diff --git a/src/target/arm7_9_common.c b/src/target/arm7_9_common.c
index 7a2b54294..3a3276466 100644
--- a/src/target/arm7_9_common.c
+++ b/src/target/arm7_9_common.c
@@ -1577,7 +1577,7 @@ int arm7_9_restore_context(struct target *target)
 	struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
 	struct armv4_5_common_s *armv4_5 = &arm7_9->armv4_5_common;
 	struct reg *reg;
-	struct armv4_5_core_reg *reg_arch_info;
+	struct arm_reg *reg_arch_info;
 	enum armv4_5_mode current_mode = armv4_5->core_mode;
 	int i, j;
 	int dirty;
@@ -2084,25 +2084,24 @@ int arm7_9_step(struct target *target, int current, uint32_t address, int handle
 	return err;
 }
 
-int arm7_9_read_core_reg(struct target *target, int num, enum armv4_5_mode mode)
+static int arm7_9_read_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode)
 {
 	uint32_t* reg_p[16];
 	uint32_t value;
 	int retval;
+	struct arm_reg *areg = r->arch_info;
 	struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
 	struct armv4_5_common_s *armv4_5 = &arm7_9->armv4_5_common;
 
 	if (!is_arm_mode(armv4_5->core_mode))
 		return ERROR_FAIL;
-
-	enum armv4_5_mode reg_mode = ((struct armv4_5_core_reg*)ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).arch_info)->mode;
-
 	if ((num < 0) || (num > 16))
 		return ERROR_INVALID_ARGUMENTS;
 
 	if ((mode != ARMV4_5_MODE_ANY)
 			&& (mode != armv4_5->core_mode)
-			&& (reg_mode != ARMV4_5_MODE_ANY))
+			&& (areg->mode != ARMV4_5_MODE_ANY))
 	{
 		uint32_t tmp_cpsr;
 
@@ -2125,10 +2124,7 @@ int arm7_9_read_core_reg(struct target *target, int num, enum armv4_5_mode mode)
 		/* read a program status register
 		 * if the register mode is MODE_ANY, we read the cpsr, otherwise a spsr
 		 */
-		struct armv4_5_core_reg *arch_info = ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).arch_info;
-		int spsr = (arch_info->mode == ARMV4_5_MODE_ANY) ? 0 : 1;
-
-		arm7_9->read_xpsr(target, &value, spsr);
+		arm7_9->read_xpsr(target, &value, areg->mode != ARMV4_5_MODE_ANY);
 	}
 
 	if ((retval = jtag_execute_queue()) != ERROR_OK)
@@ -2136,13 +2132,13 @@ int arm7_9_read_core_reg(struct target *target, int num, enum armv4_5_mode mode)
 		return retval;
 	}
 
-	ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).valid = 1;
-	ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).dirty = 0;
-	buf_set_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).value, 0, 32, value);
+	r->valid = 1;
+	r->dirty = 0;
+	buf_set_u32(r->value, 0, 32, value);
 
 	if ((mode != ARMV4_5_MODE_ANY)
 			&& (mode != armv4_5->core_mode)
-			&& (reg_mode != ARMV4_5_MODE_ANY))	{
+			&& (areg->mode != ARMV4_5_MODE_ANY))	{
 		/* restore processor mode (mask T bit) */
 		arm7_9->write_xpsr_im8(target, buf_get_u32(armv4_5->core_cache->reg_list[ARMV4_5_CPSR].value, 0, 8) & ~0x20, 0, 0);
 	}
@@ -2150,23 +2146,22 @@ int arm7_9_read_core_reg(struct target *target, int num, enum armv4_5_mode mode)
 	return ERROR_OK;
 }
 
-int arm7_9_write_core_reg(struct target *target, int num, enum armv4_5_mode mode, uint32_t value)
+static int arm7_9_write_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode, uint32_t value)
 {
 	uint32_t reg[16];
+	struct arm_reg *areg = r->arch_info;
 	struct arm7_9_common *arm7_9 = target_to_arm7_9(target);
 	struct armv4_5_common_s *armv4_5 = &arm7_9->armv4_5_common;
 
 	if (!is_arm_mode(armv4_5->core_mode))
 		return ERROR_FAIL;
-
-	enum armv4_5_mode reg_mode = ((struct armv4_5_core_reg*)ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).arch_info)->mode;
-
 	if ((num < 0) || (num > 16))
 		return ERROR_INVALID_ARGUMENTS;
 
 	if ((mode != ARMV4_5_MODE_ANY)
 			&& (mode != armv4_5->core_mode)
-			&& (reg_mode != ARMV4_5_MODE_ANY))	{
+			&& (areg->mode != ARMV4_5_MODE_ANY))	{
 		uint32_t tmp_cpsr;
 
 		/* change processor mode (mask T bit) */
@@ -2188,8 +2183,7 @@ int arm7_9_write_core_reg(struct target *target, int num, enum armv4_5_mode mode
 		/* write a program status register
 		* if the register mode is MODE_ANY, we write the cpsr, otherwise a spsr
 		*/
-		struct armv4_5_core_reg *arch_info = ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).arch_info;
-		int spsr = (arch_info->mode == ARMV4_5_MODE_ANY) ? 0 : 1;
+		int spsr = (areg->mode != ARMV4_5_MODE_ANY);
 
 		/* if we're writing the CPSR, mask the T bit */
 		if (!spsr)
@@ -2198,12 +2192,12 @@ int arm7_9_write_core_reg(struct target *target, int num, enum armv4_5_mode mode
 		arm7_9->write_xpsr(target, value, spsr);
 	}
 
-	ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).valid = 1;
-	ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, mode, num).dirty = 0;
+	r->valid = 1;
+	r->dirty = 0;
 
 	if ((mode != ARMV4_5_MODE_ANY)
 			&& (mode != armv4_5->core_mode)
-			&& (reg_mode != ARMV4_5_MODE_ANY))	{
+			&& (areg->mode != ARMV4_5_MODE_ANY))	{
 		/* restore processor mode (mask T bit) */
 		arm7_9->write_xpsr_im8(target, buf_get_u32(armv4_5->core_cache->reg_list[ARMV4_5_CPSR].value, 0, 8) & ~0x20, 0, 0);
 	}
diff --git a/src/target/arm7_9_common.h b/src/target/arm7_9_common.h
index 266bf8002..2f7132a15 100644
--- a/src/target/arm7_9_common.h
+++ b/src/target/arm7_9_common.h
@@ -139,7 +139,6 @@ int arm7_9_full_context(struct target *target);
 int arm7_9_restore_context(struct target *target);
 int arm7_9_resume(struct target *target, int current, uint32_t address, int handle_breakpoints, int debug_execution);
 int arm7_9_step(struct target *target, int current, uint32_t address, int handle_breakpoints);
-int arm7_9_read_core_reg(struct target *target, int num, enum armv4_5_mode mode);
 int arm7_9_read_memory(struct target *target, uint32_t address, uint32_t size, uint32_t count, uint8_t *buffer);
 int arm7_9_write_memory(struct target *target, uint32_t address, uint32_t size, uint32_t count, uint8_t *buffer);
 int arm7_9_bulk_write_memory(struct target *target, uint32_t address, uint32_t count, uint8_t *buffer);
diff --git a/src/target/arm7tdmi.c b/src/target/arm7tdmi.c
index 3bd523644..e7ea768f9 100644
--- a/src/target/arm7tdmi.c
+++ b/src/target/arm7tdmi.c
@@ -644,7 +644,6 @@ static void arm7tdmi_build_reg_cache(struct target *target)
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 
 	(*cache_p) = armv4_5_build_reg_cache(target, armv4_5);
-	armv4_5->core_cache = (*cache_p);
 }
 
 int arm7tdmi_init_target(struct command_context *cmd_ctx, struct target *target)
diff --git a/src/target/arm9tdmi.c b/src/target/arm9tdmi.c
index a69e49e74..38b2284b6 100644
--- a/src/target/arm9tdmi.c
+++ b/src/target/arm9tdmi.c
@@ -754,7 +754,6 @@ static void arm9tdmi_build_reg_cache(struct target *target)
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 
 	(*cache_p) = armv4_5_build_reg_cache(target, armv4_5);
-	armv4_5->core_cache = (*cache_p);
 }
 
 int arm9tdmi_init_target(struct command_context *cmd_ctx,
diff --git a/src/target/armv4_5.c b/src/target/armv4_5.c
index f8ab15322..71c7299e7 100644
--- a/src/target/armv4_5.c
+++ b/src/target/armv4_5.c
@@ -363,7 +363,7 @@ static void arm_gdb_dummy_init(void)
 static int armv4_5_get_core_reg(struct reg *reg)
 {
 	int retval;
-	struct armv4_5_core_reg *armv4_5 = reg->arch_info;
+	struct arm_reg *armv4_5 = reg->arch_info;
 	struct target *target = armv4_5->target;
 
 	if (target->state != TARGET_HALTED)
@@ -372,16 +372,18 @@ static int armv4_5_get_core_reg(struct reg *reg)
 		return ERROR_TARGET_NOT_HALTED;
 	}
 
-	retval = armv4_5->armv4_5_common->read_core_reg(target, armv4_5->num, armv4_5->mode);
-	if (retval == ERROR_OK)
+	retval = armv4_5->armv4_5_common->read_core_reg(target, reg, armv4_5->num, armv4_5->mode);
+	if (retval == ERROR_OK) {
 		reg->valid = 1;
+		reg->dirty = 0;
+	}
 
 	return retval;
 }
 
 static int armv4_5_set_core_reg(struct reg *reg, uint8_t *buf)
 {
-	struct armv4_5_core_reg *armv4_5 = reg->arch_info;
+	struct arm_reg *armv4_5 = reg->arch_info;
 	struct target *target = armv4_5->target;
 	struct armv4_5_common_s *armv4_5_target = target_to_armv4_5(target);
 	uint32_t value = buf_get_u32(buf, 0, 32);
@@ -392,8 +394,16 @@ static int armv4_5_set_core_reg(struct reg *reg, uint8_t *buf)
 		return ERROR_TARGET_NOT_HALTED;
 	}
 
+	/* Except for CPSR, the "reg" command exposes a writeback model
+	 * for the register cache.
+	 */
+	buf_set_u32(reg->value, 0, 32, value);
+	reg->dirty = 1;
+	reg->valid = 1;
+
 	if (reg == &armv4_5_target->core_cache->reg_list[ARMV4_5_CPSR])
 	{
+		/* FIXME handle J bit too; mostly for ThumbEE, also Jazelle */
 		if (value & 0x20)
 		{
 			/* T bit should be set */
@@ -415,19 +425,23 @@ static int armv4_5_set_core_reg(struct reg *reg, uint8_t *buf)
 			}
 		}
 
+		/* REVISIT Why only update core for mode change, not also
+		 * for state changes?  Possibly older cores need to stay
+		 * in ARM mode during halt mode debug, not execute Thumb;
+		 * v6/v7a/v7r seem to do that automatically...
+		 */
+
 		if (armv4_5_target->core_mode != (enum armv4_5_mode)(value & 0x1f))
 		{
 			LOG_DEBUG("changing ARM core mode to '%s'",
 					arm_mode_name(value & 0x1f));
 			armv4_5_target->core_mode = value & 0x1f;
-			armv4_5_target->write_core_reg(target, 16, ARMV4_5_MODE_ANY, value);
+			armv4_5_target->write_core_reg(target, reg,
+					16, ARMV4_5_MODE_ANY, value);
+			reg->dirty = 0;
 		}
 	}
 
-	buf_set_u32(reg->value, 0, 32, value);
-	reg->dirty = 1;
-	reg->valid = 1;
-
 	return ERROR_OK;
 }
 
@@ -441,8 +455,7 @@ struct reg_cache* armv4_5_build_reg_cache(struct target *target, struct arm *arm
 	int num_regs = ARRAY_SIZE(arm_core_regs);
 	struct reg_cache *cache = malloc(sizeof(struct reg_cache));
 	struct reg *reg_list = calloc(num_regs, sizeof(struct reg));
-	struct armv4_5_core_reg *arch_info = calloc(num_regs,
-					sizeof(struct armv4_5_core_reg));
+	struct arm_reg *arch_info = calloc(num_regs, sizeof(struct arm_reg));
 	int i;
 
 	if (!cache || !reg_list || !arch_info) {
@@ -480,6 +493,7 @@ struct reg_cache* armv4_5_build_reg_cache(struct target *target, struct arm *arm
 		cache->num_regs++;
 	}
 
+	armv4_5_common->core_cache = cache;
 	return cache;
 }
 
@@ -811,9 +825,14 @@ int armv4_5_run_algorithm_inner(struct target *target, int num_mem_params, struc
 
 	for (i = 0; i <= 16; i++)
 	{
-		if (!ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_algorithm_info->core_mode, i).valid)
-			armv4_5->read_core_reg(target, i, armv4_5_algorithm_info->core_mode);
-		context[i] = buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, armv4_5_algorithm_info->core_mode, i).value, 0, 32);
+		struct reg *r;
+
+		r = &ARMV4_5_CORE_REG_MODE(armv4_5->core_cache,
+				armv4_5_algorithm_info->core_mode, i);
+		if (!r->valid)
+			armv4_5->read_core_reg(target, r, i,
+					armv4_5_algorithm_info->core_mode);
+		context[i] = buf_get_u32(r->value, 0, 32);
 	}
 	cpsr = buf_get_u32(armv4_5->core_cache->reg_list[ARMV4_5_CPSR].value, 0, 32);
 
diff --git a/src/target/armv4_5.h b/src/target/armv4_5.h
index dbd62c0d7..c8fc55808 100644
--- a/src/target/armv4_5.h
+++ b/src/target/armv4_5.h
@@ -109,9 +109,9 @@ struct arm
 	struct etm_context *etm;
 
 	int (*full_context)(struct target *target);
-	int (*read_core_reg)(struct target *target,
+	int (*read_core_reg)(struct target *target, struct reg *reg,
 			int num, enum armv4_5_mode mode);
-	int (*write_core_reg)(struct target *target,
+	int (*write_core_reg)(struct target *target, struct reg *reg,
 			int num, enum armv4_5_mode mode, uint32_t value);
 	void *arch_info;
 };
@@ -137,7 +137,7 @@ struct armv4_5_algorithm
 	enum armv4_5_state core_state;
 };
 
-struct armv4_5_core_reg
+struct arm_reg
 {
 	int num;
 	enum armv4_5_mode mode;
diff --git a/src/target/cortex_a8.c b/src/target/cortex_a8.c
index 168fe127d..c6a46c50c 100644
--- a/src/target/cortex_a8.c
+++ b/src/target/cortex_a8.c
@@ -877,7 +877,7 @@ static int cortex_a8_restore_context(struct target *target)
 
 		/* write dirty non-{R0,CPSR} registers sharing the same mode */
 		for (i = max - 1, r = cache->reg_list + 1; i > 0; i--, r++) {
-			struct armv4_5_core_reg *reg;
+			struct arm_reg *reg;
 
 			if (!r->dirty || i == ARMV4_5_CPSR)
 				continue;
@@ -1018,16 +1018,17 @@ static int cortex_a8_store_core_reg_u32(struct target *target, int num,
 #endif
 
 
-static int cortex_a8_write_core_reg(struct target *target, int num,
-		enum armv4_5_mode mode, uint32_t value);
+static int cortex_a8_write_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode, uint32_t value);
 
-static int cortex_a8_read_core_reg(struct target *target, int num,
-		enum armv4_5_mode mode)
+static int cortex_a8_read_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode)
 {
 	uint32_t value;
 	int retval;
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 	struct reg_cache *cache = armv4_5->core_cache;
+	struct reg *cpsr_r = NULL;
 	uint32_t cpsr = 0;
 	unsigned cookie = num;
 
@@ -1042,10 +1043,10 @@ static int cortex_a8_read_core_reg(struct target *target, int num,
 			mode = ARMV4_5_MODE_ANY;
 
 		if (mode != ARMV4_5_MODE_ANY) {
-			cpsr = buf_get_u32(cache ->reg_list[ARMV4_5_CPSR]
-					.value, 0, 32);
-			cortex_a8_write_core_reg(target, 16,
-					ARMV4_5_MODE_ANY, mode);
+			cpsr_r = cache->reg_list + ARMV4_5_CPSR;
+			cpsr = buf_get_u32(cpsr_r->value, 0, 32);
+			cortex_a8_write_core_reg(target, cpsr_r,
+					16, ARMV4_5_MODE_ANY, mode);
 		}
 	}
 
@@ -1066,24 +1067,24 @@ static int cortex_a8_read_core_reg(struct target *target, int num,
 	cortex_a8_dap_read_coreregister_u32(target, &value, cookie);
 	retval = jtag_execute_queue();
 	if (retval == ERROR_OK) {
-		struct reg *r = &ARMV4_5_CORE_REG_MODE(cache, mode, num);
-
 		r->valid = 1;
 		r->dirty = 0;
 		buf_set_u32(r->value, 0, 32, value);
 	}
 
-	if (cpsr)
-		cortex_a8_write_core_reg(target, 16, ARMV4_5_MODE_ANY, cpsr);
+	if (cpsr_r)
+		cortex_a8_write_core_reg(target, cpsr_r,
+				16, ARMV4_5_MODE_ANY, cpsr);
 	return retval;
 }
 
-static int cortex_a8_write_core_reg(struct target *target, int num,
-		enum armv4_5_mode mode, uint32_t value)
+static int cortex_a8_write_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode, uint32_t value)
 {
 	int retval;
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 	struct reg_cache *cache = armv4_5->core_cache;
+	struct reg *cpsr_r = NULL;
 	uint32_t cpsr = 0;
 	unsigned cookie = num;
 
@@ -1098,10 +1099,10 @@ static int cortex_a8_write_core_reg(struct target *target, int num,
 			mode = ARMV4_5_MODE_ANY;
 
 		if (mode != ARMV4_5_MODE_ANY) {
-			cpsr = buf_get_u32(cache ->reg_list[ARMV4_5_CPSR]
-					.value, 0, 32);
-			cortex_a8_write_core_reg(target, 16,
-					ARMV4_5_MODE_ANY, mode);
+			cpsr_r = cache->reg_list + ARMV4_5_CPSR;
+			cpsr = buf_get_u32(cpsr_r->value, 0, 32);
+			cortex_a8_write_core_reg(target, cpsr_r,
+					16, ARMV4_5_MODE_ANY, mode);
 		}
 	}
 
@@ -1122,15 +1123,14 @@ static int cortex_a8_write_core_reg(struct target *target, int num,
 
 	cortex_a8_dap_write_coreregister_u32(target, value, cookie);
 	if ((retval = jtag_execute_queue()) == ERROR_OK) {
-		struct reg *r = &ARMV4_5_CORE_REG_MODE(cache, mode, num);
-
 		buf_set_u32(r->value, 0, 32, value);
 		r->valid = 1;
 		r->dirty = 0;
 	}
 
-	if (cpsr)
-		cortex_a8_write_core_reg(target, 16, ARMV4_5_MODE_ANY, cpsr);
+	if (cpsr_r)
+		cortex_a8_write_core_reg(target, cpsr_r,
+				16, ARMV4_5_MODE_ANY, cpsr);
 	return retval;
 }
 
@@ -1619,7 +1619,6 @@ static void cortex_a8_build_reg_cache(struct target *target)
 	armv4_5->core_type = ARM_MODE_MON;
 
 	(*cache_p) = armv4_5_build_reg_cache(target, armv4_5);
-	armv4_5->core_cache = (*cache_p);
 }
 
 
diff --git a/src/target/xscale.c b/src/target/xscale.c
index f13366ac0..c908fd709 100644
--- a/src/target/xscale.c
+++ b/src/target/xscale.c
@@ -1646,16 +1646,18 @@ static int xscale_deassert_reset(struct target *target)
 	return ERROR_OK;
 }
 
-static int xscale_read_core_reg(struct target *target, int num,
-		enum armv4_5_mode mode)
+static int xscale_read_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode)
 {
+	/** \todo add debug handler support for core register reads */
 	LOG_ERROR("not implemented");
 	return ERROR_OK;
 }
 
-static int xscale_write_core_reg(struct target *target, int num,
-		enum armv4_5_mode mode, uint32_t value)
+static int xscale_write_core_reg(struct target *target, struct reg *r,
+		int num, enum armv4_5_mode mode, uint32_t value)
 {
+	/** \todo add debug handler support for core register writes */
 	LOG_ERROR("not implemented");
 	return ERROR_OK;
 }
@@ -2829,7 +2831,6 @@ static void xscale_build_reg_cache(struct target *target)
 	int num_regs = sizeof(xscale_reg_arch_info) / sizeof(struct xscale_reg);
 
 	(*cache_p) = armv4_5_build_reg_cache(target, armv4_5);
-	armv4_5->core_cache = (*cache_p);
 
 	(*cache_p)->next = malloc(sizeof(struct reg_cache));
 	cache_p = &(*cache_p)->next;