lkml.org 
[lkml]   [2016]   [Nov]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:x86/boot] x86/boot: Simplify the GDTR calculation assembly code a bit
Commit-ID:  064025f7ea1ebcd9bbb99cfa9492a803e8b01d36
Gitweb: http://git.kernel.org/tip/064025f7ea1ebcd9bbb99cfa9492a803e8b01d36
Author: Wei Yang <richard.weiyang@gmail.com>
AuthorDate: Tue, 1 Nov 2016 15:49:24 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 7 Nov 2016 08:33:59 +0100

x86/boot: Simplify the GDTR calculation assembly code a bit

This patch calculates the GDTR's base address via a single instruction.

( EBP contains the address where it is loaded and GDTR's base address is
already set to "gdt" in compilation. It is fine to get the correct base
address by adding the delta to GDTR's base address. )

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1478015364-5547-1-git-send-email-richard.weiyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/boot/compressed/head_64.S | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index efdfba2..4d85e60 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -119,8 +119,7 @@ ENTRY(startup_32)
*/

/* Load new GDT with the 64bit segments using 32bit descriptor */
- leal gdt(%ebp), %eax
- movl %eax, gdt+2(%ebp)
+ addl %ebp, gdt+2(%ebp)
lgdt gdt(%ebp)

/* Enable PAE mode */
\
 
 \ /
  Last update: 2016-11-07 09:56    [W:0.034 / U:0.324 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site