From 509ae27a1874389182b3709de0940a8f8d4dfb8b Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Mon, 12 Apr 2021 17:41:01 +0800 Subject: [PATCH] arm64: kprobes: Restore local irqflag if kprobes is cancelled [ Upstream commit 738fa58ee1328481d1d7889e7c430b3401c571b9 ] 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 Acked-by: Masami Hiramatsu Link: https://lore.kernel.org/r/20210412174101.6bfb0594@xhacker.debian Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/probes/kprobes.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index f11a1a1f7026..798c3e78b84b 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -286,10 +286,12 @@ 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: -- 2.17.1