[PATCH] kexec: x86 kexec core

This is the i386 implementation of kexec.

Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 120 insertions, 0 deletions

diff --git a/arch/i386/kernel/relocate_kernel.S b/arch/i386/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..d312616effa1
--- /dev/null
+++ b/arch/i386/kernel/relocate_kernel.S
@@ -0,0 +1,120 @@
+/*
+ * relocate_kernel.S - put the kernel image in place to boot
+ * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#include <linux/linkage.h>
+
+        /*
+         * Must be relocatable PIC code callable as a C function, that once
+         * it starts can not use the previous processes stack.
+         */
+        .globl relocate_new_kernel
+relocate_new_kernel:
+        /* read the arguments and say goodbye to the stack */
+        movl  4(%esp), %ebx /* page_list */
+        movl  8(%esp), %ebp /* reboot_code_buffer */
+        movl  12(%esp), %edx /* start address */
+        movl  16(%esp), %ecx /* cpu_has_pae */
+
+        /* zero out flags, and disable interrupts */
+        pushl $0
+        popfl
+
+        /* set a new stack at the bottom of our page... */
+        lea   4096(%ebp), %esp
+
+        /* store the parameters back on the stack */
+        pushl   %edx /* store the start address */
+
+        /* Set cr0 to a known state:
+         * 31 0 == Paging disabled
+         * 18 0 == Alignment check disabled
+         * 16 0 == Write protect disabled
+         * 3  0 == No task switch
+         * 2  0 == Don't do FP software emulation.
+         * 0  1 == Proctected mode enabled
+         */
+        movl    %cr0, %eax
+        andl    $~((1<<31)|(1<<18)|(1<<16)|(1<<3)|(1<<2)), %eax
+        orl     $(1<<0), %eax
+        movl    %eax, %cr0
+
+        /* clear cr4 if applicable */
+        testl   %ecx, %ecx
+        jz      1f
+        /* Set cr4 to a known state:
+         * Setting everything to zero seems safe.
+         */
+        movl    %cr4, %eax
+        andl    $0, %eax
+        movl    %eax, %cr4
+
+        jmp 1f
+1:
+
+        /* Flush the TLB (needed?) */
+        xorl    %eax, %eax
+        movl    %eax, %cr3
+
+        /* Do the copies */
+        movl    %ebx, %ecx
+        jmp     1f
+
+0:      /* top, read another word from the indirection page */
+        movl    (%ebx), %ecx
+        addl    $4, %ebx
+1:
+        testl   $0x1,   %ecx  /* is it a destination page */
+        jz      2f
+        movl    %ecx,   %edi
+        andl    $0xfffff000, %edi
+        jmp     0b
+2:
+        testl   $0x2,   %ecx  /* is it an indirection page */
+        jz      2f
+        movl    %ecx,   %ebx
+        andl    $0xfffff000, %ebx
+        jmp     0b
+2:
+        testl   $0x4,   %ecx /* is it the done indicator */
+        jz      2f
+        jmp     3f
+2:
+        testl   $0x8,   %ecx /* is it the source indicator */
+        jz      0b           /* Ignore it otherwise */
+        movl    %ecx,   %esi /* For every source page do a copy */
+        andl    $0xfffff000, %esi
+
+        movl    $1024, %ecx
+        rep ; movsl
+        jmp     0b
+
+3:
+
+        /* To be certain of avoiding problems with self-modifying code
+         * I need to execute a serializing instruction here.
+         * So I flush the TLB, it's handy, and not processor dependent.
+         */
+        xorl    %eax, %eax
+        movl    %eax, %cr3
+
+        /* set all of the registers to known values */
+        /* leave %esp alone */
+
+        xorl    %eax, %eax
+        xorl    %ebx, %ebx
+        xorl    %ecx, %ecx
+        xorl    %edx, %edx
+        xorl    %esi, %esi
+        xorl    %edi, %edi
+        xorl    %ebp, %ebp
+        ret
+relocate_new_kernel_end:
+
+        .globl relocate_new_kernel_size
+relocate_new_kernel_size:
+        .long relocate_new_kernel_end - relocate_new_kernel