[PATCH] kexec: x86_64 kexec implementation

This is the x86_64 implementation of machine kexec.  32bit compatibility
support has been implemented, and machine_kexec has been enhanced to not care
about the changing internal kernel paget table structures.

From: Alexander Nyberg <alexn@dsv.su.se>

      build fix

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, 143 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/relocate_kernel.S b/arch/x86_64/kernel/relocate_kernel.S
new file mode 100644
index 00000000000..d24fa9b72a2
--- /dev/null
+++ b/arch/x86_64/kernel/relocate_kernel.S
@@ -0,0 +1,143 @@
+/*
+ * relocate_kernel.S - put the kernel image in place to boot
+ * Copyright (C) 2002-2005 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
+	.code64
+relocate_new_kernel:
+	/* %rdi page_list
+	 * %rsi reboot_code_buffer
+	 * %rdx start address
+	 * %rcx page_table
+	 * %r8  arg5
+	 * %r9  arg6
+	 */
+
+	/* zero out flags, and disable interrupts */
+	pushq $0
+	popfq
+
+	/* set a new stack at the bottom of our page... */
+	lea   4096(%rsi), %rsp
+
+	/* store the parameters back on the stack */
+	pushq	%rdx /* store the start address */
+
+	/* Set cr0 to a known state:
+	 * 31 1 == Paging enabled
+	 * 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
+	 */
+	movq	%cr0, %rax
+	andq	$~((1<<18)|(1<<16)|(1<<3)|(1<<2)), %rax
+	orl	$((1<<31)|(1<<0)), %eax
+	movq	%rax, %cr0
+
+	/* Set cr4 to a known state:
+	 * 10 0 == xmm exceptions disabled
+	 * 9  0 == xmm registers instructions disabled
+	 * 8  0 == performance monitoring counter disabled
+	 * 7  0 == page global disabled
+	 * 6  0 == machine check exceptions disabled
+	 * 5  1 == physical address extension enabled
+	 * 4  0 == page size extensions	disabled
+	 * 3  0 == Debug extensions disabled
+	 * 2  0 == Time stamp disable (disabled)
+	 * 1  0 == Protected mode virtual interrupts disabled
+	 * 0  0 == VME disabled
+	 */
+
+	movq	$((1<<5)), %rax
+	movq	%rax, %cr4
+
+	jmp 1f
+1:
+
+	/* Switch to the identity mapped page tables,
+	 * and flush the TLB.
+	*/
+	movq	%rcx, %cr3
+
+	/* Do the copies */
+	movq	%rdi, %rcx 	/* Put the page_list in %rcx */
+	xorq	%rdi, %rdi
+	xorq	%rsi, %rsi
+	jmp	1f
+
+0:	/* top, read another word for the indirection page */
+
+	movq	(%rbx), %rcx
+	addq	$8,	%rbx
+1:
+	testq	$0x1,	%rcx  /* is it a destination page? */
+	jz	2f
+	movq	%rcx,	%rdi
+	andq	$0xfffffffffffff000, %rdi
+	jmp	0b
+2:
+	testq	$0x2,	%rcx  /* is it an indirection page? */
+	jz	2f
+	movq	%rcx,   %rbx
+	andq	$0xfffffffffffff000, %rbx
+	jmp	0b
+2:
+	testq	$0x4,	%rcx  /* is it the done indicator? */
+	jz	2f
+	jmp	3f
+2:
+	testq	$0x8,	%rcx  /* is it the source indicator? */
+	jz	0b	      /* Ignore it otherwise */
+	movq	%rcx,   %rsi  /* For ever source page do a copy */
+	andq	$0xfffffffffffff000, %rsi
+
+	movq	$512,   %rcx
+	rep ; movsq
+	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 by reloading %cr3 here, it's handy,
+	 * and not processor dependent.
+	 */
+	movq	%cr3, %rax
+	movq	%rax, %cr3
+
+	/* set all of the registers to known values */
+	/* leave %rsp alone */
+
+	xorq	%rax, %rax
+	xorq	%rbx, %rbx
+	xorq    %rcx, %rcx
+	xorq    %rdx, %rdx
+	xorq    %rsi, %rsi
+	xorq    %rdi, %rdi
+	xorq    %rbp, %rbp
+	xorq	%r8,  %r8
+	xorq	%r9,  %r9
+	xorq	%r10, %r9
+	xorq	%r11, %r11
+	xorq	%r12, %r12
+	xorq	%r13, %r13
+	xorq	%r14, %r14
+	xorq	%r15, %r15
+
+	ret
+relocate_new_kernel_end:
+
+	.globl relocate_new_kernel_size
+relocate_new_kernel_size:
+	.quad relocate_new_kernel_end - relocate_new_kernel