xref: /linux/arch/powerpc/mm/init_32.c (revision 0ea5c948cb64bab5bc7a5516774eb8536f05aa0d)
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 #include <asm/fixmap.h>
43 
44 #include <mm/mmu_decl.h>
45 
46 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
47 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
48 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
49 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
50 #endif
51 #endif
52 #define MAX_LOW_MEM	CONFIG_LOWMEM_SIZE
53 
54 phys_addr_t total_memory;
55 phys_addr_t total_lowmem;
56 
57 #ifdef CONFIG_RELOCATABLE
58 /* Used in __va()/__pa() */
59 long long virt_phys_offset;
60 EXPORT_SYMBOL(virt_phys_offset);
61 #endif
62 
63 phys_addr_t lowmem_end_addr;
64 
65 int boot_mapsize;
66 #ifdef CONFIG_PPC_PMAC
67 unsigned long agp_special_page;
68 EXPORT_SYMBOL(agp_special_page);
69 #endif
70 
71 void MMU_init(void);
72 
73 /* max amount of low RAM to map in */
74 unsigned long __max_low_memory = MAX_LOW_MEM;
75 
76 /*
77  * MMU_init sets up the basic memory mappings for the kernel,
78  * including both RAM and possibly some I/O regions,
79  * and sets up the page tables and the MMU hardware ready to go.
80  */
MMU_init(void)81 void __init MMU_init(void)
82 {
83 	if (ppc_md.progress)
84 		ppc_md.progress("MMU:enter", 0x111);
85 
86 	total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
87 	lowmem_end_addr = memstart_addr + total_lowmem;
88 
89 #ifdef CONFIG_PPC_85xx
90 	/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
91 	 * entries, so we need to adjust lowmem to match the amount we can map
92 	 * in the fixed entries */
93 	adjust_total_lowmem();
94 #endif /* CONFIG_PPC_85xx */
95 
96 	if (total_lowmem > __max_low_memory) {
97 		total_lowmem = __max_low_memory;
98 		lowmem_end_addr = memstart_addr + total_lowmem;
99 #ifndef CONFIG_HIGHMEM
100 		total_memory = total_lowmem;
101 		memblock_enforce_memory_limit(total_lowmem);
102 #endif /* CONFIG_HIGHMEM */
103 	}
104 
105 	/* Initialize the MMU hardware */
106 	if (ppc_md.progress)
107 		ppc_md.progress("MMU:hw init", 0x300);
108 	MMU_init_hw();
109 
110 	/* Map in all of RAM starting at KERNELBASE */
111 	if (ppc_md.progress)
112 		ppc_md.progress("MMU:mapin", 0x301);
113 	mapin_ram();
114 
115 	/* Initialize early top-down ioremap allocator */
116 	ioremap_bot = IOREMAP_TOP;
117 
118 	if (ppc_md.progress)
119 		ppc_md.progress("MMU:exit", 0x211);
120 
121 	/* From now on, btext is no longer BAT mapped if it was at all */
122 #ifdef CONFIG_BOOTX_TEXT
123 	btext_unmap();
124 #endif
125 
126 	kasan_mmu_init();
127 
128 	setup_kup();
129 
130 	update_mmu_feature_fixups(MMU_FTR_KUAP);
131 
132 	/* Shortly after that, the entire linear mapping will be available */
133 	memblock_set_current_limit(lowmem_end_addr);
134 }
135