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4f881115d4
Moving these intrinsics to a base package enables other internal/runtime packages to use them. For #54766. Change-Id: I45a530422207dd94b5ad4eee51216c9410a84040 Reviewed-on: https://go-review.googlesource.com/c/go/+/613261 Reviewed-by: Cherry Mui <cherryyz@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
58 lines
1.9 KiB
Go
58 lines
1.9 KiB
Go
// Copyright 2018 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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//go:build darwin || (openbsd && !mips64)
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package runtime
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import (
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"internal/runtime/sys"
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"unsafe"
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)
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// Call fn with arg as its argument. Return what fn returns.
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// fn is the raw pc value of the entry point of the desired function.
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// Switches to the system stack, if not already there.
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// Preserves the calling point as the location where a profiler traceback will begin.
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//
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//go:nosplit
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func libcCall(fn, arg unsafe.Pointer) int32 {
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// Leave caller's PC/SP/G around for traceback.
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gp := getg()
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var mp *m
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if gp != nil {
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mp = gp.m
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}
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if mp != nil && mp.libcallsp == 0 {
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mp.libcallg.set(gp)
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mp.libcallpc = sys.GetCallerPC()
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// sp must be the last, because once async cpu profiler finds
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// all three values to be non-zero, it will use them
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mp.libcallsp = sys.GetCallerSP()
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} else {
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// Make sure we don't reset libcallsp. This makes
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// libcCall reentrant; We remember the g/pc/sp for the
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// first call on an M, until that libcCall instance
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// returns. Reentrance only matters for signals, as
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// libc never calls back into Go. The tricky case is
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// where we call libcX from an M and record g/pc/sp.
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// Before that call returns, a signal arrives on the
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// same M and the signal handling code calls another
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// libc function. We don't want that second libcCall
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// from within the handler to be recorded, and we
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// don't want that call's completion to zero
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// libcallsp.
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// We don't need to set libcall* while we're in a sighandler
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// (even if we're not currently in libc) because we block all
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// signals while we're handling a signal. That includes the
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// profile signal, which is the one that uses the libcall* info.
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mp = nil
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}
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res := asmcgocall(fn, arg)
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if mp != nil {
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mp.libcallsp = 0
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}
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return res
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}
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