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powerpc/kprobes: Do not disable External interrupts during single step

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External/Decrement exceptions have lower priority than the Debug Exception.
So, we don't have to disable the External interrupts before a single step.
However, on BookE, Critical Input Exception(CE) has higher priority than a
Debug Exception. Hence we mask them.

Signed-off-by: 	Suzuki K. Poulose <suzuki@in.ibm.com>
Cc:		Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:		Ananth N Mavinakaynahalli <ananth@in.ibm.com>
Cc:		Kumar Gala <galak@kernel.crashing.org>
Cc:		linuxppc-dev@ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Suzuki K. Poulose 2012-12-03 20:37:42 +05:30 committed by Benjamin Herrenschmidt
parent e80034047b
commit 85f395c5b0
1 changed files with 5 additions and 5 deletions
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10
arch/powerpc/kernel/kprobes.c
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@ -104,13 +104,13 @@ void __kprobes arch_remove_kprobe(struct kprobe *p)
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
/* We turn off async exceptions to ensure that the single step will
* be for the instruction we have the kprobe on, if we dont its
* possible we'd get the single step reported for an exception handler
* like Decrementer or External Interrupt */
regs->msr &= ~MSR_EE;
regs->msr |= MSR_SINGLESTEP;
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
/*
* We turn off Critical Input Exception(CE) to ensure that the single
* step will be for the instruction we have the probe on; if we don't,
* it is possible we'd get the single step reported for CE.
*/
regs->msr &= ~MSR_CE;
mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
#ifdef CONFIG_PPC_47x