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path: root/net/sched/sch_blackhole.c
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/*
 * net/sched/sch_blackhole.c	Black hole queue
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Authors:	Thomas Graf <tgraf@suug.ch>
 *
 * Note: Quantum tunneling is not supported.
 */

#include <linux/init.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <net/pkt_sched.h>

static int blackhole_enqueue(struct sk_buff *skb, struct Qdisc *sch,
			     struct sk_buff **to_free)
{
	qdisc_drop(skb, sch, to_free);
	return NET_XMIT_SUCCESS;
}

static struct sk_buff *blackhole_dequeue(struct Qdisc *sch)
{
	return NULL;
}

static struct Qdisc_ops blackhole_qdisc_ops __read_mostly = {
	.id		= "blackhole",
	.priv_size	= 0,
	.enqueue	= blackhole_enqueue,
	.dequeue	= blackhole_dequeue,
	.peek		= blackhole_dequeue,
	.owner		= THIS_MODULE,
};

static int __init blackhole_init(void)
{
	return register_qdisc(&blackhole_qdisc_ops);
}
device_initcall(blackhole_init)
n mixed-mode") stopped creating 1:1 mappings for all RAM, when running in native 64-bit mode. It turns out though that there are 64-bit EFI implementations in the wild (this particular problem has been reported on a Lenovo Yoga 710-11IKB), which still make use of the first physical page for their own private use, even though they explicitly mark it EFI_CONVENTIONAL_MEMORY in the memory map. In case there is no mapping for this particular frame in the EFI pagetables, as soon as firmware tries to make use of it, a triple fault occurs and the system reboots (in case of the Yoga 710-11IKB this is very early during bootup). Fix that by always mapping the first page of physical memory into the EFI pagetables. We're free to hand this page to the BIOS, as trim_bios_range() will reserve the first page and isolate it away from memory allocators anyway. Note that just reverting 129766708 alone is not enough on v4.9-rc1+ to fix the regression on affected hardware, as this commit: ab72a27da ("x86/efi: Consolidate region mapping logic") later made the first physical frame not to be mapped anyway. Reported-by: Hanka Pavlikova <hanka@ucw.cz> Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bp@suse.de> Cc: Laura Abbott <labbott@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vojtech Pavlik <vojtech@ucw.cz> Cc: Waiman Long <waiman.long@hpe.com> Cc: linux-efi@vger.kernel.org Cc: stable@kernel.org # v4.8+ Fixes: 129766708 ("x86/efi: Only map RAM into EFI page tables if in mixed-mode") Link: http://lkml.kernel.org/r/20170127222552.22336-1-matt@codeblueprint.co.uk [ Tidied up the changelog and the comment. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/stop_task.c')