x86/fpu: Flip the parameter order in copy_*_to_xstate()

Make it more consistent with regular memcpy() semantics, where the destination
argument comes first.

No change in functionality.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170923130016.21448-15-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/fpu/xstate.h

@@ -50,6 +50,6 @@ const void *get_xsave_field_ptr(int xstate_field);
 int using_compacted_format(void);
 int copy_xstate_to_kernel(void *kbuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
 int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned int offset, unsigned int size);
-int copy_kernel_to_xstate(const void *kbuf, struct xregs_state *xsave);
-int copy_user_to_xstate(const void __user *ubuf, struct xregs_state *xsave);
+int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf);
+int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf);
 #endif

arch/x86/kernel/fpu/regset.c

@@ -136,9 +136,9 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 
 	if (boot_cpu_has(X86_FEATURE_XSAVES)) {
 		if (kbuf)
-			ret = copy_kernel_to_xstate(kbuf, xsave);
+			ret = copy_kernel_to_xstate(xsave, kbuf);
 		else
-			ret = copy_user_to_xstate(ubuf, xsave);
+			ret = copy_user_to_xstate(xsave, ubuf);
 	} else {
 		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
 	}

arch/x86/kernel/fpu/signal.c

@@ -324,7 +324,7 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
 		fpu__drop(fpu);
 
 		if (using_compacted_format())
-			err = copy_user_to_xstate(buf_fx, &fpu->state.xsave);
+			err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
 		else
 			err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
 

arch/x86/kernel/fpu/xstate.c

@@ -1089,7 +1089,7 @@ int copy_xstate_to_user(void __user *ubuf, struct xregs_state *xsave, unsigned i
  * there we check the CPU has XSAVES and a whole standard-sized buffer
  * exists.
  */
-int copy_kernel_to_xstate(const void *kbuf, struct xregs_state *xsave)
+int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 {
 	unsigned int offset, size;
 	int i;
@@ -1142,7 +1142,7 @@ int copy_kernel_to_xstate(const void *kbuf, struct xregs_state *xsave)
  * there we check the CPU has XSAVES and a whole standard-sized buffer
  * exists.
  */
-int copy_user_to_xstate(const void __user *ubuf, struct xregs_state *xsave)
+int copy_user_to_xstate(struct xregs_state *xsave, const void __user *ubuf)
 {
 	unsigned int offset, size;
 	int i;