[PATCH 1/7] ARMv7M: use software breakpoints for algorithms

[Spencer O. <nt...@us...>]

 - armv7m_run_algorithm now requires all algorithms to use
   a software breakpoint at their exit address
 - updated all algorithms to support this

Signed-off-by: Spencer Oliver <nt...@us...>
---
 src/flash/nor/at91sam3.c  |    4 +---
 src/flash/nor/lpc2000.c   |    2 +-
 src/flash/nor/stellaris.c |    3 +--
 src/flash/nor/stm32x.c    |    3 +--
 src/target/armv7m.c       |   23 +++++------------------
 5 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/src/flash/nor/at91sam3.c b/src/flash/nor/at91sam3.c
index 1b2f27c..5f013ed 100644
--- a/src/flash/nor/at91sam3.c
+++ b/src/flash/nor/at91sam3.c
@@ -2046,9 +2046,7 @@ sam3_page_write_opcodes[] = {
 	0x10,0xf0,0x01,0x0f,
 	//  41 0024 FBD0     		beq	.L4
 	0xfb,0xd0,
-	//  42              	.done:
-	//  43 0026 FEE7     		b	.done
-	0xfe,0xe7
+	0x00,0xBE     				/* bkpt #0 */
 };
 
 
diff --git a/src/flash/nor/lpc2000.c b/src/flash/nor/lpc2000.c
index fc2b1cf..6674f17 100644
--- a/src/flash/nor/lpc2000.c
+++ b/src/flash/nor/lpc2000.c
@@ -267,7 +267,7 @@ static int lpc2000_iap_call(struct flash_bank *bank, int code, uint32_t param_ta
 				target_buffer_set_u32(target, jump_gate,
 						ARMV4_5_T_BX(12));
 				target_buffer_set_u32(target, jump_gate + 4,
-						ARMV4_5_T_B(0xfffffe));
+						ARMV5_T_BKPT(0));
 				break;
 			case lpc2000_v1:
 			case lpc2000_v2:
diff --git a/src/flash/nor/stellaris.c b/src/flash/nor/stellaris.c
index 107b1c6..e5618b9 100644
--- a/src/flash/nor/stellaris.c
+++ b/src/flash/nor/stellaris.c
@@ -805,8 +805,7 @@ static const uint8_t stellaris_write_code[] =
 	0x04,0x36,			/* adds	r6, r6, #4 */
 	0x96,0x42,			/* cmp	r6, r2 */
 	0xF4,0xD1,			/* bne	mainloop */
-						/* exit: */
-	0xFE,0xE7,			/* b exit */
+	0x00,0xBE,     		/* bkpt #0 */
 /* pFLASH_CTRL_BASE: */
 	0x00,0xD0,0x0F,0x40,	/* .word	0x400FD000 */
 /* FLASHWRITECMD: */
diff --git a/src/flash/nor/stm32x.c b/src/flash/nor/stm32x.c
index bfdd3cd..53fc4ea 100644
--- a/src/flash/nor/stm32x.c
+++ b/src/flash/nor/stm32x.c
@@ -459,8 +459,7 @@ static int stm32x_write_block(struct flash_bank *bank, uint8_t *buffer, uint32_t
 		0x01, 0xD1,					/* bne	exit */
 		0x01, 0x3A,					/* subs	r2, r2, #1 */
 		0xED, 0xD1,					/* bne	write */
-									/* exit: */
-		0xFE, 0xE7,					/* b exit */
+		0x00, 0xBE,     			/* bkpt #0 */
 		0x10, 0x20, 0x02, 0x40,		/* STM32_FLASH_CR:	.word 0x40022010 */
 		0x0C, 0x20, 0x02, 0x40		/* STM32_FLASH_SR:	.word 0x4002200C */
 	};
diff --git a/src/target/armv7m.c b/src/target/armv7m.c
index 466c0b2..056ac7b 100644
--- a/src/target/armv7m.c
+++ b/src/target/armv7m.c
@@ -338,6 +338,9 @@ int armv7m_run_algorithm(struct target *target,
 	int retval = ERROR_OK;
 	uint32_t context[ARMV7M_NUM_REGS];
 
+	/* NOTE: armv7m_run_algorithm requires that each algorithm uses a software breakpoint
+	 * at the exit point */
+
 	if (armv7m_algorithm_info->common_magic != ARMV7M_COMMON_MAGIC)
 	{
 		LOG_ERROR("current target isn't an ARMV7M target");
@@ -395,22 +398,8 @@ int armv7m_run_algorithm(struct target *target,
 		armv7m->core_cache->reg_list[ARMV7M_CONTROL].valid = 1;
 	}
 
-	/* REVISIT speed things up (3% or so in one case) by requiring
-	 * algorithms to include a BKPT instruction at each exit point.
-	 * This eliminates overheads of adding/removing a breakpoint.
-	 */
-
-	/* ARMV7M always runs in Thumb state */
-	if ((retval = breakpoint_add(target, exit_point, 2, BKPT_SOFT)) != ERROR_OK)
-	{
-		LOG_ERROR("can't add breakpoint to finish algorithm execution");
-		return ERROR_TARGET_FAILURE;
-	}
-
 	retval = armv7m_run_and_wait(target, entry_point, timeout_ms, exit_point, armv7m);
 
-	breakpoint_remove(target, exit_point);
-
 	if (retval != ERROR_OK)
 	{
 		return retval;
@@ -594,8 +583,7 @@ int armv7m_checksum_memory(struct target *target,
 								/* ncomp: */
 		0x429C,					/* cmp	r4, r3 */
 		0xD1E9,					/* bne	nbyte */
-								/* end: */
-		0xE7FE,					/* b	end */
+		0xBE00,     			/* bkpt #0 */
 		0x1DB7, 0x04C1			/* CRC32XOR:	.word 0x04C11DB7 */
 	};
 
@@ -659,8 +647,7 @@ int armv7m_blank_check_memory(struct target *target,
 		0xEA02, 0x0203,		/* and  r2, r2, r3 */
 		0x3901,				/* subs	r1, r1, #1 */
 		0xD1F9,				/* bne	loop */
-		/* end: */
-		0xE7FE,				/* b	end */
+		0xBE00,     		/* bkpt #0 */
 	};
 
 	/* make sure we have a working area */
-- 
1.6.5.1.1367.gcd48


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