/*
 * USB Debug cable driver
 *
 * Copyright (C) 2006 Greg Kroah-Hartman <greg@kroah.com>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License version
 *	2 as published by the Free Software Foundation.
 */

#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>

#define USB_DEBUG_MAX_PACKET_SIZE	8
#define USB_DEBUG_BRK_SIZE		8
static char USB_DEBUG_BRK[USB_DEBUG_BRK_SIZE] = {
	0x00,
	0xff,
	0x01,
	0xfe,
	0x00,
	0xfe,
	0x01,
	0xff,
};

static const struct usb_device_id id_table[] = {
	{ USB_DEVICE(0x0525, 0x127a) },
	{ },
};
MODULE_DEVICE_TABLE(usb, id_table);

/* This HW really does not support a serial break, so one will be
 * emulated when ever the break state is set to true.
 */
static void usb_debug_break_ctl(struct tty_struct *tty, int break_state)
{
	struct usb_serial_port *port = tty->driver_data;
	if (!break_state)
		return;
	usb_serial_generic_write(tty, port, USB_DEBUG_BRK, USB_DEBUG_BRK_SIZE);
}

static void usb_debug_process_read_urb(struct urb *urb)
{
	struct usb_serial_port *port = urb->context;

	if (urb->actual_length == USB_DEBUG_BRK_SIZE &&
		memcmp(urb->transfer_buffer, USB_DEBUG_BRK,
						USB_DEBUG_BRK_SIZE) == 0) {
		usb_serial_handle_break(port);
		return;
	}

	usb_serial_generic_process_read_urb(urb);
}

static struct usb_serial_driver debug_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"debug",
	},
	.id_table =		id_table,
	.num_ports =		1,
	.bulk_out_size =	USB_DEBUG_MAX_PACKET_SIZE,
	.break_ctl =		usb_debug_break_ctl,
	.process_read_urb =	usb_debug_process_read_urb,
};

static struct usb_serial_driver * const serial_drivers[] = {
	&debug_device, NULL
};

module_usb_serial_driver(serial_drivers, id_table);
MODULE_LICENSE("GPL");
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<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/log/?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>root</a>/<a href='/cgit.cgi/linux/net-next.git/log/net?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>net</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/ipv4?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>ipv4</a>/<a href='/cgit.cgi/linux/net-next.git/log/net/ipv4/ipip.c?id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>ipip.c</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/net/ipv4/ipip.c?id=3ad7a4b141ebd6091494913672d7166d5c2764e4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
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<tr><th>author</th><td>Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;</td><td class='right'>2017-02-01 17:45:02 +0000</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-02-01 21:17:49 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/irda?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>c8f325a59cfc718d13a50fbc746ed9b415c25e92</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/irda?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>d53fbdac9d0781e39a13b2ac6b2bd258cf3b4140</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/irda?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>net/irda</a></td></tr>
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<div class='commit-subject'>efi/fdt: Avoid FDT manipulation after ExitBootServices()</div><div class='commit-msg'>Some AArch64 UEFI implementations disable the MMU in ExitBootServices(),
after which unaligned accesses to RAM are no longer supported.

Commit:

  abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")

fixed an issue in the memory map handling of the stub FDT code, but
inadvertently created an issue with such firmware, by moving some
of the FDT manipulation to after the invocation of ExitBootServices().

Given that the stub's libfdt implementation uses the ordinary, accelerated
string functions, which rely on hardware handling of unaligned accesses,
manipulating the FDT with the MMU off may result in alignment faults.

So fix the situation by moving the update_fdt_memmap() call into the
callback function invoked by efi_exit_boot_services() right before it
calls the ExitBootServices() UEFI service (which is arguably a better
place for it anyway)

Note that disabling the MMU in ExitBootServices() is not compliant with
the UEFI spec, and carries great risk due to the fact that switching from
cached to uncached memory accesses halfway through compiler generated code
(i.e., involving a stack) can never be done in a way that is architecturally
safe.

Fixes: abfb7b686a3e ("efi/libstub/arm*: Pass latest memory map to the kernel")
Signed-off-by: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Tested-by: Riku Voipio &lt;riku.voipio@linaro.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Cc: mark.rutland@arm.com
Cc: linux-efi@vger.kernel.org
Cc: matt@codeblueprint.co.uk
Cc: leif.lindholm@linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1485971102-23330-2-git-send-email-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=c8f325a59cfc718d13a50fbc746ed9b415c25e92'>Diffstat</a> (limited to 'net/irda')</div><table summary='diffstat' class='diffstat'>