libgo/runtime/mem.c

   1 /* Defining _XOPEN_SOURCE hides the declaration of madvise() on Solaris <
   2    11 and the MADV_DONTNEED definition on IRIX 6.5.  */
   3 #undef _XOPEN_SOURCE
   4
   5 #include <errno.h>
   6 #include <unistd.h>
   7
   8 #include "runtime.h"
   9 #include "arch.h"
  10 #include "malloc.h"
  11
  12 #ifndef MAP_ANON
  13 #ifdef MAP_ANONYMOUS
  14 #define MAP_ANON MAP_ANONYMOUS
  15 #else
  16 #define USE_DEV_ZERO
  17 #define MAP_ANON 0
  18 #endif
  19 #endif
  20
  21 #ifndef MAP_NORESERVE
  22 #define MAP_NORESERVE 0
  23 #endif
  24
  25 #ifdef USE_DEV_ZERO
  26 static int dev_zero = -1;
  27 #endif
  28
  29 static _Bool
  30 addrspace_free(void *v __attribute__ ((unused)), uintptr n __attribute__ ((unused)))
  31 {
  32 #ifdef HAVE_MINCORE
  33         size_t page_size = getpagesize();
  34         size_t off;
  35         char one_byte;
  36
  37         errno = 0;
  38         for(off = 0; off < n; off += page_size)
  39                 if(mincore((char *)v + off, page_size, (void *)&one_byte) != -1
  40                    || errno != ENOMEM)
  41                         return 0;
  42 #endif
  43         return 1;
  44 }
  45
  46 static void *
  47 mmap_fixed(byte *v, uintptr n, int32 prot, int32 flags, int32 fd, uint32 offset)
  48 {
  49         void *p;
  50
  51         p = runtime_mmap((void *)v, n, prot, flags, fd, offset);
  52         if(p != v && addrspace_free(v, n)) {
  53                 // On some systems, mmap ignores v without
  54                 // MAP_FIXED, so retry if the address space is free.
  55                 if(p != MAP_FAILED)
  56                         runtime_munmap(p, n);
  57                 p = runtime_mmap((void *)v, n, prot, flags|MAP_FIXED, fd, offset);
  58         }
  59         return p;
  60 }
  61
  62 void*
  63 runtime_SysAlloc(uintptr n, uint64 *stat)
  64 {
  65         void *p;
  66         int fd = -1;
  67
  68 #ifdef USE_DEV_ZERO
  69         if (dev_zero == -1) {
  70                 dev_zero = open("/dev/zero", O_RDONLY);
  71                 if (dev_zero < 0) {
  72                         runtime_printf("open /dev/zero: errno=%d\n", errno);
  73                         exit(2);
  74                 }
  75         }
  76         fd = dev_zero;
  77 #endif
  78
  79         p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, fd, 0);
  80         if (p == MAP_FAILED) {
  81                 if(errno == EACCES) {
  82                         runtime_printf("runtime: mmap: access denied\n");
  83                         runtime_printf("if you're running SELinux, enable execmem for this process.\n");
  84                         exit(2);
  85                 }
  86                 if(errno == EAGAIN) {
  87                         runtime_printf("runtime: mmap: too much locked memory (check 'ulimit -l').\n");
  88                         runtime_exit(2);
  89                 }
  90                 return nil;
  91         }
  92         runtime_xadd64(stat, n);
  93         return p;
  94 }
  95
  96 void
  97 runtime_SysUnused(void *v __attribute__ ((unused)), uintptr n __attribute__ ((unused)))
  98 {
  99 #ifdef MADV_DONTNEED
 100         runtime_madvise(v, n, MADV_DONTNEED);
 101 #endif
 102 }
 103
 104 void
 105 runtime_SysUsed(void *v, uintptr n)
 106 {
 107         USED(v);
 108         USED(n);
 109 }
 110
 111 void
 112 runtime_SysFree(void *v, uintptr n, uint64 *stat)
 113 {
 114         runtime_xadd64(stat, -(uint64)n);
 115         runtime_munmap(v, n);
 116 }
 117
 118 void*
 119 runtime_SysReserve(void *v, uintptr n)
 120 {
 121         int fd = -1;
 122         void *p;
 123
 124 #ifdef USE_DEV_ZERO
 125         if (dev_zero == -1) {
 126                 dev_zero = open("/dev/zero", O_RDONLY);
 127                 if (dev_zero < 0) {
 128                         runtime_printf("open /dev/zero: errno=%d\n", errno);
 129                         exit(2);
 130                 }
 131         }
 132         fd = dev_zero;
 133 #endif
 134
 135         // On 64-bit, people with ulimit -v set complain if we reserve too
 136         // much address space.  Instead, assume that the reservation is okay
 137         // if we can reserve at least 64K and check the assumption in SysMap.
 138         // Only user-mode Linux (UML) rejects these requests.
 139         if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
 140                 p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0);
 141                 if (p != v) {
 142                         runtime_munmap(p, 64<<10);
 143                         return nil;
 144                 }
 145                 runtime_munmap(p, 64<<10);
 146                 return v;
 147         }
 148
 149         // Use the MAP_NORESERVE mmap() flag here because typically most of
 150         // this reservation will never be used. It does not make sense
 151         // reserve a huge amount of unneeded swap space. This is important on
 152         // systems which do not overcommit memory by default.
 153         p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_NORESERVE, fd, 0);
 154         if(p == MAP_FAILED)
 155                 return nil;
 156         return p;
 157 }
 158
 159 void
 160 runtime_SysMap(void *v, uintptr n, uint64 *stat)
 161 {
 162         void *p;
 163         int fd = -1;
 164
 165         runtime_xadd64(stat, n);
 166
 167 #ifdef USE_DEV_ZERO
 168         if (dev_zero == -1) {
 169                 dev_zero = open("/dev/zero", O_RDONLY);
 170                 if (dev_zero < 0) {
 171                         runtime_printf("open /dev/zero: errno=%d\n", errno);
 172                         exit(2);
 173                 }
 174         }
 175         fd = dev_zero;
 176 #endif
 177
 178         // On 64-bit, we don't actually have v reserved, so tread carefully.
 179         if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
 180                 p = mmap_fixed(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, fd, 0);
 181                 if(p == MAP_FAILED && errno == ENOMEM)
 182                         runtime_throw("runtime: out of memory");
 183                 if(p != v) {
 184                         runtime_printf("runtime: address space conflict: map(%p) = %p\n", v, p);
 185                         runtime_throw("runtime: address space conflict");
 186                 }
 187                 return;
 188         }
 189
 190         p = runtime_mmap(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
 191         if(p == MAP_FAILED && errno == ENOMEM)
 192                 runtime_throw("runtime: out of memory");
 193         if(p != v)
 194                 runtime_throw("runtime: cannot map pages in arena address space");
 195 }