[tip:x86/trampoline] x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot

[tip-bot for H. Peter Anvin]

Commit-ID:  ee1b06ea6aed979da3b4e6b6ffea98ad55a3c5c1
Gitweb:     http://git.kernel.org/tip/ee1b06ea6aed979da3b4e6b6ffea98ad55a3c5c1
Author:     H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 18 Feb 2011 15:47:42 -0800
Committer:  H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Fri, 18 Feb 2011 15:47:42 -0800

x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot

The initial version of this patch had %eax being a segment and %ecx
being the mode.  I had changed the interfaces, but not the actual
implementation!

Reported-by: Brian Gerst <brgerst@xxxxxxxxx>
LKML-Reference: <AANLkTikxqk=HEw9R-Du=v-1ti1HDGAY9vaNUep2XARaz@xxxxxxxxxxxxxx>
Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
Cc: Rafael J. Wysocki <rjw@xxxxxxx>
Cc: Matthieu Castet <castet.matthieu@xxxxxxx>
---
 arch/x86/kernel/reboot_32.S |   10 +++++++---
 1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/reboot_32.S b/arch/x86/kernel/reboot_32.S
index f242356..29092b3 100644
--- a/arch/x86/kernel/reboot_32.S
+++ b/arch/x86/kernel/reboot_32.S
@@ -23,10 +23,14 @@ r_base = .
 1:	popl	%ebx
 	subl	$1b, %ebx
 
+	/* Compute the equivalent real-mode segment */
+	movl	%ebx, %ecx
+	shrl	$4, %ecx
+	
 	/* Patch post-real-mode segment jump */
-	movw	dispatch_table(%ebx,%ecx,2),%cx
-	movw	%cx, 101f(%ebx)
-	movw	%ax, 102f(%ebx)
+	movw	dispatch_table(%ebx,%eax,2),%ax
+	movw	%ax, 101f(%ebx)
+	movw	%cx, 102f(%ebx)
 
 	/* Set up the IDT for real mode. */
 	lidtl	machine_real_restart_idt(%ebx)
--
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