diff --git a/target/arm/arm-semi.c b/target/arm/arm-semi.c
index 302529f227..a4741d7e11 100644
--- a/target/arm/arm-semi.c
+++ b/target/arm/arm-semi.c
@@ -106,6 +106,113 @@ static int open_modeflags[12] = {
     O_RDWR | O_CREAT | O_APPEND | O_BINARY
 };
 
+typedef enum GuestFDType {
+    GuestFDUnused = 0,
+    GuestFDHost = 1,
+} GuestFDType;
+
+/*
+ * Guest file descriptors are integer indexes into an array of
+ * these structures (we will dynamically resize as necessary).
+ */
+typedef struct GuestFD {
+    GuestFDType type;
+    int hostfd;
+} GuestFD;
+
+static GArray *guestfd_array;
+
+/*
+ * Allocate a new guest file descriptor and return it; if we
+ * couldn't allocate a new fd then return -1.
+ * This is a fairly simplistic implementation because we don't
+ * expect that most semihosting guest programs will make very
+ * heavy use of opening and closing fds.
+ */
+static int alloc_guestfd(void)
+{
+    guint i;
+
+    if (!guestfd_array) {
+        /* New entries zero-initialized, i.e. type GuestFDUnused */
+        guestfd_array = g_array_new(FALSE, TRUE, sizeof(GuestFD));
+    }
+
+    for (i = 0; i < guestfd_array->len; i++) {
+        GuestFD *gf = &g_array_index(guestfd_array, GuestFD, i);
+
+        if (gf->type == GuestFDUnused) {
+            return i;
+        }
+    }
+
+    /* All elements already in use: expand the array */
+    g_array_set_size(guestfd_array, i + 1);
+    return i;
+}
+
+/*
+ * Look up the guestfd in the data structure; return NULL
+ * for out of bounds, but don't check whether the slot is unused.
+ * This is used internally by the other guestfd functions.
+ */
+static GuestFD *do_get_guestfd(int guestfd)
+{
+    if (!guestfd_array) {
+        return NULL;
+    }
+
+    if (guestfd < 0 || guestfd >= guestfd_array->len) {
+        return NULL;
+    }
+
+    return &g_array_index(guestfd_array, GuestFD, guestfd);
+}
+
+/*
+ * Associate the specified guest fd (which must have been
+ * allocated via alloc_fd() and not previously used) with
+ * the specified host fd.
+ */
+static void associate_guestfd(int guestfd, int hostfd)
+{
+    GuestFD *gf = do_get_guestfd(guestfd);
+
+    assert(gf);
+    gf->type = GuestFDHost;
+    gf->hostfd = hostfd;
+}
+
+/*
+ * Deallocate the specified guest file descriptor. This doesn't
+ * close the host fd, it merely undoes the work of alloc_fd().
+ */
+static void dealloc_guestfd(int guestfd)
+{
+    GuestFD *gf = do_get_guestfd(guestfd);
+
+    assert(gf);
+    gf->type = GuestFDUnused;
+}
+
+/*
+ * Given a guest file descriptor, get the associated struct.
+ * If the fd is not valid, return NULL. This is the function
+ * used by the various semihosting calls to validate a handle
+ * from the guest.
+ * Note: calling alloc_guestfd() or dealloc_guestfd() will
+ * invalidate any GuestFD* obtained by calling this function.
+ */
+static GuestFD *get_guestfd(int guestfd)
+{
+    GuestFD *gf = do_get_guestfd(guestfd);
+
+    if (!gf || gf->type == GuestFDUnused) {
+        return NULL;
+    }
+    return gf;
+}
+
 #ifdef CONFIG_USER_ONLY
 static inline uint32_t set_swi_errno(TaskState *ts, uint32_t code)
 {
@@ -207,6 +314,34 @@ static void arm_semi_flen_cb(CPUState *cs, target_ulong ret, target_ulong err)
 #endif
 }
 
+static int arm_semi_open_guestfd;
+
+static void arm_semi_open_cb(CPUState *cs, target_ulong ret, target_ulong err)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    CPUARMState *env = &cpu->env;
+#ifdef CONFIG_USER_ONLY
+    TaskState *ts = cs->opaque;
+#endif
+    if (ret == (target_ulong)-1) {
+#ifdef CONFIG_USER_ONLY
+        ts->swi_errno = err;
+#else
+        syscall_err = err;
+#endif
+        dealloc_guestfd(arm_semi_open_guestfd);
+    } else {
+        associate_guestfd(arm_semi_open_guestfd, ret);
+        ret = arm_semi_open_guestfd;
+    }
+
+    if (is_a64(env)) {
+        env->xregs[0] = ret;
+    } else {
+        env->regs[0] = ret;
+    }
+}
+
 static target_ulong arm_gdb_syscall(ARMCPU *cpu, gdb_syscall_complete_cb cb,
                                     const char *fmt, ...)
 {
@@ -283,6 +418,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
 #else
     CPUARMState *ts = env;
 #endif
+    GuestFD *gf;
 
     if (is_a64(env)) {
         /* Note that the syscall number is in W0, not X0 */
@@ -295,6 +431,9 @@ target_ulong do_arm_semihosting(CPUARMState *env)
 
     switch (nr) {
     case TARGET_SYS_OPEN:
+    {
+        int guestfd;
+
         GET_ARG(0);
         GET_ARG(1);
         GET_ARG(2);
@@ -308,26 +447,52 @@ target_ulong do_arm_semihosting(CPUARMState *env)
             errno = EINVAL;
             return set_swi_errno(ts, -1);
         }
+
+        guestfd = alloc_guestfd();
+        if (guestfd < 0) {
+            unlock_user(s, arg0, 0);
+            errno = EMFILE;
+            return set_swi_errno(ts, -1);
+        }
+
         if (strcmp(s, ":tt") == 0) {
             int result_fileno = arg1 < 4 ? STDIN_FILENO : STDOUT_FILENO;
+            associate_guestfd(guestfd, result_fileno);
             unlock_user(s, arg0, 0);
-            return result_fileno;
+            return guestfd;
         }
         if (use_gdb_syscalls()) {
-            ret = arm_gdb_syscall(cpu, arm_semi_cb, "open,%s,%x,1a4", arg0,
+            arm_semi_open_guestfd = guestfd;
+            ret = arm_gdb_syscall(cpu, arm_semi_open_cb, "open,%s,%x,1a4", arg0,
                                   (int)arg2+1, gdb_open_modeflags[arg1]);
         } else {
             ret = set_swi_errno(ts, open(s, open_modeflags[arg1], 0644));
+            if (ret == (uint32_t)-1) {
+                dealloc_guestfd(guestfd);
+            } else {
+                associate_guestfd(guestfd, ret);
+                ret = guestfd;
+            }
         }
         unlock_user(s, arg0, 0);
         return ret;
+    }
     case TARGET_SYS_CLOSE:
         GET_ARG(0);
-        if (use_gdb_syscalls()) {
-            return arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", arg0);
-        } else {
-            return set_swi_errno(ts, close(arg0));
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
         }
+
+        if (use_gdb_syscalls()) {
+            ret = arm_gdb_syscall(cpu, arm_semi_cb, "close,%x", gf->hostfd);
+        } else {
+            ret = set_swi_errno(ts, close(gf->hostfd));
+        }
+        dealloc_guestfd(arg0);
+        return ret;
     case TARGET_SYS_WRITEC:
         qemu_semihosting_console_outc(env, args);
         return 0xdeadbeef;
@@ -338,17 +503,24 @@ target_ulong do_arm_semihosting(CPUARMState *env)
         GET_ARG(1);
         GET_ARG(2);
         len = arg2;
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
+        }
+
         if (use_gdb_syscalls()) {
             arm_semi_syscall_len = len;
             return arm_gdb_syscall(cpu, arm_semi_cb, "write,%x,%x,%x",
-                                   arg0, arg1, len);
+                                   gf->hostfd, arg1, len);
         } else {
             s = lock_user(VERIFY_READ, arg1, len, 1);
             if (!s) {
                 /* Return bytes not written on error */
                 return len;
             }
-            ret = set_swi_errno(ts, write(arg0, s, len));
+            ret = set_swi_errno(ts, write(gf->hostfd, s, len));
             unlock_user(s, arg1, 0);
             if (ret == (uint32_t)-1) {
                 ret = 0;
@@ -361,10 +533,17 @@ target_ulong do_arm_semihosting(CPUARMState *env)
         GET_ARG(1);
         GET_ARG(2);
         len = arg2;
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
+        }
+
         if (use_gdb_syscalls()) {
             arm_semi_syscall_len = len;
             return arm_gdb_syscall(cpu, arm_semi_cb, "read,%x,%x,%x",
-                                   arg0, arg1, len);
+                                   gf->hostfd, arg1, len);
         } else {
             s = lock_user(VERIFY_WRITE, arg1, len, 0);
             if (!s) {
@@ -372,7 +551,7 @@ target_ulong do_arm_semihosting(CPUARMState *env)
                 return len;
             }
             do {
-                ret = set_swi_errno(ts, read(arg0, s, len));
+                ret = set_swi_errno(ts, read(gf->hostfd, s, len));
             } while (ret == -1 && errno == EINTR);
             unlock_user(s, arg1, len);
             if (ret == (uint32_t)-1) {
@@ -386,31 +565,52 @@ target_ulong do_arm_semihosting(CPUARMState *env)
         return 0;
     case TARGET_SYS_ISTTY:
         GET_ARG(0);
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
+        }
+
         if (use_gdb_syscalls()) {
-            return arm_gdb_syscall(cpu, arm_semi_cb, "isatty,%x", arg0);
+            return arm_gdb_syscall(cpu, arm_semi_cb, "isatty,%x", gf->hostfd);
         } else {
-            return isatty(arg0);
+            return isatty(gf->hostfd);
         }
     case TARGET_SYS_SEEK:
         GET_ARG(0);
         GET_ARG(1);
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
+        }
+
         if (use_gdb_syscalls()) {
             return arm_gdb_syscall(cpu, arm_semi_cb, "lseek,%x,%x,0",
-                                   arg0, arg1);
+                                   gf->hostfd, arg1);
         } else {
-            ret = set_swi_errno(ts, lseek(arg0, arg1, SEEK_SET));
+            ret = set_swi_errno(ts, lseek(gf->hostfd, arg1, SEEK_SET));
             if (ret == (uint32_t)-1)
               return -1;
             return 0;
         }
     case TARGET_SYS_FLEN:
         GET_ARG(0);
+
+        gf = get_guestfd(arg0);
+        if (!gf) {
+            errno = EBADF;
+            return set_swi_errno(ts, -1);
+        }
+
         if (use_gdb_syscalls()) {
             return arm_gdb_syscall(cpu, arm_semi_flen_cb, "fstat,%x,%x",
-                                   arg0, arm_flen_buf(cpu));
+                                   gf->hostfd, arm_flen_buf(cpu));
         } else {
             struct stat buf;
-            ret = set_swi_errno(ts, fstat(arg0, &buf));
+            ret = set_swi_errno(ts, fstat(gf->hostfd, &buf));
             if (ret == (uint32_t)-1)
                 return -1;
             return buf.st_size;