Date: Thu, 7 Jan 1999 05:21:22 GMT From: assar@sics.se To: FreeBSD-gnats-submit@FreeBSD.ORG Cc: assar@sics.se Subject: kern/9359: implement support for adding syscalls in KLD modules Message-ID: <199901070521.FAA03912@mulet.e.kth.se>
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>Number: 9359
>Category: kern
>Synopsis: implement support for adding syscalls in KLD modules
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Wed Jan 6 21:30:01 PST 1999
>Closed-Date:
>Last-Modified:
>Originator: Assar Westerlund
>Release: FreeBSD 3.0-CURRENT i386
>Organization:
none
>Environment:
>Description:
KLD modules support loading of filesystems and devices but not of
system calls. Having this is quite practical. Otherwise a KLD module
does have to include the code itself for patch the sysent-table (the
code in syscall_register). Having that code once makes it more
transparent as well.
>How-To-Repeat:
>Fix:
I added the macros to sysent.h because it seemed to appropriate place.
I didn't find any appropriate place for the functions so I created a
new file kern_syscalls.c, but they could of course be placed somewhere
else.
--- sys/sysent.h 1999/01/03 05:23:22 1.1
+++ sys/sysent.h 1999/01/03 07:11:50
@@ -76,6 +76,36 @@
#ifdef KERNEL
extern struct sysentvec aout_sysvec;
extern struct sysent sysent[];
-#endif
+
+#define NO_SYSCALL (-1)
+
+struct module;
+
+struct syscall_module_data {
+ int (*chainevh)(struct module *, int, void *); /* next handler */
+ void *chainarg; /* arg for next event handler */
+ int offset; /* offset into sysent */
+ struct sysent *new_sysent; /* new sysent */
+ struct sysent old_sysent; /* old sysent */
+};
+
+#define SYSCALL_MODULE(name, offset, new_sysent, evh, arg) \
+static struct syscall_module_data name##_syscall_mod = { \
+ evh, arg, offset, new_sysent \
+}; \
+ \
+static moduledata_t name##_mod = { \
+ #name, \
+ syscall_module_handler, \
+ &name##_syscall_mod \
+}; \
+DECLARE_MODULE(name, name##_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE)
+
+int syscall_register __P((int *offset, struct sysent *new_sysent,
+ struct sysent *old_sysent));
+int syscall_deregister __P((int *offset, struct sysent *old_sysent));
+int syscall_module_handler __P((struct module *mod, int what, void *arg));
+
+#endif /* KERNEL */
#endif /* !_SYS_SYSENT_H_ */
--- conf/files 1999/01/03 06:00:36 1.1
+++ conf/files 1999/01/03 06:01:21
@@ -289,6 +289,7 @@
kern/kern_sig.c standard
kern/kern_subr.c standard
kern/kern_synch.c standard
+kern/kern_syscalls.c standard
kern/kern_sysctl.c standard
kern/kern_time.c standard
kern/kern_timeout.c standard
--- /dev/null Thu Jan 7 02:05:28 1999
+++ kern/kern_syscalls.c Sun Jan 3 06:59:07 1999
@@ -0,0 +1,94 @@
+/*-
+ * 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.
+ *
+ * $Id: kern_syscalls.c,v 1.1 1999/01/03 06:00:55 root Exp root $
+ */
+
+#include <sys/param.h>
+#include <sys/kernel.h>
+#include <sys/systm.h>
+#include <sys/malloc.h>
+#include <sys/sysproto.h>
+#include <sys/sysent.h>
+#include <sys/syscall.h>
+#include <sys/module.h>
+#include <sys/linker.h>
+#include <sys/proc.h>
+
+int
+syscall_register(int *offset, struct sysent *new_sysent,
+ struct sysent *old_sysent)
+{
+ if (*offset == NO_SYSCALL) {
+ int i;
+
+ for (i = 1; i < SYS_MAXSYSCALL; ++i)
+ if (sysent[i].sy_call == (sy_call_t *)lkmnosys)
+ break;
+ if (i == SYS_MAXSYSCALL)
+ return ENFILE;
+ *offset = i;
+ } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
+ return EINVAL;
+ else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys)
+ return EEXIST;
+
+ *old_sysent = sysent[*offset];
+ sysent[*offset] = *new_sysent;
+ return 0;
+}
+
+int
+syscall_deregister(int *offset, struct sysent *old_sysent)
+{
+ if (*offset)
+ sysent[*offset] = *old_sysent;
+ return 0;
+}
+
+int
+syscall_module_handler(struct module *mod, int what, void *arg)
+{
+ struct syscall_module_data *data = (struct syscall_module_data*)arg;
+ int error;
+
+ switch (what) {
+ case MOD_LOAD :
+ error = syscall_register(&data->offset, data->new_sysent,
+ &data->old_sysent);
+ if (error)
+ return error;
+ break;
+ case MOD_UNLOAD :
+ error = syscall_deregister(&data->offset, &data->old_sysent);
+ if (error)
+ return error;
+ break;
+ }
+ if (data->chainevh)
+ return data->chainevh(mod, what, data->chainarg);
+ else
+ return 0;
+}
>Release-Note:
>Audit-Trail:
>Unformatted:
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