3 files changed, 22 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index b6ea9e068c13..c3523d1dda58 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -152,6 +152,15 @@ struct paca_struct {
 	 */
 	struct opal_machine_check_event *opal_mc_evt;
 #endif
+#ifdef CONFIG_PPC_BOOK3S_64
+	/* Exclusive emergency stack pointer for machine check exception. */
+	void *mc_emergency_sp;
+	/*
+	 * Flag to check whether we are in machine check early handler
+	 * and already using emergency stack.
+	 */
+	u16 in_mce;
+#endif
 
 	/* Stuff for accurate time accounting */
 	u64 user_time;			/* accumulated usermode TB ticks */
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 5760b9bea936..2232aff66059 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -540,7 +540,8 @@ static void __init exc_lvl_early_init(void)
 
 /*
  * Stack space used when we detect a bad kernel stack pointer, and
- * early in SMP boots before relocation is enabled.
+ * early in SMP boots before relocation is enabled. Exclusive emergency
+ * stack for machine checks.
  */
 static void __init emergency_stack_init(void)
 {
@@ -563,6 +564,13 @@ static void __init emergency_stack_init(void)
 		sp  = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit);
 		sp += THREAD_SIZE;
 		paca[i].emergency_sp = __va(sp);
+
+#ifdef CONFIG_PPC_BOOK3S_64
+		/* emergency stack for machine check exception handling. */
+		sp  = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit);
+		sp += THREAD_SIZE;
+		paca[i].mc_emergency_sp = __va(sp);
+#endif
 	}
 }
 
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index af9d3469fb99..a90731b3d44a 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -2051,6 +2051,10 @@ static void dump_one_paca(int cpu)
 	DUMP(p, stab_addr, "lx");
 #endif
 	DUMP(p, emergency_sp, "p");
+#ifdef CONFIG_PPC_BOOK3S_64
+	DUMP(p, mc_emergency_sp, "p");
+	DUMP(p, in_mce, "x");
+#endif
 	DUMP(p, data_offset, "lx");
 	DUMP(p, hw_cpu_id, "x");
 	DUMP(p, cpu_start, "x");