x86/entry: Reverse arguments to do_syscall_64()

Reverse the order of arguments to do_syscall_64() so that the first
argument is the pt_regs pointer. This is not only consistent with
*all* other entry points from assembly, but it actually makes the
compiled code slightly better.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210510185316.3307264-3-hpa@zytor.com
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 7b2542b..00da0f5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -36,7 +36,7 @@
 #include <asm/irq_stack.h>
 
 #ifdef CONFIG_X86_64
-__visible noinstr void do_syscall_64(unsigned long nr, struct pt_regs *regs)
+__visible noinstr void do_syscall_64(struct pt_regs *regs, unsigned long nr)
 {
 	add_random_kstack_offset();
 	nr = syscall_enter_from_user_mode(regs, nr);
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index a16a529..1d9db15 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -107,8 +107,8 @@
 	PUSH_AND_CLEAR_REGS rax=$-ENOSYS
 
 	/* IRQs are off. */
-	movq	%rax, %rdi
-	movq	%rsp, %rsi
+	movq	%rsp, %rdi
+	movq	%rax, %rsi
 	call	do_syscall_64		/* returns with IRQs disabled */
 
 	/*