Date: Mon, 25 Oct 2010 15:01:01 -0700 From: Selphie Keller <selphie.keller@gmail.com> To: freebsd-hackers@freebsd.org Subject: SYSCALL_MODULE() macro and modfind() issues Message-ID: <AANLkTimVUzV3v9=y%2BWuuf%2B1fC4OYxD2Gs4j%2B=SO-M%2BP9@mail.gmail.com>
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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:
cat /usr/share/examples/kld/syscall/module/syscall.c
/*-
* Copyright (c) 1999 Assar Westerlund
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: src/share/examples/kld/syscall/module/syscall.c,v
1.6.2.1.4.1 2010/06/14 02:09:06 kensmith Exp $
*/
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/module.h>
#include <sys/sysproto.h>
#include <sys/sysent.h>
#include <sys/kernel.h>
#include <sys/systm.h>
/*
* The function for implementing the syscall.
*/
static int
hello(struct thread *td, void *arg)
{
printf("hello kernel\n");
return (0);
}
/*
* The `sysent' for the new syscall
*/
static struct sysent hello_sysent = {
0, /* sy_narg */
hello /* sy_call */
};
/*
* The offset in sysent where the syscall is allocated.
*/
static int offset = NO_SYSCALL;
/*
* The function called at load/unload.
*/
static int
load(struct module *module, int cmd, void *arg)
{
int error = 0;
switch (cmd) {
case MOD_LOAD :
printf("syscall loaded at %d\n", offset);
break;
case MOD_UNLOAD :
printf("syscall unloaded from %d\n", offset);
break;
default :
error = EOPNOTSUPP;
break;
}
return (error);
}
SYSCALL_MODULE(syscall, &offset, &hello_sysent, load, NULL);
---------------------------------------------------------------------------------------------------------------------
/* userland app to call syscall */
#include <stdio.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/module.h>
int main(int argc, char **argv) {
char *endptr;
int syscall_num;
struct module_stat stat;
/*Helloworld syscall test*/
stat.version = sizeof(stat);
modstat(modfind("syscall"), &stat);
syscall_num = stat.data.intval;
syscall (syscall_num);
}
---------------------------------------------------------------------------------------------------------------------
-Estella Mystagic (Selphie)
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