x86/fpu: Add a pkru argument to copy_uabi_to_xstate()

In preparation for moving PKRU handling code out of
fpu_copy_uabi_to_guest_fpstate() and into copy_uabi_to_xstate(), add an
argument that copy_uabi_from_kernel_to_xstate() can use to pass the
canonical location of the PKRU value. For
copy_sigframe_from_user_to_xstate() the kernel will actually restore the
PKRU value from the fpstate, but pass in the thread_struct's pkru location
anyways for consistency.

Signed-off-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/20221115230932.7126-4-khuey%40kylehuey.com

Author: khuey

arch/x86/kernel/fpu/xstate.c

@@ -1200,8 +1200,18 @@ static int copy_from_buffer(void *dst, unsigned int offset, unsigned int size,
 }
 
 
+/**
+ * copy_uabi_to_xstate - Copy a UABI format buffer to the kernel xstate
+ * @fpstate:	The fpstate buffer to copy to
+ * @kbuf:	The UABI format buffer, if it comes from the kernel
+ * @ubuf:	The UABI format buffer, if it comes from userspace
+ * @pkru:	unused
+ *
+ * Converts from the UABI format into the kernel internal hardware
+ * dependent format.
+ */
 static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
-			       const void __user *ubuf)
+			       const void __user *ubuf, u32 *pkru)
 {
 	struct xregs_state *xsave = &fpstate->regs.xsave;
 	unsigned int offset, size;
@@ -1270,7 +1280,7 @@ static int copy_uabi_to_xstate(struct fpstate *fpstate, const void *kbuf,
  */
 int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u32 *pkru)
 {
-	return copy_uabi_to_xstate(fpstate, kbuf, NULL);
+	return copy_uabi_to_xstate(fpstate, kbuf, NULL, pkru);
 }
 
 /*
@@ -1281,7 +1291,7 @@ int copy_uabi_from_kernel_to_xstate(struct fpstate *fpstate, const void *kbuf, u
 int copy_sigframe_from_user_to_xstate(struct task_struct *tsk,
 				      const void __user *ubuf)
 {
-	return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf);
+	return copy_uabi_to_xstate(tsk->thread.fpu.fpstate, NULL, ubuf, &tsk->thread.pkru);
 }
 
 static bool validate_independent_components(u64 mask)