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-rw-r--r--kernel/regset.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/kernel/regset.c b/kernel/regset.c
new file mode 100644
index 000000000..586823786
--- /dev/null
+++ b/kernel/regset.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/regset.h>
+
+static int __regset_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int size,
+ void **data)
+{
+ void *p = *data, *to_free = NULL;
+ int res;
+
+ if (!regset->regset_get)
+ return -EOPNOTSUPP;
+ if (size > regset->n * regset->size)
+ size = regset->n * regset->size;
+ if (!p) {
+ to_free = p = kzalloc(size, GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+ }
+ res = regset->regset_get(target, regset,
+ (struct membuf){.p = p, .left = size});
+ if (res < 0) {
+ kfree(to_free);
+ return res;
+ }
+ *data = p;
+ return size - res;
+}
+
+int regset_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int size,
+ void *data)
+{
+ return __regset_get(target, regset, size, &data);
+}
+EXPORT_SYMBOL(regset_get);
+
+int regset_get_alloc(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int size,
+ void **data)
+{
+ *data = NULL;
+ return __regset_get(target, regset, size, data);
+}
+EXPORT_SYMBOL(regset_get_alloc);
+
+/**
+ * copy_regset_to_user - fetch a thread's user_regset data into user memory
+ * @target: thread to be examined
+ * @view: &struct user_regset_view describing user thread machine state
+ * @setno: index in @view->regsets
+ * @offset: offset into the regset data, in bytes
+ * @size: amount of data to copy, in bytes
+ * @data: user-mode pointer to copy into
+ */
+int copy_regset_to_user(struct task_struct *target,
+ const struct user_regset_view *view,
+ unsigned int setno,
+ unsigned int offset, unsigned int size,
+ void __user *data)
+{
+ const struct user_regset *regset = &view->regsets[setno];
+ void *buf;
+ int ret;
+
+ ret = regset_get_alloc(target, regset, size, &buf);
+ if (ret > 0)
+ ret = copy_to_user(data, buf, ret) ? -EFAULT : 0;
+ kfree(buf);
+ return ret;
+}