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authorH. Peter Anvin <hpa@linux.intel.com>2012-05-08 22:22:37 +0400
committerH. Peter Anvin <hpa@linux.intel.com>2012-05-08 22:48:03 +0400
commite5684ec438a094bec0f7d5c52652c0901b48b613 (patch)
tree8cc3cf787a582977ff08ed578907d6df7dbc7e6e /arch/x86/realmode
parent968ff9ee56f1e3ed4ff4a6d10185865dc77d8f7e (diff)
downloadlinux-e5684ec438a094bec0f7d5c52652c0901b48b613.tar.xz
x86, realmode: Replace open-coded ljmpw with a macro
We cannot code an ljmpw to the real-mode segment directly, because gas refuses to assemble an ljmp with a symbolic segment. Instead of open-coding it everywhere, define a macro and use it for this case. This is specifically an ljmpw from a 16-bit segment. This is okay, as one should never enter real mode from a 32-bit segment: if one do, the CPU ends up in a bizarre (and useless) mode sometimes called "unreal mode" where segments behave like real mode but the default address and operand sizes is 32 bits. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1336501366-28617-15-git-send-email-jarkko.sakkinen@intel.com
Diffstat (limited to 'arch/x86/realmode')
-rw-r--r--arch/x86/realmode/rm/realmode.h16
-rw-r--r--arch/x86/realmode/rm/reboot_32.S6
-rw-r--r--arch/x86/realmode/rm/trampoline_32.S5
-rw-r--r--arch/x86/realmode/rm/trampoline_64.S5
-rw-r--r--arch/x86/realmode/rm/wakeup/wakeup_asm.S9
5 files changed, 25 insertions, 16 deletions
diff --git a/arch/x86/realmode/rm/realmode.h b/arch/x86/realmode/rm/realmode.h
new file mode 100644
index 000000000000..15ab6335f843
--- /dev/null
+++ b/arch/x86/realmode/rm/realmode.h
@@ -0,0 +1,16 @@
+#ifndef ARCH_X86_REALMODE_RM_REALMODE_H
+#define ARCH_X86_REALMODE_RM_REALMODE_H
+
+#ifdef __ASSEMBLY__
+
+/*
+ * 16-bit ljmpw to the real_mode_seg
+ *
+ * This must be open-coded since gas will choke on using a
+ * relocatable symbol for the segment portion.
+ */
+#define LJMPW_RM(to) .byte 0xea ; .word (to), real_mode_seg
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* ARCH_X86_REALMODE_RM_REALMODE_H */
diff --git a/arch/x86/realmode/rm/reboot_32.S b/arch/x86/realmode/rm/reboot_32.S
index 83803c222b4a..e90f8c4bbae2 100644
--- a/arch/x86/realmode/rm/reboot_32.S
+++ b/arch/x86/realmode/rm/reboot_32.S
@@ -2,6 +2,7 @@
#include <linux/init.h>
#include <asm/segment.h>
#include <asm/page_types.h>
+#include "realmode.h"
/*
* The following code and data reboots the machine by switching to real
@@ -82,10 +83,7 @@ machine_real_restart_asm16:
2:
andb $0x10, %dl
movl %edx, %cr0
- .byte 0xea /* ljmpw */
- .word 3f /* Offset */
- .word real_mode_seg /* Segment */
-
+ LJMPW_RM(3f)
3:
testb $0, %al
jz bios
diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
index 1315ef48dbf1..279f82ef7a9e 100644
--- a/arch/x86/realmode/rm/trampoline_32.S
+++ b/arch/x86/realmode/rm/trampoline_32.S
@@ -29,6 +29,7 @@
#include <linux/init.h>
#include <asm/segment.h>
#include <asm/page_types.h>
+#include "realmode.h"
.text
.code16
@@ -38,9 +39,7 @@
trampoline_data:
wbinvd # Needed for NUMA-Q should be harmless for others
- .byte 0xea # ljmpw
- .word 1f # Offset
- .word real_mode_seg # Segment
+ LJMPW_RM(1f)
1:
mov %cs, %ax # Code and data in the same place
mov %ax, %ds
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
index 77b72b45d705..7459c52f0c25 100644
--- a/arch/x86/realmode/rm/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -31,6 +31,7 @@
#include <asm/msr.h>
#include <asm/segment.h>
#include <asm/processor-flags.h>
+#include "realmode.h"
.text
.balign PAGE_SIZE
@@ -40,9 +41,7 @@ ENTRY(trampoline_data)
cli # We should be safe anyway
wbinvd
- .byte 0xea # ljmpw
- .word 1f # Offset
- .word real_mode_seg # Segment
+ LJMPW_RM(1f)
1:
mov %cs, %ax # Code and data in the same place
mov %ax, %ds
diff --git a/arch/x86/realmode/rm/wakeup/wakeup_asm.S b/arch/x86/realmode/rm/wakeup/wakeup_asm.S
index 4c5c5f2bfbec..8064e1c3591b 100644
--- a/arch/x86/realmode/rm/wakeup/wakeup_asm.S
+++ b/arch/x86/realmode/rm/wakeup/wakeup_asm.S
@@ -6,6 +6,7 @@
#include <asm/page_types.h>
#include <asm/pgtable_types.h>
#include <asm/processor-flags.h>
+#include "../realmode.h"
#include "wakeup.h"
.code16
@@ -36,9 +37,7 @@ wakeup_start:
cli
cld
- .byte 0xea /* ljmpw */
- .word 3f
- .word real_mode_seg
+ LJMPW_RM(3f)
3:
/* Apparently some dimwit BIOS programmers don't know how to
program a PM to RM transition, and we might end up here with
@@ -59,9 +58,7 @@ wakeup_start:
andb $~X86_CR0_PE, %al
movl %eax, %cr0
- .byte 0xea /* ljmpw */
- .word 3f
- .word real_mode_seg
+ LJMPW_RM(3f)
3:
/* Set up segments */
movw %cs, %ax