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 
53 phys_addr_t total_memory;
54 phys_addr_t total_lowmem;
55 
56 #ifdef CONFIG_RELOCATABLE
57 /* Used in __va()/__pa() */
58 long long virt_phys_offset;
59 EXPORT_SYMBOL(virt_phys_offset);
60 #endif
61 
62 phys_addr_t lowmem_end_addr;
63 
64 int boot_mapsize;
65 #ifdef CONFIG_PPC_PMAC
66 unsigned long agp_special_page;
67 EXPORT_SYMBOL(agp_special_page);
68 #endif
69 
70 void MMU_init(void);
71 
72 /*
73  * this tells the system to map all of ram with the segregs
74  * (i.e. page tables) instead of the bats.
75  * -- Cort
76  */
77 int __map_without_bats;
78 int __map_without_ltlbs;
79 
80 /* max amount of low RAM to map in */
81 unsigned long __max_low_memory = MAX_LOW_MEM;
82 
83 /*
84  * Check for command-line options that affect what MMU_init will do.
85  */
MMU_setup(void)86 static void __init MMU_setup(void)
87 {
88 	/* Check for nobats option (used in mapin_ram). */
89 	if (strstr(boot_command_line, "nobats")) {
90 		__map_without_bats = 1;
91 	}
92 
93 	if (strstr(boot_command_line, "noltlbs")) {
94 		__map_without_ltlbs = 1;
95 	}
96 	if (IS_ENABLED(CONFIG_PPC_8xx))
97 		return;
98 
99 	if (IS_ENABLED(CONFIG_KFENCE))
100 		__map_without_ltlbs = 1;
101 
102 	if (debug_pagealloc_enabled())
103 		__map_without_ltlbs = 1;
104 
105 	if (strict_kernel_rwx_enabled())
106 		__map_without_ltlbs = 1;
107 }
108 
109 /*
110  * MMU_init sets up the basic memory mappings for the kernel,
111  * including both RAM and possibly some I/O regions,
112  * and sets up the page tables and the MMU hardware ready to go.
113  */
MMU_init(void)114 void __init MMU_init(void)
115 {
116 	if (ppc_md.progress)
117 		ppc_md.progress("MMU:enter", 0x111);
118 
119 	/* parse args from command line */
120 	MMU_setup();
121 
122 	/*
123 	 * Reserve gigantic pages for hugetlb.  This MUST occur before
124 	 * lowmem_end_addr is initialized below.
125 	 */
126 	if (memblock.memory.cnt > 1) {
127 #ifndef CONFIG_WII
128 		memblock_enforce_memory_limit(memblock.memory.regions[0].size);
129 		pr_warn("Only using first contiguous memory region\n");
130 #else
131 		wii_memory_fixups();
132 #endif
133 	}
134 
135 	total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
136 	lowmem_end_addr = memstart_addr + total_lowmem;
137 
138 #ifdef CONFIG_FSL_BOOKE
139 	/* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
140 	 * entries, so we need to adjust lowmem to match the amount we can map
141 	 * in the fixed entries */
142 	adjust_total_lowmem();
143 #endif /* CONFIG_FSL_BOOKE */
144 
145 	if (total_lowmem > __max_low_memory) {
146 		total_lowmem = __max_low_memory;
147 		lowmem_end_addr = memstart_addr + total_lowmem;
148 #ifndef CONFIG_HIGHMEM
149 		total_memory = total_lowmem;
150 		memblock_enforce_memory_limit(total_lowmem);
151 #endif /* CONFIG_HIGHMEM */
152 	}
153 
154 	/* Initialize the MMU hardware */
155 	if (ppc_md.progress)
156 		ppc_md.progress("MMU:hw init", 0x300);
157 	MMU_init_hw();
158 
159 	/* Map in all of RAM starting at KERNELBASE */
160 	if (ppc_md.progress)
161 		ppc_md.progress("MMU:mapin", 0x301);
162 	mapin_ram();
163 
164 	/* Initialize early top-down ioremap allocator */
165 	ioremap_bot = IOREMAP_TOP;
166 
167 	if (ppc_md.progress)
168 		ppc_md.progress("MMU:exit", 0x211);
169 
170 	/* From now on, btext is no longer BAT mapped if it was at all */
171 #ifdef CONFIG_BOOTX_TEXT
172 	btext_unmap();
173 #endif
174 
175 	kasan_mmu_init();
176 
177 	setup_kup();
178 
179 	/* Shortly after that, the entire linear mapping will be available */
180 	memblock_set_current_limit(lowmem_end_addr);
181 }
182