linux-user: Implement special usbfs ioctls.

Userspace submits a USB Request Buffer to the kernel, optionally
discards it, and finally reaps the URB.  Thunk buffers from target
to host and back.

Tested by running an i386 scanner driver on ARMv7 and by running
the PowerPC lsusb utility on x86_64.  The discardurb ioctl is
not exercised in these tests.

Signed-off-by: Cortland Tölva <cst@tolva.net>
Message-Id: <20181008163521.17341-4-cst@tolva.net>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

linux-user/ioctls.h

@@ -143,6 +143,14 @@
   IOCTL(USBDEVFS_SETCONFIGURATION, IOC_W, MK_PTR(TYPE_INT))
   IOCTL(USBDEVFS_GETDRIVER, IOC_R,
         MK_PTR(MK_STRUCT(STRUCT_usbdevfs_getdriver)))
+  IOCTL_SPECIAL(USBDEVFS_SUBMITURB, IOC_W, do_ioctl_usbdevfs_submiturb,
+      MK_PTR(MK_STRUCT(STRUCT_usbdevfs_urb)))
+  IOCTL_SPECIAL(USBDEVFS_DISCARDURB, IOC_RW, do_ioctl_usbdevfs_discardurb,
+      MK_PTR(MK_STRUCT(STRUCT_usbdevfs_urb)))
+  IOCTL_SPECIAL(USBDEVFS_REAPURB, IOC_R, do_ioctl_usbdevfs_reapurb,
+      MK_PTR(TYPE_PTRVOID))
+  IOCTL_SPECIAL(USBDEVFS_REAPURBNDELAY, IOC_R, do_ioctl_usbdevfs_reapurb,
+      MK_PTR(TYPE_PTRVOID))
   IOCTL(USBDEVFS_DISCSIGNAL, IOC_W,
         MK_PTR(MK_STRUCT(STRUCT_usbdevfs_disconnectsignal)))
   IOCTL(USBDEVFS_CLAIMINTERFACE, IOC_W, MK_PTR(TYPE_INT))

linux-user/syscall.c

@@ -96,6 +96,7 @@
 #include <linux/fb.h>
 #if defined(CONFIG_USBFS)
 #include <linux/usbdevice_fs.h>
+#include <linux/usb/ch9.h>
 #endif
 #include <linux/vt.h>
 #include <linux/dm-ioctl.h>
@@ -4199,6 +4200,182 @@ static abi_long do_ioctl_ifconf(const IOCTLEntry *ie, uint8_t *buf_temp,
     return ret;
 }
 
+#if defined(CONFIG_USBFS)
+#if HOST_LONG_BITS > 64
+#error USBDEVFS thunks do not support >64 bit hosts yet.
+#endif
+struct live_urb {
+    uint64_t target_urb_adr;
+    uint64_t target_buf_adr;
+    char *target_buf_ptr;
+    struct usbdevfs_urb host_urb;
+};
+
+static GHashTable *usbdevfs_urb_hashtable(void)
+{
+    static GHashTable *urb_hashtable;
+
+    if (!urb_hashtable) {
+        urb_hashtable = g_hash_table_new(g_int64_hash, g_int64_equal);
+    }
+    return urb_hashtable;
+}
+
+static void urb_hashtable_insert(struct live_urb *urb)
+{
+    GHashTable *urb_hashtable = usbdevfs_urb_hashtable();
+    g_hash_table_insert(urb_hashtable, urb, urb);
+}
+
+static struct live_urb *urb_hashtable_lookup(uint64_t target_urb_adr)
+{
+    GHashTable *urb_hashtable = usbdevfs_urb_hashtable();
+    return g_hash_table_lookup(urb_hashtable, &target_urb_adr);
+}
+
+static void urb_hashtable_remove(struct live_urb *urb)
+{
+    GHashTable *urb_hashtable = usbdevfs_urb_hashtable();
+    g_hash_table_remove(urb_hashtable, urb);
+}
+
+static abi_long
+do_ioctl_usbdevfs_reapurb(const IOCTLEntry *ie, uint8_t *buf_temp,
+                          int fd, int cmd, abi_long arg)
+{
+    const argtype usbfsurb_arg_type[] = { MK_STRUCT(STRUCT_usbdevfs_urb) };
+    const argtype ptrvoid_arg_type[] = { TYPE_PTRVOID, 0, 0 };
+    struct live_urb *lurb;
+    void *argptr;
+    uint64_t hurb;
+    int target_size;
+    uintptr_t target_urb_adr;
+    abi_long ret;
+
+    target_size = thunk_type_size(usbfsurb_arg_type, THUNK_TARGET);
+
+    memset(buf_temp, 0, sizeof(uint64_t));
+    ret = get_errno(safe_ioctl(fd, ie->host_cmd, buf_temp));
+    if (is_error(ret)) {
+        return ret;
+    }
+
+    memcpy(&hurb, buf_temp, sizeof(uint64_t));
+    lurb = (void *)((uintptr_t)hurb - offsetof(struct live_urb, host_urb));
+    if (!lurb->target_urb_adr) {
+        return -TARGET_EFAULT;
+    }
+    urb_hashtable_remove(lurb);
+    unlock_user(lurb->target_buf_ptr, lurb->target_buf_adr,
+        lurb->host_urb.buffer_length);
+    lurb->target_buf_ptr = NULL;
+
+    /* restore the guest buffer pointer */
+    lurb->host_urb.buffer = (void *)(uintptr_t)lurb->target_buf_adr;
+
+    /* update the guest urb struct */
+    argptr = lock_user(VERIFY_WRITE, lurb->target_urb_adr, target_size, 0);
+    if (!argptr) {
+        g_free(lurb);
+        return -TARGET_EFAULT;
+    }
+    thunk_convert(argptr, &lurb->host_urb, usbfsurb_arg_type, THUNK_TARGET);
+    unlock_user(argptr, lurb->target_urb_adr, target_size);
+
+    target_size = thunk_type_size(ptrvoid_arg_type, THUNK_TARGET);
+    /* write back the urb handle */
+    argptr = lock_user(VERIFY_WRITE, arg, target_size, 0);
+    if (!argptr) {
+        g_free(lurb);
+        return -TARGET_EFAULT;
+    }
+
+    /* GHashTable uses 64-bit keys but thunk_convert expects uintptr_t */
+    target_urb_adr = lurb->target_urb_adr;
+    thunk_convert(argptr, &target_urb_adr, ptrvoid_arg_type, THUNK_TARGET);
+    unlock_user(argptr, arg, target_size);
+
+    g_free(lurb);
+    return ret;
+}
+
+static abi_long
+do_ioctl_usbdevfs_discardurb(const IOCTLEntry *ie,
+                             uint8_t *buf_temp __attribute__((unused)),
+                             int fd, int cmd, abi_long arg)
+{
+    struct live_urb *lurb;
+
+    /* map target address back to host URB with metadata. */
+    lurb = urb_hashtable_lookup(arg);
+    if (!lurb) {
+        return -TARGET_EFAULT;
+    }
+    return get_errno(safe_ioctl(fd, ie->host_cmd, &lurb->host_urb));
+}
+
+static abi_long
+do_ioctl_usbdevfs_submiturb(const IOCTLEntry *ie, uint8_t *buf_temp,
+                            int fd, int cmd, abi_long arg)
+{
+    const argtype *arg_type = ie->arg_type;
+    int target_size;
+    abi_long ret;
+    void *argptr;
+    int rw_dir;
+    struct live_urb *lurb;
+
+    /*
+     * each submitted URB needs to map to a unique ID for the
+     * kernel, and that unique ID needs to be a pointer to
+     * host memory.  hence, we need to malloc for each URB.
+     * isochronous transfers have a variable length struct.
+     */
+    arg_type++;
+    target_size = thunk_type_size(arg_type, THUNK_TARGET);
+
+    /* construct host copy of urb and metadata */
+    lurb = g_try_malloc0(sizeof(struct live_urb));
+    if (!lurb) {
+        return -TARGET_ENOMEM;
+    }
+
+    argptr = lock_user(VERIFY_READ, arg, target_size, 1);
+    if (!argptr) {
+        g_free(lurb);
+        return -TARGET_EFAULT;
+    }
+    thunk_convert(&lurb->host_urb, argptr, arg_type, THUNK_HOST);
+    unlock_user(argptr, arg, 0);
+
+    lurb->target_urb_adr = arg;
+    lurb->target_buf_adr = (uintptr_t)lurb->host_urb.buffer;
+
+    /* buffer space used depends on endpoint type so lock the entire buffer */
+    /* control type urbs should check the buffer contents for true direction */
+    rw_dir = lurb->host_urb.endpoint & USB_DIR_IN ? VERIFY_WRITE : VERIFY_READ;
+    lurb->target_buf_ptr = lock_user(rw_dir, lurb->target_buf_adr,
+        lurb->host_urb.buffer_length, 1);
+    if (lurb->target_buf_ptr == NULL) {
+        g_free(lurb);
+        return -TARGET_EFAULT;
+    }
+
+    /* update buffer pointer in host copy */
+    lurb->host_urb.buffer = lurb->target_buf_ptr;
+
+    ret = get_errno(safe_ioctl(fd, ie->host_cmd, &lurb->host_urb));
+    if (is_error(ret)) {
+        unlock_user(lurb->target_buf_ptr, lurb->target_buf_adr, 0);
+        g_free(lurb);
+    } else {
+        urb_hashtable_insert(lurb);
+    }
+
+    return ret;
+}
+#endif /* CONFIG_USBFS */
+
 static abi_long do_ioctl_dm(const IOCTLEntry *ie, uint8_t *buf_temp, int fd,
                             int cmd, abi_long arg)
 {

linux-user/syscall_defs.h

@@ -870,6 +870,10 @@ struct target_pollfd {
 #define TARGET_USBDEVFS_SETINTERFACE TARGET_IORU('U', 4)
 #define TARGET_USBDEVFS_SETCONFIGURATION TARGET_IORU('U',  5)
 #define TARGET_USBDEVFS_GETDRIVER TARGET_IOWU('U', 8)
+#define TARGET_USBDEVFS_SUBMITURB TARGET_IORU('U', 10)
+#define TARGET_USBDEVFS_DISCARDURB TARGET_IO('U', 11)
+#define TARGET_USBDEVFS_REAPURB TARGET_IOWU('U', 12)
+#define TARGET_USBDEVFS_REAPURBNDELAY TARGET_IOWU('U', 13)
 #define TARGET_USBDEVFS_DISCSIGNAL TARGET_IORU('U', 14)
 #define TARGET_USBDEVFS_CLAIMINTERFACE TARGET_IORU('U', 15)
 #define TARGET_USBDEVFS_RELEASEINTERFACE TARGET_IORU('U', 16)

linux-user/syscall_types.h

@@ -300,6 +300,26 @@ STRUCT(usbdevfs_connectinfo,
         TYPE_INT, /* devnum */
         TYPE_CHAR) /* slow */
 
+STRUCT(usbdevfs_iso_packet_desc,
+        TYPE_INT, /* length */
+        TYPE_INT, /* actual_length */
+        TYPE_INT) /* status */
+
+STRUCT(usbdevfs_urb,
+        TYPE_CHAR, /* type */
+        TYPE_CHAR, /* endpoint */
+        TYPE_INT, /* status */
+        TYPE_INT, /* flags */
+        TYPE_PTRVOID, /* buffer */
+        TYPE_INT, /* buffer_length */
+        TYPE_INT, /* actual_length */
+        TYPE_INT, /* start_frame */
+        TYPE_INT, /* union number_of_packets stream_id */
+        TYPE_INT, /* error_count */
+        TYPE_INT, /* signr */
+        TYPE_PTRVOID, /* usercontext */
+        MK_ARRAY(MK_STRUCT(STRUCT_usbdevfs_iso_packet_desc), 0)) /* desc */
+
 STRUCT(usbdevfs_ioctl,
         TYPE_INT, /* ifno */
         TYPE_INT, /* ioctl_code */