target/cortex_a: remove unused code controlled by "fast_reg_read"

The variable fast_reg_read is always zero, causing some code to
never be executed.
Such code try to read the target registers by dumping them in
memory and then reading back the memory through the debugger. But
it is broken due to lack of cache and MMU management.
This code also uses the broken memory_ap access that is going to
be removed soon.

Remove all the code that depends on fast_reg_read not zero.
Add a missing check on arm_dpm_read_current_registers() return.
Keep the unused function cortex_a_dap_write_coreregister_u32()
to balance the used "read" version.

Change-Id: If2ff28a8c49eb0a87dc85207f5431978efd158db
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4746
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>

2 files changed, 6 insertions, 84 deletions

diff --git a/src/target/cortex_a.c b/src/target/cortex_a.c
index e209c80..21943f2 100644
--- a/src/target/cortex_a.c
+++ b/src/target/cortex_a.c
@@ -307,32 +307,6 @@ static int cortex_a_exec_opcode(struct target *target,
 	return retval;
 }
 
-/**************************************************************************
-Read core register with very few exec_opcode, fast but needs work_area.
-This can cause problems with MMU active.
-**************************************************************************/
-static int cortex_a_read_regs_through_mem(struct target *target, uint32_t address,
-	uint32_t *regfile)
-{
-	int retval = ERROR_OK;
-	struct armv7a_common *armv7a = target_to_armv7a(target);
-
-	retval = cortex_a_dap_read_coreregister_u32(target, regfile, 0);
-	if (retval != ERROR_OK)
-		return retval;
-	retval = cortex_a_dap_write_coreregister_u32(target, address, 0);
-	if (retval != ERROR_OK)
-		return retval;
-	retval = cortex_a_exec_opcode(target, ARMV4_5_STMIA(0, 0xFFFE, 0, 0), NULL);
-	if (retval != ERROR_OK)
-		return retval;
-
-	retval = mem_ap_read_buf(armv7a->memory_ap,
-			(uint8_t *)(&regfile[1]), 4, 15, address);
-
-	return retval;
-}
-
 static int cortex_a_dap_read_coreregister_u32(struct target *target,
 	uint32_t *value, int regnum)
 {
@@ -395,6 +369,7 @@ static int cortex_a_dap_read_coreregister_u32(struct target *target,
 	return retval;
 }
 
+__attribute__((unused))
 static int cortex_a_dap_write_coreregister_u32(struct target *target,
 	uint32_t value, int regnum)
 {
@@ -1183,10 +1158,8 @@ static int cortex_a_resume(struct target *target, int current,
 
 static int cortex_a_debug_entry(struct target *target)
 {
-	int i;
-	uint32_t regfile[16], cpsr, spsr, dscr;
+	uint32_t spsr, dscr;
 	int retval = ERROR_OK;
-	struct working_area *regfile_working_area = NULL;
 	struct cortex_a_common *cortex_a = target_to_cortex_a(target);
 	struct armv7a_common *armv7a = target_to_armv7a(target);
 	struct arm *arm = &armv7a->arm;
@@ -1227,56 +1200,10 @@ static int cortex_a_debug_entry(struct target *target)
 		arm_dpm_report_wfar(&armv7a->dpm, wfar);
 	}
 
-	/* REVISIT fast_reg_read is never set ... */
-
-	/* Examine target state and mode */
-	if (cortex_a->fast_reg_read)
-		target_alloc_working_area(target, 64, &regfile_working_area);
-
-
-	/* First load register acessible through core debug port*/
-	if (!regfile_working_area)
-		retval = arm_dpm_read_current_registers(&armv7a->dpm);
-	else {
-		retval = cortex_a_read_regs_through_mem(target,
-				regfile_working_area->address, regfile);
-
-		target_free_working_area(target, regfile_working_area);
-		if (retval != ERROR_OK)
-			return retval;
-
-		/* read Current PSR */
-		retval = cortex_a_dap_read_coreregister_u32(target, &cpsr, 16);
-		/*  store current cpsr */
-		if (retval != ERROR_OK)
-			return retval;
-
-		LOG_DEBUG("cpsr: %8.8" PRIx32, cpsr);
-
-		arm_set_cpsr(arm, cpsr);
-
-		/* update cache */
-		for (i = 0; i <= ARM_PC; i++) {
-			reg = arm_reg_current(arm, i);
-
-			buf_set_u32(reg->value, 0, 32, regfile[i]);
-			reg->valid = 1;
-			reg->dirty = 0;
-		}
-
-		/* Fixup PC Resume Address */
-		if (cpsr & (1 << 5)) {
-			/* T bit set for Thumb or ThumbEE state */
-			regfile[ARM_PC] -= 4;
-		} else {
-			/* ARM state */
-			regfile[ARM_PC] -= 8;
-		}
-
-		reg = arm->pc;
-		buf_set_u32(reg->value, 0, 32, regfile[ARM_PC]);
-		reg->dirty = reg->valid;
-	}
+	/* First load register accessible through core debug port */
+	retval = arm_dpm_read_current_registers(&armv7a->dpm);
+	if (retval != ERROR_OK)
+		return retval;
 
 	if (arm->spsr) {
 		/* read Saved PSR */
@@ -3174,8 +3101,6 @@ static int cortex_a_init_arch_info(struct target *target,
 	cortex_a->common_magic = CORTEX_A_COMMON_MAGIC;
 	armv7a->arm.dap = dap;
 
-	cortex_a->fast_reg_read = 0;
-
 	/* register arch-specific functions */
 	armv7a->examine_debug_reason = NULL;
 
diff --git a/src/target/cortex_a.h b/src/target/cortex_a.h
index ff03432..197a599 100644
--- a/src/target/cortex_a.h
+++ b/src/target/cortex_a.h
@@ -93,9 +93,6 @@ struct cortex_a_common {
 	int brp_num_available;
 	struct cortex_a_brp *brp_list;
 
-	/* Use cortex_a_read_regs_through_mem for fast register reads */
-	int fast_reg_read;
-
 	uint32_t cpuid;
 	uint32_t didr;