X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=blobdiff_plain;f=src%2Ftarget%2Farm_semihosting.c;h=252511962da1bdbda1fe1430ad0dd6bc0df4bb84;hp=a247cc88839a4671f7e8bf0eb0d3b6273eed83af;hb=5be455a710c57bbbbd49c2d671b42098db7be5dc;hpb=cb72b7a270c7be60c1ec2ee47282156397bea846

diff --git a/src/target/arm_semihosting.c b/src/target/arm_semihosting.c
index a247cc8883..252511962d 100644
--- a/src/target/arm_semihosting.c
+++ b/src/target/arm_semihosting.c
@@ -5,6 +5,9 @@
  *   Copyright (C) 2010 by Spencer Oliver                                  *
  *   spen@spen-soft.co.uk                                                  *
  *                                                                         *
+ *   Copyright (C) 2016 by Square, Inc.                                    *
+ *   Steven Stallion <stallion@squareup.com>                               *
+ *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
  *   it under the terms of the GNU General Public License as published by  *
  *   the Free Software Foundation; either version 2 of the License, or     *
@@ -16,9 +19,7 @@
  *   GNU General Public License for more details.                          *
  *                                                                         *
  *   You should have received a copy of the GNU General Public License     *
- *   along with this program; if not, write to the                         *
- *   Free Software Foundation, Inc.,                                       *
- *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  ***************************************************************************/
 
 /**
@@ -41,14 +42,17 @@
 #include "armv4_5.h"
 #include "arm7_9_common.h"
 #include "armv7m.h"
-#include "cortex_m3.h"
+#include "armv7a.h"
+#include "cortex_m.h"
 #include "register.h"
+#include "arm_opcodes.h"
+#include "target_type.h"
 #include "arm_semihosting.h"
 #include <helper/binarybuffer.h>
 #include <helper/log.h>
 #include <sys/stat.h>
 
-static int open_modeflags[12] = {
+static const int open_modeflags[12] = {
 	O_RDONLY,
 	O_RDONLY | O_BINARY,
 	O_RDWR,
@@ -63,13 +67,59 @@ static int open_modeflags[12] = {
 	O_RDWR | O_CREAT | O_APPEND | O_BINARY
 };
 
+static int post_result(struct target *target)
+{
+	struct arm *arm = target_to_arm(target);
+
+	/* REVISIT this looks wrong ... ARM11 and Cortex-A8
+	 * should work this way at least sometimes.
+	 */
+	if (is_arm7_9(target_to_arm7_9(target)) ||
+	    is_armv7a(target_to_armv7a(target))) {
+		uint32_t spsr;
+
+		/* return value in R0 */
+		buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, arm->semihosting_result);
+		arm->core_cache->reg_list[0].dirty = 1;
+
+		/* LR --> PC */
+		buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
+			buf_get_u32(arm_reg_current(arm, 14)->value, 0, 32));
+		arm->core_cache->reg_list[15].dirty = 1;
+
+		/* saved PSR --> current PSR */
+		spsr = buf_get_u32(arm->spsr->value, 0, 32);
+
+		/* REVISIT should this be arm_set_cpsr(arm, spsr)
+		 * instead of a partially unrolled version?
+		 */
+
+		buf_set_u32(arm->cpsr->value, 0, 32, spsr);
+		arm->cpsr->dirty = 1;
+		arm->core_mode = spsr & 0x1f;
+		if (spsr & 0x20)
+			arm->core_state = ARM_STATE_THUMB;
+
+	} else {
+		/* resume execution, this will be pc+2 to skip over the
+		 * bkpt instruction */
+
+		/* return result in R0 */
+		buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, arm->semihosting_result);
+		arm->core_cache->reg_list[0].dirty = 1;
+	}
+
+	return ERROR_OK;
+}
+
 static int do_semihosting(struct target *target)
 {
 	struct arm *arm = target_to_arm(target);
+	struct gdb_fileio_info *fileio_info = target->fileio_info;
 	uint32_t r0 = buf_get_u32(arm->core_cache->reg_list[0].value, 0, 32);
 	uint32_t r1 = buf_get_u32(arm->core_cache->reg_list[1].value, 0, 32);
 	uint8_t params[16];
-	int retval, result;
+	int retval;
 
 	/*
 	 * TODO: lots of security issues are not considered yet, such as:
@@ -77,10 +127,10 @@ static int do_semihosting(struct target *target)
 	 * - no safety checks on opened/deleted/renamed file paths
 	 * Beware the target app you use this support with.
 	 *
-	 * TODO: explore mapping requests to GDB's "File-I/O Remote
-	 * Protocol Extension" ... when GDB is active.
+	 * TODO: unsupported semihosting fileio operations could be
+	 * implemented if we had a small working area at our disposal.
 	 */
-	switch (r0) {
+	switch ((arm->semihosting_op = r0)) {
 	case 0x01:	/* SYS_OPEN */
 		retval = target_read_memory(target, r1, 4, 3, params);
 		if (retval != ERROR_OK)
@@ -89,27 +139,40 @@ static int do_semihosting(struct target *target)
 			uint32_t a = target_buffer_get_u32(target, params+0);
 			uint32_t m = target_buffer_get_u32(target, params+4);
 			uint32_t l = target_buffer_get_u32(target, params+8);
-			if (l <= 255 && m <= 11) {
-				uint8_t fn[256];
-				retval = target_read_memory(target, a, 1, l, fn);
-				if (retval != ERROR_OK)
-					return retval;
-				fn[l] = 0;
-				if (strcmp((char *)fn, ":tt") == 0) {
-					if (m < 4)
-						result = dup(STDIN_FILENO);
-					else
-						result = dup(STDOUT_FILENO);
-				} else {
-					/* cygwin requires the permission setting
-					 * otherwise it will fail to reopen a previously
-					 * written file */
-					result = open((char *)fn, open_modeflags[m], 0644);
+			uint8_t fn[256];
+			retval = target_read_memory(target, a, 1, l, fn);
+			if (retval != ERROR_OK)
+				return retval;
+			fn[l] = 0;
+			if (arm->is_semihosting_fileio) {
+				if (strcmp((char *)fn, ":tt") == 0)
+					arm->semihosting_result = 0;
+				else {
+					arm->semihosting_hit_fileio = true;
+					fileio_info->identifier = "open";
+					fileio_info->param_1 = a;
+					fileio_info->param_2 = l;
+					fileio_info->param_3 = open_modeflags[m];
+					fileio_info->param_4 = 0644;
 				}
-				arm->semihosting_errno =  errno;
 			} else {
-				result = -1;
-				arm->semihosting_errno = EINVAL;
+				if (l <= 255 && m <= 11) {
+					if (strcmp((char *)fn, ":tt") == 0) {
+						if (m < 4)
+							arm->semihosting_result = dup(STDIN_FILENO);
+						else
+							arm->semihosting_result = dup(STDOUT_FILENO);
+					} else {
+						/* cygwin requires the permission setting
+						 * otherwise it will fail to reopen a previously
+						 * written file */
+						arm->semihosting_result = open((char *)fn, open_modeflags[m], 0644);
+					}
+					arm->semihosting_errno =  errno;
+				} else {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = EINVAL;
+				}
 			}
 		}
 		break;
@@ -120,33 +183,63 @@ static int do_semihosting(struct target *target)
 			return retval;
 		else {
 			int fd = target_buffer_get_u32(target, params+0);
-			result = close(fd);
-			arm->semihosting_errno = errno;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "close";
+				fileio_info->param_1 = fd;
+			} else {
+				arm->semihosting_result = close(fd);
+				arm->semihosting_errno = errno;
+			}
 		}
 		break;
 
 	case 0x03:	/* SYS_WRITEC */
-		{
+		if (arm->is_semihosting_fileio) {
+			arm->semihosting_hit_fileio = true;
+			fileio_info->identifier = "write";
+			fileio_info->param_1 = 1;
+			fileio_info->param_2 = r1;
+			fileio_info->param_3 = 1;
+		} else {
 			unsigned char c;
 			retval = target_read_memory(target, r1, 1, 1, &c);
 			if (retval != ERROR_OK)
 				return retval;
 			putchar(c);
-			result = 0;
+			arm->semihosting_result = 0;
 		}
 		break;
 
 	case 0x04:	/* SYS_WRITE0 */
-		do {
-			unsigned char c;
-			retval = target_read_memory(target, r1, 1, 1, &c);
-			if (retval != ERROR_OK)
-				return retval;
-			if (!c)
-				break;
-			putchar(c);
-		} while (1);
-		result = 0;
+		if (arm->is_semihosting_fileio) {
+			size_t count = 0;
+			for (uint32_t a = r1;; a++) {
+				unsigned char c;
+				retval = target_read_memory(target, a, 1, 1, &c);
+				if (retval != ERROR_OK)
+					return retval;
+				if (c == '\0')
+					break;
+				count++;
+			}
+			arm->semihosting_hit_fileio = true;
+			fileio_info->identifier = "write";
+			fileio_info->param_1 = 1;
+			fileio_info->param_2 = r1;
+			fileio_info->param_3 = count;
+		} else {
+			do {
+				unsigned char c;
+				retval = target_read_memory(target, r1++, 1, 1, &c);
+				if (retval != ERROR_OK)
+					return retval;
+				if (!c)
+					break;
+				putchar(c);
+			} while (1);
+			arm->semihosting_result = 0;
+		}
 		break;
 
 	case 0x05:	/* SYS_WRITE */
@@ -157,21 +250,29 @@ static int do_semihosting(struct target *target)
 			int fd = target_buffer_get_u32(target, params+0);
 			uint32_t a = target_buffer_get_u32(target, params+4);
 			size_t l = target_buffer_get_u32(target, params+8);
-			uint8_t *buf = malloc(l);
-			if (!buf) {
-				result = -1;
-				arm->semihosting_errno = ENOMEM;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "write";
+				fileio_info->param_1 = fd;
+				fileio_info->param_2 = a;
+				fileio_info->param_3 = l;
 			} else {
-				retval = target_read_buffer(target, a, l, buf);
-				if (retval != ERROR_OK) {
+				uint8_t *buf = malloc(l);
+				if (!buf) {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = ENOMEM;
+				} else {
+					retval = target_read_buffer(target, a, l, buf);
+					if (retval != ERROR_OK) {
+						free(buf);
+						return retval;
+					}
+					arm->semihosting_result = write(fd, buf, l);
+					arm->semihosting_errno = errno;
+					if (arm->semihosting_result >= 0)
+						arm->semihosting_result = l - arm->semihosting_result;
 					free(buf);
-					return retval;
 				}
-				result = write(fd, buf, l);
-				arm->semihosting_errno = errno;
-				if (result >= 0)
-					result = l - result;
-				free(buf);
 			}
 		}
 		break;
@@ -184,42 +285,60 @@ static int do_semihosting(struct target *target)
 			int fd = target_buffer_get_u32(target, params+0);
 			uint32_t a = target_buffer_get_u32(target, params+4);
 			ssize_t l = target_buffer_get_u32(target, params+8);
-			uint8_t *buf = malloc(l);
-			if (!buf) {
-				result = -1;
-				arm->semihosting_errno = ENOMEM;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "read";
+				fileio_info->param_1 = fd;
+				fileio_info->param_2 = a;
+				fileio_info->param_3 = l;
 			} else {
-				result = read(fd, buf, l);
-				arm->semihosting_errno = errno;
-				if (result >= 0) {
-					retval = target_write_buffer(target, a, result, buf);
-					if (retval != ERROR_OK) {
-						free(buf);
-						return retval;
+				uint8_t *buf = malloc(l);
+				if (!buf) {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = ENOMEM;
+				} else {
+					arm->semihosting_result = read(fd, buf, l);
+					arm->semihosting_errno = errno;
+					if (arm->semihosting_result >= 0) {
+						retval = target_write_buffer(target, a, arm->semihosting_result, buf);
+						if (retval != ERROR_OK) {
+							free(buf);
+							return retval;
+						}
+						arm->semihosting_result = l - arm->semihosting_result;
 					}
-					result = l - result;
+					free(buf);
 				}
-				free(buf);
 			}
 		}
 		break;
 
 	case 0x07:	/* SYS_READC */
-		result = getchar();
+		if (arm->is_semihosting_fileio) {
+			LOG_ERROR("SYS_READC not supported by semihosting fileio");
+			return ERROR_FAIL;
+		}
+		arm->semihosting_result = getchar();
 		break;
 
 	case 0x08:	/* SYS_ISERROR */
 		retval = target_read_memory(target, r1, 4, 1, params);
 		if (retval != ERROR_OK)
 			return retval;
-		result = (target_buffer_get_u32(target, params+0) != 0);
+		arm->semihosting_result = (target_buffer_get_u32(target, params+0) != 0);
 		break;
 
 	case 0x09:	/* SYS_ISTTY */
-		retval = target_read_memory(target, r1, 4, 1, params);
-		if (retval != ERROR_OK)
-			return retval;
-		result = isatty(target_buffer_get_u32(target, params+0));
+		if (arm->is_semihosting_fileio) {
+			arm->semihosting_hit_fileio = true;
+			fileio_info->identifier = "isatty";
+			fileio_info->param_1 = r1;
+		} else {
+			retval = target_read_memory(target, r1, 4, 1, params);
+			if (retval != ERROR_OK)
+				return retval;
+			arm->semihosting_result = isatty(target_buffer_get_u32(target, params+0));
+		}
 		break;
 
 	case 0x0a:	/* SYS_SEEK */
@@ -229,27 +348,39 @@ static int do_semihosting(struct target *target)
 		else {
 			int fd = target_buffer_get_u32(target, params+0);
 			off_t pos = target_buffer_get_u32(target, params+4);
-			result = lseek(fd, pos, SEEK_SET);
-			arm->semihosting_errno = errno;
-			if (result == pos)
-				result = 0;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "lseek";
+				fileio_info->param_1 = fd;
+				fileio_info->param_2 = pos;
+				fileio_info->param_3 = SEEK_SET;
+			} else {
+				arm->semihosting_result = lseek(fd, pos, SEEK_SET);
+				arm->semihosting_errno = errno;
+				if (arm->semihosting_result == pos)
+					arm->semihosting_result = 0;
+			}
 		}
 		break;
 
 	case 0x0c:	/* SYS_FLEN */
+		if (arm->is_semihosting_fileio) {
+			LOG_ERROR("SYS_FLEN not supported by semihosting fileio");
+			return ERROR_FAIL;
+		}
 		retval = target_read_memory(target, r1, 4, 1, params);
 		if (retval != ERROR_OK)
 			return retval;
 		else {
 			int fd = target_buffer_get_u32(target, params+0);
 			struct stat buf;
-			result = fstat(fd, &buf);
-			if (result == -1) {
+			arm->semihosting_result = fstat(fd, &buf);
+			if (arm->semihosting_result == -1) {
 				arm->semihosting_errno = errno;
-				result = -1;
+				arm->semihosting_result = -1;
 				break;
 			}
-			result = buf.st_size;
+			arm->semihosting_result = buf.st_size;
 		}
 		break;
 
@@ -260,17 +391,24 @@ static int do_semihosting(struct target *target)
 		else {
 			uint32_t a = target_buffer_get_u32(target, params+0);
 			uint32_t l = target_buffer_get_u32(target, params+4);
-			if (l <= 255) {
-				uint8_t fn[256];
-				retval = target_read_memory(target, a, 1, l, fn);
-				if (retval != ERROR_OK)
-					return retval;
-				fn[l] = 0;
-				result = remove((char *)fn);
-				arm->semihosting_errno =  errno;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "unlink";
+				fileio_info->param_1 = a;
+				fileio_info->param_2 = l;
 			} else {
-				result = -1;
-				arm->semihosting_errno = EINVAL;
+				if (l <= 255) {
+					uint8_t fn[256];
+					retval = target_read_memory(target, a, 1, l, fn);
+					if (retval != ERROR_OK)
+						return retval;
+					fn[l] = 0;
+					arm->semihosting_result = remove((char *)fn);
+					arm->semihosting_errno =  errno;
+				} else {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = EINVAL;
+				}
 			}
 		}
 		break;
@@ -284,31 +422,40 @@ static int do_semihosting(struct target *target)
 			uint32_t l1 = target_buffer_get_u32(target, params+4);
 			uint32_t a2 = target_buffer_get_u32(target, params+8);
 			uint32_t l2 = target_buffer_get_u32(target, params+12);
-			if (l1 <= 255 && l2 <= 255) {
-				uint8_t fn1[256], fn2[256];
-				retval = target_read_memory(target, a1, 1, l1, fn1);
-				if (retval != ERROR_OK)
-					return retval;
-				retval = target_read_memory(target, a2, 1, l2, fn2);
-				if (retval != ERROR_OK)
-					return retval;
-				fn1[l1] = 0;
-				fn2[l2] = 0;
-				result = rename((char *)fn1, (char *)fn2);
-				arm->semihosting_errno =  errno;
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "rename";
+				fileio_info->param_1 = a1;
+				fileio_info->param_2 = l1;
+				fileio_info->param_3 = a2;
+				fileio_info->param_4 = l2;
 			} else {
-				result = -1;
-				arm->semihosting_errno = EINVAL;
+				if (l1 <= 255 && l2 <= 255) {
+					uint8_t fn1[256], fn2[256];
+					retval = target_read_memory(target, a1, 1, l1, fn1);
+					if (retval != ERROR_OK)
+						return retval;
+					retval = target_read_memory(target, a2, 1, l2, fn2);
+					if (retval != ERROR_OK)
+						return retval;
+					fn1[l1] = 0;
+					fn2[l2] = 0;
+					arm->semihosting_result = rename((char *)fn1, (char *)fn2);
+					arm->semihosting_errno =  errno;
+				} else {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = EINVAL;
+				}
 			}
 		}
 		break;
 
 	case 0x11:	/* SYS_TIME */
-		result = time(NULL);
+		arm->semihosting_result = time(NULL);
 		break;
 
 	case 0x13:	/* SYS_ERRNO */
-		result = arm->semihosting_errno;
+		arm->semihosting_result = arm->semihosting_errno;
 		break;
 
 	case 0x15:	/* SYS_GET_CMDLINE */
@@ -321,12 +468,12 @@ static int do_semihosting(struct target *target)
 			char *arg = "foobar";
 			uint32_t s = strlen(arg) + 1;
 			if (l < s)
-				result = -1;
+				arm->semihosting_result = -1;
 			else {
-				retval = target_write_buffer(target, a, s, (void*)arg);
+				retval = target_write_buffer(target, a, s, (uint8_t *)arg);
 				if (retval != ERROR_OK)
 					return retval;
-				result = 0;
+				arm->semihosting_result = 0;
 			}
 		}
 		break;
@@ -342,7 +489,7 @@ static int do_semihosting(struct target *target)
 			retval = target_write_memory(target, a, 4, 4, params);
 			if (retval != ERROR_OK)
 				return retval;
-			result = 0;
+			arm->semihosting_result = 0;
 		}
 		break;
 
@@ -374,62 +521,125 @@ static int do_semihosting(struct target *target)
 		}
 		return target_call_event_callbacks(target, TARGET_EVENT_HALTED);
 
+	case 0x12:	/* SYS_SYSTEM */
+		/* Provide SYS_SYSTEM functionality.  Uses the
+		 * libc system command, there may be a reason *NOT*
+		 * to use this, but as I can't think of one, I
+		 * implemented it this way.
+		 */
+		retval = target_read_memory(target, r1, 4, 2, params);
+		if (retval != ERROR_OK)
+			return retval;
+		else {
+			uint32_t len = target_buffer_get_u32(target, params+4);
+			uint32_t c_ptr = target_buffer_get_u32(target, params);
+			if (arm->is_semihosting_fileio) {
+				arm->semihosting_hit_fileio = true;
+				fileio_info->identifier = "system";
+				fileio_info->param_1 = c_ptr;
+				fileio_info->param_2 = len;
+			} else {
+				uint8_t cmd[256];
+				if (len > 255) {
+					arm->semihosting_result = -1;
+					arm->semihosting_errno = EINVAL;
+				} else {
+					memset(cmd, 0x0, 256);
+					retval = target_read_memory(target, c_ptr, 1, len, cmd);
+					if (retval != ERROR_OK)
+						return retval;
+					else
+						arm->semihosting_result = system((const char *)cmd);
+				}
+			}
+		}
+		break;
 	case 0x0d:	/* SYS_TMPNAM */
 	case 0x10:	/* SYS_CLOCK */
-	case 0x12:	/* SYS_SYSTEM */
 	case 0x17:	/* angel_SWIreason_EnterSVC */
 	case 0x30:	/* SYS_ELAPSED */
 	case 0x31:	/* SYS_TICKFREQ */
 	default:
 		fprintf(stderr, "semihosting: unsupported call %#x\n",
 				(unsigned) r0);
-		result = -1;
+		arm->semihosting_result = -1;
 		arm->semihosting_errno = ENOTSUP;
 	}
 
-	/* resume execution to the original mode */
+	return ERROR_OK;
+}
 
-	/* REVISIT this looks wrong ... ARM11 and Cortex-A8
-	 * should work this way at least sometimes.
+static int get_gdb_fileio_info(struct target *target, struct gdb_fileio_info *fileio_info)
+{
+	struct arm *arm = target_to_arm(target);
+
+	/* To avoid uneccessary duplication, semihosting prepares the
+	 * fileio_info structure out-of-band when the target halts. See
+	 * do_semihosting for more detail.
 	 */
-	if (is_arm7_9(target_to_arm7_9(target)))
-	{
-		uint32_t spsr;
+	if (!arm->is_semihosting_fileio || !arm->semihosting_hit_fileio)
+		return ERROR_FAIL;
 
-		/* return value in R0 */
-		buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
-		arm->core_cache->reg_list[0].dirty = 1;
+	return ERROR_OK;
+}
 
-		/* LR --> PC */
-		buf_set_u32(arm->core_cache->reg_list[15].value, 0, 32,
-			buf_get_u32(arm_reg_current(arm,14)->value, 0, 32));
-		arm->core_cache->reg_list[15].dirty = 1;
+static int gdb_fileio_end(struct target *target, int result, int fileio_errno, bool ctrl_c)
+{
+	struct arm *arm = target_to_arm(target);
+	struct gdb_fileio_info *fileio_info = target->fileio_info;
 
-		/* saved PSR --> current PSR */
-		spsr = buf_get_u32(arm->spsr->value, 0, 32);
+	/* clear pending status */
+	arm->semihosting_hit_fileio = false;
 
-		/* REVISIT should this be arm_set_cpsr(arm, spsr)
-		 * instead of a partially unrolled version?
-		 */
+	arm->semihosting_result = result;
+	arm->semihosting_errno = fileio_errno;
 
-		buf_set_u32(arm->cpsr->value, 0, 32, spsr);
-		arm->cpsr->dirty = 1;
-		arm->core_mode = spsr & 0x1f;
-		if (spsr & 0x20)
-			arm->core_state = ARM_STATE_THUMB;
+	/* Some fileio results do not match up with what the semihosting
+	 * operation expects; for these operations, we munge the results
+	 * below:
+	 */
+	switch (arm->semihosting_op) {
+	case 0x05:	/* SYS_WRITE */
+		if (result < 0)
+			arm->semihosting_result = fileio_info->param_3;
+		else
+			arm->semihosting_result = 0;
+		break;
+
+	case 0x06:	/* SYS_READ */
+		if (result == (int)fileio_info->param_3)
+			arm->semihosting_result = 0;
+		if (result <= 0)
+			arm->semihosting_result = fileio_info->param_3;
+		break;
 
+	case 0x0a:	/* SYS_SEEK */
+		if (result > 0)
+			arm->semihosting_result = 0;
+		break;
 	}
-	else
-	{
-		/* resume execution, this will be pc+2 to skip over the
-		 * bkpt instruction */
 
-		/* return result in R0 */
-		buf_set_u32(arm->core_cache->reg_list[0].value, 0, 32, result);
-		arm->core_cache->reg_list[0].dirty = 1;
+	return post_result(target);
+}
+
+/**
+ * Initialize ARM semihosting support.
+ *
+ * @param target Pointer to the ARM target to initialize.
+ * @return An error status if there is a problem during initialization.
+ */
+int arm_semihosting_init(struct target *target)
+{
+	target->fileio_info = malloc(sizeof(*target->fileio_info));
+	if (target->fileio_info == NULL) {
+		LOG_ERROR("out of memory");
+		return ERROR_FAIL;
 	}
 
-	return target_resume(target, 1, 0, 0, 0);
+	target->type->get_gdb_fileio_info = get_gdb_fileio_info;
+	target->type->gdb_fileio_end = gdb_fileio_end;
+
+	return ERROR_OK;
 }
 
 /**
@@ -448,21 +658,42 @@ static int do_semihosting(struct target *target)
 int arm_semihosting(struct target *target, int *retval)
 {
 	struct arm *arm = target_to_arm(target);
+	struct armv7a_common *armv7a = target_to_armv7a(target);
 	uint32_t pc, lr, spsr;
 	struct reg *r;
 
 	if (!arm->is_semihosting)
 		return 0;
 
-	if (is_arm7_9(target_to_arm7_9(target)))
-	{
+	if (is_arm7_9(target_to_arm7_9(target)) ||
+	    is_armv7a(armv7a)) {
+		uint32_t vbar = 0x00000000;
+
 		if (arm->core_mode != ARM_MODE_SVC)
 			return 0;
 
+		if (is_armv7a(armv7a)) {
+			struct arm_dpm *dpm = armv7a->arm.dpm;
+
+			*retval = dpm->prepare(dpm);
+			if (*retval == ERROR_OK) {
+				*retval = dpm->instr_read_data_r0(dpm,
+								 ARMV4_5_MRC(15, 0, 0, 12, 0, 0),
+								 &vbar);
+
+				dpm->finish(dpm);
+
+				if (*retval != ERROR_OK)
+					return 1;
+			} else {
+				return 1;
+			}
+		}
+
 		/* Check for PC == 0x00000008 or 0xffff0008: Supervisor Call vector. */
 		r = arm->pc;
 		pc = buf_get_u32(r->value, 0, 32);
-		if (pc != 0x00000008 && pc != 0xffff0008)
+		if (pc != (vbar + 0x00000008) && pc != 0xffff0008)
 			return 0;
 
 		r = arm_reg_current(arm, 14);
@@ -510,9 +741,7 @@ int arm_semihosting(struct target *target, int *retval)
 			if (insn != 0xEF123456)
 				return 0;
 		}
-	}
-	else if (is_armv7m(target_to_armv7m(target)))
-	{
+	} else if (is_armv7m(target_to_armv7m(target))) {
 		uint16_t insn;
 
 		if (target->debug_reason != DBG_REASON_BREAKPOINT)
@@ -529,13 +758,40 @@ int arm_semihosting(struct target *target, int *retval)
 		/* bkpt 0xAB */
 		if (insn != 0xBEAB)
 			return 0;
-	}
-	else
-	{
+	} else {
 		LOG_ERROR("Unsupported semi-hosting Target");
 		return 0;
 	}
 
-	*retval = do_semihosting(target);
-	return 1;
+	/* Perform semihosting if we are not waiting on a fileio
+	 * operation to complete.
+	 */
+	if (!arm->semihosting_hit_fileio) {
+		*retval = do_semihosting(target);
+		if (*retval != ERROR_OK) {
+			LOG_ERROR("Failed semihosting operation");
+			return 0;
+		}
+	}
+
+	/* Post result to target if we are not waiting on a fileio
+	 * operation to complete:
+	 */
+	if (!arm->semihosting_hit_fileio) {
+		*retval = post_result(target);
+		if (*retval != ERROR_OK) {
+			LOG_ERROR("Failed to post semihosting result");
+			return 0;
+		}
+
+		*retval = target_resume(target, 1, 0, 0, 0);
+		if (*retval != ERROR_OK) {
+			LOG_ERROR("Failed to resume target");
+			return 0;
+		}
+
+		return 1;
+	}
+
+	return 0;
 }