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runtime: eliminate poisonStack checks
We haven't used poisonStack since we switched to 1-bit stack maps
(4d0f3a1
), but the checks are still there. However, nothing prevents
us from genuinely allocating an object at this address on 32-bit and
causing the runtime to crash claiming that it's found a bad pointer.
Since we're not using poisonStack anyway, just pull it out.
Fixes #15831.
Change-Id: Ia6ef604675b8433f75045e369f5acd4644a5bb38
Reviewed-on: https://go-review.googlesource.com/24211
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
parent
fca9fc52c8
commit
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@ -145,7 +145,7 @@ func writebarrierptr(dst *uintptr, src uintptr) {
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if !writeBarrier.needed {
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return
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}
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if src != 0 && (src < sys.PhysPageSize || src == poisonStack) {
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if src != 0 && src < sys.PhysPageSize {
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systemstack(func() {
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print("runtime: writebarrierptr *", dst, " = ", hex(src), "\n")
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throw("bad pointer in write barrier")
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@ -164,7 +164,7 @@ func writebarrierptr_nostore(dst *uintptr, src uintptr) {
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if !writeBarrier.needed {
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return
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}
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if src != 0 && (src < sys.PhysPageSize || src == poisonStack) {
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if src != 0 && src < sys.PhysPageSize {
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systemstack(func() { throw("bad pointer in write barrier") })
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}
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writebarrierptr_nostore1(dst, src)
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@ -127,7 +127,6 @@ const (
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const (
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uintptrMask = 1<<(8*sys.PtrSize) - 1
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poisonStack = uintptrMask & 0x6868686868686868
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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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@ -594,7 +593,7 @@ func adjustpointers(scanp unsafe.Pointer, cbv *bitvector, adjinfo *adjustinfo, f
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pp := (*uintptr)(add(scanp, i*sys.PtrSize))
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retry:
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p := *pp
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if f != nil && 0 < p && p < _PageSize && debug.invalidptr != 0 || p == poisonStack {
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if f != nil && 0 < p && p < _PageSize && debug.invalidptr != 0 {
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// Looks like a junk value in a pointer slot.
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// Live analysis wrong?
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getg().m.traceback = 2
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