1 files changed, 110 insertions, 1 deletions
diff --git a/arch/mn10300/kernel/switch_to.S b/arch/mn10300/kernel/switch_to.S
index 9074d0fb8788..de3e74fc9ea0 100644
--- a/arch/mn10300/kernel/switch_to.S
+++ b/arch/mn10300/kernel/switch_to.S
@@ -39,11 +39,17 @@ ENTRY(__switch_to)
 
 	# save prev context
 	mov	__switch_back,d0
-	mov	d0,(THREAD_PC,a0)
 	mov	sp,a2
 	mov	a2,(THREAD_SP,a0)
 	mov	a3,(THREAD_A3,a0)
 
+#ifdef CONFIG_KGDB
+	btst	0xff,(kgdb_single_step)
+	bne	__switch_to__lift_sstep_bp
+__switch_to__continue:
+#endif
+	mov	d0,(THREAD_PC,a0)
+
 	mov	(THREAD_A3,a1),a3
 	mov	(THREAD_SP,a1),a2
 
@@ -68,3 +74,106 @@ ENTRY(__switch_to)
 __switch_back:
 	and	~EPSW_NMID,epsw
 	ret	[d2,d3,a2,a3,exreg1],32
+
+#ifdef CONFIG_KGDB
+###############################################################################
+#
+# Lift the single-step breakpoints when the task being traced is switched out
+# A0 = prev
+# A1 = next
+#
+###############################################################################
+__switch_to__lift_sstep_bp:
+	add	-12,sp
+	mov	a0,e4
+	mov	a1,e5
+
+	# Clear the single-step flag to prevent us coming this way until we get
+	# switched back in
+	bclr	0xff,(kgdb_single_step)
+
+	# Remove first breakpoint
+	mov	(kgdb_sstep_bp_addr),a2
+	cmp	0,a2
+	beq	1f
+	movbu	(kgdb_sstep_bp),d0
+	movbu	d0,(a2)
+#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
+	mov	a2,d0
+	mov	a2,d1
+	add	1,d1
+	calls	flush_icache_range
+#endif
+1:
+
+	# Remove second breakpoint
+	mov	(kgdb_sstep_bp_addr+4),a2
+	cmp	0,a2
+	beq	2f
+	movbu	(kgdb_sstep_bp+1),d0
+	movbu	d0,(a2)
+#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
+	mov	a2,d0
+	mov	a2,d1
+	add	1,d1
+	calls	flush_icache_range
+#endif
+2:
+
+	# Change the resumption address and return
+	mov	__switch_back__reinstall_sstep_bp,d0
+	mov	e4,a0
+	mov	e5,a1
+	add	12,sp
+	bra	__switch_to__continue
+
+###############################################################################
+#
+# Reinstall the single-step breakpoints when the task being traced is switched
+# back in (A1 points to the new thread_struct).
+#
+###############################################################################
+__switch_back__reinstall_sstep_bp:
+	add	-12,sp
+	mov	a0,e4			# save the return value
+	mov	0xff,d3
+
+	# Reinstall first breakpoint
+	mov	(kgdb_sstep_bp_addr),a2
+	cmp	0,a2
+	beq	1f
+	movbu	(a2),d0
+	movbu	d0,(kgdb_sstep_bp)
+	movbu	d3,(a2)
+#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
+	mov	a2,d0
+	mov	a2,d1
+	add	1,d1
+	calls	flush_icache_range
+#endif
+1:
+
+	# Reinstall second breakpoint
+	mov	(kgdb_sstep_bp_addr+4),a2
+	cmp	0,a2
+	beq	2f
+	movbu	(a2),d0
+	movbu	d0,(kgdb_sstep_bp+1)
+	movbu	d3,(a2)
+#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
+	mov	a2,d0
+	mov	a2,d1
+	add	1,d1
+	calls	flush_icache_range
+#endif
+2:
+
+	mov	d3,(kgdb_single_step)
+
+	# Restore the return value (the previous thread_struct pointer)
+	mov	e4,a0
+	mov	a0,d0
+	add	12,sp
+	bra	__switch_back
+
+#endif /* CONFIG_KGDB */