e_version = 1,
e_flags = 0, e_phnum = 0, e_shnum = 27, e_shstrndx = 24, e_entry =
611480,
e_phoff = 0, e_shoff = 39412, e_notenum = 4, e_phdr = 0x0,
e_shdr = 0x8066008, e_note = 0x80664b0, rel_addr = 610304,
rel_size = 40960}}
(gdb) print memory_ranges
$2 = 2
(gdb) print memory_range[0]
$3 = {start = 256, end = 651264, type = 0}
(gdb) print memory_range[1]
$4 = {start = 1048576, end = 29556736, type = 0}
(gdb) print memory_range[2]
$5 = {start = 0, end = 0, type = 0}
(gdb) quit
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