On Tue, May 3, 2016 at 3:51 PM, Russell King <rmk at arm.linux.org.uk> wrote:
> The man page for mmap() and munmap() says that mmap() and munmap()
> only works for page-aligned addresses, sizes and offsets. Arrange
> to give these interfaces what they want.
>
If I read correctly, it talks only offsets to be page aligned.
> Signed-off-by: Russell King <rmk at arm.linux.org.uk>
Anyway, changes looks good to me.
Reviewed-by: Pratyush Anand <panand at redhat.com>
> ---
> kdump/kdump.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/kdump/kdump.c b/kdump/kdump.c
> index 821ee7c..3247a54 100644
> --- a/kdump/kdump.c
> +++ b/kdump/kdump.c
> @@ -25,22 +25,35 @@
> #define MAP_WINDOW_SIZE (64*1024*1024)
> #define DEV_MEM "/dev/mem"
>
> +#define ALIGN_MASK(x,y) (((x) + (y)) & ~(y))
> +#define ALIGN(x,y) ALIGN_MASK(x, (y) - 1)
> +
> static void *map_addr(int fd, unsigned long size, off_t offset)
> {
> + unsigned long page_size = getpagesize();
> + unsigned long map_offset = offset & (page_size - 1);
> + size_t len = ALIGN(size + map_offset, page_size);
> void *result;
> - result = mmap(0, size, PROT_READ, MAP_SHARED, fd, offset);
> +
> + result = mmap(0, len, PROT_READ, MAP_SHARED, fd, offset - map_offset);
> if (result == MAP_FAILED) {
> fprintf(stderr, "Cannot mmap " DEV_MEM " offset: %llu size: %lu: %s\n",
> (unsigned long long)offset, size, strerror(errno));
> exit(5);
> }
> - return result;
> + return result + map_offset;
> }
>
> static void unmap_addr(void *addr, unsigned long size)
> {
> + unsigned long page_size = getpagesize();
> + unsigned long map_offset = (uintptr_t)addr & (page_size - 1);
> + size_t len = ALIGN(size + map_offset, page_size);
> int ret;
> - ret = munmap(addr, size);
> +
> + addr -= map_offset;
> +
> + ret = munmap(addr, len);
> if (ret < 0) {
> fprintf(stderr, "munmap failed: %s\n",
> strerror(errno));
> --
> 1.9.1
>
