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4a19081358
Also, crash early on non-Linux SMP ARM systems when GOARM < 7; without the proper synchronization, SMP cannot work. Linux is okay because we call kernel-provided routines for synchronization and barriers, and the kernel takes care of providing the right routines for the current system. On non-Linux systems we are left to fend for ourselves. It is possible to use different synchronization on GOARM=6, but it's too late to do that in the Go 1.5 cycle. We don't believe there are any non-Linux SMP GOARM=6 systems anyway. Fixes #12067. Change-Id: I771a556e47893ed540ec2cd33d23c06720157ea3 Reviewed-on: https://go-review.googlesource.com/13363 Reviewed-by: Austin Clements <austin@google.com>
36 lines
1.2 KiB
Go
36 lines
1.2 KiB
Go
// Copyright 2013 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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package runtime
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import "unsafe"
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func lwp_mcontext_init(mc *mcontextt, stk unsafe.Pointer, mp *m, gp *g, fn uintptr) {
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// Machine dependent mcontext initialisation for LWP.
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mc.__gregs[_REG_R15] = uint32(funcPC(lwp_tramp))
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mc.__gregs[_REG_R13] = uint32(uintptr(stk))
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mc.__gregs[_REG_R0] = uint32(uintptr(unsafe.Pointer(mp)))
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mc.__gregs[_REG_R1] = uint32(uintptr(unsafe.Pointer(gp)))
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mc.__gregs[_REG_R2] = uint32(fn)
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}
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func checkgoarm() {
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// TODO(minux): FP checks like in os_linux_arm.go.
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// osinit not called yet, so ncpu not set: must use getncpu directly.
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if getncpu() > 1 && goarm < 7 {
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print("runtime: this system has multiple CPUs and must use\n")
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print("atomic synchronization instructions. Recompile using GOARM=7.\n")
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exit(1)
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}
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}
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//go:nosplit
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func cputicks() int64 {
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// Currently cputicks() is used in blocking profiler and to seed runtime·fastrand1().
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// runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
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// TODO: need more entropy to better seed fastrand1.
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return nanotime()
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}
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