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https://github.com/golang/go
synced 2024-10-04 14:31:21 -06:00
1249d3a518
32-bit Windows uses "structured exception handling" (SEH) to handle hardware faults: that there is a per-thread linked list of fault handlers maintained in user space instead of something like Unix's signal handlers. The structures in the linked list are required to live on the OS stack, and the usual discipline is that the function that pushes a record (allocated from the current stack frame) onto the list pops that record before returning. Not to pop the entry before returning creates a dangling pointer error: the list head points to a stack frame that no longer exists. Go pushes an SEH record in the top frame of every OS thread, and that record suffices for all Go execution on that thread, at least until cgo gets involved. If we call into C using cgo, that called C code may push its own SEH records, but by the convention it must pop them before returning back to the Go code. We assume it does, and that's fine. If the C code calls back into Go, we want the Go SEH handler to become active again, not whatever C has set up. So runtime.callbackasm1, which handles a call from C back into Go, pushes a new SEH record before calling the Go code and pops it when the Go code returns. That's also fine. It can happen that when Go calls C calls Go like this, the inner Go code panics. We allow a defer in the outer Go to recover the panic, effectively wiping not only the inner Go frames but also the C calls. This sequence was not popping the SEH stack up to what it was before the cgo calls, so it was creating the dangling pointer warned about above. When eventually the m stack was used enough to overwrite the dangling SEH records, the SEH chain was lost, and any future panic would not end up in Go's handler. The bug in TestCallbackPanic and friends was thus creating a situation where TestSetPanicOnFault - which causes a hardware fault - would not find the Go fault handler and instead crash the binary. Add checks to TestCallbackPanicLocked to diagnose the mistake in that test instead of leaving a bad state for another test case to stumble over. Fix bug by restoring SEH chain during deferred "endcgo" cleanup. This bug is likely present in Go 1.2.1, but since it depends on Go calling C calling Go, with the inner Go panicking and the outer Go recovering the panic, it seems not important enough to bother fixing before Go 1.3. Certainly no one has complained. Fixes #7470. LGTM=alex.brainman R=golang-codereviews, alex.brainman CC=golang-codereviews, iant, khr https://golang.org/cl/71440043
97 lines
2.2 KiB
Go
97 lines
2.2 KiB
Go
// Copyright 2010 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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// Export guts for testing.
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package runtime
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var Fadd64 = fadd64
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var Fsub64 = fsub64
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var Fmul64 = fmul64
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var Fdiv64 = fdiv64
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var F64to32 = f64to32
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var F32to64 = f32to64
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var Fcmp64 = fcmp64
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var Fintto64 = fintto64
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var F64toint = f64toint
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func entersyscall()
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func exitsyscall()
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func golockedOSThread() bool
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func stackguard() (sp, limit uintptr)
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var Entersyscall = entersyscall
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var Exitsyscall = exitsyscall
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var LockedOSThread = golockedOSThread
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var Stackguard = stackguard
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type LFNode struct {
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Next *LFNode
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Pushcnt uintptr
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}
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func lfstackpush_go(head *uint64, node *LFNode)
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func lfstackpop_go(head *uint64) *LFNode
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var LFStackPush = lfstackpush_go
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var LFStackPop = lfstackpop_go
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type ParFor struct {
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body *byte
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done uint32
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Nthr uint32
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nthrmax uint32
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thrseq uint32
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Cnt uint32
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Ctx *byte
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wait bool
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}
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func newParFor(nthrmax uint32) *ParFor
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func parForSetup(desc *ParFor, nthr, n uint32, ctx *byte, wait bool, body func(*ParFor, uint32))
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func parForDo(desc *ParFor)
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func parForIters(desc *ParFor, tid uintptr) (uintptr, uintptr)
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var NewParFor = newParFor
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var ParForSetup = parForSetup
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var ParForDo = parForDo
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func ParForIters(desc *ParFor, tid uint32) (uint32, uint32) {
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begin, end := parForIters(desc, uintptr(tid))
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return uint32(begin), uint32(end)
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}
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func testSchedLocalQueue()
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func testSchedLocalQueueSteal()
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var TestSchedLocalQueue1 = testSchedLocalQueue
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var TestSchedLocalQueueSteal1 = testSchedLocalQueueSteal
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func haveGoodHash() bool
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func stringHash(s string, seed uintptr) uintptr
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func bytesHash(b []byte, seed uintptr) uintptr
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func int32Hash(i uint32, seed uintptr) uintptr
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func int64Hash(i uint64, seed uintptr) uintptr
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var HaveGoodHash = haveGoodHash
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var StringHash = stringHash
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var BytesHash = bytesHash
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var Int32Hash = int32Hash
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var Int64Hash = int64Hash
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var hashLoad float64 // declared in hashmap.c
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var HashLoad = &hashLoad
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func memclrBytes(b []byte)
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var MemclrBytes = memclrBytes
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func gogoBytes() int32
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var GogoBytes = gogoBytes
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func getseh_go() uintptr
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var GetSEH = getseh_go
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