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 package runtime 6 7 import "unsafe" 8 9 // Don't split the stack as this function may be invoked without a valid G, 10 // which prevents us from allocating more stack. 11 //go:nosplit 12 func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer { 13 v := mmap(nil, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_PRIVATE, -1, 0) 14 if uintptr(v) < 4096 { 15 return nil 16 } 17 mSysStatInc(sysStat, n) 18 return v 19 } 20 21 func sysUnused(v unsafe.Pointer, n uintptr) { 22 // Linux's MADV_DONTNEED is like BSD's MADV_FREE. 23 madvise(v, n, _MADV_FREE) 24 } 25 26 func sysUsed(v unsafe.Pointer, n uintptr) { 27 } 28 29 // Don't split the stack as this function may be invoked without a valid G, 30 // which prevents us from allocating more stack. 31 //go:nosplit 32 func sysFree(v unsafe.Pointer, n uintptr, sysStat *uint64) { 33 mSysStatDec(sysStat, n) 34 munmap(v, n) 35 } 36 37 func sysFault(v unsafe.Pointer, n uintptr) { 38 mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE|_MAP_FIXED, -1, 0) 39 } 40 41 func sysReserve(v unsafe.Pointer, n uintptr, reserved *bool) unsafe.Pointer { 42 *reserved = true 43 p := mmap(v, n, _PROT_NONE, _MAP_ANON|_MAP_PRIVATE, -1, 0) 44 if uintptr(p) < 4096 { 45 return nil 46 } 47 return p 48 } 49 50 const ( 51 _ENOMEM = 12 52 ) 53 54 func sysMap(v unsafe.Pointer, n uintptr, reserved bool, sysStat *uint64) { 55 mSysStatInc(sysStat, n) 56 p := mmap(v, n, _PROT_READ|_PROT_WRITE, _MAP_ANON|_MAP_FIXED|_MAP_PRIVATE, -1, 0) 57 if uintptr(p) == _ENOMEM { 58 throw("runtime: out of memory") 59 } 60 if p != v { 61 throw("runtime: cannot map pages in arena address space") 62 } 63 } 64
