diff options
Diffstat (limited to 'src/runtime/stubs.go')
| -rw-r--r-- | src/runtime/stubs.go | 164 |
1 files changed, 37 insertions, 127 deletions
diff --git a/src/runtime/stubs.go b/src/runtime/stubs.go index 9889567d6..217307a1e 100644 --- a/src/runtime/stubs.go +++ b/src/runtime/stubs.go @@ -23,12 +23,7 @@ func roundup(p unsafe.Pointer, n uintptr) unsafe.Pointer { return unsafe.Pointer(uintptr(p) + delta) } -// in runtime.c func getg() *g -func acquirem() *m -func releasem(mp *m) -func gomcache() *mcache -func readgstatus(*g) uint32 // proc.c // mcall switches from the g to the g0 stack and invokes fn(g), // where g is the goroutine that made the call. @@ -43,95 +38,30 @@ func readgstatus(*g) uint32 // proc.c //go:noescape func mcall(fn func(*g)) -// onM switches from the g to the g0 stack and invokes fn(). -// When fn returns, onM switches back to the g and returns, -// continuing execution on the g stack. -// If arguments must be passed to fn, they can be written to -// g->m->ptrarg (pointers) and g->m->scalararg (non-pointers) -// before the call and then consulted during fn. -// Similarly, fn can pass return values back in those locations. -// If fn is written in Go, it can be a closure, which avoids the need for -// ptrarg and scalararg entirely. -// After reading values out of ptrarg and scalararg it is conventional -// to zero them to avoid (memory or information) leaks. +// systemstack runs fn on a system stack. +// If systemstack is called from the per-OS-thread (g0) stack, or +// if systemstack is called from the signal handling (gsignal) stack, +// systemstack calls fn directly and returns. +// Otherwise, systemstack is being called from the limited stack +// of an ordinary goroutine. In this case, systemstack switches +// to the per-OS-thread stack, calls fn, and switches back. +// It is common to use a func literal as the argument, in order +// to share inputs and outputs with the code around the call +// to system stack: // -// If onM is called from a g0 stack, it invokes fn and returns, -// without any stack switches. -// -// If onM is called from a gsignal stack, it crashes the program. -// The implication is that functions used in signal handlers must -// not use onM. -// -// NOTE(rsc): We could introduce a separate onMsignal that is -// like onM but if called from a gsignal stack would just run fn on -// that stack. The caller of onMsignal would be required to save the -// old values of ptrarg/scalararg and restore them when the call -// was finished, in case the signal interrupted an onM sequence -// in progress on the g or g0 stacks. Until there is a clear need for this, -// we just reject onM in signal handling contexts entirely. -// -//go:noescape -func onM(fn func()) - -// onMsignal is like onM but is allowed to be used in code that -// might run on the gsignal stack. Code running on a signal stack -// may be interrupting an onM sequence on the main stack, so -// if the onMsignal calling sequence writes to ptrarg/scalararg, -// it must first save the old values and then restore them when -// finished. As an exception to the rule, it is fine not to save and -// restore the values if the program is trying to crash rather than -// return from the signal handler. -// Once all the runtime is written in Go, there will be no ptrarg/scalararg -// and the distinction between onM and onMsignal (and perhaps mcall) -// can go away. -// -// If onMsignal is called from a gsignal stack, it invokes fn directly, -// without a stack switch. Otherwise onMsignal behaves like onM. +// ... set up y ... +// systemstack(func() { +// x = bigcall(y) +// }) +// ... use x ... // //go:noescape -func onM_signalok(fn func()) +func systemstack(fn func()) -func badonm() { - gothrow("onM called from signal goroutine") +func badsystemstack() { + gothrow("systemstack called from unexpected goroutine") } -// C functions that run on the M stack. -// Call using mcall. -func gosched_m(*g) -func park_m(*g) -func recovery_m(*g) - -// More C functions that run on the M stack. -// Call using onM. -func mcacheRefill_m() -func largeAlloc_m() -func gc_m() -func gcscan_m() -func gcmark_m() -func gccheckmark_m() -func gccheckmarkenable_m() -func gccheckmarkdisable_m() -func gcinstallmarkwb_m() -func gcinstalloffwb_m() -func gcmarknewobject_m() -func gcmarkwb_m() -func finishsweep_m() -func scavenge_m() -func setFinalizer_m() -func removeFinalizer_m() -func markallocated_m() -func unrollgcprog_m() -func unrollgcproginplace_m() -func setgcpercent_m() -func setmaxthreads_m() -func ready_m() -func deferproc_m() -func goexit_m() -func startpanic_m() -func dopanic_m() -func readmemstats_m() -func writeheapdump_m() - // memclr clears n bytes starting at ptr. // in memclr_*.s //go:noescape @@ -142,12 +72,6 @@ func memclr(ptr unsafe.Pointer, n uintptr) //go:noescape func memmove(to unsafe.Pointer, from unsafe.Pointer, n uintptr) -func starttheworld() -func stoptheworld() -func newextram() -func lockOSThread() -func unlockOSThread() - // exported value for testing var hashLoad = loadFactor @@ -169,16 +93,9 @@ func noescape(p unsafe.Pointer) unsafe.Pointer { return unsafe.Pointer(x ^ 0) } -func entersyscall() -func reentersyscall(pc uintptr, sp unsafe.Pointer) -func entersyscallblock() -func exitsyscall() - func cgocallback(fn, frame unsafe.Pointer, framesize uintptr) func gogo(buf *gobuf) func gosave(buf *gobuf) -func read(fd int32, p unsafe.Pointer, n int32) int32 -func close(fd int32) int32 func mincore(addr unsafe.Pointer, n uintptr, dst *byte) int32 //go:noescape @@ -186,33 +103,32 @@ func jmpdefer(fv *funcval, argp uintptr) func exit1(code int32) func asminit() func setg(gg *g) -func exit(code int32) func breakpoint() -func nanotime() int64 -func usleep(usec uint32) - -// careful: cputicks is not guaranteed to be monotonic! In particular, we have -// noticed drift between cpus on certain os/arch combinations. See issue 8976. -func cputicks() int64 -func mmap(addr unsafe.Pointer, n uintptr, prot, flags, fd int32, off uint32) unsafe.Pointer -func munmap(addr unsafe.Pointer, n uintptr) -func madvise(addr unsafe.Pointer, n uintptr, flags int32) func reflectcall(fn, arg unsafe.Pointer, n uint32, retoffset uint32) -func osyield() func procyield(cycles uint32) func cgocallback_gofunc(fv *funcval, frame unsafe.Pointer, framesize uintptr) -func readgogc() int32 -func purgecachedstats(c *mcache) -func gostringnocopy(b *byte) string func goexit() //go:noescape -func write(fd uintptr, p unsafe.Pointer, n int32) int32 - -//go:noescape func cas(ptr *uint32, old, new uint32) bool +// casp cannot have a go:noescape annotation, because +// while ptr and old do not escape, new does. If new is marked as +// not escaping, the compiler will make incorrect escape analysis +// decisions about the value being xchg'ed. +// Instead, make casp a wrapper around the actual atomic. +// When calling the wrapper we mark ptr as noescape explicitly. + +//go:nosplit +func casp(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool { + return casp1((*unsafe.Pointer)(noescape(unsafe.Pointer(ptr))), noescape(old), new) +} + +func casp1(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool + +func nop() // call to prevent inlining of function body + //go:noescape func casuintptr(ptr *uintptr, old, new uintptr) bool @@ -268,18 +184,10 @@ func asmcgocall(fn, arg unsafe.Pointer) //go:noescape func asmcgocall_errno(fn, arg unsafe.Pointer) int32 -//go:noescape -func open(name *byte, mode, perm int32) int32 - -//go:noescape -func gotraceback(*bool) int32 - +// argp used in Defer structs when there is no argp. const _NoArgs = ^uintptr(0) -func newstack() -func newproc() func morestack() -func mstart() func rt0_go() // return0 is a stub used to return 0 from deferproc. @@ -321,3 +229,5 @@ func call134217728(fn, arg unsafe.Pointer, n, retoffset uint32) func call268435456(fn, arg unsafe.Pointer, n, retoffset uint32) func call536870912(fn, arg unsafe.Pointer, n, retoffset uint32) func call1073741824(fn, arg unsafe.Pointer, n, retoffset uint32) + +func systemstack_switch() |