bd942ba3db
mmu_mapin_ram() loops over total_lowmem to setup page tables. However, if total_lowmem is less that 16M, the subtraction rolls over and results in a number just under 4G (because total_lowmem is an unsigned value). This patch rejigs the loop from countup to countdown to eliminate the bug. Special thanks to Magnus Hjorth who wrote the original patch to fix this bug. This patch improves on his by making the loop code simpler (which also eliminates the possibility of another rollover at the high end) and also applies the change to arch/powerpc. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
136 lines
3.6 KiB
C
136 lines
3.6 KiB
C
/*
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* This file contains the routines for initializing the MMU
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* on the 4xx series of chips.
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* -- paulus
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*
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* Derived from arch/ppc/mm/init.c:
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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*
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* Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
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* and Cort Dougan (PReP) (cort@cs.nmt.edu)
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* Copyright (C) 1996 Paul Mackerras
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* Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
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*
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* Derived from "arch/i386/mm/init.c"
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/ptrace.h>
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#include <linux/mman.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/stddef.h>
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#include <linux/vmalloc.h>
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#include <linux/init.h>
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#include <linux/delay.h>
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#include <linux/highmem.h>
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#include <asm/pgalloc.h>
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#include <asm/prom.h>
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#include <asm/io.h>
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#include <asm/mmu_context.h>
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#include <asm/pgtable.h>
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#include <asm/mmu.h>
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#include <asm/uaccess.h>
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#include <asm/smp.h>
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#include <asm/bootx.h>
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#include <asm/machdep.h>
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#include <asm/setup.h>
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#include "mmu_decl.h"
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extern int __map_without_ltlbs;
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/*
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* MMU_init_hw does the chip-specific initialization of the MMU hardware.
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*/
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void __init MMU_init_hw(void)
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{
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/*
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* The Zone Protection Register (ZPR) defines how protection will
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* be applied to every page which is a member of a given zone. At
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* present, we utilize only two of the 4xx's zones.
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* The zone index bits (of ZSEL) in the PTE are used for software
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* indicators, except the LSB. For user access, zone 1 is used,
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* for kernel access, zone 0 is used. We set all but zone 1
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* to zero, allowing only kernel access as indicated in the PTE.
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* For zone 1, we set a 01 binary (a value of 10 will not work)
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* to allow user access as indicated in the PTE. This also allows
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* kernel access as indicated in the PTE.
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*/
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mtspr(SPRN_ZPR, 0x10000000);
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flush_instruction_cache();
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/*
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* Set up the real-mode cache parameters for the exception vector
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* handlers (which are run in real-mode).
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*/
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mtspr(SPRN_DCWR, 0x00000000); /* All caching is write-back */
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/*
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* Cache instruction and data space where the exception
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* vectors and the kernel live in real-mode.
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*/
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mtspr(SPRN_DCCR, 0xF0000000); /* 512 MB of data space at 0x0. */
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mtspr(SPRN_ICCR, 0xF0000000); /* 512 MB of instr. space at 0x0. */
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}
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#define LARGE_PAGE_SIZE_16M (1<<24)
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#define LARGE_PAGE_SIZE_4M (1<<22)
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unsigned long __init mmu_mapin_ram(void)
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{
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unsigned long v, s;
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phys_addr_t p;
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v = KERNELBASE;
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p = PPC_MEMSTART;
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s = total_lowmem;
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if (__map_without_ltlbs)
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return 0;
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while (s >= LARGE_PAGE_SIZE_16M) {
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pmd_t *pmdp;
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unsigned long val = p | _PMD_SIZE_16M | _PAGE_HWEXEC | _PAGE_HWWRITE;
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pmdp = pmd_offset(pgd_offset_k(v), v);
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pmd_val(*pmdp++) = val;
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pmd_val(*pmdp++) = val;
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pmd_val(*pmdp++) = val;
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pmd_val(*pmdp++) = val;
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v += LARGE_PAGE_SIZE_16M;
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p += LARGE_PAGE_SIZE_16M;
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s -= LARGE_PAGE_SIZE_16M;
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}
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while (s >= LARGE_PAGE_SIZE_4M) {
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pmd_t *pmdp;
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unsigned long val = p | _PMD_SIZE_4M | _PAGE_HWEXEC | _PAGE_HWWRITE;
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pmdp = pmd_offset(pgd_offset_k(v), v);
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pmd_val(*pmdp) = val;
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v += LARGE_PAGE_SIZE_4M;
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p += LARGE_PAGE_SIZE_4M;
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s -= LARGE_PAGE_SIZE_4M;
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}
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return total_lowmem - s;
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}
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