freebsd-skq/lib/libstand/sbrk.c
peter a07fee2cdf Fix the real problem that broke the Alpha loader this last week. It
was not the fault of the module code, nor FICL.  The malloc code requires
sbrk() to return addresses that were at least 16 byte aligned.  If the
Alpha loader happened to be 8 byte but not 16 byte aligned in length, then
you would get a zfree() panic at startup.

Incidently, this affected the i386 loader as well, and explains why
the static heap changed things and why jlemon had trouble when the bss
was not ending at a multiple of 8 bytes.

My fix is to 16 byte align it on all arches, even though the x86 version
only required 8 byte alignment (struct MemNode is smaller there).  We could
page align it if we wanted to be paranoid, but it isn't presently necessary.
2000-05-12 22:43:20 +00:00

62 lines
1.9 KiB
C

/*-
* Copyright (c) 1998 Michael Smith
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
/*
* Minimal sbrk() emulation required for malloc support.
*/
#include <string.h>
#include "stand.h"
static size_t maxheap, heapsize = 0;
static void *heapbase;
void
setheap(void *base, void *top)
{
/* Align start address to 16 bytes for the malloc code. Sigh. */
heapbase = (void *)(((uintptr_t)base + 15) & ~15);
maxheap = top - heapbase;
}
char *
sbrk(int incr)
{
char *ret;
if ((heapsize + incr) <= maxheap) {
ret = heapbase + heapsize;
bzero(ret, incr);
heapsize += incr;
return(ret);
}
errno = ENOMEM;
return((char *)-1);
}