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)
  64 {
  65         void *p;
  66         int fd = -1;
  67
  68         mstats.sys += n;
  69
  70 #ifdef USE_DEV_ZERO
  71         if (dev_zero == -1) {
  72                 dev_zero = open("/dev/zero", O_RDONLY);
  73                 if (dev_zero < 0) {
  74                         runtime_printf("open /dev/zero: errno=%d\n", errno);
  75                         exit(2);
  76                 }
  77         }
  78         fd = dev_zero;
  79 #endif
  80
  81         p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, fd, 0);
  82         if (p == MAP_FAILED) {
  83                 if(errno == EACCES) {
  84                         runtime_printf("runtime: mmap: access denied\n");
  85                         runtime_printf("if you're running SELinux, enable execmem for this process.\n");
  86                         exit(2);
  87                 }
  88                 if(errno == EAGAIN) {
  89                         runtime_printf("runtime: mmap: too much locked memory (check 'ulimit -l').\n");
  90                         runtime_exit(2);
  91                 }
  92                 return nil;
  93         }
  94         return p;
  95 }
  96
  97 void
  98 runtime_SysUnused(void *v __attribute__ ((unused)), uintptr n __attribute__ ((unused)))
  99 {
 100 #ifdef MADV_DONTNEED
 101         runtime_madvise(v, n, MADV_DONTNEED);
 102 #endif
 103 }
 104
 105 void
 106 runtime_SysFree(void *v, uintptr n)
 107 {
 108         mstats.sys -= n;
 109         runtime_munmap(v, n);
 110 }
 111
 112 void*
 113 runtime_SysReserve(void *v, uintptr n)
 114 {
 115         int fd = -1;
 116         void *p;
 117
 118 #ifdef USE_DEV_ZERO
 119         if (dev_zero == -1) {
 120                 dev_zero = open("/dev/zero", O_RDONLY);
 121                 if (dev_zero < 0) {
 122                         runtime_printf("open /dev/zero: errno=%d\n", errno);
 123                         exit(2);
 124                 }
 125         }
 126         fd = dev_zero;
 127 #endif
 128
 129         // On 64-bit, people with ulimit -v set complain if we reserve too
 130         // much address space.  Instead, assume that the reservation is okay
 131         // if we can reserve at least 64K and check the assumption in SysMap.
 132         // Only user-mode Linux (UML) rejects these requests.
 133         if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
 134                 p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0);
 135                 if (p != v)
 136                         return nil;
 137                 runtime_munmap(p, 64<<10);
 138                 return v;
 139         }
 140
 141         // Use the MAP_NORESERVE mmap() flag here because typically most of
 142         // this reservation will never be used. It does not make sense
 143         // reserve a huge amount of unneeded swap space. This is important on
 144         // systems which do not overcommit memory by default.
 145         p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE|MAP_NORESERVE, fd, 0);
 146         if(p == MAP_FAILED)
 147                 return nil;
 148         return p;
 149 }
 150
 151 void
 152 runtime_SysMap(void *v, uintptr n)
 153 {
 154         void *p;
 155         int fd = -1;
 156
 157         mstats.sys += n;
 158
 159 #ifdef USE_DEV_ZERO
 160         if (dev_zero == -1) {
 161                 dev_zero = open("/dev/zero", O_RDONLY);
 162                 if (dev_zero < 0) {
 163                         runtime_printf("open /dev/zero: errno=%d\n", errno);
 164                         exit(2);
 165                 }
 166         }
 167         fd = dev_zero;
 168 #endif
 169
 170         // On 64-bit, we don't actually have v reserved, so tread carefully.
 171         if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
 172                 p = mmap_fixed(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, fd, 0);
 173                 if(p == MAP_FAILED && errno == ENOMEM)
 174                         runtime_throw("runtime: out of memory");
 175                 if(p != v) {
 176                         runtime_printf("runtime: address space conflict: map(%p) = %p\n", v, p);
 177                         runtime_throw("runtime: address space conflict");
 178                 }
 179                 return;
 180         }
 181
 182         p = runtime_mmap(v, n, PROT_READ|PROT_WRITE, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
 183         if(p == MAP_FAILED && errno == ENOMEM)
 184                 runtime_throw("runtime: out of memory");
 185         if(p != v)
 186                 runtime_throw("runtime: cannot map pages in arena address space");
 187 }