runtime: implement xadduintptr and update system mstats using it
The motivation is that sysAlloc/Free() currently aren't safe to be
called without a valid G, because arm's xadd64() uses locks that require
a valid G.
The solution here was proposed by Dmitry Vyukov: use xadduintptr()
instead of xadd64(), until arm can support xadd64 on all of its
architectures (not a trivial task for arm).
Change-Id: I250252079357ea2e4360e1235958b1c22051498f
Reviewed-on: https://go-review.googlesource.com/9002
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
diff --git a/src/runtime/atomic_arm.go b/src/runtime/atomic_arm.go
index 75206ab..02a1f35 100644
--- a/src/runtime/atomic_arm.go
+++ b/src/runtime/atomic_arm.go
@@ -27,6 +27,10 @@
}
}
+//go:noescape
+//go:linkname xadduintptr runtime.xadd
+func xadduintptr(ptr *uintptr, delta uintptr) uintptr
+
//go:nosplit
func xchg(addr *uint32, v uint32) uint32 {
for {
