This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / i386 / kernel / fixup.c

diff --git a/arch/i386/kernel/fixup.c b/arch/i386/kernel/fixup.c
new file mode 100644 (file)
index 0000000..15a8f20
--- /dev/null
+++ b/arch/i386/kernel/fixup.c
@@ -0,0 +1,86 @@
+/******************************************************************************
+ * 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);