From 5fce15a2a3cd94427bb9979d73acf14013ec7f31 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Fri, 14 Nov 2014 12:55:23 -0500
Subject: [dev.cc] runtime: fix lfstack for amd64 addresses in top half of addr
 space

While we are here, add the linux/power64 version.

LGTM=austin
R=austin
CC=aram, dvyukov, golang-codereviews
https://golang.org/cl/177750043
---
 src/runtime/lfstack_linux_power64x.go | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 src/runtime/lfstack_linux_power64x.go

(limited to 'src/runtime/lfstack_linux_power64x.go')

diff --git a/src/runtime/lfstack_linux_power64x.go b/src/runtime/lfstack_linux_power64x.go
new file mode 100644
index 0000000000..7a122bf92c
--- /dev/null
+++ b/src/runtime/lfstack_linux_power64x.go
@@ -0,0 +1,26 @@
+// Copyright 2014 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build power64 power64le
+// +build linux
+
+package runtime
+
+import "unsafe"
+
+// On Power64, Linux limits the user address space to 43 bits.
+// (https://www.kernel.org/doc/ols/2001/ppc64.pdf)
+// In addition to the 21 bits taken from the top, we can take 3 from the
+// bottom, because node must be pointer-aligned, giving a total of 24 bits
+// of count.
+
+func lfstackPack(node *lfnode, cnt uintptr) uint64 {
+	return uint64(uintptr(unsafe.Pointer(node)))<<21 | uint64(cnt&(1<<24-1))
+}
+
+func lfstackUnpack(val uint64) (node *lfnode, cnt uintptr) {
+	node = (*lfnode)(unsafe.Pointer(uintptr(val >> 24 << 3)))
+	cnt = uintptr(val & (1<<24 - 1))
+	return
+}
-- 
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