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// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "runtime.h"
#include "arch_GOARCH.h"
#include "defs_GOOS_GOARCH.h"
#include "os_GOOS.h"
#include "malloc.h"
enum
{
_PAGE_SIZE = 4096,
EACCES = 13,
};
static int32
addrspace_free(void *v, uintptr n)
{
int32 errval;
uintptr chunk;
uintptr off;
// NOTE: vec must be just 1 byte long here.
// Mincore returns ENOMEM if any of the pages are unmapped,
// but we want to know that all of the pages are unmapped.
// To make these the same, we can only ask about one page
// at a time. See golang.org/issue/7476.
static byte vec[1];
for(off = 0; off < n; off += chunk) {
chunk = _PAGE_SIZE * sizeof vec;
if(chunk > (n - off))
chunk = n - off;
errval = runtime·mincore((int8*)v + off, chunk, vec);
// ENOMEM means unmapped, which is what we want.
// Anything else we assume means the pages are mapped.
if (errval != -ENOMEM)
return 0;
}
return 1;
}
static void *
mmap_fixed(byte *v, uintptr n, int32 prot, int32 flags, int32 fd, uint32 offset)
{
void *p;
p = runtime·mmap(v, n, prot, flags, fd, offset);
if(p != v && addrspace_free(v, n)) {
// On some systems, mmap ignores v without
// MAP_FIXED, so retry if the address space is free.
if(p > (void*)4096)
runtime·munmap(p, n);
p = runtime·mmap(v, n, prot, flags|MAP_FIXED, fd, offset);
}
return p;
}
void*
runtime·SysAlloc(uintptr n, uint64 *stat)
{
void *p;
p = runtime·mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
if(p < (void*)4096) {
if(p == (void*)EACCES) {
runtime·printf("runtime: mmap: access denied\n");
runtime·printf("if you're running SELinux, enable execmem for this process.\n");
runtime·exit(2);
}
if(p == (void*)EAGAIN) {
runtime·printf("runtime: mmap: too much locked memory (check 'ulimit -l').\n");
runtime·exit(2);
}
return nil;
}
runtime·xadd64(stat, n);
return p;
}
void
runtime·SysUnused(void *v, uintptr n)
{
runtime·madvise(v, n, MADV_DONTNEED);
}
void
runtime·SysUsed(void *v, uintptr n)
{
USED(v);
USED(n);
}
void
runtime·SysFree(void *v, uintptr n, uint64 *stat)
{
runtime·xadd64(stat, -(uint64)n);
runtime·munmap(v, n);
}
void
runtime·SysFault(void *v, uintptr n)
{
runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0);
}
void*
runtime·SysReserve(void *v, uintptr n, bool *reserved)
{
void *p;
// On 64-bit, people with ulimit -v set complain if we reserve too
// much address space. Instead, assume that the reservation is okay
// if we can reserve at least 64K and check the assumption in SysMap.
// Only user-mode Linux (UML) rejects these requests.
if(sizeof(void*) == 8 && n > 1LL<<32) {
p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
if (p != v) {
if(p >= (void*)4096)
runtime·munmap(p, 64<<10);
return nil;
}
runtime·munmap(p, 64<<10);
*reserved = false;
return v;
}
p = runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
if((uintptr)p < 4096)
return nil;
*reserved = true;
return p;
}
void
runtime·SysMap(void *v, uintptr n, bool reserved, uint64 *stat)
{
void *p;
runtime·xadd64(stat, n);
// On 64-bit, we don't actually have v reserved, so tread carefully.
if(!reserved) {
p = mmap_fixed(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
if(p == (void*)ENOMEM)
runtime·throw("runtime: out of memory");
if(p != v) {
runtime·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
runtime·throw("runtime: address space conflict");
}
return;
}
p = runtime·mmap(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
if(p == (void*)ENOMEM)
runtime·throw("runtime: out of memory");
if(p != v)
runtime·throw("runtime: cannot map pages in arena address space");
}
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