From ca9128f18fe75878ba2d5e0df09ae755c085f72a Mon Sep 17 00:00:00 2001
From: Srdjan Petrovic <spetrovic@google.com>
Date: Fri, 17 Apr 2015 17:27:07 -0700
Subject: runtime: merge clone0 and clone

We initially added clone0 to handle the case when G or M don't exist, but
it turns out that we could have just modified clone.  (It also helps that
the function we're invoking in clone0 no longer needs arguments.)

As a side-effect, newosproc0 is now supported on all linux archs.

Change-Id: Ie603af75d8f164310fc16446052d83743961f3ca
Reviewed-on: https://go-review.googlesource.com/9164
Reviewed-by: David Crawshaw <crawshaw@golang.org>
---
 src/runtime/sys_linux_amd64.s | 47 +++++++++++++------------------------------
 1 file changed, 14 insertions(+), 33 deletions(-)

(limited to 'src/runtime/sys_linux_amd64.s')

diff --git a/src/runtime/sys_linux_amd64.s b/src/runtime/sys_linux_amd64.s
index 43a65b7ccd..3a0c47fb63 100644
--- a/src/runtime/sys_linux_amd64.s
+++ b/src/runtime/sys_linux_amd64.s
@@ -302,14 +302,16 @@ TEXT runtime·futex(SB),NOSPLIT,$0
 
 // int32 clone(int32 flags, void *stack, M *mp, G *gp, void (*fn)(void));
 TEXT runtime·clone(SB),NOSPLIT,$0
-	MOVL	flags+8(SP), DI
-	MOVQ	stack+16(SP), SI
+	MOVL	flags+0(FP), DI
+	MOVQ	stack+8(FP), SI
+	MOVQ	$0, DX
+	MOVQ	$0, R10
 
 	// Copy mp, gp, fn off parent stack for use by child.
 	// Careful: Linux system call clobbers CX and R11.
-	MOVQ	mm+24(SP), R8
-	MOVQ	gg+32(SP), R9
-	MOVQ	fn+40(SP), R12
+	MOVQ	mp+16(FP), R8
+	MOVQ	gp+24(FP), R9
+	MOVQ	fn+32(FP), R12
 
 	MOVL	$56, AX
 	SYSCALL
@@ -323,6 +325,12 @@ TEXT runtime·clone(SB),NOSPLIT,$0
 	// In child, on new stack.
 	MOVQ	SI, SP
 
+	// If g or m are nil, skip Go-related setup.
+	CMPQ	R8, $0    // m
+	JEQ	nog
+	CMPQ	R9, $0    // g
+	JEQ	nog
+
 	// Initialize m->procid to Linux tid
 	MOVL	$186, AX	// gettid
 	SYSCALL
@@ -338,6 +346,7 @@ TEXT runtime·clone(SB),NOSPLIT,$0
 	MOVQ	R9, g(CX)
 	CALL	runtime·stackcheck(SB)
 
+nog:
 	// Call fn
 	CALL	R12
 
@@ -347,34 +356,6 @@ TEXT runtime·clone(SB),NOSPLIT,$0
 	SYSCALL
 	JMP	-3(PC)	// keep exiting
 
-// int32 clone0(int32 flags, void *stack, void* fn, void* fnarg);
-TEXT runtime·clone0(SB),NOSPLIT,$16-36
-	MOVL	flags+0(FP), DI
-	MOVQ	stack+8(FP), SI
-	MOVQ	fn+16(FP), R12      // used by the child
-	MOVQ	fnarg+24(FP), R13   // used by the child
-	MOVL	$0, DX
-	MOVL	$0, R10
-	MOVL	$56, AX
-	SYSCALL
-
-	CMPQ	AX, $0
-	JEQ	child
-	// In parent, return.
-	MOVL	AX, ret+32(FP)
-	RET
-child:
-	MOVQ	SI, SP
-	MOVQ	R12, AX  // fn
-	MOVQ	R13, DI  // fnarg
-	CALL	AX
-
-	// fn shouldn't return; if it does, exit.
-	MOVL	$111, DI
-	MOVL	$60, AX
-	SYSCALL
-	JMP	-3(PC)	// keep exiting
-
 TEXT runtime·sigaltstack(SB),NOSPLIT,$-8
 	MOVQ	new+8(SP), DI
 	MOVQ	old+16(SP), SI
-- 
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