diff options
Diffstat (limited to 'test/mmap/mmap-arm.c')
-rw-r--r-- | test/mmap/mmap-arm.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/test/mmap/mmap-arm.c b/test/mmap/mmap-arm.c new file mode 100644 index 000000000..8b94c6199 --- /dev/null +++ b/test/mmap/mmap-arm.c @@ -0,0 +1,46 @@ +/* When trying to map /dev/mem with offset 0xFFFFF000 on the ARM platform, mmap + * returns -EOVERFLOW. + * + * Since off_t is defined as a long int and the sign bit is set in the address, + * the shift operation shifts in ones instead of zeroes + * from the left. This results the offset sent to the kernel function becomes + * 0xFFFFFFFF instead of 0x000FFFFF with MMAP2_PAGE_SHIFT set to 12. + */ + +#include <unistd.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/mman.h> + +#define FATAL do { fprintf(stderr, "Error at line %d, file %s (%d) [%s]\n", \ + __LINE__, __FILE__, errno, strerror(errno)); exit(1); } while(0) + +#define MAP_SIZE 4096UL +#define MAP_MASK (MAP_SIZE - 1) + +int main(int argc, char **argv) { + void* map_base = 0; + int fd; + off_t target = 0xfffff000; + if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) { + /* skip test for non-root users */ + if (errno == EACCES) + return 0; + FATAL; + } + printf("/dev/mem opened.\n"); + fflush(stdout); + + /* Map one page */ + map_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, + fd, target & ~MAP_MASK); + if(map_base == (void *) -1) FATAL; + printf("Memory mapped at address %p.\n", map_base); + fflush(stdout); + if(munmap(map_base, MAP_SIZE) == -1) FATAL; + close(fd); + return 0; +} |