1 files changed, 114 insertions, 0 deletions
diff --git a/linux-user/uaccess.c b/linux-user/uaccess.c
new file mode 100644
index 000000000..425cbf677
--- /dev/null
+++ b/linux-user/uaccess.c
@@ -0,0 +1,114 @@
+/* User memory access */
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+
+#include "qemu.h"
+#include "user-internals.h"
+
+void *lock_user(int type, abi_ulong guest_addr, ssize_t len, bool copy)
+{
+    void *host_addr;
+
+    guest_addr = cpu_untagged_addr(thread_cpu, guest_addr);
+    if (!access_ok_untagged(type, guest_addr, len)) {
+        return NULL;
+    }
+    host_addr = g2h_untagged(guest_addr);
+#ifdef DEBUG_REMAP
+    if (copy) {
+        host_addr = g_memdup(host_addr, len);
+    } else {
+        host_addr = g_malloc0(len);
+    }
+#endif
+    return host_addr;
+}
+
+#ifdef DEBUG_REMAP
+void unlock_user(void *host_ptr, abi_ulong guest_addr, ssize_t len)
+{
+    void *host_ptr_conv;
+
+    if (!host_ptr) {
+        return;
+    }
+    host_ptr_conv = g2h(thread_cpu, guest_addr);
+    if (host_ptr == host_ptr_conv) {
+        return;
+    }
+    if (len > 0) {
+        memcpy(host_ptr_conv, host_ptr, len);
+    }
+    g_free(host_ptr);
+}
+#endif
+
+void *lock_user_string(abi_ulong guest_addr)
+{
+    ssize_t len = target_strlen(guest_addr);
+    if (len < 0) {
+        return NULL;
+    }
+    return lock_user(VERIFY_READ, guest_addr, len + 1, 1);
+}
+
+/* copy_from_user() and copy_to_user() are usually used to copy data
+ * buffers between the target and host.  These internally perform
+ * locking/unlocking of the memory.
+ */
+int copy_from_user(void *hptr, abi_ulong gaddr, ssize_t len)
+{
+    int ret = 0;
+    void *ghptr = lock_user(VERIFY_READ, gaddr, len, 1);
+
+    if (ghptr) {
+        memcpy(hptr, ghptr, len);
+        unlock_user(ghptr, gaddr, 0);
+    } else {
+        ret = -TARGET_EFAULT;
+    }
+    return ret;
+}
+
+int copy_to_user(abi_ulong gaddr, void *hptr, ssize_t len)
+{
+    int ret = 0;
+    void *ghptr = lock_user(VERIFY_WRITE, gaddr, len, 0);
+
+    if (ghptr) {
+        memcpy(ghptr, hptr, len);
+        unlock_user(ghptr, gaddr, len);
+    } else {
+        ret = -TARGET_EFAULT;
+    }
+
+    return ret;
+}
+
+/* Return the length of a string in target memory or -TARGET_EFAULT if
+   access error  */
+ssize_t target_strlen(abi_ulong guest_addr1)
+{
+    uint8_t *ptr;
+    abi_ulong guest_addr;
+    size_t max_len, len;
+
+    guest_addr = guest_addr1;
+    for(;;) {
+        max_len = TARGET_PAGE_SIZE - (guest_addr & ~TARGET_PAGE_MASK);
+        ptr = lock_user(VERIFY_READ, guest_addr, max_len, 1);
+        if (!ptr)
+            return -TARGET_EFAULT;
+        len = qemu_strnlen((const char *)ptr, max_len);
+        unlock_user(ptr, guest_addr, 0);
+        guest_addr += len;
+        /* we don't allow wrapping or integer overflow */
+        if (guest_addr == 0 || (guest_addr - guest_addr1) > 0x7fffffff) {
+            return -TARGET_EFAULT;
+        }
+        if (len != max_len) {
+            break;
+        }
+    }
+    return guest_addr - guest_addr1;
+}