semihosting: support fileio operation

This patch adds support for bridging semihosting to GDB's File-I/O
remote protocol extension. For the most part operations match up 1:1,
however some require a working area to complete successfully, namely
operations that devolve to read, stat, and gettimeofday.

A new command was added to enable support for fileio named `arm
semihosting_fileio`, which ensures that the default behavior remains
intact for those that prefer it.

Finally, redundant logging was removed from the target_arch_state
function; this permits ARM targets to quiesce log output when polling
for a fileio reply. This prevents filling the logs with halt/resume
messages when using semihosting fileio.

Change-Id: Ifbb864fc2373336a501cc0332675b887b552e1ee
Signed-off-by: Steven Stallion <stallion@squareup.com>
Reviewed-on: http://openocd.zylin.com/3566
Tested-by: jenkins
Reviewed-by: Steven Stallion <sstallion@gmail.com>
Reviewed-by: Paul Fertser <fercerpav@gmail.com>

doc/openocd.texi

@@ -7404,6 +7404,17 @@ requests by using a special SVC instruction that is trapped at the
 Supervisor Call vector by OpenOCD.
 @end deffn
 
+@deffn Command {arm semihosting_fileio} [@option{enable}|@option{disable}]
+@cindex ARM semihosting
+Display status of semihosting fileio, after optionally changing that
+status.
+
+Enabling this option forwards semihosting I/O to GDB process using the
+File-I/O remote protocol extension. This is especially useful for
+interacting with remote files or displaying console messages in the
+debugger.
+@end deffn
+
 @section ARMv4 and ARMv5 Architecture
 @cindex ARMv4
 @cindex ARMv5

src/target/arm.h

@@ -130,6 +130,18 @@ struct arm {
 	/** Flag reporting whether semihosting is active. */
 	bool is_semihosting;
 
+	/** Flag reporting whether semihosting fileio is active. */
+	bool is_semihosting_fileio;
+
+	/** Flag reporting whether semihosting fileio operation is active. */
+	bool semihosting_hit_fileio;
+
+	/** Current semihosting operation. */
+	int semihosting_op;
+
+	/** Current semihosting result. */
+	int semihosting_result;
+
 	/** Value to be returned by semihosting SYS_ERRNO request. */
 	int semihosting_errno;
 

src/target/arm7tdmi.c

@@ -30,6 +30,7 @@
 #include "target_type.h"
 #include "register.h"
 #include "arm_opcodes.h"
+#include "arm_semihosting.h"
 
 /*
  * For information about ARM7TDMI, see ARM DDI 0210C (r4p1)
@@ -615,7 +616,7 @@ static void arm7tdmi_build_reg_cache(struct target *target)
 int arm7tdmi_init_target(struct command_context *cmd_ctx, struct target *target)
 {
 	arm7tdmi_build_reg_cache(target);
-
+	arm_semihosting_init(target);
 	return ERROR_OK;
 }
 

src/target/arm9tdmi.c

@@ -30,6 +30,7 @@
 #include "target_type.h"
 #include "register.h"
 #include "arm_opcodes.h"
+#include "arm_semihosting.h"
 
 /*
  * NOTE:  this holds code that's used with multiple ARM9 processors:
@@ -714,6 +715,7 @@ int arm9tdmi_init_target(struct command_context *cmd_ctx,
 		struct target *target)
 {
 	arm9tdmi_build_reg_cache(target);
+	arm_semihosting_init(target);
 	return ERROR_OK;
 }
 

src/target/arm_semihosting.h

@@ -19,6 +19,7 @@
 #ifndef OPENOCD_TARGET_ARM_SEMIHOSTING_H
 #define OPENOCD_TARGET_ARM_SEMIHOSTING_H
 
+int arm_semihosting_init(struct target *target);
 int arm_semihosting(struct target *target, int *retval);
 
 #endif /* OPENOCD_TARGET_ARM_SEMIHOSTING_H */

src/target/armv4_5.c

@@ -666,14 +666,19 @@ int arm_arch_state(struct target *target)
 		return ERROR_FAIL;
 	}
 
+	/* avoid filling log waiting for fileio reply */
+	if (arm->semihosting_hit_fileio)
+		return ERROR_OK;
+
 	LOG_USER("target halted in %s state due to %s, current mode: %s\n"
-		"cpsr: 0x%8.8" PRIx32 " pc: 0x%8.8" PRIx32 "%s",
+		"cpsr: 0x%8.8" PRIx32 " pc: 0x%8.8" PRIx32 "%s%s",
 		arm_state_strings[arm->core_state],
 		debug_reason_name(target),
 		arm_mode_name(arm->core_mode),
 		buf_get_u32(arm->cpsr->value, 0, 32),
 		buf_get_u32(arm->pc->value, 0, 32),
-		arm->is_semihosting ? ", semihosting" : "");
+		arm->is_semihosting ? ", semihosting" : "",
+		arm->is_semihosting_fileio ? " fileio" : "");
 
 	return ERROR_OK;
 }
@@ -1055,6 +1060,37 @@ COMMAND_HANDLER(handle_arm_semihosting_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_arm_semihosting_fileio_command)
+{
+	struct target *target = get_current_target(CMD_CTX);
+
+	if (target == NULL) {
+		LOG_ERROR("No target selected");
+		return ERROR_FAIL;
+	}
+
+	struct arm *arm = target_to_arm(target);
+
+	if (!is_arm(arm)) {
+		command_print(CMD_CTX, "current target isn't an ARM");
+		return ERROR_FAIL;
+	}
+
+	if (!arm->is_semihosting) {
+		command_print(CMD_CTX, "semihosting is not enabled");
+		return ERROR_FAIL;
+	}
+
+	if (CMD_ARGC > 0)
+		COMMAND_PARSE_ENABLE(CMD_ARGV[0], arm->is_semihosting_fileio);
+
+	command_print(CMD_CTX, "semihosting fileio is %s",
+		arm->is_semihosting_fileio
+		? "enabled" : "disabled");
+
+	return ERROR_OK;
+}
+
 static const struct command_registration arm_exec_command_handlers[] = {
 	{
 		.name = "reg",
@@ -1097,6 +1133,13 @@ static const struct command_registration arm_exec_command_handlers[] = {
 		.usage = "['enable'|'disable']",
 		.help = "activate support for semihosting operations",
 	},
+	{
+		"semihosting_fileio",
+		.handler = handle_arm_semihosting_fileio_command,
+		.mode = COMMAND_EXEC,
+		.usage = "['enable'|'disable']",
+		.help = "activate support for semihosting fileio operations",
+	},
 
 	COMMAND_REGISTRATION_DONE
 };

src/target/armv7m.c

@@ -536,11 +536,15 @@ int armv7m_arch_state(struct target *target)
 	struct arm *arm = &armv7m->arm;
 	uint32_t ctrl, sp;
 
+	/* avoid filling log waiting for fileio reply */
+	if (arm->semihosting_hit_fileio)
+		return ERROR_OK;
+
 	ctrl = buf_get_u32(arm->core_cache->reg_list[ARMV7M_CONTROL].value, 0, 32);
 	sp = buf_get_u32(arm->core_cache->reg_list[ARMV7M_R13].value, 0, 32);
 
 	LOG_USER("target halted due to %s, current mode: %s %s\n"
-		"xPSR: %#8.8" PRIx32 " pc: %#8.8" PRIx32 " %csp: %#8.8" PRIx32 "%s",
+		"xPSR: %#8.8" PRIx32 " pc: %#8.8" PRIx32 " %csp: %#8.8" PRIx32 "%s%s",
 		debug_reason_name(target),
 		arm_mode_name(arm->core_mode),
 		armv7m_exception_string(armv7m->exception_number),
@@ -548,7 +552,8 @@ int armv7m_arch_state(struct target *target)
 		buf_get_u32(arm->pc->value, 0, 32),
 		(ctrl & 0x02) ? 'p' : 'm',
 		sp,
-		arm->is_semihosting ? ", semihosting" : "");
+		arm->is_semihosting ? ", semihosting" : "",
+		arm->is_semihosting_fileio ? " fileio" : "");
 
 	return ERROR_OK;
 }

src/target/cortex_a.c

@@ -3103,6 +3103,7 @@ static int cortex_a_init_target(struct command_context *cmd_ctx,
 	struct target *target)
 {
 	/* examine_first() does a bunch of this */
+	arm_semihosting_init(target);
 	return ERROR_OK;
 }
 

src/target/cortex_m.c

@@ -1696,6 +1696,7 @@ static int cortex_m_init_target(struct command_context *cmd_ctx,
 	struct target *target)
 {
 	armv7m_build_reg_cache(target);
+	arm_semihosting_init(target);
 	return ERROR_OK;
 }
 

src/target/hla_target.c

@@ -341,7 +341,7 @@ static int adapter_init_target(struct command_context *cmd_ctx,
 	LOG_DEBUG("%s", __func__);
 
 	armv7m_build_reg_cache(target);
-
+	arm_semihosting_init(target);
 	return ERROR_OK;
 }
 

src/target/target.c

@@ -1944,13 +1944,10 @@ int target_arch_state(struct target *target)
 {
 	int retval;
 	if (target == NULL) {
-		LOG_USER("No target has been configured");
+		LOG_WARNING("No target has been configured");
 		return ERROR_OK;
 	}
 
-	LOG_USER("%s: target state: %s", target_name(target),
-		 target_state_name(target));
-
 	if (target->state != TARGET_HALTED)
 		return ERROR_OK;