Add possibility to add flags to syscalls in syscalls.master to mark

syscalls as NOLOCK and MPSAFE. The flags have slightly different semantics:
 NOLOCK - the syscall doesn't grab any locks whatsoever.
 MPSAFE - the syscall deals with its own locking.

What this means in practice is that NOLOCK syscalls can always be done
without the biglock. The MPSAFE syscalls can be done without the biglock
on CPUs that don't handle interrupts that require biglock (to preserve
lock ordering).

deraadt@ ok

2 files changed, 20 insertions, 6 deletions

diff --git a/sys/kern/makesyscalls.sh b/sys/kern/makesyscalls.sh
index e641fe5df65..1f162b3fda3 100644
--- a/sys/kern/makesyscalls.sh
+++ b/sys/kern/makesyscalls.sh
@@ -1,5 +1,5 @@
 #! /bin/sh -
-#	$OpenBSD: makesyscalls.sh,v 1.10 2002/03/14 23:44:37 millert Exp $
+#	$OpenBSD: makesyscalls.sh,v 1.11 2007/11/27 18:04:01 art Exp $
 #	$NetBSD: makesyscalls.sh,v 1.26 1998/01/09 06:17:51 thorpej Exp $
 #
 # Copyright (c) 1994,1996 Christopher G. Demetriou
@@ -247,6 +247,7 @@ function parserr(was, wanted) {
 }
 function parseline() {
 	f=3			# toss number and type
+	sycall_flags="0"
 	if ($NF != "}") {
 		funcalias=$NF
 		end=NF-1
@@ -254,6 +255,14 @@ function parseline() {
 		funcalias=""
 		end=NF
 	}
+	if ($f == "MPSAFE") {		# allow MP-safe syscalls
+		sycall_flags = sprintf("SY_MPSAFE | %s", sycall_flags)
+		f++
+	}
+	if ($f == "NOLOCK") {		# syscall does not need locks
+		sycall_flags = sprintf("SY_NOLOCK | %s", sycall_flags)
+		f++
+	}
 	if ($f ~ /^[a-z0-9_]*$/) {      # allow syscall alias
 		funcalias=$f
 		f++
@@ -359,8 +368,8 @@ function putent(nodefs, compatwrap) {
 
 	# output syscall switch entry
 	if (nodefs == "INDIR") {
-		printf("\t{ 0, 0,\n\t    sys_nosys },\t\t\t/* %d = %s (indir) */\n", \
-		    syscall, funcalias) > sysent
+		printf("\t{ 0, 0, %s,\n\t    sys_nosys },\t\t\t/* %d = %s (indir) */\n", \
+		    sycall_flags, syscall, funcalias) > sysent
 	} else {
 #		printf("\t{ { %d", argc) > sysent
 #		for (i = 1; i <= argc; i++) {
@@ -382,7 +391,7 @@ function putent(nodefs, compatwrap) {
 			wfn = sprintf("%s", funcname);
 		else
 			wfn = sprintf("%s(%s)", compatwrap, funcname);
-		printf(",\n\t    %s },", wfn) > sysent
+		printf(", %s,\n\t    %s },", sycall_flags, wfn) > sysent
 		for (i = 0; i < (33 - length(wfn)) / 8; i++)
 			printf("\t") > sysent
 		if (compatwrap == "")
@@ -451,7 +460,7 @@ $2 == "OBSOL" || $2 == "UNIMPL" {
 	for (i = 3; i <= NF; i++)
 		comment=comment " " $i
 
-	printf("\t{ 0, 0,\n\t    sys_nosys },\t\t\t/* %d = %s */\n", \
+	printf("\t{ 0, 0, 0,\n\t    sys_nosys },\t\t\t/* %d = %s */\n", \
 	    syscall, comment) > sysent
 	printf("\t\"#%d (%s)\",\t\t/* %d = %s */\n", \
 	    syscall, comment, syscall, comment) > sysnames
diff --git a/sys/sys/systm.h b/sys/sys/systm.h
index 2e36c9997cc..abddd429c1c 100644
--- a/sys/sys/systm.h
+++ b/sys/sys/systm.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: systm.h,v 1.72 2007/06/01 19:25:08 deraadt Exp $	*/
+/*	$OpenBSD: systm.h,v 1.73 2007/11/27 18:04:01 art Exp $	*/
 /*	$NetBSD: systm.h,v 1.50 1996/06/09 04:55:09 briggs Exp $	*/
 
 /*-
@@ -110,8 +110,13 @@ typedef int	sy_call_t(struct proc *, void *, register_t *);
 extern struct sysent {		/* system call table */
 	short	sy_narg;	/* number of args */
 	short	sy_argsize;	/* total size of arguments */
+	int	sy_flags;
 	sy_call_t *sy_call;	/* implementing function */
 } sysent[];
+
+#define SY_MPSAFE		0x01
+#define SY_NOLOCK		0x02
+
 #if	_BYTE_ORDER == _BIG_ENDIAN
 #define SCARG(p, k)	((p)->k.be.datum)	/* get arg from args pointer */
 #elif	_BYTE_ORDER == _LITTLE_ENDIAN