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Diffstat (limited to 'src/pkg/runtime/stack.h')
-rw-r--r-- | src/pkg/runtime/stack.h | 113 |
1 files changed, 0 insertions, 113 deletions
diff --git a/src/pkg/runtime/stack.h b/src/pkg/runtime/stack.h deleted file mode 100644 index 18ab30b69..000000000 --- a/src/pkg/runtime/stack.h +++ /dev/null @@ -1,113 +0,0 @@ -// Copyright 2011 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. - -/* -Stack layout parameters. -Included both by runtime (compiled via 6c) and linkers (compiled via gcc). - -The per-goroutine g->stackguard is set to point StackGuard bytes -above the bottom of the stack. Each function compares its stack -pointer against g->stackguard to check for overflow. To cut one -instruction from the check sequence for functions with tiny frames, -the stack is allowed to protrude StackSmall bytes below the stack -guard. Functions with large frames don't bother with the check and -always call morestack. The sequences are (for amd64, others are -similar): - - guard = g->stackguard - frame = function's stack frame size - argsize = size of function arguments (call + return) - - stack frame size <= StackSmall: - CMPQ guard, SP - JHI 3(PC) - MOVQ m->morearg, $(argsize << 32) - CALL morestack(SB) - - stack frame size > StackSmall but < StackBig - LEAQ (frame-StackSmall)(SP), R0 - CMPQ guard, R0 - JHI 3(PC) - MOVQ m->morearg, $(argsize << 32) - CALL morestack(SB) - - stack frame size >= StackBig: - MOVQ m->morearg, $((argsize << 32) | frame) - CALL morestack(SB) - -The bottom StackGuard - StackSmall bytes are important: there has -to be enough room to execute functions that refuse to check for -stack overflow, either because they need to be adjacent to the -actual caller's frame (deferproc) or because they handle the imminent -stack overflow (morestack). - -For example, deferproc might call malloc, which does one of the -above checks (without allocating a full frame), which might trigger -a call to morestack. This sequence needs to fit in the bottom -section of the stack. On amd64, morestack's frame is 40 bytes, and -deferproc's frame is 56 bytes. That fits well within the -StackGuard - StackSmall = 128 bytes at the bottom. -The linkers explore all possible call traces involving non-splitting -functions to make sure that this limit cannot be violated. - */ - -enum { - // StackSystem is a number of additional bytes to add - // to each stack below the usual guard area for OS-specific - // purposes like signal handling. Used on Windows and on - // Plan 9 because they do not use a separate stack. -#ifdef GOOS_windows - StackSystem = 512 * sizeof(uintptr), -#else -#ifdef GOOS_plan9 - // The size of the note handler frame varies among architectures, - // but 512 bytes should be enough for every implementation. - StackSystem = 512, -#else - StackSystem = 0, -#endif // Plan 9 -#endif // Windows - - // The amount of extra stack to allocate beyond the size - // needed for the single frame that triggered the split. - StackExtra = 2048, - - // The minimum stack segment size to allocate. - // If the amount needed for the splitting frame + StackExtra - // is less than this number, the stack will have this size instead. - StackMin = 8192, - StackSystemRounded = StackSystem + (-StackSystem & (StackMin-1)), - FixedStack = StackMin + StackSystemRounded, - - // 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. - StackGuard = 256 + 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. - StackLimit = StackGuard - StackSystem - StackSmall, - - // The assumed size of the top-of-stack data block. - // The actual size can be smaller than this but cannot be larger. - // Checked in proc.c's runtime.malg. - StackTop = 88, -}; - -// Goroutine preemption request. -// Stored into g->stackguard0 to cause split stack check failure. -// Must be greater than any real sp. -// 0xfffffade in hex. -#define StackPreempt ((uint64)-1314) |