Re: [PATCH 1/5] perf tests: Add tip/pid mmap automated tests

[Jiri Olsa <jolsa@redhat.com>]

On Mon, Mar 17, 2014 at 01:50:12PM +0900, Namhyung Kim wrote:
> Hi Jiri,
> 
> On Fri, 14 Mar 2014 15:00:02 +0100, Jiri Olsa wrote:
> > +static int thread_init(struct thread_data *td)
> > +{
> > +	void *map;
> > +
> > +	map = mmap(NULL, page_size, PROT_READ|PROT_WRITE,
> > +		   MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> 
> Shouldn't it be an executable mapping to be found by MAP__FUNCTION?

yea.. looks like my arch implies PROT_EXEC via PROT_READ, man mmap:

  On some hardware architectures (e.g., i386), PROT_WRITE implies PROT_READ.   It  is  architecture  dependent  whether  PROT_READ
  implies PROT_EXEC or not.  Portable programs should always set PROT_EXEC if they intend to execute code in the new mapping.


mm/mmap.c:

        /*
         * Does the application expect PROT_READ to imply PROT_EXEC?
         *
         * (the exception is when the underlying filesystem is noexec
         *  mounted, in which case we dont add PROT_EXEC.)
         */
        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
                        prot |= PROT_EXEC;


I'll set the PROT_EXEC as the man page says.


thanks,
jirka