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runtime: merge stack{1,2}.go -> stack.go
* rename stack1.go -> stack.go * prepend contents of stack2.go to stack.go Updates #12952 Change-Id: I60d409af37162a5a7596c678dfebc2cea89564ff Reviewed-on: https://go-review.googlesource.com/16008 Reviewed-by: Austin Clements <austin@google.com> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Nodir Turakulov
Brad Fitzpatrick
parent
69a99ccc62
commit
db2e73faeb
@ -6,6 +6,107 @@ package runtime
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import "unsafe"
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/*
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Stack layout parameters.
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Included both by runtime (compiled via 6c) and linkers (compiled via gcc).
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The per-goroutine g->stackguard is set to point StackGuard bytes
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above the bottom of the stack. Each function compares its stack
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pointer against g->stackguard to check for overflow. To cut one
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instruction from the check sequence for functions with tiny frames,
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the stack is allowed to protrude StackSmall bytes below the stack
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guard. Functions with large frames don't bother with the check and
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always call morestack. The sequences are (for amd64, others are
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similar):
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guard = g->stackguard
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frame = function's stack frame size
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argsize = size of function arguments (call + return)
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stack frame size <= StackSmall:
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CMPQ guard, SP
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JHI 3(PC)
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MOVQ m->morearg, $(argsize << 32)
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CALL morestack(SB)
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stack frame size > StackSmall but < StackBig
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LEAQ (frame-StackSmall)(SP), R0
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CMPQ guard, R0
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JHI 3(PC)
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MOVQ m->morearg, $(argsize << 32)
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CALL morestack(SB)
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stack frame size >= StackBig:
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MOVQ m->morearg, $((argsize << 32) | frame)
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CALL morestack(SB)
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The bottom StackGuard - StackSmall bytes are important: there has
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to be enough room to execute functions that refuse to check for
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stack overflow, either because they need to be adjacent to the
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actual caller's frame (deferproc) or because they handle the imminent
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stack overflow (morestack).
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For example, deferproc might call malloc, which does one of the
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above checks (without allocating a full frame), which might trigger
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a call to morestack. This sequence needs to fit in the bottom
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section of the stack. On amd64, morestack's frame is 40 bytes, and
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deferproc's frame is 56 bytes. That fits well within the
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StackGuard - StackSmall bytes at the bottom.
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The linkers explore all possible call traces involving non-splitting
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functions to make sure that this limit cannot be violated.
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*/
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const (
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// StackSystem is a number of additional bytes to add
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// to each stack below the usual guard area for OS-specific
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// purposes like signal handling. Used on Windows, Plan 9,
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// and Darwin/ARM because they do not use a separate stack.
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_StackSystem = goos_windows*512*ptrSize + goos_plan9*512 + goos_darwin*goarch_arm*1024
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// The minimum size of stack used by Go code
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_StackMin = 2048
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// The minimum stack size to allocate.
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// The hackery here rounds FixedStack0 up to a power of 2.
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_FixedStack0 = _StackMin + _StackSystem
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_FixedStack1 = _FixedStack0 - 1
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_FixedStack2 = _FixedStack1 | (_FixedStack1 >> 1)
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_FixedStack3 = _FixedStack2 | (_FixedStack2 >> 2)
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_FixedStack4 = _FixedStack3 | (_FixedStack3 >> 4)
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_FixedStack5 = _FixedStack4 | (_FixedStack4 >> 8)
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_FixedStack6 = _FixedStack5 | (_FixedStack5 >> 16)
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_FixedStack = _FixedStack6 + 1
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// Functions that need frames bigger than this use an extra
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// instruction to do the stack split check, to avoid overflow
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// in case SP - framesize wraps below zero.
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// This value can be no bigger than the size of the unmapped
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// space at zero.
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_StackBig = 4096
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// The stack guard is a pointer this many bytes above the
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// bottom of the stack.
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_StackGuard = 640*stackGuardMultiplier + _StackSystem
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// After a stack split check the SP is allowed to be this
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// many bytes below the stack guard. This saves an instruction
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// in the checking sequence for tiny frames.
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_StackSmall = 128
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// The maximum number of bytes that a chain of NOSPLIT
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// functions can use.
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_StackLimit = _StackGuard - _StackSystem - _StackSmall
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)
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// Goroutine preemption request.
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// Stored into g->stackguard0 to cause split stack check failure.
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// Must be greater than any real sp.
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// 0xfffffade in hex.
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const (
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_StackPreempt = uintptrMask & -1314
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_StackFork = uintptrMask & -1234
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)
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const (
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// stackDebug == 0: no logging
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// == 1: logging of per-stack operations
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@ -1,106 +0,0 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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/*
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Stack layout parameters.
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Included both by runtime (compiled via 6c) and linkers (compiled via gcc).
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The per-goroutine g->stackguard is set to point StackGuard bytes
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above the bottom of the stack. Each function compares its stack
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pointer against g->stackguard to check for overflow. To cut one
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instruction from the check sequence for functions with tiny frames,
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the stack is allowed to protrude StackSmall bytes below the stack
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guard. Functions with large frames don't bother with the check and
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always call morestack. The sequences are (for amd64, others are
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similar):
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guard = g->stackguard
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frame = function's stack frame size
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argsize = size of function arguments (call + return)
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stack frame size <= StackSmall:
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CMPQ guard, SP
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JHI 3(PC)
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MOVQ m->morearg, $(argsize << 32)
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CALL morestack(SB)
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stack frame size > StackSmall but < StackBig
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LEAQ (frame-StackSmall)(SP), R0
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CMPQ guard, R0
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JHI 3(PC)
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MOVQ m->morearg, $(argsize << 32)
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CALL morestack(SB)
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stack frame size >= StackBig:
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MOVQ m->morearg, $((argsize << 32) | frame)
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CALL morestack(SB)
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The bottom StackGuard - StackSmall bytes are important: there has
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to be enough room to execute functions that refuse to check for
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stack overflow, either because they need to be adjacent to the
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actual caller's frame (deferproc) or because they handle the imminent
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stack overflow (morestack).
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For example, deferproc might call malloc, which does one of the
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above checks (without allocating a full frame), which might trigger
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a call to morestack. This sequence needs to fit in the bottom
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section of the stack. On amd64, morestack's frame is 40 bytes, and
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deferproc's frame is 56 bytes. That fits well within the
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StackGuard - StackSmall bytes at the bottom.
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The linkers explore all possible call traces involving non-splitting
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functions to make sure that this limit cannot be violated.
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*/
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const (
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// StackSystem is a number of additional bytes to add
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// to each stack below the usual guard area for OS-specific
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// purposes like signal handling. Used on Windows, Plan 9,
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// and Darwin/ARM because they do not use a separate stack.
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_StackSystem = goos_windows*512*ptrSize + goos_plan9*512 + goos_darwin*goarch_arm*1024
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// The minimum size of stack used by Go code
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_StackMin = 2048
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// The minimum stack size to allocate.
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// The hackery here rounds FixedStack0 up to a power of 2.
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_FixedStack0 = _StackMin + _StackSystem
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_FixedStack1 = _FixedStack0 - 1
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_FixedStack2 = _FixedStack1 | (_FixedStack1 >> 1)
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_FixedStack3 = _FixedStack2 | (_FixedStack2 >> 2)
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_FixedStack4 = _FixedStack3 | (_FixedStack3 >> 4)
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_FixedStack5 = _FixedStack4 | (_FixedStack4 >> 8)
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_FixedStack6 = _FixedStack5 | (_FixedStack5 >> 16)
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_FixedStack = _FixedStack6 + 1
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// Functions that need frames bigger than this use an extra
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// instruction to do the stack split check, to avoid overflow
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// in case SP - framesize wraps below zero.
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// This value can be no bigger than the size of the unmapped
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// space at zero.
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_StackBig = 4096
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// The stack guard is a pointer this many bytes above the
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// bottom of the stack.
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_StackGuard = 640*stackGuardMultiplier + _StackSystem
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// After a stack split check the SP is allowed to be this
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// many bytes below the stack guard. This saves an instruction
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// in the checking sequence for tiny frames.
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_StackSmall = 128
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// The maximum number of bytes that a chain of NOSPLIT
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// functions can use.
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_StackLimit = _StackGuard - _StackSystem - _StackSmall
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)
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// Goroutine preemption request.
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// Stored into g->stackguard0 to cause split stack check failure.
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// Must be greater than any real sp.
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// 0xfffffade in hex.
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const (
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_StackPreempt = uintptrMask & -1314
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_StackFork = uintptrMask & -1234
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)
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