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#include <errno.h>
#include <unistd.h>
#include "runtime.h"
#include "arch.h"
#include "malloc.h"
#ifndef MAP_ANON
#ifdef MAP_ANONYMOUS
#define MAP_ANON MAP_ANONYMOUS
#else
#define USE_DEV_ZERO
#define MAP_ANON 0
#endif
#endif
#ifdef USE_DEV_ZERO
static int dev_zero = -1;
#endif
static _Bool
addrspace_free(void *v __attribute__ ((unused)), uintptr n __attribute__ ((unused)))
{
#ifdef HAVE_MINCORE
size_t page_size = getpagesize();
size_t off;
char one_byte;
errno = 0;
for(off = 0; off < n; off += page_size)
if(mincore((char *)v + off, page_size, (void *)&one_byte) != -1
|| errno != ENOMEM)
return 0;
#endif
return 1;
}
void*
runtime_SysAlloc(uintptr n)
{
void *p;
int fd = -1;
mstats.sys += n;
#ifdef USE_DEV_ZERO
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}
fd = dev_zero;
#endif
p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
if (p == MAP_FAILED) {
if(errno == EACCES) {
printf("runtime: mmap: access denied\n");
printf("if you're running SELinux, enable execmem for this process.\n");
exit(2);
}
return nil;
}
return p;
}
void
runtime_SysUnused(void *v, uintptr n)
{
USED(v);
USED(n);
// TODO(rsc): call madvise MADV_DONTNEED
}
void
runtime_SysFree(void *v, uintptr n)
{
mstats.sys -= n;
runtime_munmap(v, n);
}
void*
runtime_SysReserve(void *v, uintptr n)
{
int fd = -1;
// On 64-bit, people with ulimit -v set complain if we reserve too
// much address space. Instead, assume that the reservation is okay
// and check the assumption in SysMap.
if(sizeof(void*) == 8)
return v;
#ifdef USE_DEV_ZERO
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}
fd = dev_zero;
#endif
return runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0);
}
void
runtime_SysMap(void *v, uintptr n)
{
void *p;
int fd = -1;
mstats.sys += n;
#ifdef USE_DEV_ZERO
if (dev_zero == -1) {
dev_zero = open("/dev/zero", O_RDONLY);
if (dev_zero < 0) {
printf("open /dev/zero: errno=%d\n", errno);
exit(2);
}
}
fd = dev_zero;
#endif
// On 64-bit, we don't actually have v reserved, so tread carefully.
if(sizeof(void*) == 8) {
p = runtime_mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
if(p != v && addrspace_free(v, n)) {
// On some systems, mmap ignores v without
// MAP_FIXED, so retry if the address space is free.
p = runtime_mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
}
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|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
if(p != v)
runtime_throw("runtime: cannot map pages in arena address space");
}
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