Commit graph

9 commits

Author SHA1 Message Date
Simon Horman
6672f76a5a kdump/kexec: calculate note size at compile time
Currently the size of the per-cpu region reserved to save crash notes is
set by the per-architecture value MAX_NOTE_BYTES.  Which in turn is
currently set to 1024 on all supported architectures.

While testing ia64 I recently discovered that this value is in fact too
small.  The particular setup I was using actually needs 1172 bytes.  This
lead to very tedious failure mode where the tail of one elf note would
overwrite the head of another if they ended up being alocated sequentially
by kmalloc, which was often the case.

It seems to me that a far better approach is to caclculate the size that
the area needs to be.  This patch does just that.

If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) is
needed then this should be as easy as making MAX_NOTE_BYTES larger in
arch/asm-ia64/kexec.h.  Perhaps 2048 would be a good choice.  However, I
think that the approach in this patch is a much more robust idea.

Acked-by:  Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-08 11:15:07 -07:00
Ian Campbell
79e030114a [PATCH] i386: Allow i386 crash kernels to handle x86_64 dumps
The specific case I am encountering is kdump under Xen with a 64 bit
hypervisor and 32 bit kernel/userspace.  The dump created is 64 bit due to
the hypervisor but the dump kernel is 32 bit for maximum compatibility.

It's possibly less likely to be useful in a purely native scenario but I
see no reason to disallow it.

[akpm@linux-foundation.org: build fix]
Signed-off-by: Ian Campbell <ian.campbell@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Acked-by: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Horms <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2007-05-02 19:27:09 +02:00
Jan Beulich
00f1ea6967 [PATCH] x86: adjust inclusion of asm/fixmap.h
Move inclusion of asm/fixmap.h to where it is really used rather than
where it may have been used long ago (requires a few other adjustments
to includes due to previous implicit dependencies).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
2007-05-02 19:27:04 +02:00
Magnus Damm
3566561bfa [PATCH] i386: Avoid overwriting the current pgd (V4, i386)
kexec: Avoid overwriting the current pgd (V4, i386)

This patch upgrades the i386-specific kexec code to avoid overwriting the
current pgd. Overwriting the current pgd is bad when CONFIG_CRASH_DUMP is used
to start a secondary kernel that dumps the memory of the previous kernel.

The code introduces a new set of page tables. These tables are used to provide
an executable identity mapping without overwriting the current pgd.

Signed-off-by: Magnus Damm <magnus@valinux.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26 10:52:38 +02:00
Vivek Goyal
f05b690248 [PATCH] Kdump: i386 compiler warning fix
Fixes a compilation warning message in i386

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:27 -08:00
Vivek Goyal
e996e58133 [PATCH] kdump: save registers early (inline functions)
- If system panics then cpu register states are captured through funciton
  crash_get_current_regs().  This is not a inline function hence a stack frame
  is pushed on to the stack and then cpu register state is captured.  Later
  this frame is popped and new frames are pushed (machine_kexec).

- In theory this is not very right as we are capturing register states for a
  frame and that frame is no more valid.  This seems to have created back
  trace problems for ppc64.

- This patch fixes it up.  The very first thing it does after entering
  crash_kexec() is to capture the register states.  Anyway we don't want the
  back trace beyond crash_kexec().  crash_get_current_regs() has been made
  inline

- crash_setup_regs() is the top architecture dependent function which should
  be responsible for capturing the register states as well as to do some
  architecture dependent tricks.  For ex.  fixing up ss and esp for i386.
  crash_setup_regs() has also been made inline to ensure no new call frame is
  pushed onto stack.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:27 -08:00
Vivek Goyal
cc57165874 [PATCH] kdump: dynamic per cpu allocation of memory for saving cpu registers
- In case of system crash, current state of cpu registers is saved in memory
  in elf note format.  So far memory for storing elf notes was being allocated
  statically for NR_CPUS.

- This patch introduces dynamic allocation of memory for storing elf notes.
  It uses alloc_percpu() interface.  This should lead to better memory usage.

- Introduced based on Andi Kleen's and Eric W. Biederman's suggestions.

- This patch also moves memory allocation for elf notes from architecture
  dependent portion to architecture independent portion.  Now crash_notes is
  architecture independent.  The whole idea is that size of memory to be
  allocated per cpu (MAX_NOTE_BYTES) can be architecture dependent and
  allocation of this memory can be architecture independent.

Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:26 -08:00
Vivek Goyal
625f1c8219 [PATCH] Kdump: Export crash notes section address through sysfs
o Following patch exports kexec global variable "crash_notes" to user space
  through sysfs as kernel attribute in /sys/kernel.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:51 -07:00
Eric W. Biederman
5033cba087 [PATCH] kexec: x86 kexec core
This is the i386 implementation of kexec.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25 16:24:49 -07:00