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authorH. Peter Anvin <hpa@zytor.com>2012-06-17 08:47:37 +0400
committerH. Peter Anvin <hpa@zytor.com>2012-06-17 21:51:01 +0400
commit650513979a437c32d7a0a84f0ed952a55bbb5583 (patch)
treeb831bcbfdfce6abb31573e67669272f368626b5b /arch/x86/realmode/rm
parentcfaf025112d3856637ff34a767ef785ef5cf2ca9 (diff)
downloadlinux-650513979a437c32d7a0a84f0ed952a55bbb5583.tar.xz
x86-64, reboot: Allow reboot=bios and reboot-cpu override on x86-64
With the revamped realmode trampoline code, it is trivial to extend support for reboot=bios to x86-64. Furthermore, while we are at it, remove the restriction that only we can only override the reboot CPU on 32 bits. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Link: http://lkml.kernel.org/n/tip-jopx7y6g6dbcx4tpal8q0jlr@git.kernel.org
Diffstat (limited to 'arch/x86/realmode/rm')
-rw-r--r--arch/x86/realmode/rm/Makefile2
-rw-r--r--arch/x86/realmode/rm/header.S4
-rw-r--r--arch/x86/realmode/rm/reboot.S (renamed from arch/x86/realmode/rm/reboot_32.S)26
3 files changed, 27 insertions, 5 deletions
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 5b84a2d30888..b2d534cab25f 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -22,7 +22,7 @@ wakeup-objs += video-bios.o
realmode-y += header.o
realmode-y += trampoline_$(BITS).o
realmode-y += stack.o
-realmode-$(CONFIG_X86_32) += reboot_32.o
+realmode-y += reboot.o
realmode-$(CONFIG_ACPI_SLEEP) += $(wakeup-objs)
targets += $(realmode-y)
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index fadf48378ada..a28221d94e69 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -6,6 +6,7 @@
#include <linux/linkage.h>
#include <asm/page_types.h>
+#include <asm/segment.h>
#include "realmode.h"
@@ -28,8 +29,9 @@ GLOBAL(real_mode_header)
.long pa_wakeup_header
#endif
/* APM/BIOS reboot */
-#ifdef CONFIG_X86_32
.long pa_machine_real_restart_asm
+#ifdef CONFIG_X86_64
+ .long __KERNEL32_CS
#endif
END(real_mode_header)
diff --git a/arch/x86/realmode/rm/reboot_32.S b/arch/x86/realmode/rm/reboot.S
index 114044876b3d..6bf8feac5557 100644
--- a/arch/x86/realmode/rm/reboot_32.S
+++ b/arch/x86/realmode/rm/reboot.S
@@ -2,6 +2,8 @@
#include <linux/init.h>
#include <asm/segment.h>
#include <asm/page_types.h>
+#include <asm/processor-flags.h>
+#include <asm/msr-index.h>
#include "realmode.h"
/*
@@ -12,13 +14,31 @@
* doesn't work with at least one type of 486 motherboard. It is easy
* to stop this code working; hence the copious comments.
*
- * This code is called with the restart type (0 = BIOS, 1 = APM) in %eax.
+ * This code is called with the restart type (0 = BIOS, 1 = APM) in
+ * the primary argument register (%eax for 32 bit, %edi for 64 bit).
*/
.section ".text32", "ax"
.code32
-
- .balign 16
ENTRY(machine_real_restart_asm)
+
+#ifdef CONFIG_X86_64
+
+ /* Disable paging to drop us out of long mode */
+ movl %cr0, %eax
+ andl $~X86_CR0_PG, %eax
+ movl %eax, %cr0
+ jmp 1f /* "A branch" may be needed here, assume near is OK */
+
+1:
+ xorl %eax, %eax
+ xorl %edx, %edx
+ movl $MSR_EFER, %ecx
+ wrmsr
+
+ movl %edi, %eax
+
+#endif /* CONFIG_X86_64 */
+
/* Set up the IDT for real mode. */
lidtl pa_machine_real_restart_idt