mem_bsd.go

Documentation: runtime

		 1  // Copyright 2010 The Go Authors. All rights reserved.
		 2  // Use of this source code is governed by a BSD-style
		 3  // license that can be found in the LICENSE file.
		 4  
		 5  //go:build dragonfly || freebsd || netbsd || openbsd || solaris
		 6  // +build dragonfly freebsd netbsd openbsd solaris
		 7  
		 8  package runtime
		 9  
		10  import (
		11  	"unsafe"
		12  )
		13  
		14  // Don't split the stack as this function may be invoked without a valid G,
		15  // which prevents us from allocating more stack.
		16  //go:nosplit
		17  func sysAlloc(n uintptr, sysStat *sysMemStat) unsafe.Pointer {
		18  	v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
		19  	if err != 0 {
		20  		return nil
		21  	}
		22  	sysStat.add(int64(n))
		23  	return v
		24  }
		25  
		26  func sysUnused(v unsafe.Pointer, n uintptr) {
		27  	madvise(v, n, _MADV_FREE)
		28  }
		29  
		30  func sysUsed(v unsafe.Pointer, n uintptr) {
		31  }
		32  
		33  func sysHugePage(v unsafe.Pointer, n uintptr) {
		34  }
		35  
		36  // Don't split the stack as this function may be invoked without a valid G,
		37  // which prevents us from allocating more stack.
		38  //go:nosplit
		39  func sysFree(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
		40  	sysStat.add(-int64(n))
		41  	munmap(v, n)
		42  }
		43  
		44  func sysFault(v unsafe.Pointer, n uintptr) {
		45  	mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
		46  }
		47  
		48  // Indicates not to reserve swap space for the mapping.
		49  const _sunosMAP_NORESERVE = 0x40
		50  
		51  func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
		52  	flags := int32(_MAP_ANON | _MAP_PRIVATE)
		53  	if GOOS == "solaris" || GOOS == "illumos" {
		54  		// Be explicit that we don't want to reserve swap space
		55  		// for PROT_NONE anonymous mappings. This avoids an issue
		56  		// wherein large mappings can cause fork to fail.
		57  		flags |= _sunosMAP_NORESERVE
		58  	}
		59  	p, err := mmap(v, n, _PROT_NONE, flags, -1, 0)
		60  	if err != 0 {
		61  		return nil
		62  	}
		63  	return p
		64  }
		65  
		66  const _sunosEAGAIN = 11
		67  const _ENOMEM = 12
		68  
		69  func sysMap(v unsafe.Pointer, n uintptr, sysStat *sysMemStat) {
		70  	sysStat.add(int64(n))
		71  
		72  	p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
		73  	if err == _ENOMEM || ((GOOS == "solaris" || GOOS == "illumos") && err == _sunosEAGAIN) {
		74  		throw("runtime: out of memory")
		75  	}
		76  	if p != v || err != 0 {
		77  		throw("runtime: cannot map pages in arena address space")
		78  	}
		79  }
		80
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