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ARM: 7876/1: clear Thumb-2 IT state on exception handling

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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@arm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Marc Zyngier 2013-11-04 11:42:29 +01:00 committed by Russell King
parent 384b38b669
commit e16b31bf47
2 changed files with 7 additions and 1 deletions
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1
arch/arm/kernel/entry-armv.S
View File

@ -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)

7
arch/arm/mm/extable.c
View File

@ -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;
}