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authorH. Peter Anvin <hpa@linux.intel.com>2012-05-08 21:22:37 +0300
committerH. Peter Anvin <hpa@linux.intel.com>2012-05-08 11:48:03 -0700
commite5684ec438a094bec0f7d5c52652c0901b48b613 (patch)
tree8cc3cf787a582977ff08ed578907d6df7dbc7e6e /arch/x86/realmode/rm/trampoline_64.S
parent968ff9ee56f1e3ed4ff4a6d10185865dc77d8f7e (diff)
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/rm/trampoline_64.S')
-rw-r--r--arch/x86/realmode/rm/trampoline_64.S5
1 files changed, 2 insertions, 3 deletions
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