[3.11.y.z extended stable] Patch "ARM: 7876/1: clear Thumb-2 IT state on exception handling" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Thu Dec 5 11:21:54 UTC 2013
This is a note to let you know that I have just added a patch titled
ARM: 7876/1: clear Thumb-2 IT state on exception handling
to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 610ea8ee6178cc5a4b0504123941546328905d2b Mon Sep 17 00:00:00 2001
From: Marc Zyngier <Marc.Zyngier at arm.com>
Date: Mon, 4 Nov 2013 11:42:29 +0100
Subject: ARM: 7876/1: clear Thumb-2 IT state on exception handling
commit e16b31bf47738f4498d7ce632e12d7d2a6a2492a upstream.
The exception handling code fails to clear the IT state, potentially
leading to incorrect execution of the fixup if the size of the IT
block is more than one.
Let fixup_exception do the IT sanitizing if a fixup has been found,
and restore CPSR from the stack when returning from a data abort.
Cc: Will Deacon <will.deacon at arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
arch/arm/kernel/entry-armv.S | 1 +
arch/arm/mm/extable.c | 7 ++++++-
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 9cbe70c..ec3e5cf 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -192,6 +192,7 @@ __dabt_svc:
svc_entry
mov r2, sp
dabt_helper
+ THUMB( ldr r5, [sp, #S_PSR] ) @ potentially updated CPSR
svc_exit r5 @ return from exception
UNWIND(.fnend )
ENDPROC(__dabt_svc)
diff --git a/arch/arm/mm/extable.c b/arch/arm/mm/extable.c
index 9d28562..312e15e 100644
--- a/arch/arm/mm/extable.c
+++ b/arch/arm/mm/extable.c
@@ -9,8 +9,13 @@ int fixup_exception(struct pt_regs *regs)
const struct exception_table_entry *fixup;
fixup = search_exception_tables(instruction_pointer(regs));
- if (fixup)
+ if (fixup) {
regs->ARM_pc = fixup->fixup;
+#ifdef CONFIG_THUMB2_KERNEL
+ /* Clear the IT state to avoid nasty surprises in the fixup */
+ regs->ARM_cpsr &= ~PSR_IT_MASK;
+#endif
+ }
return fixup != NULL;
}
--
1.8.3.2
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