xref: /kernel/linux/linux-6.6/arch/powerpc/mm/init_32.c (revision 62306a36) 
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  PowerPC version
4 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
5 *
6 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
7 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
8 *    Copyright (C) 1996 Paul Mackerras
9 *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
10 *
11 *  Derived from "arch/i386/mm/init.c"
12 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
13 */
14
15#include <linux/module.h>
16#include <linux/sched.h>
17#include <linux/kernel.h>
18#include <linux/errno.h>
19#include <linux/string.h>
20#include <linux/types.h>
21#include <linux/mm.h>
22#include <linux/stddef.h>
23#include <linux/init.h>
24#include <linux/highmem.h>
25#include <linux/initrd.h>
26#include <linux/pagemap.h>
27#include <linux/memblock.h>
28#include <linux/gfp.h>
29#include <linux/slab.h>
30#include <linux/hugetlb.h>
31
32#include <asm/io.h>
33#include <asm/mmu.h>
34#include <asm/smp.h>
35#include <asm/machdep.h>
36#include <asm/btext.h>
37#include <asm/tlb.h>
38#include <asm/sections.h>
39#include <asm/hugetlb.h>
40#include <asm/kup.h>
41#include <asm/kasan.h>
42
43#include <mm/mmu_decl.h>
44
45#if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
46/* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
47#if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
48#error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
49#endif
50#endif
51#define MAX_LOW_MEM	CONFIG_LOWMEM_SIZE
52
53phys_addr_t total_memory;
54phys_addr_t total_lowmem;
55
56#ifdef CONFIG_RELOCATABLE
57/* Used in __va()/__pa() */
58long long virt_phys_offset;
59EXPORT_SYMBOL(virt_phys_offset);
60#endif
61
62phys_addr_t lowmem_end_addr;
63
64int boot_mapsize;
65#ifdef CONFIG_PPC_PMAC
66unsigned long agp_special_page;
67EXPORT_SYMBOL(agp_special_page);
68#endif
69
70void MMU_init(void);
71
72/* max amount of low RAM to map in */
73unsigned long __max_low_memory = MAX_LOW_MEM;
74
75/*
76 * MMU_init sets up the basic memory mappings for the kernel,
77 * including both RAM and possibly some I/O regions,
78 * and sets up the page tables and the MMU hardware ready to go.
79 */
80void __init MMU_init(void)
81{
82	if (ppc_md.progress)
83		ppc_md.progress("MMU:enter", 0x111);
84
85	total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
86	lowmem_end_addr = memstart_addr + total_lowmem;
87
88#ifdef CONFIG_PPC_85xx
89	/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
90	 * entries, so we need to adjust lowmem to match the amount we can map
91	 * in the fixed entries */
92	adjust_total_lowmem();
93#endif /* CONFIG_PPC_85xx */
94
95	if (total_lowmem > __max_low_memory) {
96		total_lowmem = __max_low_memory;
97		lowmem_end_addr = memstart_addr + total_lowmem;
98#ifndef CONFIG_HIGHMEM
99		total_memory = total_lowmem;
100		memblock_enforce_memory_limit(total_lowmem);
101#endif /* CONFIG_HIGHMEM */
102	}
103
104	/* Initialize the MMU hardware */
105	if (ppc_md.progress)
106		ppc_md.progress("MMU:hw init", 0x300);
107	MMU_init_hw();
108
109	/* Map in all of RAM starting at KERNELBASE */
110	if (ppc_md.progress)
111		ppc_md.progress("MMU:mapin", 0x301);
112	mapin_ram();
113
114	/* Initialize early top-down ioremap allocator */
115	ioremap_bot = IOREMAP_TOP;
116
117	if (ppc_md.progress)
118		ppc_md.progress("MMU:exit", 0x211);
119
120	/* From now on, btext is no longer BAT mapped if it was at all */
121#ifdef CONFIG_BOOTX_TEXT
122	btext_unmap();
123#endif
124
125	kasan_mmu_init();
126
127	setup_kup();
128
129	update_mmu_feature_fixups(MMU_FTR_KUAP);
130
131	/* Shortly after that, the entire linear mapping will be available */
132	memblock_set_current_limit(lowmem_end_addr);
133}
134