/*
 * fs/kernfs/symlink.c - kernfs symlink implementation
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
 *
 * This file is released under the GPLv2.
 */

#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/namei.h>

#include "kernfs-internal.h"

/**
 * kernfs_create_link - create a symlink
 * @parent: directory to create the symlink in
 * @name: name of the symlink
 * @target: target node for the symlink to point to
 *
 * Returns the created node on success, ERR_PTR() value on error.
 */
struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
				       const char *name,
				       struct kernfs_node *target)
{
	struct kernfs_node *kn;
	int error;

	kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK);
	if (!kn)
		return ERR_PTR(-ENOMEM);

	if (kernfs_ns_enabled(parent))
		kn->ns = target->ns;
	kn->symlink.target_kn = target;
	kernfs_get(target);	/* ref owned by symlink */

	error = kernfs_add_one(kn);
	if (!error)
		return kn;

	kernfs_put(kn);
	return ERR_PTR(error);
}

static int kernfs_get_target_path(struct kernfs_node *parent,
				  struct kernfs_node *target, char *path)
{
	struct kernfs_node *base, *kn;
	char *s = path;
	int len = 0;

	/* go up to the root, stop at the base */
	base = parent;
	while (base->parent) {
		kn = target->parent;
		while (kn->parent && base != kn)
			kn = kn->parent;

		if (base == kn)
			break;

		strcpy(s, "../");
		s += 3;
		base = base->parent;
	}

	/* determine end of target string for reverse fillup */
	kn = target;
	while (kn->parent && kn != base) {
		len += strlen(kn->name) + 1;
		kn = kn->parent;
	}

	/* check limits */
	if (len < 2)
		return -EINVAL;
	len--;
	if ((s - path) + len > PATH_MAX)
		return -ENAMETOOLONG;

	/* reverse fillup of target string from target to base */
	kn = target;
	while (kn->parent && kn != base) {
		int slen = strlen(kn->name);

		len -= slen;
		strncpy(s + len, kn->name, slen);
		if (len)
			s[--len] = '/';

		kn = kn->parent;
	}

	return 0;
}

static int kernfs_getlink(struct dentry *dentry, char *path)
{
	struct kernfs_node *kn = dentry->d_fsdata;
	struct kernfs_node *parent = kn->parent;
	struct kernfs_node *target = kn->symlink.target_kn;
	int error;

	mutex_lock(&kernfs_mutex);
	error = kernfs_get_target_path(parent, target, path);
	mutex_unlock(&kernfs_mutex);

	return error;
}

static const char *kernfs_iop_get_link(struct dentry *dentry,
				       struct inode *inode,
				       struct delayed_call *done)
{
	char *body;
	int error;

	if (!dentry)
		return ERR_PTR(-ECHILD);
	body = kzalloc(PAGE_SIZE, GFP_KERNEL);
	if (!body)
		return ERR_PTR(-ENOMEM);
	error = kernfs_getlink(dentry, body);
	if (unlikely(error < 0)) {
		kfree(body);
		return ERR_PTR(error);
	}
	set_delayed_call(done, kfree_link, body);
	return body;
}

const struct inode_operations kernfs_symlink_iops = {
	.listxattr	= kernfs_iop_listxattr,
	.get_link	= kernfs_iop_get_link,
	.setattr	= kernfs_iop_setattr,
	.getattr	= kernfs_iop_getattr,
	.permission	= kernfs_iop_permission,
};
417a4783da3b24e8c9e017ac649326f'>xfrm6_mode_beet.c</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='bf29bddf0417a4783da3b24e8c9e017ac649326f'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Jiri Kosina &lt;jkosina@suse.cz&gt;</td><td class='right'>2017-01-27 22:25:52 +0000</td></tr>
<tr><th>committer</th><td>Ingo Molnar &lt;mingo@kernel.org&gt;</td><td class='right'>2017-01-28 09:18:56 +0100</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/xfrm6_mode_beet.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>bf29bddf0417a4783da3b24e8c9e017ac649326f</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/ipv6/xfrm6_mode_beet.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>54a05a4883b73f80e4e1d8c4b15750aa01c39932</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/ipv6/xfrm6_mode_beet.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>net/ipv6/xfrm6_mode_beet.c</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/ipv6/xfrm6_mode_beet.c?id=883af14e67e8b8702b5560aa64c888c0cd0bd66c'>883af14e67e8b8702b5560aa64c888c0cd0bd66c</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/ipv6/xfrm6_mode_beet.c?id=bf29bddf0417a4783da3b24e8c9e017ac649326f&amp;id2=883af14e67e8b8702b5560aa64c888c0cd0bd66c'>diff</a>)</td></tr></table>
<div class='commit-subject'>x86/efi: Always map the first physical page into the EFI pagetables</div><div class='commit-msg'>Commit:

  129766708 ("x86/efi: Only map RAM into EFI page tables if in 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 &lt;hanka@ucw.cz&gt;
Signed-off-by: Jiri Kosina &lt;jkosina@suse.cz&gt;
Signed-off-by: Matt Fleming &lt;matt@codeblueprint.co.uk&gt;
Cc: Ard Biesheuvel &lt;ard.biesheuvel@linaro.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Borislav Petkov &lt;bp@suse.de&gt;
Cc: Laura Abbott &lt;labbott@redhat.com&gt;
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vojtech Pavlik &lt;vojtech@ucw.cz&gt;
Cc: Waiman Long &lt;waiman.long@hpe.com&gt;
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 &lt;mingo@kernel.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=bf29bddf0417a4783da3b24e8c9e017ac649326f'>Diffstat</a> (limited to 'net/ipv6/xfrm6_mode_beet.c')</div><table summary='diffstat' class='diffstat'>