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Revision 597399d0cb91d049fcb78fb45c7694771b583bb7 authored by Will Deacon on 16 October 2019, 04:04:18 UTC, committed by Will Deacon on 16 October 2019, 17:11:38 UTC 
arm64: tags: Preserve tags for addresses translated via TTBR1
 
Sign-extending TTBR1 addresses when converting to an untagged address
breaks the documented POSIX semantics for mlock() in some obscure error
cases where we end up returning -EINVAL instead of -ENOMEM as a direct
result of rewriting the upper address bits.

Rework the untagged_addr() macro to preserve the upper address bits for
TTBR1 addresses and only clear the tag bits for user addresses. This
matches the behaviour of the 'clear_address_tag' assembly macro, so
rename that and align the implementations at the same time so that they
use the same instruction sequences for the tag manipulation.

Link: https://lore.kernel.org/stable/20191014162651.GF19200@arrakis.emea.arm.com/
Reported-by: Jan Stancek <jstancek@redhat.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
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Raw File
dev.c 
// SPDX-License-Identifier: GPL-2.0
/*
 * Moved here from drivers/net/net_init.c, which is:
 *	Written 1993,1994,1995 by Donald Becker.
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ltalk.h>

static void ltalk_setup(struct net_device *dev)
{
	/* Fill in the fields of the device structure with localtalk-generic values. */

	dev->type		= ARPHRD_LOCALTLK;
	dev->hard_header_len 	= LTALK_HLEN;
	dev->mtu		= LTALK_MTU;
	dev->addr_len		= LTALK_ALEN;
	dev->tx_queue_len	= 10;

	dev->broadcast[0]	= 0xFF;

	dev->flags		= IFF_BROADCAST|IFF_MULTICAST|IFF_NOARP;
}

/**
 * alloc_ltalkdev - Allocates and sets up an localtalk device
 * @sizeof_priv: Size of additional driver-private structure to be allocated
 *	for this localtalk device
 *
 * Fill in the fields of the device structure with localtalk-generic
 * values. Basically does everything except registering the device.
 *
 * Constructs a new net device, complete with a private data area of
 * size @sizeof_priv.  A 32-byte (not bit) alignment is enforced for
 * this private data area.
 */

struct net_device *alloc_ltalkdev(int sizeof_priv)
{
	return alloc_netdev(sizeof_priv, "lt%d", NET_NAME_UNKNOWN,
			    ltalk_setup);
}
EXPORT_SYMBOL(alloc_ltalkdev);
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