On Friday, November 06, 2015 02:07:23 PM Jan Stancek wrote:
> This test failed on ppc64 with 64k pagesize because memory
> allocation used mmap() instead of advancing heap.
>
> Use mallopt(M_MMAP_THRESHOLD,..) with large enough value
> to discourage use of mmap().
>
> Also set length in mprotect to pagesize, kernel silently aligns
> it to pagesize anyway.
>
> Signed-off-by: Jan Stancek <jstancek@xxxxxxxxxx>
> Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
> Cc: Stephen Smalley <sds@xxxxxxxxxxxxx>
> ---
> tests/mmap/mprotect_heap.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/tests/mmap/mprotect_heap.c b/tests/mmap/mprotect_heap.c
> index 691299493c3f..8b4321d6fc0b 100644
> --- a/tests/mmap/mprotect_heap.c
> +++ b/tests/mmap/mprotect_heap.c
> @@ -3,6 +3,7 @@
> #include <stdlib.h>
> #include <errno.h>
> #include <sys/mman.h>
> +#include <malloc.h>
>
> int main(void)
> {
> @@ -10,13 +11,19 @@ int main(void)
> int rc;
> int pagesize = getpagesize();
>
> + rc = mallopt(M_MMAP_THRESHOLD, pagesize * 16);
> + if (rc != 1) {
> + fprintf(stderr, "mallopt failed: %d\n", rc);
> + exit(1);
> + }
Can you explain how you arrived at 16? It looks a bit like a magic number to
me, which always gives me pause. Based on a quick read of the man page, it
would seem like any value greater than "pagesize" would work, yes?
> rc = posix_memalign(&ptr, pagesize, pagesize);
> if (rc) {
> fprintf(stderr, "posix_memalign failed: %d\n", rc);
> exit(1);
> }
>
> - rc = mprotect(ptr, 4096, PROT_READ | PROT_EXEC);
> + rc = mprotect(ptr, pagesize, PROT_READ | PROT_EXEC);
> if (rc < 0) {
> perror("mprotect");
> exit(1);
--
paul moore
www.paul-moore.com
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