static void set_tls_desc(struct task_struct *p, int idx,
const struct user_desc *info, int n)
{
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();
while (n-- > 0) {
if (LDT_empty(info))
desc->a = desc->b = 0;
else
fill_ldt(desc, info);
++info;
++desc;
}
if (t == ¤t->thread)
load_TLS(t, cpu);
put_cpu();
}
int set_tls_array(struct thread_struct *t, int idx, unsigned long addr, unsigned int limit)
{
struct user_desc info;
struct desc_struct *desc;
if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
return -EINVAL;
desc = t->tls_array + idx - GDT_ENTRY_TLS_MIN;
info.entry_number = idx;
info.base_addr = addr;
info.limit = limit;
info.contents = 0;
info.read_exec_only = 0;
info.seg_not_present = 0;
info.seg_32bit = 1;
info.limit_in_pages = 1;
info.useable = 0;
/* FIXME */
fill_ldt(desc, &info);
#if 0
desc->a = LDT_entry_a(&info);
desc->b = LDT_entry_b(&info);
#endif
return 0;
}
static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
{
struct mm_struct *mm = current->mm;
struct desc_struct ldt;
int error;
struct user_desc ldt_info;
int oldsize, newsize;
struct ldt_struct *new_ldt, *old_ldt;
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;
}
if ((oldmode && !ldt_info.base_addr && !ldt_info.limit) ||
LDT_empty(&ldt_info)) {
/* The user wants to clear the entry. */
memset(&ldt, 0, sizeof(ldt));
} else {
#ifdef CONFIG_PAX_SEGMEXEC
if ((mm->pax_flags & MF_PAX_SEGMEXEC) && (ldt_info.contents & MODIFY_LDT_CONTENTS_CODE)) {
error = -EINVAL;
goto out;
}
#endif
if (!IS_ENABLED(CONFIG_X86_16BIT) && !ldt_info.seg_32bit) {
error = -EINVAL;
goto out;
}
fill_ldt(&ldt, &ldt_info);
if (oldmode)
ldt.avl = 0;
}
mutex_lock(&mm->context.lock);
old_ldt = mm->context.ldt;
oldsize = old_ldt ? old_ldt->size : 0;
newsize = max((int)(ldt_info.entry_number + 1), oldsize);
error = -ENOMEM;
new_ldt = alloc_ldt_struct(newsize);
if (!new_ldt)
goto out_unlock;
if (old_ldt)
memcpy(new_ldt->entries, old_ldt->entries, oldsize * LDT_ENTRY_SIZE);
new_ldt->entries[ldt_info.entry_number] = ldt;
finalize_ldt_struct(new_ldt);
install_ldt(mm, new_ldt);
free_ldt_struct(old_ldt);
error = 0;
out_unlock:
mutex_unlock(&mm->context.lock);
out:
return error;
}
