diff options
Diffstat (limited to 'src/runtime/runtime2.go')
| -rw-r--r-- | src/runtime/runtime2.go | 46 |
1 files changed, 39 insertions, 7 deletions
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go index 13c5dee078..27700b6217 100644 --- a/src/runtime/runtime2.go +++ b/src/runtime/runtime2.go @@ -117,6 +117,38 @@ func (gp guintptr) ptr() *g { return (*g)(unsafe.Pointer(gp)) } +// ps, ms, gs, and mcache are structures that must be manipulated at a level +// lower than that of the normal Go language. For example the routine that +// stops the world removes the p from the m structure informing the GC that +// this P is stopped and then it moves the g to the global runnable queue. +// If write barriers were allowed to happen at this point not only does +// the GC think the thread is stopped but the underlying structures +// like a p or m are not in a state that is not coherent enough to +// support the write barrier actions. +// This is particularly painful since a partially executed write barrier +// may mark the object but be delinquent in informing the GC that the +// object needs to be scanned. + +// setGNoWriteBarriers does *gdst = gval without a write barrier. +func setGNoWriteBarrier(gdst **g, gval *g) { + *(*uintptr)(unsafe.Pointer(gdst)) = uintptr(unsafe.Pointer(gval)) +} + +// setMNoWriteBarriers does *mdst = mval without a write barrier. +func setMNoWriteBarrier(mdst **m, mval *m) { + *(*uintptr)(unsafe.Pointer(mdst)) = uintptr(unsafe.Pointer(mval)) +} + +// setPNoWriteBarriers does *pdst = pval without a write barrier. +func setPNoWriteBarrier(pdst **p, pval *p) { + *(*uintptr)(unsafe.Pointer(pdst)) = uintptr(unsafe.Pointer(pval)) +} + +// setMcacheNoWriteBarriers does *mcachedst = mcacheval without a write barrier. +func setMcacheNoWriteBarrier(mcachedst **mcache, mcacheval *mcache) { + *(*uintptr)(unsafe.Pointer(mcachedst)) = uintptr(unsafe.Pointer(mcacheval)) +} + type gobuf struct { // The offsets of sp, pc, and g are known to (hard-coded in) libmach. sp uintptr @@ -233,13 +265,13 @@ type m struct { morebuf gobuf // gobuf arg to morestack // Fields not known to debuggers. - procid uint64 // for debuggers, but offset not hard-coded - gsignal *g // signal-handling g - tls [4]uintptr // thread-local storage (for x86 extern register) - mstartfn unsafe.Pointer // todo go func() - curg *g // current running goroutine - caughtsig *g // goroutine running during fatal signal - p *p // attached p for executing go code (nil if not executing go code) + procid uint64 // for debuggers, but offset not hard-coded + gsignal *g // signal-handling g + tls [4]uintptr // thread-local storage (for x86 extern register) + mstartfn uintptr // TODO: type as func(); note: this is a non-heap allocated func() + curg *g // current running goroutine + caughtsig *g // goroutine running during fatal signal + p *p // attached p for executing go code (nil if not executing go code) nextp *p id int32 mallocing int32 |