diff options
Diffstat (limited to 'arch/powerpc/mm/nohash/40x.c')
| -rw-r--r-- | arch/powerpc/mm/nohash/40x.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/arch/powerpc/mm/nohash/40x.c b/arch/powerpc/mm/nohash/40x.c new file mode 100644 index 0000000000..3684d6e570 --- /dev/null +++ b/arch/powerpc/mm/nohash/40x.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * 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 + */ + +#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/io.h> +#include <asm/mmu_context.h> +#include <asm/mmu.h> +#include <linux/uaccess.h> +#include <asm/smp.h> +#include <asm/bootx.h> +#include <asm/machdep.h> +#include <asm/setup.h> + +#include <mm/mmu_decl.h> + +/* + * 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 base, unsigned long top) +{ + unsigned long v, s, mapped; + phys_addr_t p; + + v = KERNELBASE; + p = 0; + s = total_lowmem; + + if (IS_ENABLED(CONFIG_KFENCE)) + return 0; + + if (debug_pagealloc_enabled()) + return 0; + + if (strict_kernel_rwx_enabled()) + return 0; + + while (s >= LARGE_PAGE_SIZE_16M) { + pmd_t *pmdp; + unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_RW; + + pmdp = pmd_off_k(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_RW; + + pmdp = pmd_off_k(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)); +} |