SYSCALL_MODULE() macro and modfind() issues

[John Baldwin]

On Tuesday, October 26, 2010 4:00:14 am Selphie Keller wrote:
> Thanks Andriy,
> 
> Took a look at the change to src/sys/sys/sysent.h
> 
> @@ -149,7 +149,7 @@ static struct syscall_module_data name##
>  };                                                             \
>                                                                 \
>  static moduledata_t name##_mod = {                             \
> -       #name,                                                  \
> +       "sys/" #name,                                           \
>         syscall_module_handler,                                 \
>         &name##_syscall_mod                                     \
>  };                                                             \
> 
> applied the MFC prefix to pmap port:
> 
> --- /usr/ports/sysutils/pmap/work/pmap/pmap/pmap.c.orig 2010-10-26
> 00:55:32.000000000 -0700
> +++ /usr/ports/sysutils/pmap/work/pmap/pmap/pmap.c      2010-10-26
> 00:56:10.000000000 -0700
> @@ -86,12 +86,12 @@ main(int argc, char **argv)
>      struct kinfo_proc *kp;
>      int        pmap_helper_syscall;
> 
> -    if ((modid = modfind("pmap_helper")) == -1) {
> +    if ((modid = modfind("sys/pmap_helper")) == -1) {
>                 /* module not found, try to load */
>                 modid = kldload("pmap_helper.ko");
>                 if (modid == -1)
>                         err(1, "unable to load pmap_helper module");
> -               modid = modfind("pmap_helper");
> +               modid = modfind("sys/pmap_helper");
>                 if (modid == -1)
>                         err(1, "pmap_helper module loaded but not found");
>         }
> 
> which restored functionality on freebsd 8.1.

The best approach might be to have something like this:

static int
pmap_find(void)
{
	int modid;

	modid = modfind("pmap_helper");
	if (modid == -1)
		modid = modfind("sys/pmap_helper");
	return (modid);
}

then in the original main() routine use this:

	if ((modid = pmap_find()) == -1) {
		/* module not found, try to load */
		modid  = kldload("pmap_helper.ko");
		if (modid == -1)
			err(1, "unable to load pmap_helper module");
		modid = pmap_find();
		if (modid == -1)
			err(1, "pmap_helper module loaded but not found");
	}

This would make the code work for both old and new versions.

> -Estella Mystagic (Selphie)
> 
> On Tue, Oct 26, 2010 at 12:28 AM, Andriy Gapon <avg at icyb.net.ua> wrote:
> > on 26/10/2010 01:01 Selphie Keller said the following:
> >> hi fbsd-hackers,
> >>
> >> Noticed a issue in 8.1-release, 8.1p1-release and 8.1-stable
> >> amd64/i386, to where modfind() will no longer find pmap_helper for the
> >> /usr/ports/sysutils/pmap port, or other syscall modules using
> >> SYSCALL_MODULE() macro.
> >> The issue is that modfind() function no longer finds any modules using
> >> SYSCALL_MODULE() macro to register the kernel module. Making it
> >> difficult for userland apps to call the syscall provided. modfind()
> >> always returns -1 which prevents modstat() from getting the required
> >> information to perform the syscall.
> >>
> >> Also tested, the demo syscall module:
> >
> > After commit r205320 and, apparently, its MFC you need to prefix the 
module with
> > "sys/".  For example:
> > modstat(modfind("sys/syscall"), &stat);
> >
> > P.S.
> > Perhaps a KPI breakage in a stable branch?
> > --
> > Andriy Gapon
> >
> _______________________________________________
> freebsd-hackers at freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> To unsubscribe, send any mail to "freebsd-hackers-unsubscribe at freebsd.org"
> 

-- 
John Baldwin