freebsd-dev/stand/ofw/libofw/ofw_copy.c
Nathan Whitehorn 861a0b4808 Fix regression introduced in r328806, preventing boot at least on all
PowerPC Apple hardware, and likely all Open Firmware systems.

The loader would allocate memory for its heap at whatever address Open
Firmware gave it, which would in general be the lowest unallocated address,
usually starting a page or two above 0. As the kernel is linked at 1 MB,
and loader insists on running the kernel at its link address, any heap
larger than 1 MB would overlap the kernel, causing loader memory allocations
to corrupt the kernel and vice versa.

Although r328806 made this problem much worse by increasing the heap size
to 8 MB, causing 88% of the loader heap to overlap with the kernel, the
problem has always existed. The old heap size was 1 MB and, unless that
started exactly at zero, which would cause other problems, some number of
pages of the loader heap still overlapped with the kernel.

This patch solves the issue in two ways and cleans up some related code:
- Moves the loader heap inside of the loader. This guarantees that the
  heap will be contiguous with the loader and simplifies the heap
  allocation code at no cost, since the heap lives in BSS.
- Moves the loader, previously at 28 MB and dangerously close to the kernel
  it loads, a bit higher to 44 MB. This has the effect of breaking loader
  on non-embedded PPC machines with < 48 MB of RAM, but we did not support
  those anyway.

The fundamental problem is that the way loader loads ELF files is
incredibly fragile, but that can't be fixed without fundamental
architectural changes.

MFC after:	10 days
2018-02-03 23:49:21 +00:00

174 lines
4.5 KiB
C

/*-
* Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/*
* MD primitives supporting placement of module data
*
* XXX should check load address/size against memory top.
*/
#include <stand.h>
#include "libofw.h"
#define READIN_BUF (4 * 1024)
#define PAGE_SIZE 0x1000
#define PAGE_MASK 0x0fff
#define MAPMEM_PAGE_INC 128 /* Half-MB at a time */
#define roundup(x, y) ((((x)+((y)-1))/(y))*(y))
static int
ofw_mapmem(vm_offset_t dest, const size_t len)
{
void *destp, *addr;
size_t dlen;
size_t resid;
size_t nlen;
static vm_offset_t last_dest = 0;
static size_t last_len = 0;
nlen = len;
/*
* Check to see if this region fits in a prior mapping.
* Allocations are generally sequential, so only check
* the last one.
*/
if (dest >= last_dest &&
(dest + len) <= (last_dest + last_len)) {
return (0);
}
/*
* Trim area covered by existing mapping, if any
*/
if (dest < (last_dest + last_len) && dest >= last_dest) {
nlen -= (last_dest + last_len) - dest;
dest = last_dest + last_len;
}
destp = (void *)(dest & ~PAGE_MASK);
resid = dest & PAGE_MASK;
/*
* To avoid repeated mappings on small allocations,
* never map anything less than MAPMEM_PAGE_INC pages at a time
*/
if ((nlen + resid) < PAGE_SIZE*MAPMEM_PAGE_INC) {
dlen = PAGE_SIZE*MAPMEM_PAGE_INC;
} else
dlen = roundup(nlen + resid, PAGE_SIZE);
if (OF_call_method("claim", memory, 3, 1, destp, dlen, 0, &addr)
== -1) {
printf("ofw_mapmem: physical claim failed\n");
return (ENOMEM);
}
/*
* We only do virtual memory management when real_mode is false.
*/
if (real_mode == 0) {
if (OF_call_method("claim", mmu, 3, 1, destp, dlen, 0, &addr)
== -1) {
printf("ofw_mapmem: virtual claim failed\n");
return (ENOMEM);
}
if (OF_call_method("map", mmu, 4, 0, destp, destp, dlen, 0)
== -1) {
printf("ofw_mapmem: map failed\n");
return (ENOMEM);
}
}
last_dest = (vm_offset_t) destp;
last_len = dlen;
return (0);
}
ssize_t
ofw_copyin(const void *src, vm_offset_t dest, const size_t len)
{
if (ofw_mapmem(dest, len)) {
printf("ofw_copyin: map error\n");
return (0);
}
bcopy(src, (void *)dest, len);
return(len);
}
ssize_t
ofw_copyout(const vm_offset_t src, void *dest, const size_t len)
{
bcopy((void *)src, dest, len);
return(len);
}
ssize_t
ofw_readin(const int fd, vm_offset_t dest, const size_t len)
{
void *buf;
size_t resid, chunk, get;
ssize_t got;
vm_offset_t p;
p = dest;
chunk = min(READIN_BUF, len);
buf = malloc(chunk);
if (buf == NULL) {
printf("ofw_readin: buf malloc failed\n");
return(0);
}
if (ofw_mapmem(dest, len)) {
printf("ofw_readin: map error\n");
free(buf);
return (0);
}
for (resid = len; resid > 0; resid -= got, p += got) {
get = min(chunk, resid);
got = read(fd, buf, get);
if (got <= 0) {
if (got < 0)
printf("ofw_readin: read failed\n");
break;
}
bcopy(buf, (void *)p, got);
}
free(buf);
return(len - resid);
}