/*
 * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

/*
 * objtool:
 *
 * The 'check' subcmd analyzes every .o file and ensures the validity of its
 * stack trace metadata.  It enforces a set of rules on asm code and C inline
 * assembly code so that stack traces can be reliable.
 *
 * For more information, see tools/objtool/Documentation/stack-validation.txt.
 */

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <subcmd/exec-cmd.h>
#include <subcmd/pager.h>

#include "builtin.h"

#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))

struct cmd_struct {
	const char *name;
	int (*fn)(int, const char **);
	const char *help;
};

static const char objtool_usage_string[] =
	"objtool [OPTIONS] COMMAND [ARGS]";

static struct cmd_struct objtool_cmds[] = {
	{"check",	cmd_check,	"Perform stack metadata validation on an object file" },
};

bool help;

static void cmd_usage(void)
{
	unsigned int i, longest = 0;

	printf("\n usage: %s\n\n", objtool_usage_string);

	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
		if (longest < strlen(objtool_cmds[i].name))
			longest = strlen(objtool_cmds[i].name);
	}

	puts(" Commands:");
	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
		printf("   %-*s   ", longest, objtool_cmds[i].name);
		puts(objtool_cmds[i].help);
	}

	printf("\n");

	exit(1);
}

static void handle_options(int *argc, const char ***argv)
{
	while (*argc > 0) {
		const char *cmd = (*argv)[0];

		if (cmd[0] != '-')
			break;

		if (!strcmp(cmd, "--help") || !strcmp(cmd, "-h")) {
			help = true;
			break;
		} else {
			fprintf(stderr, "Unknown option: %s\n", cmd);
			fprintf(stderr, "\n Usage: %s\n",
				objtool_usage_string);
			exit(1);
		}

		(*argv)++;
		(*argc)--;
	}
}

static void handle_internal_command(int argc, const char **argv)
{
	const char *cmd = argv[0];
	unsigned int i, ret;

	for (i = 0; i < ARRAY_SIZE(objtool_cmds); i++) {
		struct cmd_struct *p = objtool_cmds+i;

		if (strcmp(p->name, cmd))
			continue;

		ret = p->fn(argc, argv);

		exit(ret);
	}

	cmd_usage();
}

int main(int argc, const char **argv)
{
	static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";

	/* libsubcmd init */
	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
	pager_init(UNUSED);

	argv++;
	argc--;
	handle_options(&argc, &argv);

	if (!argc || help)
		cmd_usage();

	handle_internal_command(argc, argv);

	return 0;
}
t-next.git/log/include/video?id=d7df2443cd5f67fc6ee7c05a88e4996e8177f91b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
v class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='3895dbf8985f656675b5bde610723a29cbce3fa7'/><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>Eric W. Biederman &lt;ebiederm@xmission.com&gt;</td><td class='right'>2017-01-03 14:18:43 +1300</td></tr>
<tr><th>committer</th><td>Eric W. Biederman &lt;ebiederm@xmission.com&gt;</td><td class='right'>2017-01-10 13:34:43 +1300</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/dccp/ccids/lib?id=3895dbf8985f656675b5bde610723a29cbce3fa7'>3895dbf8985f656675b5bde610723a29cbce3fa7</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/dccp/ccids/lib?id=3895dbf8985f656675b5bde610723a29cbce3fa7'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=3895dbf8985f656675b5bde610723a29cbce3fa7'>91d4517f09918fd573998eb40b8f35f08ed1c470</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/dccp/ccids/lib?id=3895dbf8985f656675b5bde610723a29cbce3fa7'>net/dccp/ccids/lib</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/dccp/ccids/lib?id=0c744ea4f77d72b3dcebb7a8f2684633ec79be88'>0c744ea4f77d72b3dcebb7a8f2684633ec79be88</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/dccp/ccids/lib?id=3895dbf8985f656675b5bde610723a29cbce3fa7&amp;id2=0c744ea4f77d72b3dcebb7a8f2684633ec79be88'>diff</a>)</td></tr></table>
<div class='commit-subject'>mnt: Protect the mountpoint hashtable with mount_lock</div><div class='commit-msg'>Protecting the mountpoint hashtable with namespace_sem was sufficient
until a call to umount_mnt was added to mntput_no_expire.  At which
point it became possible for multiple calls of put_mountpoint on
the same hash chain to happen on the same time.

Kristen Johansen &lt;kjlx@templeofstupid.com&gt; reported:
&gt; This can cause a panic when simultaneous callers of put_mountpoint
&gt; attempt to free the same mountpoint.  This occurs because some callers
&gt; hold the mount_hash_lock, while others hold the namespace lock.  Some
&gt; even hold both.
&gt;
&gt; In this submitter's case, the panic manifested itself as a GP fault in
&gt; put_mountpoint() when it called hlist_del() and attempted to dereference
&gt; a m_hash.pprev that had been poisioned by another thread.

Al Viro observed that the simple fix is to switch from using the namespace_sem
to the mount_lock to protect the mountpoint hash table.

I have taken Al's suggested patch moved put_mountpoint in pivot_root
(instead of taking mount_lock an additional time), and have replaced
new_mountpoint with get_mountpoint a function that does the hash table
lookup and addition under the mount_lock.   The introduction of get_mounptoint
ensures that only the mount_lock is needed to manipulate the mountpoint
hashtable.

d_set_mounted is modified to only set DCACHE_MOUNTED if it is not
already set.  This allows get_mountpoint to use the setting of
DCACHE_MOUNTED to ensure adding a struct mountpoint for a dentry
happens exactly once.

Cc: stable@vger.kernel.org
Fixes: ce07d891a089 ("mnt: Honor MNT_LOCKED when detaching mounts")
Reported-by: Krister Johansen &lt;kjlx@templeofstupid.com&gt;
Suggested-by: Al Viro &lt;viro@ZenIV.linux.org.uk&gt;
Acked-by: Al Viro &lt;viro@ZenIV.linux.org.uk&gt;
Signed-off-by: "Eric W. Biederman" &lt;ebiederm@xmission.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=3895dbf8985f656675b5bde610723a29cbce3fa7'>Diffstat</a> (limited to 'net/dccp/ccids/lib')</div><table summary='diffstat' class='diffstat'>