cmd/dist, cmd/link, runtime: fix stack size when cross-compiling aix/ppc64

This commit allows to cross-compiling aix/ppc64. The nosplit limit must
twice as large as on others platforms because of AIX syscalls.
The stack limit, especially stackGuardMultiplier, was set by cmd/dist
during the bootstrap and doesn't depend on GOOS/GOARCH target.

Fixes #29572

Change-Id: Id51e38885e1978d981aa9e14972eaec17294322e
Reviewed-on: https://go-review.googlesource.com/c/157117
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 15 insertions, 2 deletions

diff --git a/src/cmd/internal/objabi/stack.go b/src/cmd/internal/objabi/stack.go
index 11433932e2..62ab0398a6 100644
--- a/src/cmd/internal/objabi/stack.go
+++ b/src/cmd/internal/objabi/stack.go
@@ -10,11 +10,24 @@ const (
 	STACKSYSTEM = 0
 	StackSystem = STACKSYSTEM
 	StackBig    = 4096
-	StackGuard  = 880*stackGuardMultiplier + StackSystem
 	StackSmall  = 128
-	StackLimit  = StackGuard - StackSystem - StackSmall
 )
 
 const (
 	StackPreempt = -1314 // 0xfff...fade
 )
+
+// Initialize StackGuard and StackLimit according to target system.
+var StackGuard = 880*stackGuardMultiplier() + StackSystem
+var StackLimit = StackGuard - StackSystem - StackSmall
+
+// stackGuardMultiplier returns a multiplier to apply to the default
+// stack guard size. Larger multipliers are used for non-optimized
+// builds that have larger stack frames or for specific targets.
+func stackGuardMultiplier() int {
+	// On AIX, a larger stack is needed for syscalls.
+	if GOOS == "aix" {
+		return 2
+	}
+	return stackGuardMultiplierDefault
+}