[deliverable/linux.git] / arch / x86 / kernel / ldt_32.c

/*
 * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
 */

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/ldt.h>
#include <asm/desc.h>
#include <asm/mmu_context.h>

#ifdef CONFIG_SMP /* avoids "defined but not used" warnig */
static void flush_ldt(void *null)
{
	if (current->active_mm)
		load_LDT(&current->active_mm->context);
}
#endif

static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
{
	void *oldldt;
	void *newldt;
	int oldsize;

	if (mincount <= pc->size)
		return 0;
	oldsize = pc->size;
	mincount = (mincount+511)&(~511);
	if (mincount*LDT_ENTRY_SIZE > PAGE_SIZE)
		newldt = vmalloc(mincount*LDT_ENTRY_SIZE);
	else
		newldt = kmalloc(mincount*LDT_ENTRY_SIZE, GFP_KERNEL);

	if (!newldt)
		return -ENOMEM;

	if (oldsize)
		memcpy(newldt, pc->ldt, oldsize*LDT_ENTRY_SIZE);
	oldldt = pc->ldt;
	memset(newldt+oldsize*LDT_ENTRY_SIZE, 0, (mincount-oldsize)*LDT_ENTRY_SIZE);
	pc->ldt = newldt;
	wmb();
	pc->size = mincount;
	wmb();

	if (reload) {
#ifdef CONFIG_SMP
		cpumask_t mask;
		preempt_disable();
		load_LDT(pc);
		mask = cpumask_of_cpu(smp_processor_id());
		if (!cpus_equal(current->mm->cpu_vm_mask, mask))
			smp_call_function(flush_ldt, NULL, 1, 1);
		preempt_enable();
#else
		load_LDT(pc);
#endif
	}
	if (oldsize) {
		if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE)
			vfree(oldldt);
		else
			kfree(oldldt);
	}
	return 0;
}

static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
{
	int err = alloc_ldt(new, old->size, 0);
	if (err < 0)
		return err;
	memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE);
	return 0;
}

/*
 * we do not have to muck with descriptors here, that is
 * done in switch_mm() as needed.
 */
int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
	struct mm_struct * old_mm;
	int retval = 0;

	init_MUTEX(&mm->context.sem);
	mm->context.size = 0;
	old_mm = current->mm;
	if (old_mm && old_mm->context.size > 0) {
		down(&old_mm->context.sem);
		retval = copy_ldt(&mm->context, &old_mm->context);
		up(&old_mm->context.sem);
	}
	return retval;
}

/*
 * No need to lock the MM as we are the last user
 */
void destroy_context(struct mm_struct *mm)
{
	if (mm->context.size) {
		if (mm == current->active_mm)
			clear_LDT();
		if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
			vfree(mm->context.ldt);
		else
			kfree(mm->context.ldt);
		mm->context.size = 0;
	}
}

static int read_ldt(void __user * ptr, unsigned long bytecount)
{
	int err;
	unsigned long size;
	struct mm_struct * mm = current->mm;

	if (!mm->context.size)
		return 0;
	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;

	down(&mm->context.sem);
	size = mm->context.size*LDT_ENTRY_SIZE;
	if (size > bytecount)
		size = bytecount;

	err = 0;
	if (copy_to_user(ptr, mm->context.ldt, size))
		err = -EFAULT;
	up(&mm->context.sem);
	if (err < 0)
		goto error_return;
	if (size != bytecount) {
		/* zero-fill the rest */
		if (clear_user(ptr+size, bytecount-size) != 0) {
			err = -EFAULT;
			goto error_return;
		}
	}
	return bytecount;
error_return:
	return err;
}

static int read_default_ldt(void __user * ptr, unsigned long bytecount)
{
	int err;
	unsigned long size;

	err = 0;
	size = 5*sizeof(struct desc_struct);
	if (size > bytecount)
		size = bytecount;

	err = size;
	if (clear_user(ptr, size))
		err = -EFAULT;

	return err;
}

static int write_ldt(void __user * ptr, unsigned long bytecount, int oldmode)
{
	struct mm_struct * mm = current->mm;
	__u32 entry_1, entry_2;
	int error;
	struct user_desc ldt_info;

	error = -EINVAL;
	if (bytecount != sizeof(ldt_info))
		goto out;
	error = -EFAULT; 	
	if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
		goto out;

	error = -EINVAL;
	if (ldt_info.entry_number >= LDT_ENTRIES)
		goto out;
	if (ldt_info.contents == 3) {
		if (oldmode)
			goto out;
		if (ldt_info.seg_not_present == 0)
			goto out;
	}

	down(&mm->context.sem);
	if (ldt_info.entry_number >= mm->context.size) {
		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
		if (error < 0)
			goto out_unlock;
	}

   	/* Allow LDTs to be cleared by the user. */
   	if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
		if (oldmode || LDT_empty(&ldt_info)) {
			entry_1 = 0;
			entry_2 = 0;
			goto install;
		}
	}

	entry_1 = LDT_entry_a(&ldt_info);
	entry_2 = LDT_entry_b(&ldt_info);
	if (oldmode)
		entry_2 &= ~(1 << 20);

	/* Install the new entry ...  */
install:
	write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1, entry_2);
	error = 0;

out_unlock:
	up(&mm->context.sem);
out:
	return error;
}

asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
{
	int ret = -ENOSYS;

	switch (func) {
	case 0:
		ret = read_ldt(ptr, bytecount);
		break;
	case 1:
		ret = write_ldt(ptr, bytecount, 1);
		break;
	case 2:
		ret = read_default_ldt(ptr, bytecount);
		break;
	case 0x11:
		ret = write_ldt(ptr, bytecount, 0);
		break;
	}
	return ret;
}
Commit	Line	Data
1da177e4	1	/*
1da177e4 LT	2	* Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
	3	* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
	4	*/
	5
	6	#include <linux/errno.h>
	7	#include <linux/sched.h>
	8	#include <linux/string.h>
	9	#include <linux/mm.h>
	10	#include <linux/smp.h>
1da177e4 LT	11	#include <linux/vmalloc.h>
	12	#include <linux/slab.h>
	13
	14	#include <asm/uaccess.h>
	15	#include <asm/system.h>
	16	#include <asm/ldt.h>
	17	#include <asm/desc.h>
8d1ed636	18	#include <asm/mmu_context.h>
1da177e4 LT	19
	20	#ifdef CONFIG_SMP /* avoids "defined but not used" warnig */
	21	static void flush_ldt(void *null)
	22	{
	23	if (current->active_mm)
	24	load_LDT(&current->active_mm->context);
	25	}
	26	#endif
	27
	28	static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
	29	{
	30	void *oldldt;
	31	void *newldt;
	32	int oldsize;
	33
	34	if (mincount <= pc->size)
	35	return 0;
	36	oldsize = pc->size;
	37	mincount = (mincount+511)&(~511);
	38	if (mincount*LDT_ENTRY_SIZE > PAGE_SIZE)
	39	newldt = vmalloc(mincount*LDT_ENTRY_SIZE);
	40	else
	41	newldt = kmalloc(mincount*LDT_ENTRY_SIZE, GFP_KERNEL);
	42
	43	if (!newldt)
	44	return -ENOMEM;
	45
	46	if (oldsize)
	47	memcpy(newldt, pc->ldt, oldsize*LDT_ENTRY_SIZE);
	48	oldldt = pc->ldt;
	49	memset(newldt+oldsizeLDT_ENTRY_SIZE, 0, (mincount-oldsize)LDT_ENTRY_SIZE);
	50	pc->ldt = newldt;
	51	wmb();
	52	pc->size = mincount;
	53	wmb();
	54
	55	if (reload) {
	56	#ifdef CONFIG_SMP
	57	cpumask_t mask;
	58	preempt_disable();
	59	load_LDT(pc);
	60	mask = cpumask_of_cpu(smp_processor_id());
	61	if (!cpus_equal(current->mm->cpu_vm_mask, mask))
	62	smp_call_function(flush_ldt, NULL, 1, 1);
	63	preempt_enable();
	64	#else
	65	load_LDT(pc);
	66	#endif
	67	}
	68	if (oldsize) {
	69	if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE)
	70	vfree(oldldt);
	71	else
	72	kfree(oldldt);
	73	}
	74	return 0;
	75	}
	76
	77	static inline int copy_ldt(mm_context_t new, mm_context_t old)
	78	{
	79	int err = alloc_ldt(new, old->size, 0);
	80	if (err < 0)
	81	return err;
	82	memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE);
83	return 0;
84	}
85
86	/*
87	* we do not have to muck with descriptors here, that is
88	* done in switch_mm() as needed.
89	*/
90	int init_new_context(struct task_struct tsk, struct mm_struct mm)
91	{
92	struct mm_struct * old_mm;
93	int retval = 0;
94
95	init_MUTEX(&mm->context.sem);
96	mm->context.size = 0;
97	old_mm = current->mm;
98	if (old_mm && old_mm->context.size > 0) {
99	down(&old_mm->context.sem);
100	retval = copy_ldt(&mm->context, &old_mm->context);
101	up(&old_mm->context.sem);
102	}
103	return retval;
104	}
105
106	/*
107	* No need to lock the MM as we are the last user
108	*/
109	void destroy_context(struct mm_struct *mm)
110	{
111	if (mm->context.size) {
112	if (mm == current->active_mm)
113	clear_LDT();
114	if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
115	vfree(mm->context.ldt);
116	else
117	kfree(mm->context.ldt);
118	mm->context.size = 0;
119	}
120	}
121
122	static int read_ldt(void __user * ptr, unsigned long bytecount)
123	{
124	int err;
125	unsigned long size;
126	struct mm_struct * mm = current->mm;
127
128	if (!mm->context.size)
129	return 0;
130	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
131	bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
132
133	down(&mm->context.sem);
134	size = mm->context.size*LDT_ENTRY_SIZE;
135	if (size > bytecount)
136	size = bytecount;
137
138	err = 0;
139	if (copy_to_user(ptr, mm->context.ldt, size))
140	err = -EFAULT;
141	up(&mm->context.sem);
142	if (err < 0)
143	goto error_return;
144	if (size != bytecount) {
145	/* zero-fill the rest */
146	if (clear_user(ptr+size, bytecount-size) != 0) {
147	err = -EFAULT;
148	goto error_return;
149	}
150	}
151	return bytecount;
152	error_return:
153	return err;
154	}
155
156	static int read_default_ldt(void __user * ptr, unsigned long bytecount)
157	{
158	int err;
159	unsigned long size;
1da177e4 LT	160
1da177e4 LT	161	err = 0;
1da177e4 LT	162	size = 5*sizeof(struct desc_struct);
	163	if (size > bytecount)
	164	size = bytecount;
	165
	166	err = size;
e5e3a042	167	if (clear_user(ptr, size))
1da177e4 LT	168	err = -EFAULT;
	169
	170	return err;
	171	}
	172
	173	static int write_ldt(void __user * ptr, unsigned long bytecount, int oldmode)
	174	{
	175	struct mm_struct * mm = current->mm;
f2f30ebc	176	__u32 entry_1, entry_2;
1da177e4 LT	177	int error;
	178	struct user_desc ldt_info;
	179
	180	error = -EINVAL;
	181	if (bytecount != sizeof(ldt_info))
	182	goto out;
	183	error = -EFAULT;
	184	if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
	185	goto out;
	186
	187	error = -EINVAL;
	188	if (ldt_info.entry_number >= LDT_ENTRIES)
	189	goto out;
	190	if (ldt_info.contents == 3) {
	191	if (oldmode)
	192	goto out;
	193	if (ldt_info.seg_not_present == 0)
	194	goto out;
	195	}
	196
	197	down(&mm->context.sem);
	198	if (ldt_info.entry_number >= mm->context.size) {
	199	error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
	200	if (error < 0)
	201	goto out_unlock;
	202	}
	203
1da177e4 LT	204	/* Allow LDTs to be cleared by the user. */
	205	if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
	206	if (oldmode \|\| LDT_empty(&ldt_info)) {
	207	entry_1 = 0;
	208	entry_2 = 0;
	209	goto install;
	210	}
	211	}
	212
	213	entry_1 = LDT_entry_a(&ldt_info);
	214	entry_2 = LDT_entry_b(&ldt_info);
	215	if (oldmode)
	216	entry_2 &= ~(1 << 20);
	217
	218	/* Install the new entry ... */
	219	install:
f2f30ebc	220	write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1, entry_2);
1da177e4 LT	221	error = 0;
	222
	223	out_unlock:
	224	up(&mm->context.sem);
	225	out:
	226	return error;
	227	}
	228
	229	asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
	230	{
	231	int ret = -ENOSYS;
	232
	233	switch (func) {
	234	case 0:
	235	ret = read_ldt(ptr, bytecount);
	236	break;
	237	case 1:
	238	ret = write_ldt(ptr, bytecount, 1);
	239	break;
	240	case 2:
	241	ret = read_default_ldt(ptr, bytecount);
	242	break;
	243	case 0x11:
	244	ret = write_ldt(ptr, bytecount, 0);
	245	break;
	246	}
	247	return ret;
	248	}