kernel/regset.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <linux/export.h>
   3 #include <linux/slab.h>
   4 #include <linux/regset.h>
   5
   6 static int __regset_get(struct task_struct *target,
   7                         const struct user_regset *regset,
   8                         unsigned int size,
   9                         void **data)
  10 {
  11         void *p = *data, *to_free = NULL;
  12         int res;
  13
  14         if (!regset->regset_get)
  15                 return -EOPNOTSUPP;
  16         if (size > regset->n * regset->size)
  17                 size = regset->n * regset->size;
  18         if (!p) {
  19                 to_free = p = kzalloc(size, GFP_KERNEL);
  20                 if (!p)
  21                         return -ENOMEM;
  22         }
  23         res = regset->regset_get(target, regset,
  24                            (struct membuf){.p = p, .left = size});
  25         if (res < 0) {
  26                 kfree(to_free);
  27                 return res;
  28         }
  29         *data = p;
  30         return size - res;
  31 }
  32
  33 int regset_get(struct task_struct *target,
  34                const struct user_regset *regset,
  35                unsigned int size,
  36                void *data)
  37 {
  38         return __regset_get(target, regset, size, &data);
  39 }
  40 EXPORT_SYMBOL(regset_get);
  41
  42 int regset_get_alloc(struct task_struct *target,
  43                      const struct user_regset *regset,
  44                      unsigned int size,
  45                      void **data)
  46 {
  47         *data = NULL;
  48         return __regset_get(target, regset, size, data);
  49 }
  50 EXPORT_SYMBOL(regset_get_alloc);
  51
  52 /**
  53  * copy_regset_to_user - fetch a thread's user_regset data into user memory
  54  * @target:     thread to be examined
  55  * @view:       &struct user_regset_view describing user thread machine state
  56  * @setno:      index in @view->regsets
  57  * @offset:     offset into the regset data, in bytes
  58  * @size:       amount of data to copy, in bytes
  59  * @data:       user-mode pointer to copy into
  60  */
  61 int copy_regset_to_user(struct task_struct *target,
  62                         const struct user_regset_view *view,
  63                         unsigned int setno,
  64                         unsigned int offset, unsigned int size,
  65                         void __user *data)
  66 {
  67         const struct user_regset *regset = &view->regsets[setno];
  68         void *buf;
  69         int ret;
  70
  71         ret = regset_get_alloc(target, regset, size, &buf);
  72         if (ret > 0)
  73                 ret = copy_to_user(data, buf, ret) ? -EFAULT : 0;
  74         kfree(buf);
  75         return ret;
  76 }