Re: [x86, kaslr] PANIC: early exception 0e rip 10:ffffffff8ae04c6e error 0 cr2 ffffffff81972b28

[Fengguang Wu <fengguang.wu@intel.com>]

On Wed, Jan 15, 2014 at 02:32:52PM -0800, Kees Cook wrote:
> On Wed, Jan 15, 2014 at 4:24 AM, Fengguang Wu <fengguang.wu@intel.com> wrote:
> > Kees,
> >
> > This script can reproduce the problem. Please modify the -initrd line
> > before use.
> >
> > Usage:
> >         ./kvm-0day.sh vmlinuz-3.12.0-rc4-00008-g6e6a493
> >
> > #!/bin/bash
> >
> > kernel=$1
> >
> > kvm=(
> >         qemu-system-x86_64 -cpu kvm64 -enable-kvm
> >         -kernel $kernel
> >         -initrd /kernel-tests/initrd/yocto-minimal-x86_64.cgz
> >         # -initrd /kernel-tests/initrd/yocto-minimal-i386.cgz
> >         # -initrd /kernel-tests/initrd/quantal-core-i386.cgz
> >         # -initrd /kernel-tests/initrd/quantal-core-x86_64.cgz
> >         -smp 2
> >         -m 256M
> >         -net nic,vlan=0,macaddr=00:00:00:00:00:00,model=virtio
> >         -net user,vlan=0
> >         -net nic,vlan=1,model=e1000
> >         -net user,vlan=1
> >         -boot order=nc
> >         -no-reboot
> >         -watchdog i6300esb
> >         -serial stdio
> >         -display none
> >         -monitor null
> > )
> >
> > append=(
> >         debug
> >         sched_debug
> >         apic=debug
> >         ignore_loglevel
> >         # dyndbg=\"func kobject_release +p\"
> >         sysrq_always_enabled
> >         panic=10
> >         prompt_ramdisk=0
> >         earlyprintk=ttyS0,115200
> >         console=ttyS0,115200
> >         console=tty0
> >         vga=normal
> >         root=/dev/ram0
> >         rw
> > )
> >
> > "${kvm[@]}" --append "${append[*]}"
> 
> Thanks! I'm using your yocto image and this script, but I still am not
> encountering the problem. I'm building next-20140114 using the
> randconfig you sent in the original report. It looks like you're built
> against a slightly different kernel version? Is there some way you can
> push the tree you're building to git somewhere for me to fetch?

Kees, judging from the below bisect log, next-20140114 boots fine.
If you still have access to commit 82fa9637a2ba285bcc7c5050c73010b2c1b3d803
in the tip tree, it's the right one to test.

git bisect start 6e6a4932b0f569b1a5bb4fcbf5dde1b1a42f01bb v3.11 --
git bisect good b7c09ad4014e3678e8cc01fdf663c9f43b272dc6  # 22:54     20+      0  Merge branch 'for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs
git bisect good 654fdd041227d7de1594baa61c58f2c87bd0640f  # 23:15     20+      1  Merge branch 'x86-urgent-for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect good 0b936842c86392dad2c880539e824881e5d8ba77  # 23:35     20+      0  Merge
git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc
git bisect good 3dbecf0aa9692cffbb71313a380c0ecc606c5920  # 23:56     20+      0  Merge tag 'xfs-for-linus-v3.12-rc4' of
git://oss.sgi.com/xfs/xfs
git bisect good 13caa8ed93513dd216ede0c84d833e39fc2e3e2a  # 00:06     20+      0  Merge
git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending
git bisect good 8ab3820fd5b2896d66da7bb2a906bc382e63e7bc  # 00:18     20+      0  x86, kaslr: Return location from decompress_kernel
git bisect  bad 82fa9637a2ba285bcc7c5050c73010b2c1b3d803  # 00:18      0-    988  x86, kaslr: Select random position from e820 maps
git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3  # 00:27     20+     52  x86, kaslr: Provide randomness functions
# first bad commit: [82fa9637a2ba285bcc7c5050c73010b2c1b3d803] x86, kaslr: Select random position from e820 maps
git bisect good 5bfce5ef55cbe78ee2ee6e97f2e26a8a582008f3  # 00:39     60+     52  x86, kaslr: Provide randomness functions
git bisect good 1955a14a5ba6e3c3b11117812d11dc550ccc37ae  # 00:59     60+    149  Add linux-next specific files for 20140110
git bisect good 8bcd53c437d5fdd04fddd8c7e29ecbdc682e7ce1  # 01:22     60+     60  Revert "x86, kaslr: Select random position from e820
maps"
git bisect good a6da83f98267bc8ee4e34aa899169991eb0ceb93  # 01:38     60+     42  Merge branch 'merge' of
git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc
git bisect good cf1c1d193e37b9f79eedddc6bbd71b9f5f9751e5  # 01:45     72+   1972  Add linux-next specific files for 20140114
 
Thanks,
Fengguang