x86: switch to ->regset_get()

	All instances of ->get() in arch/x86 switched; that might or might
not be worth splitting up.  Notes:

	* for xstateregs_get() the amount we want to store is determined at
the boot time; see init_xstate_size() and update_regset_xstate_info() for
details.  task->thread.fpu.state.xsave ends with a flexible array member and
the amount of data in it depends upon the FPU features supported/enabled.

	* fpregs_get() writes slightly less than full ->thread.fpu.state.fsave
(the last word is not copied); we pass the full size of state.fsave and let
membuf_write() trim to the amount declared by regset - __regset_get() will
make sure that the space in buffer is no more than that.

	* copy_xstate_to_user() and its helpers are gone now.

	* fpregs_soft_get() was getting user_regset_copyout() arguments
wrong.  Since "x86: x86 user_regset math_emu" back in 2008...  I really
doubt that it's worth splitting out for -stable, though - you need
a 486SX box for that to trigger...

[Kevin's braino fix for copy_xstate_to_kernel() essentially duplicated here]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 26 deletions

diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c
index 71d3fef1edc9..64a496a0687f 100644
--- a/arch/x86/kernel/tls.c
+++ b/arch/x86/kernel/tls.c
@@ -256,36 +256,16 @@ int regset_tls_active(struct task_struct *target,
 }
 
 int regset_tls_get(struct task_struct *target, const struct user_regset *regset,
-		   unsigned int pos, unsigned int count,
-		   void *kbuf, void __user *ubuf)
+		   struct membuf to)
 {
 	const struct desc_struct *tls;
+	struct user_desc v;
+	int pos;
 
-	if (pos >= GDT_ENTRY_TLS_ENTRIES * sizeof(struct user_desc) ||
-	    (pos % sizeof(struct user_desc)) != 0 ||
-	    (count % sizeof(struct user_desc)) != 0)
-		return -EINVAL;
-
-	pos /= sizeof(struct user_desc);
-	count /= sizeof(struct user_desc);
-
-	tls = &target->thread.tls_array[pos];
-
-	if (kbuf) {
-		struct user_desc *info = kbuf;
-		while (count-- > 0)
-			fill_user_desc(info++, GDT_ENTRY_TLS_MIN + pos++,
-				       tls++);
-	} else {
-		struct user_desc __user *u_info = ubuf;
-		while (count-- > 0) {
-			struct user_desc info;
-			fill_user_desc(&info, GDT_ENTRY_TLS_MIN + pos++, tls++);
-			if (__copy_to_user(u_info++, &info, sizeof(info)))
-				return -EFAULT;
-		}
+	for (pos = 0, tls = target->thread.tls_array; to.left; pos++, tls++) {
+		fill_user_desc(&v, GDT_ENTRY_TLS_MIN + pos, tls);
+		membuf_write(&to, &v, sizeof(v));
 	}
-
 	return 0;
 }