Fri Aug 7 19:34:46 2009 UTC ()
Add text to the description saying that normal applications should not
use syscall().
Add text to bugs saying that high bits of the syscall number may be masked.
Fixes bug PR/11088


(dsl)
diff -r1.17 -r1.18 src/lib/libc/sys/syscall.2
cvs diff -r1.17 -r1.18 src/lib/libc/sys/syscall.2 (expand / switch to unified diff)

--- src/lib/libc/sys/syscall.2 2007/11/23 20:29:40 1.17
+++ src/lib/libc/sys/syscall.2 2009/08/07 19:34:46 1.18
@@ -1,14 +1,14 @@ @@ -1,14 +1,14 @@
1.\" $NetBSD: syscall.2,v 1.17 2007/11/23 20:29:40 dsl Exp $ 1.\" $NetBSD: syscall.2,v 1.18 2009/08/07 19:34:46 dsl Exp $
2.\" 2.\"
3.\" Copyright (c) 1980, 1991, 1993 3.\" Copyright (c) 1980, 1991, 1993
4.\" The Regents of the University of California. All rights reserved. 4.\" The Regents of the University of California. All rights reserved.
5.\" 5.\"
6.\" Redistribution and use in source and binary forms, with or without 6.\" Redistribution and use in source and binary forms, with or without
7.\" modification, are permitted provided that the following conditions 7.\" modification, are permitted provided that the following conditions
8.\" are met: 8.\" are met:
9.\" 1. Redistributions of source code must retain the above copyright 9.\" 1. Redistributions of source code must retain the above copyright
10.\" notice, this list of conditions and the following disclaimer. 10.\" notice, this list of conditions and the following disclaimer.
11.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\" notice, this list of conditions and the following disclaimer in the 12.\" notice, this list of conditions and the following disclaimer in the
13.\" documentation and/or other materials provided with the distribution. 13.\" documentation and/or other materials provided with the distribution.
14.\" 3. Neither the name of the University nor the names of its contributors 14.\" 3. Neither the name of the University nor the names of its contributors
@@ -19,27 +19,27 @@ @@ -19,27 +19,27 @@
19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28.\" SUCH DAMAGE. 28.\" SUCH DAMAGE.
29.\" 29.\"
30.\" @(#)syscall.2 8.1 (Berkeley) 6/16/93 30.\" @(#)syscall.2 8.1 (Berkeley) 6/16/93
31.\" 31.\"
32.Dd November 23, 2006 32.Dd August 7, 2009
33.Dt SYSCALL 2 33.Dt SYSCALL 2
34.Os 34.Os
35.Sh NAME 35.Sh NAME
36.Nm syscall , 36.Nm syscall ,
37.Nm __syscall 37.Nm __syscall
38.Nd indirect system call 38.Nd indirect system call
39.Sh LIBRARY 39.Sh LIBRARY
40.Lb libc 40.Lb libc
41.Sh SYNOPSIS 41.Sh SYNOPSIS
42.In sys/syscall.h 42.In sys/syscall.h
43.In unistd.h 43.In unistd.h
44.Ft int 44.Ft int
45.Fn syscall "int number" "..." 45.Fn syscall "int number" "..."
@@ -47,48 +47,53 @@ @@ -47,48 +47,53 @@
47.Fn __syscall "quad_t number" "..." 47.Fn __syscall "quad_t number" "..."
48.Sh DESCRIPTION 48.Sh DESCRIPTION
49.Fn syscall 49.Fn syscall
50performs the system call whose assembly language 50performs the system call whose assembly language
51interface has the specified 51interface has the specified
52.Fa number 52.Fa number
53with the specified arguments. 53with the specified arguments.
54Symbolic constants for system calls can be found in the header file 54Symbolic constants for system calls can be found in the header file
55.Ao Pa sys/syscall.h Ac . 55.Ao Pa sys/syscall.h Ac .
56The 56The
57.Nm __syscall 57.Nm __syscall
58form should be used when one or more of the parameters is a 58form should be used when one or more of the parameters is a
5964-bit argument to ensure that argument alignment is correct. 5964-bit argument to ensure that argument alignment is correct.
 60.Pp
60This system call is useful for testing new system calls that 61This system call is useful for testing new system calls that
61do not have entries in the C library. 62do not have entries in the C library.
 63It should not be used in normal applications.
62.Sh RETURN VALUES 64.Sh RETURN VALUES
63The return values are defined by the system call being invoked. 65The return values are defined by the system call being invoked.
64In general, a 0 return value indicates success. 66In general, a 0 return value indicates success.
65A \-1 return value indicates an error, 67A \-1 return value indicates an error,
66and an error code is stored in 68and an error code is stored in
67.Va errno . 69.Va errno .
68.Sh HISTORY 70.Sh HISTORY
69The 71The
70.Fn syscall 72.Fn syscall
71function call appeared in 73function call appeared in
72.Bx 4.0 . 74.Bx 4.0 .
73.Sh BUGS 75.Sh BUGS
74There is no way to simulate system calls that have multiple return values 76There is no way to simulate system calls that have multiple return values
75such as 77such as
76.Xr pipe 2 . 78.Xr pipe 2 .
77.Pp 79.Pp
78Since architectures return 32 bit and 64 bit results in different registers, 80Since architectures return 32 bit and 64 bit results in different registers,
79it may be impossible to portably convert the result of 81it may be impossible to portably convert the result of
80.Fn __syscall 82.Fn __syscall
81to a 32bit value. 83to a 32bit value.
82For instance sparc returns 32 bit values in %o0 and 64 bit values in %o0:%o1 84For instance sparc returns 32 bit values in %o0 and 64 bit values in %o0:%o1
83(with %o0 containing the most significant part) so a 32 bit right shift 85(with %o0 containing the most significant part) so a 32 bit right shift
84of the result is needed to get a correct 32 bit result. 86of the result is needed to get a correct 32 bit result.
85.Pp 87.Pp
 88Many architectures mask off the unwanted high bits of the syscall number,
 89rather than returning an error.
 90.Pp
86Due to ABI implementation differences in passing struct or union 91Due to ABI implementation differences in passing struct or union
87type arguments to system calls between different processors, all 92type arguments to system calls between different processors, all
88system calls pass instead pointers to such structs or unions, even 93system calls pass instead pointers to such structs or unions, even
89when the documentation of the system call mentions otherwise. 94when the documentation of the system call mentions otherwise.
90The conversion between passing structs and unions is handled normally 95The conversion between passing structs and unions is handled normally
91via userland stubs. 96via userland stubs.
92The correct arguments for the kernel entry 97The correct arguments for the kernel entry
93points for each system call can be found in the header file 98points for each system call can be found in the header file
94.Ao Pa sys/syscallargs.h Ac 99.Ao Pa sys/syscallargs.h Ac