7fa5b1ae33
directly to ioctl(2). Because of how ioctl command is build using _IO*() macros we have only 13 bits to encode structure size. So the structure can be up to 8kB-1. Currently we define IOCPARM_MAX as PAGE_SIZE. This is IMHO wrong for three main reasons: 1. It is confusing on archs with page size larger than 8kB (not really sure if we support such archs (sparc64?)), as even if PAGE_SIZE is bigger than 8kB, we won't be able to encode anything larger in ioctl command. 2. It is a waste. Why the structure can be only 4kB on most archs if we have 13 bits dedicated for that, not 12? 3. It shouldn't depend on architecture and page size. My ioctl command can work on one arch, but can't on the other? Increase IOCPARM_MAX to 8kB and make it independed of PAGE_SIZE and architecture it is compiled for. This allows to use all the bits on all the archs for size. Note that this doesn't mean we will copy more on every ioctl(2) call. No. We still copyin(9)/copyout(9) only exact number of bytes encoded in ioctl command. Practical use for this change is ZFS. zfs_cmd_t structure used for ZFS ioctls is larger than 4kB. Silence on: arch@ MFC after: 1 month
81 lines
3.2 KiB
C
81 lines
3.2 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1990, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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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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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, 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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* @(#)ioccom.h 8.2 (Berkeley) 3/28/94
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* $FreeBSD$
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*/
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#ifndef _SYS_IOCCOM_H_
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#define _SYS_IOCCOM_H_
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/*
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* Ioctl's have the command encoded in the lower word, and the size of
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* any in or out parameters in the upper word. The high 3 bits of the
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* upper word are used to encode the in/out status of the parameter.
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*/
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#define IOCPARM_SHIFT 13 /* number of bits for ioctl size */
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#define IOCPARM_MASK ((1 << IOCPARM_SHIFT) - 1) /* parameter length mask */
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#define IOCPARM_LEN(x) (((x) >> 16) & IOCPARM_MASK)
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#define IOCBASECMD(x) ((x) & ~(IOCPARM_MASK << 16))
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#define IOCGROUP(x) (((x) >> 8) & 0xff)
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#define IOCPARM_MAX (1 << IOCPARM_SHIFT) /* max size of ioctl */
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#define IOC_VOID 0x20000000 /* no parameters */
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#define IOC_OUT 0x40000000 /* copy out parameters */
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#define IOC_IN 0x80000000 /* copy in parameters */
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#define IOC_INOUT (IOC_IN|IOC_OUT)
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#define IOC_DIRMASK (IOC_VOID|IOC_OUT|IOC_IN)
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#define _IOC(inout,group,num,len) ((unsigned long) \
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((inout) | (((len) & IOCPARM_MASK) << 16) | ((group) << 8) | (num)))
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#define _IO(g,n) _IOC(IOC_VOID, (g), (n), 0)
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#define _IOWINT(g,n) _IOC(IOC_VOID, (g), (n), sizeof(int))
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#define _IOR(g,n,t) _IOC(IOC_OUT, (g), (n), sizeof(t))
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#define _IOW(g,n,t) _IOC(IOC_IN, (g), (n), sizeof(t))
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/* this should be _IORW, but stdio got there first */
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#define _IOWR(g,n,t) _IOC(IOC_INOUT, (g), (n), sizeof(t))
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#ifdef _KERNEL
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#if defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD5) || \
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defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
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#define IOCPARM_IVAL(x) ((int)(intptr_t)(void *)*(caddr_t *)(void *)(x))
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#endif
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#else
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#include <sys/cdefs.h>
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__BEGIN_DECLS
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int ioctl(int, unsigned long, ...);
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__END_DECLS
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#endif
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#endif /* !_SYS_IOCCOM_H_ */
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