| /* |
| * mmap.c |
| */ |
| |
| #include <stdint.h> |
| #include <errno.h> |
| #include <sys/syscall.h> |
| #include <sys/mman.h> |
| #include <unistd.h> |
| #include <bitsize.h> |
| |
| /* |
| * Set in SYSCALLS whether or not we should use an unadorned mmap() system |
| * call (typical on 64-bit architectures). |
| */ |
| #if (_BITSIZE == 32 && defined(__NR_mmap2)) || (_BITSIZE == 64 && !defined(__NR_mmap)) |
| |
| /* |
| * Some architectures use a fixed value for MMAP2_SHIFT, other use the |
| * current page size. This, of course, isn't documented or even |
| * #define'd anywhere. |
| */ |
| #if defined(__cris__) || defined(__m68k__) || defined(__mips__) |
| /* Use the current page size */ |
| #else |
| # define MMAP2_SHIFT 12 /* Fixed by syscall definition */ |
| #endif |
| |
| |
| /* This architecture uses mmap2(). The Linux mmap2() system call takes |
| a page offset as the offset argument. We need to make sure we have |
| the proper conversion in place. */ |
| |
| extern void *__mmap2(void *, size_t, int, int, int, size_t); |
| |
| void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset) |
| { |
| #ifdef MMAP2_SHIFT |
| const int mmap2_shift = MMAP2_SHIFT; |
| #else |
| extern unsigned int __page_shift; |
| const int mmap2_shift = __page_shift; |
| #endif |
| extern unsigned int __page_size; |
| const unsigned int mmap2_mask = __page_size - 1; |
| |
| if ( offset & mmap2_mask ) { |
| errno = EINVAL; |
| return MAP_FAILED; |
| } |
| |
| return __mmap2(start, length, prot, flags, fd, (size_t)offset >> mmap2_shift); |
| } |
| |
| #endif |