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x86: introduce ldt_write accessor 

Create a ldt write accessor like the 32 bit one.

Preparatory patch for merging ldt.c and anyway necessary for
64bit paravirt ops.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Thomas Gleixner 2008-01-30 13:30:13 +01:00 committed by Ingo Molnar
parent 4edc8f5454
commit fc2d625c4f
2 changed files with 12 additions and 5 deletions
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8
arch/x86/kernel/ldt_64.c
View File

@ -172,7 +172,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
{
struct task_struct *me = current;
struct mm_struct *mm = me->mm;
__u32 entry_1, entry_2, *lp;
__u32 entry_1, entry_2;
int error;
struct user_desc ldt_info;
@ -202,8 +202,6 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
goto out_unlock;
}
lp = (__u32 *)((ldt_info.entry_number << 3) + (char *)mm->context.ldt);
/* Allow LDTs to be cleared by the user. */
if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
if (oldmode || LDT_empty(&ldt_info)) {
@ -220,8 +218,8 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
/* Install the new entry ... */
install:
*lp = entry_1;
*(lp+1) = entry_2;
write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1,
entry_2);
error = 0;
out_unlock:

9
include/asm-x86/desc_64.h
View File

@ -38,6 +38,15 @@ extern struct desc_struct default_ldt[];
extern struct gate_struct idt_table[];
extern struct desc_ptr cpu_gdt_descr[];
static inline void write_ldt_entry(struct desc_struct *ldt,
int entry, u32 entry_low, u32 entry_high)
{
__u32 *lp = (__u32 *)((entry << 3) + (char *)ldt);
lp[0] = entry_low;
lp[1] = entry_high;
}
/* the cpu gdt accessor */
#define cpu_gdt(_cpu) ((struct desc_struct *)cpu_gdt_descr[_cpu].address)