klibc/klibc/mmap.c

   1 /*
   2  * mmap.c
   3  */
   4
   5 #include <stdint.h>
   6 #include <errno.h>
   7 #include <sys/syscall.h>
   8 #include <sys/mman.h>
   9 #include <asm/page.h>           /* For PAGE_SHIFT */
  10
  11 #if defined(__sparc__)
  12 # define MMAP2_SHIFT    12      /* Fixed by syscall definition */
  13 #else
  14 # define MMAP2_SHIFT    PAGE_SHIFT
  15 #endif
  16 #define MMAP2_MASK      ((1UL << MMAP2_SHIFT)-1)
  17
  18 /*
  19  * Prefer mmap2() over mmap(), except on the architectures listed
  20  */
  21
  22 #if defined(__NR_mmap2) && !defined(__sparc__) && !defined(__ia64__)
  23
  24 /* This architecture uses mmap2() */
  25
  26 static inline _syscall6(void *,mmap2,void *,start,size_t,length,int,prot,int,flags,int,fd,off_t,offset);
  27
  28 /* The Linux mmap2() system call takes a page offset as the offset argument.
  29    We need to make sure we have the proper conversion in place. */
  30
  31 void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
  32 {
  33   if ( offset & MMAP2_MASK ) {
  34     errno = EINVAL;
  35     return MAP_FAILED;
  36   }
  37
  38   return mmap2(start, length, prot, flags, fd, (size_t)offset >> MMAP2_SHIFT);
  39 }
  40
  41 #else
  42
  43 /* This architecture uses a plain mmap() system call */
  44 /* Only use this for architectures where mmap() is a real 6-argument system call! */
  45
  46 _syscall6(void *,mmap,void *,start,size_t,length,int,prot,int,flags,int,fd,off_t,offset)
  47
  48 #endif
  49
  50
  51