/* * This file contains the routines for initializing the MMU * on the 4xx series of chips. * -- paulus * * Derived from arch/ppc/mm/init.c: * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) * * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au) * and Cort Dougan (PReP) (cort@cs.nmt.edu) * Copyright (C) 1996 Paul Mackerras * * Derived from "arch/i386/mm/init.c" * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * */ #include <linux/signal.h> #include <linux/sched.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/string.h> #include <linux/types.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/mm.h> #include <linux/swap.h> #include <linux/stddef.h> #include <linux/vmalloc.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/highmem.h> #include <linux/memblock.h> #include <asm/pgalloc.h> #include <asm/prom.h> #include <asm/io.h> #include <asm/mmu_context.h> #include <asm/pgtable.h> #include <asm/mmu.h> #include <asm/uaccess.h> #include <asm/smp.h> #include <asm/bootx.h> #include <asm/machdep.h> #include <asm/setup.h> #include "mmu_decl.h" extern int __map_without_ltlbs; /* * MMU_init_hw does the chip-specific initialization of the MMU hardware. */ void __init MMU_init_hw(void) { /* * The Zone Protection Register (ZPR) defines how protection will * be applied to every page which is a member of a given zone. At * present, we utilize only two of the 4xx's zones. * The zone index bits (of ZSEL) in the PTE are used for software * indicators, except the LSB. For user access, zone 1 is used, * for kernel access, zone 0 is used. We set all but zone 1 * to zero, allowing only kernel access as indicated in the PTE. * For zone 1, we set a 01 binary (a value of 10 will not work) * to allow user access as indicated in the PTE. This also allows * kernel access as indicated in the PTE. */ mtspr(SPRN_ZPR, 0x10000000); flush_instruction_cache(); /* * Set up the real-mode cache parameters for the exception vector * handlers (which are run in real-mode). */ mtspr(SPRN_DCWR, 0x00000000); /* All caching is write-back */ /* * Cache instruction and data space where the exception * vectors and the kernel live in real-mode. */ mtspr(SPRN_DCCR, 0xFFFF0000); /* 2GByte of data space at 0x0. */ mtspr(SPRN_ICCR, 0xFFFF0000); /* 2GByte of instr. space at 0x0. */ } #define LARGE_PAGE_SIZE_16M (1<<24) #define LARGE_PAGE_SIZE_4M (1<<22) unsigned long __init mmu_mapin_ram(unsigned long top) { unsigned long v, s, mapped; phys_addr_t p; v = KERNELBASE; p = 0; s = total_lowmem; if (__map_without_ltlbs) return 0; while (s >= LARGE_PAGE_SIZE_16M) { pmd_t *pmdp; unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_HWWRITE; pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v); *pmdp++ = __pmd(val); *pmdp++ = __pmd(val); *pmdp++ = __pmd(val); *pmdp++ = __pmd(val); v += LARGE_PAGE_SIZE_16M; p += LARGE_PAGE_SIZE_16M; s -= LARGE_PAGE_SIZE_16M; } while (s >= LARGE_PAGE_SIZE_4M) { pmd_t *pmdp; unsigned long val = p | _PMD_SIZE_4M | _PAGE_EXEC | _PAGE_HWWRITE; pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v); *pmdp = __pmd(val); v += LARGE_PAGE_SIZE_4M; p += LARGE_PAGE_SIZE_4M; s -= LARGE_PAGE_SIZE_4M; } mapped = total_lowmem - s; /* If the size of RAM is not an exact power of two, we may not * have covered RAM in its entirety with 16 and 4 MiB * pages. Consequently, restrict the top end of RAM currently * allocable so that calls to the MEMBLOCK to allocate PTEs for "tail" * coverage with normal-sized pages (or other reasons) do not * attempt to allocate outside the allowed range. */ memblock_set_current_limit(mapped); return mapped; } void setup_initial_memory_limit(phys_addr_t first_memblock_base, phys_addr_t first_memblock_size) { /* We don't currently support the first MEMBLOCK not mapping 0 * physical on those processors */ BUG_ON(first_memblock_base != 0); /* 40x can only access 16MB at the moment (see head_40x.S) */ memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000)); }