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Commit 1bd5718c authored by Roland McGrath's avatar Roland McGrath Committed by Ingo Molnar
Browse files

x86: x86 TLS desc_struct cleanup 



This cleans up the TLS code to use struct desc_struct and to separate the
encoding and installation magic from the interface wrappers.

Signed-off-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 1eeaed76

arch/x86/kernel/tls.c

+45 −44
Original line number Diff line number Diff line
@@ -24,6 +24,29 @@ static int get_free_idx(void) 
	return -ESRCH;

}



static void set_tls_desc(struct task_struct *p, int idx,

			 const struct user_desc *info)

{

	struct thread_struct *t = &p->thread;

	struct desc_struct *desc = &t->tls_array[idx - GDT_ENTRY_TLS_MIN];

	int cpu;



	/*

	 * We must not get preempted while modifying the TLS.

	 */

	cpu = get_cpu();



	if (LDT_empty(info))

		desc->a = desc->b = 0;

	else

		fill_ldt(desc, info);



	if (t == &current->thread)

		load_TLS(t, cpu);



	put_cpu();

}



/*

 * Set a given TLS descriptor:

 */
@@ -31,10 +54,7 @@ int do_set_thread_area(struct task_struct *p, int idx, 
		       struct user_desc __user *u_info,

		       int can_allocate)

{

	struct thread_struct *t = &p->thread;

	struct user_desc info;

	u32 *desc;

	int cpu;



	if (copy_from_user(&info, u_info, sizeof(info)))

		return -EFAULT;
@@ -57,23 +77,8 @@ int do_set_thread_area(struct task_struct *p, int idx, 
	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)

		return -EINVAL;



	desc = (u32 *) &t->tls_array[idx - GDT_ENTRY_TLS_MIN];

	set_tls_desc(p, idx, &info);



	/*

	 * We must not get preempted while modifying the TLS.

	 */

	cpu = get_cpu();



	if (LDT_empty(&info)) {

		desc[0] = 0;

		desc[1] = 0;

	} else

		fill_ldt((struct desc_struct *)desc, &info);



	if (t == &current->thread)

		load_TLS(t, cpu);



	put_cpu();

	return 0;

}
@@ -87,42 +92,38 @@ asmlinkage int sys_set_thread_area(struct user_desc __user *u_info) 
 * Get the current Thread-Local Storage area:

 */



#define GET_LIMIT(desc)		(((desc)[0] & 0x0ffff) | ((desc)[1] & 0xf0000))

#define GET_32BIT(desc)		(((desc)[1] >> 22) & 1)

#define GET_CONTENTS(desc)	(((desc)[1] >> 10) & 3)

#define GET_WRITABLE(desc)	(((desc)[1] >>  9) & 1)

#define GET_LIMIT_PAGES(desc)	(((desc)[1] >> 23) & 1)

#define GET_PRESENT(desc)	(((desc)[1] >> 15) & 1)

#define GET_USEABLE(desc)	(((desc)[1] >> 20) & 1)

#define GET_LONGMODE(desc)	(((desc)[1] >> 21) & 1)

static void fill_user_desc(struct user_desc *info, int idx,

			   const struct desc_struct *desc)



{

	memset(info, 0, sizeof(*info));

	info->entry_number = idx;

	info->base_addr = get_desc_base(desc);

	info->limit = get_desc_limit(desc);

	info->seg_32bit = desc->d;

	info->contents = desc->type >> 2;

	info->read_exec_only = !(desc->type & 2);

	info->limit_in_pages = desc->g;

	info->seg_not_present = !desc->p;

	info->useable = desc->avl;

#ifdef CONFIG_X86_64

	info->lm = desc->l;

#endif

}



int do_get_thread_area(struct task_struct *p, int idx,

		       struct user_desc __user *u_info)

{

	struct thread_struct *t = &p->thread;

	struct user_desc info;

	u32 *desc;



	if (idx == -1 && get_user(idx, &u_info->entry_number))

		return -EFAULT;



	if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)

		return -EINVAL;



	desc = (u32 *) &t->tls_array[idx - GDT_ENTRY_TLS_MIN];



	memset(&info, 0, sizeof(struct user_desc));

	info.entry_number = idx;

	info.base_addr = get_desc_base((struct desc_struct *)desc);

	info.limit = GET_LIMIT(desc);

	info.seg_32bit = GET_32BIT(desc);

	info.contents = GET_CONTENTS(desc);

	info.read_exec_only = !GET_WRITABLE(desc);

	info.limit_in_pages = GET_LIMIT_PAGES(desc);

	info.seg_not_present = !GET_PRESENT(desc);

	info.useable = GET_USEABLE(desc);

#ifdef CONFIG_X86_64

	info.lm = GET_LONGMODE(desc);

#endif

	fill_user_desc(&info, idx,

		       &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]);



	if (copy_to_user(u_info, &info, sizeof(info)))

		return -EFAULT;

include/asm-x86/desc.h

+9 −2
Original line number Diff line number Diff line
@@ -7,7 +7,8 @@ 
#include <asm/mmu.h>

#include <linux/smp.h>



static inline void fill_ldt(struct desc_struct *desc, struct user_desc *info)

static inline void fill_ldt(struct desc_struct *desc,

			    const struct user_desc *info)

{

	desc->limit0 = info->limit & 0x0ffff;

	desc->base0 = info->base_addr & 0x0000ffff;
@@ -275,10 +276,16 @@ static inline void load_LDT(mm_context_t *pc) 
	preempt_enable();

}



static inline unsigned long get_desc_base(struct desc_struct *desc)

static inline unsigned long get_desc_base(const struct desc_struct *desc)

{

	return desc->base0 | ((desc->base1) << 16) | ((desc->base2) << 24);

}



static inline unsigned long get_desc_limit(const struct desc_struct *desc)

{

	return desc->limit0 | (desc->limit << 16);

}



static inline void _set_gate(int gate, unsigned type, void *addr,

			      unsigned dpl, unsigned ist, unsigned seg)

{