freebsd-dev/sys/arm/include/param.h
Ian Lepore 45cd4c8cef Revert the recent armv6 changes to ALIGNED_POINTER(), restoring the
fully-pessimized implementation that requires a type to be aligned to
its natural size.

On armv6+ the compiler might generate load-/store-multiple instructions
which require 4-byte alignment even though the source code is only
accessing individual uint32_t values in a way that doesn't require any
particular alignment at all.  The compiler apparently feels free to
combine multiple accesses into a single instruction that requires a
more-strict alignment, and no set of compiler flags seems to disable
this behavior (at least in clang 3.8).

This fixes alignment faults on arm systems using wifi adapters.  The
wifi code uses ALIGNED_POINTER(p, uint32_t) to decide whether it needs
to copy-align tcp headers.  Because clang is combining several uint32_t
accesses into a single ldm instruction, we need to say that accessing a
uint32_t requires 4-byte alignment.

Approved by:	re(gjb)
2016-06-21 17:53:42 +00:00

153 lines
4.9 KiB
C

/*-
* Copyright (c) 2001 David E. O'Brien
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* from: @(#)param.h 5.8 (Berkeley) 6/28/91
* $FreeBSD$
*/
#ifndef _ARM_INCLUDE_PARAM_H_
#define _ARM_INCLUDE_PARAM_H_
/*
* Machine dependent constants for StrongARM
*/
#include <machine/_align.h>
#define STACKALIGNBYTES (8 - 1)
#define STACKALIGN(p) ((u_int)(p) & ~STACKALIGNBYTES)
#define __PCI_REROUTE_INTERRUPT
#if __ARM_ARCH >= 6
#define _V6_SUFFIX "v6"
#else
#define _V6_SUFFIX ""
#endif
#ifdef __ARM_BIG_ENDIAN
#define _EB_SUFFIX "eb"
#else
#define _EB_SUFFIX ""
#endif
#ifndef MACHINE
#define MACHINE "arm"
#endif
#ifndef MACHINE_ARCH
#define MACHINE_ARCH "arm" _V6_SUFFIX _EB_SUFFIX
#endif
#if defined(SMP) || defined(KLD_MODULE)
#ifndef MAXCPU
#define MAXCPU 4
#endif
#else
#define MAXCPU 1
#endif /* SMP || KLD_MODULE */
#ifndef MAXMEMDOM
#define MAXMEMDOM 1
#endif
#define ALIGNBYTES _ALIGNBYTES
#define ALIGN(p) _ALIGN(p)
/*
* ALIGNED_POINTER is a boolean macro that checks whether an address
* is valid to fetch data elements of type t from on this architecture.
* This does not reflect the optimal alignment, just the possibility
* (within reasonable limits).
*
* armv4 and v5 require alignment to the type's size. armv6 requires 8-byte
* alignment for the ldrd/strd instructions, but otherwise follows armv7 rules.
* armv7 requires that an 8-byte type be aligned to at least a 4-byte boundary;
* access to smaller types can be unaligned, except that the compiler may
* optimize access to adjacent uint32_t values into a single load/store-multiple
* instruction which requires 4-byte alignment, so we must provide the most-
* pessimistic answer possible even on armv7.
*/
#define ALIGNED_POINTER(p, t) ((((unsigned)(p)) & (sizeof(t)-1)) == 0)
/*
* CACHE_LINE_SIZE is the compile-time maximum cache line size for an
* architecture. It should be used with appropriate caution.
*/
#define CACHE_LINE_SHIFT 6
#define CACHE_LINE_SIZE (1 << CACHE_LINE_SHIFT)
#define PAGE_SHIFT 12
#define PAGE_SIZE (1 << PAGE_SHIFT) /* Page size */
#define PAGE_MASK (PAGE_SIZE - 1)
#define PDR_SHIFT 20 /* log2(NBPDR) */
#define NBPDR (1 << PDR_SHIFT)
#define PDRMASK (NBPDR - 1)
#define NPDEPG (1 << (32 - PDR_SHIFT))
#define MAXPAGESIZES 2 /* maximum number of supported page sizes */
#ifndef KSTACK_PAGES
#define KSTACK_PAGES 2
#endif /* !KSTACK_PAGES */
#ifndef FPCONTEXTSIZE
#define FPCONTEXTSIZE (0x100)
#endif
#ifndef KSTACK_GUARD_PAGES
#define KSTACK_GUARD_PAGES 1
#endif /* !KSTACK_GUARD_PAGES */
#define USPACE_SVC_STACK_TOP (kstack_pages * PAGE_SIZE)
/*
* Mach derived conversion macros
*/
#define trunc_page(x) ((x) & ~PAGE_MASK)
#define round_page(x) (((x) + PAGE_MASK) & ~PAGE_MASK)
#define trunc_1mpage(x) ((unsigned)(x) & ~PDRMASK)
#define round_1mpage(x) ((((unsigned)(x)) + PDRMASK) & ~PDRMASK)
#define atop(x) ((unsigned)(x) >> PAGE_SHIFT)
#define ptoa(x) ((unsigned)(x) << PAGE_SHIFT)
#define arm32_btop(x) ((unsigned)(x) >> PAGE_SHIFT)
#define arm32_ptob(x) ((unsigned)(x) << PAGE_SHIFT)
#define pgtok(x) ((x) * (PAGE_SIZE / 1024))
#endif /* !_ARM_INCLUDE_PARAM_H_ */