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Subject[PATCH v3 5/5] arm64: fault: re-enable irq if it was disabled for single stepping
Date
We disable irq before single stepping and re-enable it after it.
However, if stepped instruction will cause a fault then we will enter
into fault handler with interrupt disabled, which is not desired.
But, we should be safe if we re-enable interrupt in fault handler if
it was disabled for single stepping.

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/arm64/mm/fault.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index ce5290dacba3..2b88807eb964 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -589,6 +589,8 @@ static const struct fault_info fault_info[] = {
{ do_bad, SIGBUS, 0, "unknown 63" },
};

+static DEFINE_PER_CPU(bool, irq_enable_needed);
+
/*
* Dispatch a data abort to the relevant handler.
*/
@@ -597,6 +599,12 @@ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
{
const struct fault_info *inf = esr_to_fault_info(esr);
struct siginfo info;
+ bool *irq_en_needed = this_cpu_ptr(&irq_enable_needed);
+
+ if (*irq_en_needed) {
+ regs->pstate &= ~PSR_I_BIT;
+ *irq_en_needed = false;
+ }

if (!inf->fn(addr, esr, regs))
return;
@@ -672,8 +680,6 @@ void __init hook_debug_fault_code(int nr,
debug_fault_info[nr].name = name;
}

-static DEFINE_PER_CPU(bool, irq_enable_needed);
-
asmlinkage int __exception do_debug_exception(unsigned long addr,
unsigned int esr,
struct pt_regs *regs)
--
2.9.4
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