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Subject[PATCH v2 1/4] kprobes/powerpc: Do not disable External interrupts during single step
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From: Suzuki K. Poulose <suzuki@in.ibm.com>

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
---
arch/powerpc/kernel/kprobes.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index e88c643..4901b34 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -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


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