Source file src/runtime/mem_darwin.go

     1	// Copyright 2018 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	package runtime
     6	
     7	import (
     8		"unsafe"
     9	)
    10	
    11	// Don't split the stack as this function may be invoked without a valid G,
    12	// which prevents us from allocating more stack.
    13	//go:nosplit
    14	func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer {
    15		v, err := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0)
    16		if err != 0 {
    17			return nil
    18		}
    19		mSysStatInc(sysStat, n)
    20		return v
    21	}
    22	
    23	func sysUnused(v unsafe.Pointer, n uintptr) {
    24		// MADV_FREE_REUSABLE is like MADV_FREE except it also propagates
    25		// accounting information about the process to task_info.
    26		madvise(v, n, _MADV_FREE_REUSABLE)
    27	}
    28	
    29	func sysUsed(v unsafe.Pointer, n uintptr) {
    30		// MADV_FREE_REUSE is necessary to keep the kernel's accounting
    31		// accurate. If called on any memory region that hasn't been
    32		// MADV_FREE_REUSABLE'd, it's a no-op.
    33		madvise(v, n, _MADV_FREE_REUSE)
    34	}
    35	
    36	func sysHugePage(v unsafe.Pointer, n uintptr) {
    37	}
    38	
    39	// Don't split the stack as this function may be invoked without a valid G,
    40	// which prevents us from allocating more stack.
    41	//go:nosplit
    42	func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) {
    43		mSysStatDec(sysStat, n)
    44		munmap(v, n)
    45	}
    46	
    47	func sysFault(v unsafe.Pointer, n uintptr) {
    48		mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0)
    49	}
    50	
    51	func sysReserve(v unsafe.Pointer, n uintptr) unsafe.Pointer {
    52		flags := int32(_MAP_ANON | _MAP_PRIVATE)
    53		if raceenabled {
    54			// Currently the race detector expects memory to live within a certain
    55			// range, and on Darwin 10.10 mmap is prone to ignoring hints, moreso
    56			// than later versions and other BSDs (#26475). So, even though it's
    57			// potentially dangerous to MAP_FIXED, we do it in the race detection
    58			// case because it'll help maintain the race detector's invariants.
    59			//
    60			// TODO(mknyszek): Drop this once support for Darwin 10.10 is dropped,
    61			// and reconsider this when #24133 is addressed.
    62			flags |= _MAP_FIXED
    63		}
    64		p, err := mmap(v, n, _PROT_NONE, flags, -1, 0)
    65		if err != 0 {
    66			return nil
    67		}
    68		return p
    69	}
    70	
    71	const _ENOMEM = 12
    72	
    73	func sysMap(v unsafe.Pointer, n uintptr, sysStat *uint64) {
    74		mSysStatInc(sysStat, n)
    75	
    76		p, err := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0)
    77		if err == _ENOMEM {
    78			throw("runtime: out of memory")
    79		}
    80		if p != v || err != 0 {
    81			throw("runtime: cannot map pages in arena address space")
    82		}
    83	}
    84	

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