+/******************************************************************************
+ * 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>
+#include <linux/version.h>
+
+#define DP(_f, _args...) printk(KERN_ALERT " " _f "\n" , ## _args )
+
+fastcall void do_fixup_4gb_segment(struct pt_regs *regs, long error_code)
+{
+ static unsigned long printed = 1;
+ char info[100];
+ int i;
+
+ if (test_and_set_bit(0, &printed))
+ return;
+
+ HYPERVISOR_vm_assist(
+ VMASST_CMD_disable, VMASST_TYPE_4gb_segments_notify);
+
+ sprintf(info, "%s (pid=%d)", current->comm, current->tgid);
+
+
+ DP("");
+ DP("***************************************************************");
+ DP("***************************************************************");
+ DP("** WARNING: Currently emulating unsupported memory accesses **");
+ DP("** in /lib/tls glibc libraries. The emulation is **");
+ DP("** slow. To ensure full performance you should **");
+ DP("** install a 'xen-friendly' (nosegneg) version of **");
+ DP("** the library, or disable tls support by executing **");
+ DP("** the following as root: **");
+ DP("** mv /lib/tls /lib/tls.disabled **");
+ DP("** Offending process: %-38.38s **", info);
+ DP("***************************************************************");
+ DP("***************************************************************");
+ DP("");
+
+ for (i = 5; i > 0; i--) {
+ touch_softlockup_watchdog();
+ 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);