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Subject[PATCH -mm 04/43] user_regset helpers
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This adds some inlines to linux/regset.h intended for arch code to use in
its user_regset get and set functions. These make it pretty easy to deal
with the interface's optional kernel-space or user-space pointers and its
generalized access to a part of the register data at a time.

In simple cases where the internal data structure matches the exported
layout (core dump format), a get function can be nothing but a call to
user_regset_copyout, and a set function a call to user_regset_copyin.

In other cases the exported layout is usually made up of a few pieces each
stored contiguously in a different internal data structure. These helpers
make it straightforward to write a get or set function by processing each
contiguous chunk of the data in order. The start_pos and end_pos arguments
are always constants, so these inlines collapse to a small amount of code.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/regset.h | 116 ++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 116 insertions(+), 0 deletions(-)
diff --git a/include/linux/regset.h b/include/linux/regset.h
index 85d0fb0..761c931 100644
--- a/include/linux/regset.h
+++ b/include/linux/regset.h
@@ -15,6 +15,7 @@

#include <linux/compiler.h>
#include <linux/types.h>
+#include <linux/uaccess.h>
struct task_struct;
struct user_regset;

@@ -203,4 +204,119 @@ struct user_regset_view {
const struct user_regset_view *task_user_regset_view(struct task_struct *tsk);


+/*
+ * These are helpers for writing regset get/set functions in arch code.
+ * Because @start_pos and @end_pos are always compile-time constants,
+ * these are inlined into very little code though they look large.
+ *
+ * Use one or more calls sequentially for each chunk of regset data stored
+ * contiguously in memory. Call with constants for @start_pos and @end_pos,
+ * giving the range of byte positions in the regset that data corresponds
+ * to; @end_pos can be -1 if this chunk is at the end of the regset layout.
+ * Each call updates the arguments to point past its chunk.
+ */
+
+static inline int user_regset_copyout(unsigned int *pos, unsigned int *count,
+ void **kbuf,
+ void __user **ubuf, const void *data,
+ const int start_pos, const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ data += *pos - start_pos;
+ if (*kbuf) {
+ memcpy(*kbuf, data, copy);
+ *kbuf += copy;
+ } else if (__copy_to_user(*ubuf, data, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
+ const void **kbuf,
+ const void __user **ubuf, void *data,
+ const int start_pos, const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ data += *pos - start_pos;
+ if (*kbuf) {
+ memcpy(data, *kbuf, copy);
+ *kbuf += copy;
+ } else if (__copy_from_user(data, *ubuf, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+/*
+ * These two parallel the two above, but for portions of a regset layout
+ * that always read as all-zero or for which writes are ignored.
+ */
+static inline int user_regset_copyout_zero(unsigned int *pos,
+ unsigned int *count,
+ void **kbuf, void __user **ubuf,
+ const int start_pos,
+ const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ if (*kbuf) {
+ memset(*kbuf, 0, copy);
+ *kbuf += copy;
+ } else if (__clear_user(*ubuf, copy))
+ return -EFAULT;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+static inline int user_regset_copyin_ignore(unsigned int *pos,
+ unsigned int *count,
+ const void **kbuf,
+ const void __user **ubuf,
+ const int start_pos,
+ const int end_pos)
+{
+ if (*count == 0)
+ return 0;
+ BUG_ON(*pos < start_pos);
+ if (end_pos < 0 || *pos < end_pos) {
+ unsigned int copy = (end_pos < 0 ? *count
+ : min(*count, end_pos - *pos));
+ if (*kbuf)
+ *kbuf += copy;
+ else
+ *ubuf += copy;
+ *pos += copy;
+ *count -= copy;
+ }
+ return 0;
+}
+
+
#endif /* <linux/regset.h> */
--
1.5.3.6


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