// We want to trigger a bounds check on the g0 stack. To do this, we
	// need to call a splittable function through systemstack().
	// SetGCPercent contains such a systemstack call.
	gogc := debug.SetGCPercent(100)
	debug.SetGCPercent(gogc)
}

// Regression test for https://go.dev/issue/62440. It should be possible for C
// threads to call into Go from different stacks without crashing due to g0
// stack bounds checks.
//

	// signal stack of the creating thread. We always create a
	// new signal stack here, to avoid having two Go threads using
	// the same signal stack. This breaks the case of a thread
	// created in C that calls sigaltstack and then calls a Go
	// function, because we will lose track of the C code's
	// sigaltstack, but it's the best we can do.
	signalstack(&gp.m.gsignal.stack)
	gp.m.newSigstack = true

	on   bool     // profiling is on
	log  *profBuf // profile events written here

	// extra holds extra stacks accumulated in addNonGo
	// corresponding to profiling signals arriving on
	// non-Go-created threads. Those stacks are written
	// to log the next time a normal Go thread gets the
	// signal handler.
	// Assuming the stacks are 2 words each (we don't get
	// a full traceback from those threads), plus one word

be preempted, that must not grow the user stack, or that switch user
goroutines. Code running on the system stack is implicitly
non-preemptible and the garbage collector does not scan system stacks.
While running on the system stack, the current user stack is not used
for execution.

nosplit functions
-----------------

Most functions start with a prologue that inspects the stack pointer
and the current G's stack bound and calls `morestack` if the stack

// license that can be found in the LICENSE file.

//go:build !plan9 && !windows
// +build !plan9,!windows

// Test handling of Go-allocated signal stacks when calling from
// C-created threads with and without signal stacks. (See issue
// #22930.)

package main

/*
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>

#ifdef _AIX

				Counters:  make(map[string]int64),
				Stacks:    make(map[string]int64),
			}
			upload.Programs = append(upload.Programs, x)
			for k, v := range p.Counters {
				if cfg.HasCounter(p.Program, k) && report.X <= cfg.Rate(p.Program, k) {
					x.Counters[k] = v
				}
			}
			// and the same for Stacks
			// this can be made more efficient, when it matters
			for k, v := range p.Stacks {
				before, _, _ := strings.Cut(k, "\n")

// alternate signal stack. If the alternate signal stack is not set
// for the thread (the normal case) then set the alternate signal
// stack to the gsignal stack. If the alternate signal stack is set
// for the thread (the case when a non-Go thread sets the alternate
// signal stack and then calls a Go function) then set the gsignal
// stack to the alternate signal stack. We also set the alternate

func newosproc(mp *m) {
	stk := unsafe.Pointer(mp.g0.stack.hi)
	if false {
		print("newosproc stk=", stk, " m=", mp, " g=", mp.g0, " thr_start=", abi.FuncPCABI0(thr_start), " id=", mp.id, " ostk=", &mp, "\n")
	}

	param := thrparam{
		start_func: abi.FuncPCABI0(thr_start),
		arg:        unsafe.Pointer(mp),
		stack_base: mp.g0.stack.lo,
		stack_size: uintptr(stk) - mp.g0.stack.lo,
		child_tid:  nil, // minit will record tid

				x := s.base() + i*s.elemsize
				trace.HeapObjectExists(x, s.typePointersOfUnchecked(x).typ)
			}
			abits.advance()
		}
	}

	// Write out all the goroutine stacks.
	forEachGRace(func(gp *g) {
		trace.GoroutineStackExists(gp.stack.lo, gp.stack.hi-gp.stack.lo)
	})
	traceRelease(trace)
}

func traceSpanTypeAndClass(s *mspan) traceArg {
	if s.state.get() == mSpanInUse {
		return traceArg(s.spanclass) << 1
	}

	which goroutines were created, where N limits the number of ancestor goroutines to
	report. This also extends the information returned by runtime.Stack.
	Setting N to 0 will report no ancestry information.

	tracefpunwindoff: setting tracefpunwindoff=1 forces the execution tracer to
	use the runtime's default stack unwinder instead of frame pointer unwinding.