This is a note to let you know that I've just added the patch titled
powerpc/kexec: Fix memory corruption from unallocated slaves
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
powerpc-kexec-fix-memory-corruption-from-unallocated-slaves.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From 3d2cea732d68aa270c360f55d8669820ebce188a Mon Sep 17 00:00:00 2001
From: Milton Miller <[email protected]>
Date: Tue, 10 May 2011 19:28:33 +0000
Subject: powerpc/kexec: Fix memory corruption from unallocated slaves
From: Milton Miller <[email protected]>
commit 3d2cea732d68aa270c360f55d8669820ebce188a upstream.
Commit 1fc711f7ffb01089efc58042cfdbac8573d1b59a (powerpc/kexec: Fix race
in kexec shutdown) moved the write to signal the cpu had exited the kernel
from before the transition to real mode in kexec_smp_wait to kexec_wait.
Unfornately it missed that kexec_wait is used both by cpus leaving the
kernel and by secondary slave cpus that were not allocated a paca for
what ever reason -- they could be beyond nr_cpus or not described in
the current device tree for whatever reason (for example, kexec-load
was not refreshed after a cpu hotplug operation). Cpus coming through
that path they will write to paca[NR_CPUS] which is beyond the space
allocated for the paca data and overwrite memory not allocated to pacas
but very likely still real mode accessable).
Move the write back to kexec_smp_wait, which is used only by cpus that
found their paca, but after the transition to real mode.
Signed-off-by: Milton Miller <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/powerpc/kernel/misc_64.S | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -463,7 +463,8 @@ _GLOBAL(disable_kernel_fp)
* wait for the flag to change, indicating this kernel is going away but
* the slave code for the next one is at addresses 0 to 100.
*
- * This is used by all slaves.
+ * This is used by all slaves, even those that did not find a matching
+ * paca in the secondary startup code.
*
* Physical (hardware) cpu id should be in r3.
*/
@@ -472,10 +473,6 @@ _GLOBAL(kexec_wait)
1: mflr r5
addi r5,r5,kexec_flag-1b
- li r4,KEXEC_STATE_REAL_MODE
- stb r4,PACAKEXECSTATE(r13)
- SYNC
-
99: HMT_LOW
#ifdef CONFIG_KEXEC /* use no memory without kexec */
lwz r4,0(r5)
@@ -500,11 +497,17 @@ kexec_flag:
*
* get phys id from paca
* switch to real mode
+ * mark the paca as no longer used
* join other cpus in kexec_wait(phys_id)
*/
_GLOBAL(kexec_smp_wait)
lhz r3,PACAHWCPUID(r13)
bl real_mode
+
+ li r4,KEXEC_STATE_REAL_MODE
+ stb r4,PACAKEXECSTATE(r13)
+ SYNC
+
b .kexec_wait
/*
Patches currently in longterm-queue-2.6.32 which might be from [email protected]
are
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