diff options
Diffstat (limited to 'src/runtime/stack.go')
| -rw-r--r-- | src/runtime/stack.go | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 39dbed5114..e1e6c7e82a 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -85,6 +85,13 @@ const ( _FixedStack6 = _FixedStack5 | (_FixedStack5 >> 16) _FixedStack = _FixedStack6 + 1 + // Functions that need frames bigger than this use an extra + // instruction to do the stack split check, to avoid overflow + // in case SP - framesize wraps below zero. + // This value can be no bigger than the size of the unmapped + // space at zero. + _StackBig = 4096 + // The stack guard is a pointer this many bytes above the // bottom of the stack. // @@ -94,10 +101,15 @@ const ( // This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit. _StackGuard = 928*sys.StackGuardMultiplier + _StackSystem + // After a stack split check the SP is allowed to be this + // many bytes below the stack guard. This saves an instruction + // in the checking sequence for tiny frames. + _StackSmall = 128 + // The maximum number of bytes that a chain of NOSPLIT // functions can use. // This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit. - _StackLimit = _StackGuard - _StackSystem - abi.StackSmall + _StackLimit = _StackGuard - _StackSystem - _StackSmall ) const ( |