release/src-rt-6.x/linux/linux-2.6/arch/x86_64/ia32/tls32.c

   1 #include <linux/kernel.h>
   2 #include <linux/errno.h>
   3 #include <linux/sched.h>
   4 #include <linux/user.h>
   5
   6 #include <asm/uaccess.h>
   7 #include <asm/desc.h>
   8 #include <asm/system.h>
   9 #include <asm/ldt.h>
  10 #include <asm/processor.h>
  11 #include <asm/proto.h>
  12
  13 /*
  14  * sys_alloc_thread_area: get a yet unused TLS descriptor index.
  15  */
  16 static int get_free_idx(void)
  17 {
  18         struct thread_struct *t = &current->thread;
  19         int idx;
  20
  21         for (idx = 0; idx < GDT_ENTRY_TLS_ENTRIES; idx++)
  22                 if (desc_empty((struct n_desc_struct *)(t->tls_array) + idx))
  23                         return idx + GDT_ENTRY_TLS_MIN;
  24         return -ESRCH;
  25 }
  26
  27 /*
  28  * Set a given TLS descriptor:
  29  * When you want addresses > 32bit use arch_prctl()
  30  */
  31 int do_set_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
  32 {
  33         struct user_desc info;
  34         struct n_desc_struct *desc;
  35         int cpu, idx;
  36
  37         if (copy_from_user(&info, u_info, sizeof(info)))
  38                 return -EFAULT;
  39
  40         idx = info.entry_number;
  41
  42         /*
  43          * index -1 means the kernel should try to find and
  44          * allocate an empty descriptor:
  45          */
  46         if (idx == -1) {
  47                 idx = get_free_idx();
  48                 if (idx < 0)
  49                         return idx;
  50                 if (put_user(idx, &u_info->entry_number))
  51                         return -EFAULT;
  52         }
  53
  54         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
  55                 return -EINVAL;
  56
  57         desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
  58
  59         /*
  60          * We must not get preempted while modifying the TLS.
  61          */
  62         cpu = get_cpu();
  63
  64         if (LDT_empty(&info)) {
  65                 desc->a = 0;
  66                 desc->b = 0;
  67         } else {
  68                 desc->a = LDT_entry_a(&info);
  69                 desc->b = LDT_entry_b(&info);
  70         }
  71         if (t == &current->thread)
  72                 load_TLS(t, cpu);
  73
  74         put_cpu();
  75         return 0;
  76 }
  77
  78 asmlinkage long sys32_set_thread_area(struct user_desc __user *u_info)
  79 {
  80         return do_set_thread_area(&current->thread, u_info);
  81 }
  82
  83
  84 /*
  85  * Get the current Thread-Local Storage area:
  86  */
  87
  88 #define GET_BASE(desc) ( \
  89         (((desc)->a >> 16) & 0x0000ffff) | \
  90         (((desc)->b << 16) & 0x00ff0000) | \
  91         ( (desc)->b        & 0xff000000)   )
  92
  93 #define GET_LIMIT(desc) ( \
  94         ((desc)->a & 0x0ffff) | \
  95          ((desc)->b & 0xf0000) )
  96
  97 #define GET_32BIT(desc)         (((desc)->b >> 22) & 1)
  98 #define GET_CONTENTS(desc)      (((desc)->b >> 10) & 3)
  99 #define GET_WRITABLE(desc)      (((desc)->b >>  9) & 1)
 100 #define GET_LIMIT_PAGES(desc)   (((desc)->b >> 23) & 1)
 101 #define GET_PRESENT(desc)       (((desc)->b >> 15) & 1)
 102 #define GET_USEABLE(desc)       (((desc)->b >> 20) & 1)
 103 #define GET_LONGMODE(desc)      (((desc)->b >> 21) & 1)
 104
 105 int do_get_thread_area(struct thread_struct *t, struct user_desc __user *u_info)
 106 {
 107         struct user_desc info;
 108         struct n_desc_struct *desc;
 109         int idx;
 110
 111         if (get_user(idx, &u_info->entry_number))
 112                 return -EFAULT;
 113         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 114                 return -EINVAL;
 115
 116         desc = ((struct n_desc_struct *)t->tls_array) + idx - GDT_ENTRY_TLS_MIN;
 117
 118         memset(&info, 0, sizeof(struct user_desc));
 119         info.entry_number = idx;
 120         info.base_addr = GET_BASE(desc);
 121         info.limit = GET_LIMIT(desc);
 122         info.seg_32bit = GET_32BIT(desc);
 123         info.contents = GET_CONTENTS(desc);
 124         info.read_exec_only = !GET_WRITABLE(desc);
 125         info.limit_in_pages = GET_LIMIT_PAGES(desc);
 126         info.seg_not_present = !GET_PRESENT(desc);
 127         info.useable = GET_USEABLE(desc);
 128         info.lm = GET_LONGMODE(desc);
 129
 130         if (copy_to_user(u_info, &info, sizeof(info)))
 131                 return -EFAULT;
 132         return 0;
 133 }
 134
 135 asmlinkage long sys32_get_thread_area(struct user_desc __user *u_info)
 136 {
 137         return do_get_thread_area(&current->thread, u_info);
 138 }
 139
 140
 141 int ia32_child_tls(struct task_struct *p, struct pt_regs *childregs)
 142 {
 143         struct n_desc_struct *desc;
 144         struct user_desc info;
 145         struct user_desc __user *cp;
 146         int idx;
 147
 148         cp = (void __user *)childregs->rsi;
 149         if (copy_from_user(&info, cp, sizeof(info)))
 150                 return -EFAULT;
 151         if (LDT_empty(&info))
 152                 return -EINVAL;
 153
 154         idx = info.entry_number;
 155         if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX)
 156                 return -EINVAL;
 157
 158         desc = (struct n_desc_struct *)(p->thread.tls_array) + idx - GDT_ENTRY_TLS_MIN;
 159         desc->a = LDT_entry_a(&info);
 160         desc->b = LDT_entry_b(&info);
 161
 162         return 0;
 163 }