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arm64: kprobes: Restore local irqflag if kprobes is cancelled

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If instruction being single stepped caused a page fault, the kprobes
is cancelled to let the page fault handler continue as a normal page
fault. But the local irqflags are disabled so cpu will restore pstate
with DAIF masked. After pagefault is serviced, the kprobes is
triggerred again, we overwrite the saved_irqflag by calling
kprobes_save_local_irqflag(). NOTE, DAIF is masked in this new saved
irqflag. After kprobes is serviced, the cpu pstate is retored with
DAIF masked.

This patch is inspired by one patch for riscv from Liao Chang.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20210412174101.6bfb0594@xhacker.debian
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Jisheng Zhang 2021-04-12 17:41:01 +08:00 committed by Will Deacon
parent 2decad92f4
commit 738fa58ee1
1 changed files with 4 additions and 2 deletions
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6
arch/arm64/kernel/probes/kprobes.c
View file

@ -267,10 +267,12 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
if (!instruction_pointer(regs))
BUG();
if (kcb->kprobe_status == KPROBE_REENTER)
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
else
} else {
kprobes_restore_local_irqflag(kcb, regs);
reset_current_kprobe();
}
break;
case KPROBE_HIT_ACTIVE: