runtime: zero saved frame pointer when reusing goroutine stack on arm64

When a goroutine stack is reused on arm64, the spot on the stack where
the "caller's" frame pointer goes for the topmost frame should be
explicitly zeroed. Otherwise, the frame pointer check in adjustframe
with debugCheckBP enabled will fail on the topmost frame of a call stack
the first time a reused stack is grown.

Updates #39524, #58432

Change-Id: Ic1210dc005e3ecdbf9cd5d7b98846566e56df8f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/481636
Reviewed-by: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index fafab7f58c487c6c4c7ab1e2bc3e441483e7c304..8fab6d46d1488a6b157431208554feabdb64c61f 100644 (file)
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -4540,12 +4540,14 @@ func newproc1(fn *funcval, callergp *g, callerpc uintptr) *g {
        totalSize := uintptr(4*goarch.PtrSize + sys.MinFrameSize) // extra space in case of reads slightly beyond frame
        totalSize = alignUp(totalSize, sys.StackAlign)
        sp := newg.stack.hi - totalSize
-       spArg := sp
        if usesLR {
                // caller's LR
                *(*uintptr)(unsafe.Pointer(sp)) = 0
                prepGoExitFrame(sp)
-               spArg += sys.MinFrameSize
+       }
+       if GOARCH == "arm64" {
+               // caller's FP
+               *(*uintptr)(unsafe.Pointer(sp - goarch.PtrSize)) = 0
        }
 
        memclrNoHeapPointers(unsafe.Pointer(&newg.sched), unsafe.Sizeof(newg.sched))