5 files changed, 54 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 8f6617cf2689..7e5a1722e4f2 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -182,9 +182,11 @@ transfer_to_handler:
          */
 	kuap_save_and_lock r11, r12, r9, r2, r0
 	addi	r2, r12, -THREAD
+#ifndef CONFIG_VMAP_STACK
 	lwz	r9,KSP_LIMIT(r12)
 	cmplw	r1,r9			/* if r1 <= ksp_limit */
 	ble-	stack_ovf		/* then the kernel stack overflowed */
+#endif
 5:
 #if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_E500)
 	lwz	r12,TI_LOCAL_FLAGS(r2)
@@ -289,6 +291,7 @@ reenable_mmu:
 	b	fast_exception_return
 #endif
 
+#ifndef CONFIG_VMAP_STACK
 /*
  * On kernel stack overflow, load up an initial stack pointer
  * and call StackOverflow(regs), which should not return.
@@ -314,6 +317,7 @@ stack_ovf:
 	mtspr	SPRN_SRR1,r10
 	SYNC
 	RFI
+#endif
 
 #ifdef CONFIG_TRACE_IRQFLAGS
 trace_syscall_entry_irq_off:
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index e36987aede86..c39209d56020 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -55,6 +55,10 @@
 	addi	r11, r11, THREAD_SIZE - INT_FRAME_SIZE
 	tophys_novmstack r11, r11
 1:
+#ifdef CONFIG_VMAP_STACK
+	mtcrf	0x7f, r11
+	bt	32 - THREAD_ALIGN_SHIFT, stack_overflow
+#endif
 .endm
 
 .macro EXCEPTION_PROLOG_2 handle_dar_dsisr=0
@@ -299,4 +303,28 @@ label:
 	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, transfer_to_handler, \
 			  ret_from_except)
 
+.macro vmap_stack_overflow_exception
+#ifdef CONFIG_VMAP_STACK
+#ifdef CONFIG_SMP
+	mfspr	r11, SPRN_SPRG_THREAD
+	tovirt(r11, r11)
+	lwz	r11, TASK_CPU - THREAD(r11)
+	slwi	r11, r11, 3
+	addis	r11, r11, emergency_ctx@ha
+#else
+	lis	r11, emergency_ctx@ha
+#endif
+	lwz	r11, emergency_ctx@l(r11)
+	cmpwi	cr1, r11, 0
+	bne	cr1, 1f
+	lis	r11, init_thread_union@ha
+	addi	r11, r11, init_thread_union@l
+1:	addi	r11, r11, THREAD_SIZE - INT_FRAME_SIZE
+	EXCEPTION_PROLOG_2
+	SAVE_NVGPRS(r11)
+	addi	r3, r1, STACK_FRAME_OVERHEAD
+	EXC_XFER_STD(0, stack_overflow_exception)
+#endif
+.endm
+
 #endif /* __HEAD_32_H__ */
diff --git a/arch/powerpc/kernel/setup.h b/arch/powerpc/kernel/setup.h
index c82577c4b15d..2dd0d9cb5a20 100644
--- a/arch/powerpc/kernel/setup.h
+++ b/arch/powerpc/kernel/setup.h
@@ -35,7 +35,7 @@ void exc_lvl_early_init(void);
 static inline void exc_lvl_early_init(void) { };
 #endif
 
-#ifdef CONFIG_PPC64
+#if defined(CONFIG_PPC64) || defined(CONFIG_VMAP_STACK)
 void emergency_stack_init(void);
 #else
 static inline void emergency_stack_init(void) { };
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index f014c4f7a337..a55b4d9ab824 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -161,6 +161,18 @@ void __init irqstack_early_init(void)
 	}
 }
 
+#ifdef CONFIG_VMAP_STACK
+void *emergency_ctx[NR_CPUS] __ro_after_init;
+
+void __init emergency_stack_init(void)
+{
+	unsigned int i;
+
+	for_each_possible_cpu(i)
+		emergency_ctx[i] = alloc_stack();
+}
+#endif
+
 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
 void __init exc_lvl_early_init(void)
 {
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 014ff0701f24..82a3438300fd 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1637,6 +1637,15 @@ void StackOverflow(struct pt_regs *regs)
 	panic("kernel stack overflow");
 }
 
+void stack_overflow_exception(struct pt_regs *regs)
+{
+	enum ctx_state prev_state = exception_enter();
+
+	die("Kernel stack overflow", regs, SIGSEGV);
+
+	exception_exit(prev_state);
+}
+
 void kernel_fp_unavailable_exception(struct pt_regs *regs)
 {
 	enum ctx_state prev_state = exception_enter();