4f3dc90023
and casuword(9), but do not mix value read and indication of fault. I know (or remember) enough assembly to handle x86 and powerpc. For arm, mips and sparc64, implement fueword() and casueword() as wrappers around fuword() and casuword(), which means that the functions cannot distinguish between -1 and fault. On architectures where fueword() and casueword() are native, implement fuword() and casuword() using fueword() and casuword(), to reduce assembly code duplication. Sponsored by: The FreeBSD Foundation Tested by: pho MFC after: 2 weeks (ia64 needs treating)
150 lines
4.3 KiB
Groff
150 lines
4.3 KiB
Groff
.\" $NetBSD: fetch.9,v 1.2 1996/01/09 21:59:24 perry Exp $
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.\"
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.\" Copyright (c) 1996 Jason R. Thorpe.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed by Kenneth Stailey.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed for the NetBSD Project
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.\" by Jason R. Thorpe.
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd October 21, 2014
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.Dt FETCH 9
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.Os
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.Sh NAME
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.Nm fetch ,
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.Nm fubyte ,
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.Nm fuswintr ,
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.Nm fuword ,
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.Nm fuword16 ,
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.Nm fuword32 ,
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.Nm fuword64 ,
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.Nm fueword ,
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.Nm fueword32 ,
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.Nm fueword64
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.Nd fetch data from user-space
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/systm.h
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.Ft int
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.Fn fubyte "const void *base"
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.Ft long
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.Fn fuword "const void *base"
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.Ft int
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.Fn fuword16 "void *base"
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.Ft int32_t
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.Fn fuword32 "const void *base"
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.Ft int64_t
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.Fn fuword64 "const void *base"
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.Ft long
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.Fn fueword "const void *base" "long *val"
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.Ft int32_t
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.Fn fueword32 "const void *base" "int32_t *val"
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.Ft int64_t
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.Fn fueword64 "const void *base" "int64_t *val"
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.In sys/resourcevar.h
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.Ft int
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.Fn fuswintr "void *base"
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.Sh DESCRIPTION
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The
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.Nm
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functions are designed to copy small amounts of data from user-space
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of the current process.
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If read is successful, it is performed atomically.
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The data read must be naturally aligned.
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.Pp
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The
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.Nm
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routines provide the following functionality:
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.Bl -tag -width "fueword32()"
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.It Fn fubyte
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Fetches a byte of data from the user-space address
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.Pa base .
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The byte read is zero-extended into the results variable.
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.It Fn fuword
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Fetches a word of data (long) from the user-space address
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.Pa base .
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.It Fn fuword16
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Fetches 16 bits of data from the user-space address
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.Pa base .
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The half-word read is zero-extended into the results variable.
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.It Fn fuword32
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Fetches 32 bits of data from the user-space address
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.Pa base .
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.It Fn fuword64
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Fetches 64 bits of data from the user-space address
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.Pa base .
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.It Fn fuswintr
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Fetches a short word of data from the user-space address
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.Pa base .
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This function is safe to call during an interrupt context.
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.It Fn fueword
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Fetches a word of data (long) from the user-space address
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.Pa base
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and stores the result in the variable pointed by
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.Pa val .
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.It Fn fueword32
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Fetches 32 bits of data from the user-space address
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.Pa base
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and stores the result in the variable pointed by
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.Pa val .
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.It Fn fueword64
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Fetches 64 bits of data from the user-space address
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.Pa base
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and stores the result in the variable pointed by
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.Pa val .
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.El
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.Pp
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The callers of
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.Fn fuword ,
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.Fn fuword32
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and
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.Fn fuword64
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functions cannot distinguish between -1 read from
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userspace and function failure.
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.Sh RETURN VALUES
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The
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.Fn fubyte ,
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.Fn fuword ,
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.Fn fuword16 ,
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.Fn fuword32 ,
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.Fn fuword64 ,
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and
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.Fn fuswintr
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functions return the data fetched or -1 on failure.
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The
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.Fn fueword ,
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.Fn fueword32
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and
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.Fn fueword64
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functions return 0 on success and -1 on failure.
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.Sh SEE ALSO
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.Xr copy 9 ,
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.Xr store 9
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