From: Nicholas Piggin <npiggin@gmail.com>
Date: Mon, 19 Dec 2016 18:30:07 +0000 (+1000)
Subject: powerpc: Mark system reset as an NMI with nmi_enter/exit()
X-Git-Tag: v4.14-rc1~913^2~33
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2b4f3ac5642672595ef6f71d1572b32475e94863;p=platform%2Fkernel%2Flinux-rpi.git

powerpc: Mark system reset as an NMI with nmi_enter/exit()

System reset is a non-maskable interrupt from Linux's point of view
(occurs under local_irq_disable()), so it should use nmi_enter/exit.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 2393d3c..6a81a45 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -279,6 +279,14 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
 
 void system_reset_exception(struct pt_regs *regs)
 {
+	/*
+	 * Avoid crashes in case of nested NMI exceptions. Recoverability
+	 * is determined by RI and in_nmi
+	 */
+	bool nested = in_nmi();
+	if (!nested)
+		nmi_enter();
+
 	/* See if any machine dependent calls */
 	if (ppc_md.system_reset_exception) {
 		if (ppc_md.system_reset_exception(regs))
@@ -297,6 +305,9 @@ out:
 	if (!(regs->msr & MSR_RI))
 		panic("Unrecoverable System Reset");
 
+	if (!nested)
+		nmi_exit();
+
 	/* What should we do here? We could issue a shutdown or hard reset. */
 }