source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/arch/i386/kernel/fixup.c @ 34

Last change on this file since 34 was 34, checked in by hartmans, 18 years ago

Add xen and xen-common

File size: 3.0 KB
Line 
1/******************************************************************************
2 * fixup.c
3 *
4 * Binary-rewriting of certain IA32 instructions, on notification by Xen.
5 * Used to avoid repeated slow emulation of common instructions used by the
6 * user-space TLS (Thread-Local Storage) libraries.
7 *
8 * **** NOTE ****
9 *  Issues with the binary rewriting have caused it to be removed. Instead
10 *  we rely on Xen's emulator to boot the kernel, and then print a banner
11 *  message recommending that the user disables /lib/tls.
12 *
13 * Copyright (c) 2004, K A Fraser
14 *
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2 of the License, or
18 * (at your option) any later version.
19 *
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
23 * GNU General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
28 */
29
30#include <linux/init.h>
31#include <linux/sched.h>
32#include <linux/slab.h>
33#include <linux/kernel.h>
34#include <linux/delay.h>
35#include <linux/version.h>
36
37#define DP(_f, _args...) printk(KERN_ALERT "  " _f "\n" , ## _args )
38
39fastcall void do_fixup_4gb_segment(struct pt_regs *regs, long error_code)
40{
41        static unsigned long printed = 0;
42        char info[100];
43        int i;
44
45        /* Ignore statically-linked init. */
46        if (current->tgid == 1)
47                return;
48           
49        HYPERVISOR_vm_assist(
50                VMASST_CMD_disable, VMASST_TYPE_4gb_segments_notify);
51
52        if (test_and_set_bit(0, &printed))
53                return;
54
55        sprintf(info, "%s (pid=%d)", current->comm, current->tgid);
56
57        DP("");
58        DP("***************************************************************");
59        DP("***************************************************************");
60        DP("** WARNING: Currently emulating unsupported memory accesses  **");
61        DP("**          in /lib/tls glibc libraries. The emulation is    **");
62        DP("**          slow. To ensure full performance you should      **");
63        DP("**          install a 'xen-friendly' (nosegneg) version of   **");
64        DP("**          the library, or disable tls support by executing **");
65        DP("**          the following as root:                           **");
66        DP("**          mv /lib/tls /lib/tls.disabled                    **");
67        DP("** Offending process: %-38.38s **", info);
68        DP("***************************************************************");
69        DP("***************************************************************");
70        DP("");
71
72        for (i = 5; i > 0; i--) {
73                touch_softlockup_watchdog();
74                printk("Pausing... %d", i);
75                mdelay(1000);
76                printk("\b\b\b\b\b\b\b\b\b\b\b\b");
77        }
78
79        printk("Continuing...\n\n");
80}
81
82static int __init fixup_init(void)
83{
84        HYPERVISOR_vm_assist(
85                VMASST_CMD_enable, VMASST_TYPE_4gb_segments_notify);
86        return 0;
87}
88__initcall(fixup_init);
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