USB: Use (get|put)_unaligned for accessing wMaxPacketSize

In 9792987721c7980453fe6447c3fa6593b44f8458 Stefan describes a usecase
where the previous behavior of leaving wMaxPacketSize be unaligned
caused fatal problems.  The initial fix for this problem was incomplete
however as it showed another cases of non-aligned access that previously
worked implicitly.  This switches to making sure that all access of
wMaxPacketSize are done via (get|put)_unaligned.

In order to maintain a level of readability to the code in some cases
we now use a variable for the value of wMaxPacketSize and in others, a
macro.

Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Remy Bohmer <linux@bohmer.net>

OpenRISC:
Tested-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>

Beagleboard xM, Pandaboard run-tested, s5p_goni build-tested.
Signed-off-by: Tom Rini <trini@ti.com>

common/cmd_usb.c

@@ -28,6 +28,7 @@
 #include <common.h>
 #include <command.h>
 #include <asm/byteorder.h>
+#include <asm/unaligned.h>
 #include <part.h>
 #include <usb.h>
 
@@ -240,7 +241,7 @@ void usb_display_ep_desc(struct usb_endpoint_descriptor *epdesc)
 		printf("Interrupt");
 		break;
 	}
-	printf(" MaxPacket %d", epdesc->wMaxPacketSize);
+	printf(" MaxPacket %d", get_unaligned(&epdesc->wMaxPacketSize));
 	if ((epdesc->bmAttributes & 0x03) == 0x3)
 		printf(" Interval %dms", epdesc->bInterval);
 	printf("\n");

common/usb.c

@@ -49,6 +49,7 @@
 #include <asm/processor.h>
 #include <linux/ctype.h>
 #include <asm/byteorder.h>
+#include <asm/unaligned.h>
 
 #include <usb.h>
 #ifdef CONFIG_4xx
@@ -279,30 +280,32 @@ usb_set_maxpacket_ep(struct usb_device *dev, int if_idx, int ep_idx)
 {
 	int b;
 	struct usb_endpoint_descriptor *ep;
+	u16 ep_wMaxPacketSize;
 
 	ep = &dev->config.if_desc[if_idx].ep_desc[ep_idx];
 
 	b = ep->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
+	ep_wMaxPacketSize = get_unaligned(&ep->wMaxPacketSize);
 
 	if ((ep->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) ==
 						USB_ENDPOINT_XFER_CONTROL) {
 		/* Control => bidirectional */
-		dev->epmaxpacketout[b] = ep->wMaxPacketSize;
-		dev->epmaxpacketin[b] = ep->wMaxPacketSize;
+		dev->epmaxpacketout[b] = ep_wMaxPacketSize;
+		dev->epmaxpacketin[b] = ep_wMaxPacketSize;
 		USB_PRINTF("##Control EP epmaxpacketout/in[%d] = %d\n",
 			   b, dev->epmaxpacketin[b]);
 	} else {
 		if ((ep->bEndpointAddress & 0x80) == 0) {
 			/* OUT Endpoint */
-			if (ep->wMaxPacketSize > dev->epmaxpacketout[b]) {
-				dev->epmaxpacketout[b] = ep->wMaxPacketSize;
+			if (ep_wMaxPacketSize > dev->epmaxpacketout[b]) {
+				dev->epmaxpacketout[b] = ep_wMaxPacketSize;
 				USB_PRINTF("##EP epmaxpacketout[%d] = %d\n",
 					   b, dev->epmaxpacketout[b]);
 			}
 		} else {
 			/* IN Endpoint */
-			if (ep->wMaxPacketSize > dev->epmaxpacketin[b]) {
-				dev->epmaxpacketin[b] = ep->wMaxPacketSize;
+			if (ep_wMaxPacketSize > dev->epmaxpacketin[b]) {
+				dev->epmaxpacketin[b] = ep_wMaxPacketSize;
 				USB_PRINTF("##EP epmaxpacketin[%d] = %d\n",
 					   b, dev->epmaxpacketin[b]);
 			}
@@ -333,6 +336,7 @@ int usb_parse_config(struct usb_device *dev, unsigned char *buffer, int cfgno)
 	struct usb_descriptor_header *head;
 	int index, ifno, epno, curr_if_num;
 	int i;
+	u16 ep_wMaxPacketSize;
 
 	ifno = -1;
 	epno = -1;
@@ -378,8 +382,15 @@ int usb_parse_config(struct usb_device *dev, unsigned char *buffer, int cfgno)
 			dev->config.if_desc[ifno].no_of_ep++;
 			memcpy(&dev->config.if_desc[ifno].ep_desc[epno],
 				&buffer[index], buffer[index]);
-			le16_to_cpus(&(dev->config.if_desc[ifno].ep_desc[epno].\
-							       wMaxPacketSize));
+			ep_wMaxPacketSize = get_unaligned(&dev->config.\
+							if_desc[ifno].\
+							ep_desc[epno].\
+							wMaxPacketSize);
+			put_unaligned(le16_to_cpu(ep_wMaxPacketSize),
+					&dev->config.\
+					if_desc[ifno].\
+					ep_desc[epno].\
+					wMaxPacketSize);
 			USB_PRINTF("if %d, ep %d\n", ifno, epno);
 			break;
 		default:

drivers/serial/usbtty.c

@@ -25,6 +25,7 @@
 #include <config.h>
 #include <circbuf.h>
 #include <stdio_dev.h>
+#include <asm/unaligned.h>
 #include "usbtty.h"
 #include "usb_cdc_acm.h"
 #include "usbdescriptors.h"
@@ -626,6 +627,9 @@ static void usbtty_init_strings (void)
 	usb_strings = usbtty_string_table;
 }
 
+#define init_wMaxPacketSize(x)	le16_to_cpu(get_unaligned(\
+			&ep_descriptor_ptrs[(x) - 1]->wMaxPacketSize));
+
 static void usbtty_init_instances (void)
 {
 	int i;
@@ -688,14 +692,12 @@ static void usbtty_init_instances (void)
 		endpoint_instance[i].rcv_attributes =
 			ep_descriptor_ptrs[i - 1]->bmAttributes;
 
-		endpoint_instance[i].rcv_packetSize =
-			le16_to_cpu(ep_descriptor_ptrs[i - 1]->wMaxPacketSize);
+		endpoint_instance[i].rcv_packetSize = init_wMaxPacketSize(i);
 
 		endpoint_instance[i].tx_attributes =
 			ep_descriptor_ptrs[i - 1]->bmAttributes;
 
-		endpoint_instance[i].tx_packetSize =
-			le16_to_cpu(ep_descriptor_ptrs[i - 1]->wMaxPacketSize);
+		endpoint_instance[i].tx_packetSize = init_wMaxPacketSize(i);
 
 		endpoint_instance[i].tx_attributes =
 			ep_descriptor_ptrs[i - 1]->bmAttributes;

drivers/usb/gadget/epautoconf.c

@@ -25,6 +25,7 @@
 #include <linux/usb/ch9.h>
 #include <asm/errno.h>
 #include <linux/usb/gadget.h>
+#include <asm/unaligned.h>
 #include "gadget_chips.h"
 
 #define isdigit(c)      ('0' <= (c) && (c) <= '9')
@@ -127,7 +128,7 @@ static int ep_matches(
 	 * where it's an output parameter representing the full speed limit.
 	 * the usb spec fixes high speed bulk maxpacket at 512 bytes.
 	 */
-	max = 0x7ff & le16_to_cpu(desc->wMaxPacketSize);
+	max = 0x7ff & le16_to_cpu(get_unaligned(&desc->wMaxPacketSize));
 	switch (type) {
 	case USB_ENDPOINT_XFER_INT:
 		/* INT:  limit 64 bytes full speed, 1024 high speed */
@@ -143,7 +144,8 @@ static int ep_matches(
 			return 0;
 
 		/* BOTH:  "high bandwidth" works only at high speed */
-		if ((desc->wMaxPacketSize & __constant_cpu_to_le16(3<<11))) {
+		if ((get_unaligned(&desc->wMaxPacketSize) &
+					__constant_cpu_to_le16(3<<11))) {
 			if (!gadget->is_dualspeed)
 				return 0;
 			/* configure your hardware with enough buffering!! */
@@ -176,7 +178,7 @@ static int ep_matches(
 		/* min() doesn't work on bitfields with gcc-3.5 */
 		if (size > 64)
 			size = 64;
-		desc->wMaxPacketSize = cpu_to_le16(size);
+		put_unaligned(cpu_to_le16(size), &desc->wMaxPacketSize);
 	}
 	return 1;
 }

drivers/usb/gadget/s3c_udc_otg.c

@@ -40,6 +40,7 @@
 #include <linux/usb/gadget.h>
 
 #include <asm/byteorder.h>
+#include <asm/unaligned.h>
 #include <asm/io.h>
 
 #include <asm/mach-types.h>
@@ -586,7 +587,8 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 	if (!_ep || !desc || ep->desc || _ep->name == ep0name
 	    || desc->bDescriptorType != USB_DT_ENDPOINT
 	    || ep->bEndpointAddress != desc->bEndpointAddress
-	    || ep_maxpacket(ep) < le16_to_cpu(desc->wMaxPacketSize)) {
+	    || ep_maxpacket(ep) <
+	    le16_to_cpu(get_unaligned(&desc->wMaxPacketSize))) {
 
 		DEBUG("%s: bad ep or descriptor\n", __func__);
 		return -EINVAL;
@@ -603,8 +605,8 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 
 	/* hardware _could_ do smaller, but driver doesn't */
 	if ((desc->bmAttributes == USB_ENDPOINT_XFER_BULK
-	     && le16_to_cpu(desc->wMaxPacketSize) != ep_maxpacket(ep))
-	    || !desc->wMaxPacketSize) {
+	     && le16_to_cpu(get_unaligned(&desc->wMaxPacketSize)) !=
+	     ep_maxpacket(ep)) || !get_unaligned(&desc->wMaxPacketSize)) {
 
 		DEBUG("%s: bad %s maxpacket\n", __func__, _ep->name);
 		return -ERANGE;
@@ -620,7 +622,7 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 	ep->stopped = 0;
 	ep->desc = desc;
 	ep->pio_irqs = 0;
-	ep->ep.maxpacket = le16_to_cpu(desc->wMaxPacketSize);
+	ep->ep.maxpacket = le16_to_cpu(get_unaligned(&desc->wMaxPacketSize));
 
 	/* Reset halt state */
 	s3c_udc_set_nak(ep);

include/usbdescriptors.h

@@ -199,7 +199,7 @@ struct usb_endpoint_descriptor {
 	u8 bmAttributes;
 	u16 wMaxPacketSize;
 	u8 bInterval;
-} __attribute__ ((packed)) __attribute__ ((aligned(2)));
+} __attribute__ ((packed));
 
 struct usb_interface_descriptor {
 	u8 bLength;