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authorBrian Gerst <brgerst@gmail.com>2010-07-31 12:48:23 -0400
committerH. Peter Anvin <hpa@zytor.com>2010-08-01 16:05:23 -0700
commit72c511dd596cff88d6523f231a0fbb8f73006d51 (patch)
tree030e17e0947ec0a3c00d04099568e242abf00ea7 /arch/x86/kernel
parentc15a5958a0b6dbf06b3c05972694f04a0c50a4cf (diff)
downloadop-kernel-dev-72c511dd596cff88d6523f231a0fbb8f73006d51.zip
op-kernel-dev-72c511dd596cff88d6523f231a0fbb8f73006d51.tar.gz
x86-32, asm: Directly access per-cpu GDT
Use a direct per-cpu reference for the GDT instead of using a scratch register. Signed-off-by: Brian Gerst <brgerst@gmail.com> LKML-Reference: <1280594903-6341-2-git-send-email-brgerst@gmail.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/entry_32.S11
1 files changed, 5 insertions, 6 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index cd49141..233c582 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -611,14 +611,14 @@ ldt_ss:
* compensating for the offset by changing to the ESPFIX segment with
* a base address that matches for the difference.
*/
+#define GDT_ESPFIX_SS PER_CPU_VAR(gdt_page) + (GDT_ENTRY_ESPFIX_SS * 8)
mov %esp, %edx /* load kernel esp */
mov PT_OLDESP(%esp), %eax /* load userspace esp */
mov %dx, %ax /* eax: new kernel esp */
sub %eax, %edx /* offset (low word is 0) */
- PER_CPU(gdt_page, %ebx)
shr $16, %edx
- mov %dl, GDT_ENTRY_ESPFIX_SS * 8 + 4(%ebx) /* bits 16..23 */
- mov %dh, GDT_ENTRY_ESPFIX_SS * 8 + 7(%ebx) /* bits 24..31 */
+ mov %dl, GDT_ESPFIX_SS + 4 /* bits 16..23 */
+ mov %dh, GDT_ESPFIX_SS + 7 /* bits 24..31 */
pushl $__ESPFIX_SS
CFI_ADJUST_CFA_OFFSET 4
push %eax /* new kernel esp */
@@ -791,9 +791,8 @@ ptregs_clone:
* normal stack and adjusts ESP with the matching offset.
*/
/* fixup the stack */
- PER_CPU(gdt_page, %ebx)
- mov GDT_ENTRY_ESPFIX_SS * 8 + 4(%ebx), %al /* bits 16..23 */
- mov GDT_ENTRY_ESPFIX_SS * 8 + 7(%ebx), %ah /* bits 24..31 */
+ mov GDT_ESPFIX_SS + 4, %al /* bits 16..23 */
+ mov GDT_ESPFIX_SS + 7, %ah /* bits 24..31 */
shl $16, %eax
addl %esp, %eax /* the adjusted stack pointer */
pushl $__KERNEL_DS
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