1 files changed, 107 insertions, 132 deletions

diff --git a/include/linux/regset.h b/include/linux/regset.h
index 8e0c9febf495..ad1ca6fe04f4 100644
--- a/include/linux/regset.h
+++ b/include/linux/regset.h
@@ -1,12 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * User-mode machine state access
  *
  * Copyright (C) 2007 Red Hat, Inc.  All rights reserved.
  *
- * This copyrighted material is made available to anyone wishing to use,
- * modify, copy, or redistribute it subject to the terms and conditions
- * of the GNU General Public License v.2.
- *
  * Red Hat Author: Roland McGrath.
  */
 
@@ -20,6 +17,64 @@
 struct task_struct;
 struct user_regset;
 
+struct membuf {
+	void *p;
+	size_t left;
+};
+
+static inline int membuf_zero(struct membuf *s, size_t size)
+{
+	if (s->left) {
+		if (size > s->left)
+			size = s->left;
+		memset(s->p, 0, size);
+		s->p += size;
+		s->left -= size;
+	}
+	return s->left;
+}
+
+static inline int membuf_write(struct membuf *s, const void *v, size_t size)
+{
+	if (s->left) {
+		if (size > s->left)
+			size = s->left;
+		memcpy(s->p, v, size);
+		s->p += size;
+		s->left -= size;
+	}
+	return s->left;
+}
+
+static inline struct membuf membuf_at(const struct membuf *s, size_t offs)
+{
+	struct membuf n = *s;
+
+	if (offs > n.left)
+		offs = n.left;
+	n.p += offs;
+	n.left -= offs;
+
+	return n;
+}
+
+/* current s->p must be aligned for v; v must be a scalar */
+#define membuf_store(s, v)				\
+({							\
+	struct membuf *__s = (s);			\
+        if (__s->left) {				\
+		typeof(v) __v = (v);			\
+		size_t __size = sizeof(__v);		\
+		if (unlikely(__size > __s->left)) {	\
+			__size = __s->left;		\
+			memcpy(__s->p, &__v, __size);	\
+		} else {				\
+			*(typeof(__v + 0) *)__s->p = __v;	\
+		}					\
+		__s->p += __size;			\
+		__s->left -= __size;			\
+	}						\
+	__s->left;})
 
 /**
  * user_regset_active_fn - type of @active function in &struct user_regset
@@ -39,26 +94,9 @@ struct user_regset;
 typedef int user_regset_active_fn(struct task_struct *target,
 				  const struct user_regset *regset);
 
-/**
- * user_regset_get_fn - type of @get function in &struct user_regset
- * @target:	thread being examined
- * @regset:	regset being examined
- * @pos:	offset into the regset data to access, in bytes
- * @count:	amount of data to copy, in bytes
- * @kbuf:	if not %NULL, a kernel-space pointer to copy into
- * @ubuf:	if @kbuf is %NULL, a user-space pointer to copy into
- *
- * Fetch register values.  Return %0 on success; -%EIO or -%ENODEV
- * are usual failure returns.  The @pos and @count values are in
- * bytes, but must be properly aligned.  If @kbuf is non-null, that
- * buffer is used and @ubuf is ignored.  If @kbuf is %NULL, then
- * ubuf gives a userland pointer to access directly, and an -%EFAULT
- * return value is possible.
- */
-typedef int user_regset_get_fn(struct task_struct *target,
+typedef int user_regset_get2_fn(struct task_struct *target,
 			       const struct user_regset *regset,
-			       unsigned int pos, unsigned int count,
-			       void *kbuf, void __user *ubuf);
+			       struct membuf to);
 
 /**
  * user_regset_set_fn - type of @set function in &struct user_regset
@@ -113,7 +151,8 @@ typedef int user_regset_writeback_fn(struct task_struct *target,
  * @align:		Required alignment, in bytes.
  * @bias:		Bias from natural indexing.
  * @core_note_type:	ELF note @n_type value used in core dumps.
- * @get:		Function to fetch values.
+ * @core_note_name:	ELF note name to qualify the note type.
+ * @regset_get:		Function to fetch values.
  * @set:		Function to store values.
  * @active:		Function to report if regset is active, or %NULL.
  * @writeback:		Function to write data back to user memory, or %NULL.
@@ -122,14 +161,22 @@ typedef int user_regset_writeback_fn(struct task_struct *target,
  * This is part of the state of an individual thread, not necessarily
  * actual CPU registers per se.  A register set consists of a number of
  * similar slots, given by @n.  Each slot is @size bytes, and aligned to
- * @align bytes (which is at least @size).
+ * @align bytes (which is at least @size).  For dynamically-sized
+ * regsets, @n must contain the maximum possible number of slots for the
+ * regset.
  *
- * These functions must be called only on the current thread or on a
- * thread that is in %TASK_STOPPED or %TASK_TRACED state, that we are
- * guaranteed will not be woken up and return to user mode, and that we
- * have called wait_task_inactive() on.  (The target thread always might
- * wake up for SIGKILL while these functions are working, in which case
- * that thread's user_regset state might be scrambled.)
+ * For backward compatibility, the @get and @set methods must pad to, or
+ * accept, @n * @size bytes, even if the current regset size is smaller.
+ * The precise semantics of these operations depend on the regset being
+ * accessed.
+ *
+ * The functions to which &struct user_regset members point must be
+ * called only on the current thread or on a thread that is in
+ * %TASK_STOPPED or %TASK_TRACED state, that we are guaranteed will not
+ * be woken up and return to user mode, and that we have called
+ * wait_task_inactive() on.  (The target thread always might wake up for
+ * SIGKILL while these functions are working, in which case that
+ * thread's user_regset state might be scrambled.)
  *
  * The @pos argument must be aligned according to @align; the @count
  * argument must be a multiple of @size.  These functions are not
@@ -144,6 +191,10 @@ typedef int user_regset_writeback_fn(struct task_struct *target,
  *
  * If nonzero, @core_note_type gives the n_type field (NT_* value)
  * of the core file note in which this regset's data appears.
+ * @core_note_name specifies the note name.  The preferred way to
+ * specify these two fields is to use the @USER_REGSET_NOTE_TYPE()
+ * macro.
+ *
  * NT_PRSTATUS is a special case in that the regset data starts at
  * offsetof(struct elf_prstatus, pr_reg) into the note data; that is
  * part of the per-machine ELF formats userland knows about.  In
@@ -152,7 +203,7 @@ typedef int user_regset_writeback_fn(struct task_struct *target,
  * omitted when there is an @active function and it returns zero.
  */
 struct user_regset {
-	user_regset_get_fn		*get;
+	user_regset_get2_fn		*regset_get;
 	user_regset_set_fn		*set;
 	user_regset_active_fn		*active;
 	user_regset_writeback_fn	*writeback;
@@ -161,8 +212,13 @@ struct user_regset {
 	unsigned int 			align;
 	unsigned int 			bias;
 	unsigned int 			core_note_type;
+	const char			*core_note_name;
 };
 
+#define USER_REGSET_NOTE_TYPE(type) \
+	.core_note_type			= (NT_ ## type), \
+	.core_note_name			= (NN_ ## type)
+
 /**
  * struct user_regset_view - available regsets
  * @name:	Identifier, e.g. UTS_MACHINE string.
@@ -204,44 +260,6 @@ 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,
@@ -267,44 +285,15 @@ static inline int user_regset_copyin(unsigned int *pos, unsigned int *count,
 	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)
+static inline void 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;
+		return;
 	BUG_ON(*pos < start_pos);
 	if (end_pos < 0 || *pos < end_pos) {
 		unsigned int copy = (end_pos < 0 ? *count
@@ -316,34 +305,21 @@ static inline int user_regset_copyin_ignore(unsigned int *pos,
 		*pos += copy;
 		*count -= copy;
 	}
-	return 0;
 }
 
-/**
- * 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
- */
-static inline 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];
+extern int regset_get(struct task_struct *target,
+		      const struct user_regset *regset,
+		      unsigned int size, void *data);
 
-	if (!regset->get)
-		return -EOPNOTSUPP;
+extern int regset_get_alloc(struct task_struct *target,
+			    const struct user_regset *regset,
+			    unsigned int size,
+			    void **data);
 
-	if (!access_ok(VERIFY_WRITE, data, size))
-		return -EFAULT;
-
-	return regset->get(target, regset, offset, size, NULL, data);
-}
+extern 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);
 
 /**
  * copy_regset_from_user - store into thread's user_regset data from user memory
@@ -365,11 +341,10 @@ static inline int copy_regset_from_user(struct task_struct *target,
 	if (!regset->set)
 		return -EOPNOTSUPP;
 
-	if (!access_ok(VERIFY_READ, data, size))
+	if (!access_ok(data, size))
 		return -EFAULT;
 
 	return regset->set(target, regset, offset, size, NULL, data);
 }
 
-
 #endif	/* <linux/regset.h> */