1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/arch/alpha/mm/init.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 */
7
8 /* 2.3.x zone allocator, 1999 Andrea Arcangeli <andrea@suse.de> */
9
10 #include <linux/pagemap.h>
11 #include <linux/signal.h>
12 #include <linux/sched.h>
13 #include <linux/kernel.h>
14 #include <linux/errno.h>
15 #include <linux/string.h>
16 #include <linux/types.h>
17 #include <linux/ptrace.h>
18 #include <linux/mman.h>
19 #include <linux/mm.h>
20 #include <linux/swap.h>
21 #include <linux/init.h>
22 #include <linux/memblock.h> /* max_low_pfn */
23 #include <linux/vmalloc.h>
24 #include <linux/gfp.h>
25
26 #include <linux/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/pgalloc.h>
29 #include <asm/hwrpb.h>
30 #include <asm/dma.h>
31 #include <asm/mmu_context.h>
32 #include <asm/console.h>
33 #include <asm/tlb.h>
34 #include <asm/setup.h>
35 #include <asm/sections.h>
36
37 extern void die_if_kernel(char *,struct pt_regs *,long);
38
39 static struct pcb_struct original_pcb;
40
41 pgd_t *
pgd_alloc(struct mm_struct * mm)42 pgd_alloc(struct mm_struct *mm)
43 {
44 pgd_t *ret, *init;
45
46 ret = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
47 init = pgd_offset(&init_mm, 0UL);
48 if (ret) {
49 #ifdef CONFIG_ALPHA_LARGE_VMALLOC
50 memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
51 (PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t));
52 #else
53 pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]);
54 #endif
55
56 /* The last PGD entry is the VPTB self-map. */
57 pgd_val(ret[PTRS_PER_PGD-1])
58 = pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL));
59 }
60 return ret;
61 }
62
63
64 /*
65 * BAD_PAGE is the page that is used for page faults when linux
66 * is out-of-memory. Older versions of linux just did a
67 * do_exit(), but using this instead means there is less risk
68 * for a process dying in kernel mode, possibly leaving an inode
69 * unused etc..
70 *
71 * BAD_PAGETABLE is the accompanying page-table: it is initialized
72 * to point to BAD_PAGE entries.
73 *
74 * ZERO_PAGE is a special page that is used for zero-initialized
75 * data and COW.
76 */
77 pmd_t *
__bad_pagetable(void)78 __bad_pagetable(void)
79 {
80 memset((void *) EMPTY_PGT, 0, PAGE_SIZE);
81 return (pmd_t *) EMPTY_PGT;
82 }
83
84 pte_t
__bad_page(void)85 __bad_page(void)
86 {
87 memset((void *) EMPTY_PGE, 0, PAGE_SIZE);
88 return pte_mkdirty(mk_pte(virt_to_page(EMPTY_PGE), PAGE_SHARED));
89 }
90
91 static inline unsigned long
load_PCB(struct pcb_struct * pcb)92 load_PCB(struct pcb_struct *pcb)
93 {
94 register unsigned long sp __asm__("$30");
95 pcb->ksp = sp;
96 return __reload_thread(pcb);
97 }
98
99 /* Set up initial PCB, VPTB, and other such nicities. */
100
101 static inline void
switch_to_system_map(void)102 switch_to_system_map(void)
103 {
104 unsigned long newptbr;
105 unsigned long original_pcb_ptr;
106
107 /* Initialize the kernel's page tables. Linux puts the vptb in
108 the last slot of the L1 page table. */
109 memset(swapper_pg_dir, 0, PAGE_SIZE);
110 newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT;
111 pgd_val(swapper_pg_dir[1023]) =
112 (newptbr << 32) | pgprot_val(PAGE_KERNEL);
113
114 /* Set the vptb. This is often done by the bootloader, but
115 shouldn't be required. */
116 if (hwrpb->vptb != 0xfffffffe00000000UL) {
117 wrvptptr(0xfffffffe00000000UL);
118 hwrpb->vptb = 0xfffffffe00000000UL;
119 hwrpb_update_checksum(hwrpb);
120 }
121
122 /* Also set up the real kernel PCB while we're at it. */
123 init_thread_info.pcb.ptbr = newptbr;
124 init_thread_info.pcb.flags = 1; /* set FEN, clear everything else */
125 original_pcb_ptr = load_PCB(&init_thread_info.pcb);
126 tbia();
127
128 /* Save off the contents of the original PCB so that we can
129 restore the original console's page tables for a clean reboot.
130
131 Note that the PCB is supposed to be a physical address, but
132 since KSEG values also happen to work, folks get confused.
133 Check this here. */
134
135 if (original_pcb_ptr < PAGE_OFFSET) {
136 original_pcb_ptr = (unsigned long)
137 phys_to_virt(original_pcb_ptr);
138 }
139 original_pcb = *(struct pcb_struct *) original_pcb_ptr;
140 }
141
142 int callback_init_done;
143
144 void * __init
callback_init(void * kernel_end)145 callback_init(void * kernel_end)
146 {
147 struct crb_struct * crb;
148 pgd_t *pgd;
149 pmd_t *pmd;
150 void *two_pages;
151
152 /* Starting at the HWRPB, locate the CRB. */
153 crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset);
154
155 if (alpha_using_srm) {
156 /* Tell the console whither it is to be remapped. */
157 if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb))
158 __halt(); /* "We're boned." --Bender */
159
160 /* Edit the procedure descriptors for DISPATCH and FIXUP. */
161 crb->dispatch_va = (struct procdesc_struct *)
162 (VMALLOC_START + (unsigned long)crb->dispatch_va
163 - crb->map[0].va);
164 crb->fixup_va = (struct procdesc_struct *)
165 (VMALLOC_START + (unsigned long)crb->fixup_va
166 - crb->map[0].va);
167 }
168
169 switch_to_system_map();
170
171 /* Allocate one PGD and one PMD. In the case of SRM, we'll need
172 these to actually remap the console. There is an assumption
173 here that only one of each is needed, and this allows for 8MB.
174 On systems with larger consoles, additional pages will be
175 allocated as needed during the mapping process.
176
177 In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC,
178 we need to allocate the PGD we use for vmalloc before we start
179 forking other tasks. */
180
181 two_pages = (void *)
182 (((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK);
183 kernel_end = two_pages + 2*PAGE_SIZE;
184 memset(two_pages, 0, 2*PAGE_SIZE);
185
186 pgd = pgd_offset_k(VMALLOC_START);
187 pgd_set(pgd, (pmd_t *)two_pages);
188 pmd = pmd_offset(pgd, VMALLOC_START);
189 pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE));
190
191 if (alpha_using_srm) {
192 static struct vm_struct console_remap_vm;
193 unsigned long nr_pages = 0;
194 unsigned long vaddr;
195 unsigned long i, j;
196
197 /* calculate needed size */
198 for (i = 0; i < crb->map_entries; ++i)
199 nr_pages += crb->map[i].count;
200
201 /* register the vm area */
202 console_remap_vm.flags = VM_ALLOC;
203 console_remap_vm.size = nr_pages << PAGE_SHIFT;
204 vm_area_register_early(&console_remap_vm, PAGE_SIZE);
205
206 vaddr = (unsigned long)console_remap_vm.addr;
207
208 /* Set up the third level PTEs and update the virtual
209 addresses of the CRB entries. */
210 for (i = 0; i < crb->map_entries; ++i) {
211 unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT;
212 crb->map[i].va = vaddr;
213 for (j = 0; j < crb->map[i].count; ++j) {
214 /* Newer consoles (especially on larger
215 systems) may require more pages of
216 PTEs. Grab additional pages as needed. */
217 if (pmd != pmd_offset(pgd, vaddr)) {
218 memset(kernel_end, 0, PAGE_SIZE);
219 pmd = pmd_offset(pgd, vaddr);
220 pmd_set(pmd, (pte_t *)kernel_end);
221 kernel_end += PAGE_SIZE;
222 }
223 set_pte(pte_offset_kernel(pmd, vaddr),
224 pfn_pte(pfn, PAGE_KERNEL));
225 pfn++;
226 vaddr += PAGE_SIZE;
227 }
228 }
229 }
230
231 callback_init_done = 1;
232 return kernel_end;
233 }
234
235
236 #ifndef CONFIG_DISCONTIGMEM
237 /*
238 * paging_init() sets up the memory map.
239 */
paging_init(void)240 void __init paging_init(void)
241 {
242 unsigned long zones_size[MAX_NR_ZONES] = {0, };
243 unsigned long dma_pfn, high_pfn;
244
245 dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
246 high_pfn = max_pfn = max_low_pfn;
247
248 if (dma_pfn >= high_pfn)
249 zones_size[ZONE_DMA] = high_pfn;
250 else {
251 zones_size[ZONE_DMA] = dma_pfn;
252 zones_size[ZONE_NORMAL] = high_pfn - dma_pfn;
253 }
254
255 /* Initialize mem_map[]. */
256 free_area_init(zones_size);
257
258 /* Initialize the kernel's ZERO_PGE. */
259 memset((void *)ZERO_PGE, 0, PAGE_SIZE);
260 }
261 #endif /* CONFIG_DISCONTIGMEM */
262
263 #if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM)
264 void
srm_paging_stop(void)265 srm_paging_stop (void)
266 {
267 /* Move the vptb back to where the SRM console expects it. */
268 swapper_pg_dir[1] = swapper_pg_dir[1023];
269 tbia();
270 wrvptptr(0x200000000UL);
271 hwrpb->vptb = 0x200000000UL;
272 hwrpb_update_checksum(hwrpb);
273
274 /* Reload the page tables that the console had in use. */
275 load_PCB(&original_pcb);
276 tbia();
277 }
278 #endif
279
280 void __init
mem_init(void)281 mem_init(void)
282 {
283 set_max_mapnr(max_low_pfn);
284 high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
285 memblock_free_all();
286 mem_init_print_info(NULL);
287 }
288