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/******************************************************************************
* fixup.c
*
* Binary-rewriting of certain IA32 instructions, on notification by Xen.
* Used to avoid repeated slow emulation of common instructions used by the
* user-space TLS (Thread-Local Storage) libraries.
*
* **** NOTE ****
* Issues with the binary rewriting have caused it to be removed. Instead
* we rely on Xen's emulator to boot the kernel, and then print a banner
* message recommending that the user disables /lib/tls.
*
* Copyright (c) 2004, K A Fraser
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#define DP(_f) printk(KERN_ALERT " " _f "\n")
fastcall void do_fixup_4gb_segment(struct pt_regs *regs, long error_code)
{
static unsigned long printed = 0;
int i;
if ( !test_and_set_bit(0, &printed) )
{
HYPERVISOR_vm_assist(VMASST_CMD_disable,
VMASST_TYPE_4gb_segments_notify);
DP("");
DP("***************************************************************");
DP("***************************************************************");
DP("** WARNING: Currently emulating unsupported memory accesses **");
DP("** in /lib/tls libraries. The emulation is very **");
DP("** slow, and may not work correctly with all **");
DP("** programs (e.g., some may 'Segmentation fault'). **");
DP("** TO ENSURE FULL PERFORMANCE AND CORRECT FUNCTION, **");
DP("** YOU MUST EXECUTE THE FOLLOWING AS ROOT: **");
DP("** mv /lib/tls /lib/tls.disabled **");
DP("***************************************************************");
DP("***************************************************************");
DP("");
for ( i = 5; i > 0; i-- )
{
printk("Pausing... %d", i);
mdelay(1000);
printk("\b\b\b\b\b\b\b\b\b\b\b\b");
}
printk("Continuing...\n\n");
}
}
static int __init fixup_init(void)
{
HYPERVISOR_vm_assist(VMASST_CMD_enable,
VMASST_TYPE_4gb_segments_notify);
return 0;
}
__initcall(fixup_init);
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