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Diffstat (limited to 'src/internal/abi/stack.go')
| -rw-r--r-- | src/internal/abi/stack.go | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/src/internal/abi/stack.go b/src/internal/abi/stack.go new file mode 100644 index 0000000..8e3327e --- /dev/null +++ b/src/internal/abi/stack.go @@ -0,0 +1,33 @@ +// Copyright 2023 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. + +package abi + +const ( + // StackNosplitBase is the base maximum number of bytes that a chain of + // NOSPLIT functions can use. + // + // This value must be multiplied by the stack guard multiplier, so do not + // use it directly. See runtime/stack.go:stackNosplit and + // cmd/internal/objabi/stack.go:StackNosplit. + StackNosplitBase = 800 + + // We have three different sequences for stack bounds checks, depending on + // whether the stack frame of a function is small, big, or huge. + + // After a stack split check the SP is allowed to be StackSmall bytes below + // the stack guard. + // + // Functions that need frames <= StackSmall can perform the stack check + // using a single comparison directly between the stack guard and the SP + // because we ensure that StackSmall bytes of stack space are available + // beyond the stack guard. + StackSmall = 128 + + // Functions that need frames <= StackBig can assume that neither + // SP-framesize nor stackGuard-StackSmall will underflow, and thus use a + // more efficient check. In order to ensure this, StackBig must be <= the + // size of the unmapped space at zero. + StackBig = 4096 +) |