2 * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
3 * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
4 * Copyright (C) 2002 Andi Kleen
6 * This handles calls from both 32bit and 64bit mode.
9 #include <linux/errno.h>
10 #include <linux/sched.h>
11 #include <linux/string.h>
13 #include <linux/smp.h>
14 #include <linux/vmalloc.h>
15 #include <linux/slab.h>
17 #include <asm/uaccess.h>
18 #include <asm/system.h>
21 #include <asm/proto.h>
24 static void flush_ldt(void *null)
26 if (current->active_mm)
27 load_LDT(¤t->active_mm->context);
31 static int alloc_ldt(mm_context_t *pc, unsigned mincount, int reload)
37 if (mincount <= (unsigned)pc->size)
40 mincount = (mincount + 511) & (~511);
41 if (mincount * LDT_ENTRY_SIZE > PAGE_SIZE)
42 newldt = vmalloc(mincount * LDT_ENTRY_SIZE);
44 newldt = kmalloc(mincount * LDT_ENTRY_SIZE, GFP_KERNEL);
50 memcpy(newldt, pc->ldt, oldsize * LDT_ENTRY_SIZE);
52 memset(newldt + oldsize * LDT_ENTRY_SIZE, 0,
53 (mincount - oldsize) * LDT_ENTRY_SIZE);
64 mask = cpumask_of_cpu(smp_processor_id());
66 if (!cpus_equal(current->mm->cpu_vm_mask, mask))
67 smp_call_function(flush_ldt, NULL, 1, 1);
74 if (oldsize * LDT_ENTRY_SIZE > PAGE_SIZE)
82 static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
84 int err = alloc_ldt(new, old->size, 0);
88 memcpy(new->ldt, old->ldt, old->size * LDT_ENTRY_SIZE);
93 * we do not have to muck with descriptors here, that is
94 * done in switch_mm() as needed.
96 int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
98 struct mm_struct *old_mm;
101 mutex_init(&mm->context.lock);
102 mm->context.size = 0;
103 old_mm = current->mm;
104 if (old_mm && old_mm->context.size > 0) {
105 mutex_lock(&old_mm->context.lock);
106 retval = copy_ldt(&mm->context, &old_mm->context);
107 mutex_unlock(&old_mm->context.lock);
113 * Don't touch the LDT register - we're already in the next thread.
115 void destroy_context(struct mm_struct *mm)
117 if (mm->context.size) {
118 if ((unsigned)mm->context.size * LDT_ENTRY_SIZE > PAGE_SIZE)
119 vfree(mm->context.ldt);
121 kfree(mm->context.ldt);
122 mm->context.size = 0;
126 static int read_ldt(void __user *ptr, unsigned long bytecount)
130 struct mm_struct *mm = current->mm;
132 if (!mm->context.size)
134 if (bytecount > LDT_ENTRY_SIZE * LDT_ENTRIES)
135 bytecount = LDT_ENTRY_SIZE * LDT_ENTRIES;
137 mutex_lock(&mm->context.lock);
138 size = mm->context.size * LDT_ENTRY_SIZE;
139 if (size > bytecount)
143 if (copy_to_user(ptr, mm->context.ldt, size))
145 mutex_unlock(&mm->context.lock);
148 if (size != bytecount) {
149 /* zero-fill the rest */
150 if (clear_user(ptr + size, bytecount - size) != 0) {
160 static int read_default_ldt(void __user *ptr, unsigned long bytecount)
162 /* Arbitrary number */
163 /* x86-64 default LDT is all zeros */
166 if (clear_user(ptr, bytecount))
171 static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
173 struct task_struct *me = current;
174 struct mm_struct *mm = me->mm;
175 __u32 entry_1, entry_2;
177 struct user_desc ldt_info;
181 if (bytecount != sizeof(ldt_info))
184 if (copy_from_user(&ldt_info, ptr, bytecount))
188 if (ldt_info.entry_number >= LDT_ENTRIES)
190 if (ldt_info.contents == 3) {
193 if (ldt_info.seg_not_present == 0)
197 mutex_lock(&mm->context.lock);
198 if (ldt_info.entry_number >= (unsigned)mm->context.size) {
199 error = alloc_ldt(¤t->mm->context,
200 ldt_info.entry_number + 1, 1);
205 /* Allow LDTs to be cleared by the user. */
206 if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
207 if (oldmode || LDT_empty(&ldt_info)) {
214 entry_1 = LDT_entry_a(&ldt_info);
215 entry_2 = LDT_entry_b(&ldt_info);
217 entry_2 &= ~(1 << 20);
219 /* Install the new entry ... */
221 write_ldt_entry(mm->context.ldt, ldt_info.entry_number, entry_1,
226 mutex_unlock(&mm->context.lock);
231 asmlinkage int sys_modify_ldt(int func, void __user *ptr,
232 unsigned long bytecount)
238 ret = read_ldt(ptr, bytecount);
241 ret = write_ldt(ptr, bytecount, 1);
244 ret = read_default_ldt(ptr, bytecount);
247 ret = write_ldt(ptr, bytecount, 0);