152 lines
3.0 KiB
C
152 lines
3.0 KiB
C
#include <errno.h>
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#include <unistd.h>
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#include "runtime.h"
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#include "arch.h"
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#include "malloc.h"
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#ifndef MAP_ANON
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#ifdef MAP_ANONYMOUS
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#define MAP_ANON MAP_ANONYMOUS
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#else
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#define USE_DEV_ZERO
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#define MAP_ANON 0
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#endif
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#endif
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#ifdef USE_DEV_ZERO
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static int dev_zero = -1;
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#endif
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static _Bool
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addrspace_free(void *v __attribute__ ((unused)), uintptr n __attribute__ ((unused)))
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{
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#ifdef HAVE_MINCORE
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size_t page_size = getpagesize();
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size_t off;
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char one_byte;
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errno = 0;
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for(off = 0; off < n; off += page_size)
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if(mincore((char *)v + off, page_size, (void *)&one_byte) != -1
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|| errno != ENOMEM)
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return 0;
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#endif
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return 1;
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}
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void*
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runtime_SysAlloc(uintptr n)
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{
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void *p;
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int fd = -1;
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mstats.sys += n;
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#ifdef USE_DEV_ZERO
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if (dev_zero == -1) {
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dev_zero = open("/dev/zero", O_RDONLY);
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if (dev_zero < 0) {
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printf("open /dev/zero: errno=%d\n", errno);
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exit(2);
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}
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}
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fd = dev_zero;
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#endif
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p = runtime_mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
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if (p == MAP_FAILED) {
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if(errno == EACCES) {
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printf("runtime: mmap: access denied\n");
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printf("if you're running SELinux, enable execmem for this process.\n");
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exit(2);
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}
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return nil;
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}
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return p;
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}
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void
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runtime_SysUnused(void *v, uintptr n)
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{
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USED(v);
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USED(n);
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// TODO(rsc): call madvise MADV_DONTNEED
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}
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void
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runtime_SysFree(void *v, uintptr n)
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{
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mstats.sys -= n;
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runtime_munmap(v, n);
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}
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void*
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runtime_SysReserve(void *v, uintptr n)
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{
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int fd = -1;
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void *p;
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// On 64-bit, people with ulimit -v set complain if we reserve too
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// much address space. Instead, assume that the reservation is okay
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// and check the assumption in SysMap.
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if(sizeof(void*) == 8)
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return v;
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#ifdef USE_DEV_ZERO
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if (dev_zero == -1) {
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dev_zero = open("/dev/zero", O_RDONLY);
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if (dev_zero < 0) {
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printf("open /dev/zero: errno=%d\n", errno);
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exit(2);
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}
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}
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fd = dev_zero;
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#endif
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p = runtime_mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, fd, 0);
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if((uintptr)p < 4096 || -(uintptr)p < 4096) {
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return nil;
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}
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return p;
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}
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void
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runtime_SysMap(void *v, uintptr n)
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{
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void *p;
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int fd = -1;
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mstats.sys += n;
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#ifdef USE_DEV_ZERO
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if (dev_zero == -1) {
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dev_zero = open("/dev/zero", O_RDONLY);
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if (dev_zero < 0) {
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printf("open /dev/zero: errno=%d\n", errno);
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exit(2);
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}
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}
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fd = dev_zero;
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#endif
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// On 64-bit, we don't actually have v reserved, so tread carefully.
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if(sizeof(void*) == 8) {
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p = runtime_mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, fd, 0);
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if(p != v && addrspace_free(v, n)) {
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// On some systems, mmap ignores v without
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// MAP_FIXED, so retry if the address space is free.
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p = runtime_mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
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}
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if(p != v) {
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runtime_printf("runtime: address space conflict: map(%p) = %p\n", v, p);
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runtime_throw("runtime: address space conflict");
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}
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return;
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}
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p = runtime_mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, fd, 0);
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if(p != v)
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runtime_throw("runtime: cannot map pages in arena address space");
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}
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