1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * This file contains the routines for handling the MMU on those
4 * PowerPC implementations where the MMU substantially follows the
5 * architecture specification. This includes the 6xx, 7xx, 7xxx,
6 * and 8260 implementations but excludes the 8xx and 4xx.
7 * -- paulus
8 *
9 * Derived from arch/ppc/mm/init.c:
10 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
11 *
12 * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
13 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
14 * Copyright (C) 1996 Paul Mackerras
15 *
16 * Derived from "arch/i386/mm/init.c"
17 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
18 */
19
20#include <linux/kernel.h>
21#include <linux/mm.h>
22#include <linux/init.h>
23#include <linux/highmem.h>
24#include <linux/memblock.h>
25
26#include <asm/mmu.h>
27#include <asm/machdep.h>
28#include <asm/text-patching.h>
29#include <asm/sections.h>
30
31#include <mm/mmu_decl.h>
32
33u8 __initdata early_hash[SZ_256K] __aligned(SZ_256K) = {0};
34
35static struct hash_pte __initdata *Hash = (struct hash_pte *)early_hash;
36static unsigned long __initdata Hash_size, Hash_mask;
37static unsigned int __initdata hash_mb, hash_mb2;
38unsigned long __initdata _SDR1;
39
40struct ppc_bat BATS[8][2]; /* 8 pairs of IBAT, DBAT */
41
42static struct batrange { /* stores address ranges mapped by BATs */
43 unsigned long start;
44 unsigned long limit;
45 phys_addr_t phys;
46} bat_addrs[8];
47
48#ifdef CONFIG_SMP
49unsigned long mmu_hash_lock;
50#endif
51
52/*
53 * Return PA for this VA if it is mapped by a BAT, or 0
54 */
55phys_addr_t v_block_mapped(unsigned long va)
56{
57 int b;
58 for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b)
59 if (va >= bat_addrs[b].start && va < bat_addrs[b].limit)
60 return bat_addrs[b].phys + (va - bat_addrs[b].start);
61 return 0;
62}
63
64/*
65 * Return VA for a given PA or 0 if not mapped
66 */
67unsigned long p_block_mapped(phys_addr_t pa)
68{
69 int b;
70 for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b)
71 if (pa >= bat_addrs[b].phys
72 && pa < (bat_addrs[b].limit-bat_addrs[b].start)
73 +bat_addrs[b].phys)
74 return bat_addrs[b].start+(pa-bat_addrs[b].phys);
75 return 0;
76}
77
78int __init find_free_bat(void)
79{
80 int b;
81 int n = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
82
83 for (b = 0; b < n; b++) {
84 struct ppc_bat *bat = BATS[b];
85
86 if (!(bat[1].batu & 3))
87 return b;
88 }
89 return -1;
90}
91
92/*
93 * This function calculates the size of the larger block usable to map the
94 * beginning of an area based on the start address and size of that area:
95 * - max block size is 256 on 6xx.
96 * - base address must be aligned to the block size. So the maximum block size
97 * is identified by the lowest bit set to 1 in the base address (for instance
98 * if base is 0x16000000, max size is 0x02000000).
99 * - block size has to be a power of two. This is calculated by finding the
100 * highest bit set to 1.
101 */
102unsigned int bat_block_size(unsigned long base, unsigned long top)
103{
104 unsigned int max_size = SZ_256M;
105 unsigned int base_shift = (ffs(base) - 1) & 31;
106 unsigned int block_shift = (fls(x: top - base) - 1) & 31;
107
108 return min3(max_size, 1U << base_shift, 1U << block_shift);
109}
110
111/*
112 * Set up one of the IBAT (block address translation) register pairs.
113 * The parameters are not checked; in particular size must be a power
114 * of 2 between 128k and 256M.
115 */
116static void setibat(int index, unsigned long virt, phys_addr_t phys,
117 unsigned int size, pgprot_t prot)
118{
119 unsigned int bl = (size >> 17) - 1;
120 int wimgxpp;
121 struct ppc_bat *bat = BATS[index];
122 unsigned long flags = pgprot_val(prot);
123
124 if (!cpu_has_feature(CPU_FTR_NEED_COHERENT))
125 flags &= ~_PAGE_COHERENT;
126
127 wimgxpp = (flags & _PAGE_COHERENT) | (_PAGE_EXEC ? BPP_RX : BPP_XX);
128 bat[0].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
129 bat[0].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
130 if (!is_kernel_addr(virt))
131 bat[0].batu |= 1; /* Vp = 1 */
132}
133
134static void clearibat(int index)
135{
136 struct ppc_bat *bat = BATS[index];
137
138 bat[0].batu = 0;
139 bat[0].batl = 0;
140}
141
142static unsigned long __init __mmu_mapin_ram(unsigned long base, unsigned long top)
143{
144 int idx;
145
146 while ((idx = find_free_bat()) != -1 && base != top) {
147 unsigned int size = bat_block_size(base, top);
148
149 if (size < 128 << 10)
150 break;
151 setbat(idx, PAGE_OFFSET + base, base, size, PAGE_KERNEL_X);
152 base += size;
153 }
154
155 return base;
156}
157
158unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
159{
160 unsigned long done;
161 unsigned long border = (unsigned long)__srwx_boundary - PAGE_OFFSET;
162 unsigned long size;
163
164 size = roundup_pow_of_two((unsigned long)_einittext - PAGE_OFFSET);
165 setibat(index: 0, PAGE_OFFSET, phys: 0, size, prot: PAGE_KERNEL_X);
166
167 if (debug_pagealloc_enabled_or_kfence()) {
168 pr_debug_once("Read-Write memory mapped without BATs\n");
169 if (base >= border)
170 return base;
171 if (top >= border)
172 top = border;
173 }
174
175 if (!strict_kernel_rwx_enabled() || base >= border || top <= border)
176 return __mmu_mapin_ram(base, top);
177
178 done = __mmu_mapin_ram(base, top: border);
179 if (done != border)
180 return done;
181
182 return __mmu_mapin_ram(base: border, top);
183}
184
185static bool is_module_segment(unsigned long addr)
186{
187 if (!IS_ENABLED(CONFIG_EXECMEM))
188 return false;
189 if (addr < ALIGN_DOWN(MODULES_VADDR, SZ_256M))
190 return false;
191 if (addr > ALIGN(MODULES_END, SZ_256M) - 1)
192 return false;
193 return true;
194}
195
196int mmu_mark_initmem_nx(void)
197{
198 int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
199 int i;
200 unsigned long base = (unsigned long)_stext - PAGE_OFFSET;
201 unsigned long top = ALIGN((unsigned long)_etext - PAGE_OFFSET, SZ_128K);
202 unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
203 unsigned long size;
204
205 for (i = 0; i < nb - 1 && base < top;) {
206 size = bat_block_size(base, top);
207 setibat(index: i++, PAGE_OFFSET + base, phys: base, size, prot: PAGE_KERNEL_X);
208 base += size;
209 }
210 if (base < top) {
211 size = bat_block_size(base, top);
212 if ((top - base) > size) {
213 size <<= 1;
214 if (strict_kernel_rwx_enabled() && base + size > border)
215 pr_warn("Some RW data is getting mapped X. "
216 "Adjust CONFIG_DATA_SHIFT to avoid that.\n");
217 }
218 setibat(index: i++, PAGE_OFFSET + base, phys: base, size, prot: PAGE_KERNEL_X);
219 base += size;
220 }
221 for (; i < nb; i++)
222 clearibat(index: i);
223
224 update_bats();
225
226 BUILD_BUG_ON(ALIGN_DOWN(MODULES_VADDR, SZ_256M) < TASK_SIZE);
227
228 for (i = TASK_SIZE >> 28; i < 16; i++) {
229 /* Do not set NX on VM space for modules */
230 if (is_module_segment(addr: i << 28))
231 continue;
232
233 mtsr(mfsr(i << 28) | 0x10000000, i << 28);
234 }
235 return 0;
236}
237
238int mmu_mark_rodata_ro(void)
239{
240 int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
241 int i;
242
243 for (i = 0; i < nb; i++) {
244 struct ppc_bat *bat = BATS[i];
245
246 if (bat_addrs[i].start < (unsigned long)__end_rodata)
247 bat[1].batl = (bat[1].batl & ~BPP_RW) | BPP_RX;
248 }
249
250 update_bats();
251
252 return 0;
253}
254
255/*
256 * Set up one of the D BAT (block address translation) register pairs.
257 * The parameters are not checked; in particular size must be a power
258 * of 2 between 128k and 256M.
259 */
260void __init setbat(int index, unsigned long virt, phys_addr_t phys,
261 unsigned int size, pgprot_t prot)
262{
263 unsigned int bl;
264 int wimgxpp;
265 struct ppc_bat *bat;
266 unsigned long flags = pgprot_val(prot);
267
268 if (index == -1)
269 index = find_free_bat();
270 if (index == -1) {
271 pr_err("%s: no BAT available for mapping 0x%llx\n", __func__,
272 (unsigned long long)phys);
273 return;
274 }
275 bat = BATS[index];
276
277 if ((flags & _PAGE_NO_CACHE) ||
278 (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0))
279 flags &= ~_PAGE_COHERENT;
280
281 bl = (size >> 17) - 1;
282 /* Do DBAT first */
283 wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
284 | _PAGE_COHERENT | _PAGE_GUARDED);
285 wimgxpp |= (flags & _PAGE_WRITE) ? BPP_RW : BPP_RX;
286 bat[1].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
287 bat[1].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
288 if (!is_kernel_addr(virt))
289 bat[1].batu |= 1; /* Vp = 1 */
290 if (flags & _PAGE_GUARDED) {
291 /* G bit must be zero in IBATs */
292 flags &= ~_PAGE_EXEC;
293 }
294
295 bat_addrs[index].start = virt;
296 bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
297 bat_addrs[index].phys = phys;
298}
299
300/*
301 * Preload a translation in the hash table
302 */
303static void hash_preload(struct mm_struct *mm, unsigned long ea)
304{
305 pmd_t *pmd;
306
307 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
308 return;
309 pmd = pmd_off(mm, va: ea);
310 if (!pmd_none(pmd: *pmd))
311 add_hash_page(mm->context.id, ea, pmd_val(pmd: *pmd));
312}
313
314/*
315 * This is called at the end of handling a user page fault, when the
316 * fault has been handled by updating a PTE in the linux page tables.
317 * We use it to preload an HPTE into the hash table corresponding to
318 * the updated linux PTE.
319 *
320 * This must always be called with the pte lock held.
321 */
322void __update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
323 pte_t *ptep)
324{
325 /*
326 * We don't need to worry about _PAGE_PRESENT here because we are
327 * called with either mm->page_table_lock held or ptl lock held
328 */
329
330 /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
331 if (!pte_young(pte: *ptep) || address >= TASK_SIZE)
332 return;
333
334 /* We have to test for regs NULL since init will get here first thing at boot */
335 if (!current->thread.regs)
336 return;
337
338 /* We also avoid filling the hash if not coming from a fault */
339 if (TRAP(current->thread.regs) != 0x300 && TRAP(current->thread.regs) != 0x400)
340 return;
341
342 hash_preload(mm: vma->vm_mm, ea: address);
343}
344
345/*
346 * Initialize the hash table and patch the instructions in hashtable.S.
347 */
348void __init MMU_init_hw(void)
349{
350 unsigned int n_hpteg, lg_n_hpteg;
351
352 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
353 return;
354
355 if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);
356
357#define LG_HPTEG_SIZE 6 /* 64 bytes per HPTEG */
358#define SDR1_LOW_BITS ((n_hpteg - 1) >> 10)
359#define MIN_N_HPTEG 1024 /* min 64kB hash table */
360
361 /*
362 * Allow 1 HPTE (1/8 HPTEG) for each page of memory.
363 * This is less than the recommended amount, but then
364 * Linux ain't AIX.
365 */
366 n_hpteg = total_memory / (PAGE_SIZE * 8);
367 if (n_hpteg < MIN_N_HPTEG)
368 n_hpteg = MIN_N_HPTEG;
369 lg_n_hpteg = __ilog2(n_hpteg);
370 if (n_hpteg & (n_hpteg - 1)) {
371 ++lg_n_hpteg; /* round up if not power of 2 */
372 n_hpteg = 1 << lg_n_hpteg;
373 }
374 Hash_size = n_hpteg << LG_HPTEG_SIZE;
375
376 /*
377 * Find some memory for the hash table.
378 */
379 if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
380 Hash = memblock_alloc_or_panic(Hash_size, Hash_size);
381 _SDR1 = __pa(Hash) | SDR1_LOW_BITS;
382
383 pr_info("Total memory = %lldMB; using %ldkB for hash table\n",
384 (unsigned long long)(total_memory >> 20), Hash_size >> 10);
385
386
387 Hash_mask = n_hpteg - 1;
388 hash_mb2 = hash_mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
389 if (lg_n_hpteg > 16)
390 hash_mb2 = 16 - LG_HPTEG_SIZE;
391}
392
393void __init MMU_init_hw_patch(void)
394{
395 unsigned int hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
396 unsigned int hash = (unsigned int)Hash - PAGE_OFFSET;
397
398 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
399 return;
400
401 if (ppc_md.progress)
402 ppc_md.progress("hash:patch", 0x345);
403 if (ppc_md.progress)
404 ppc_md.progress("hash:done", 0x205);
405
406 /* WARNING: Make sure nothing can trigger a KASAN check past this point */
407
408 /*
409 * Patch up the instructions in hashtable.S:create_hpte
410 */
411 modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16);
412 modify_instruction_site(&patch__hash_page_A1, 0x7c0, hash_mb << 6);
413 modify_instruction_site(&patch__hash_page_A2, 0x7c0, hash_mb2 << 6);
414 modify_instruction_site(&patch__hash_page_B, 0xffff, hmask);
415 modify_instruction_site(&patch__hash_page_C, 0xffff, hmask);
416
417 /*
418 * Patch up the instructions in hashtable.S:flush_hash_page
419 */
420 modify_instruction_site(&patch__flush_hash_A0, 0xffff, hash >> 16);
421 modify_instruction_site(&patch__flush_hash_A1, 0x7c0, hash_mb << 6);
422 modify_instruction_site(&patch__flush_hash_A2, 0x7c0, hash_mb2 << 6);
423 modify_instruction_site(&patch__flush_hash_B, 0xffff, hmask);
424}
425
426void setup_initial_memory_limit(phys_addr_t first_memblock_base,
427 phys_addr_t first_memblock_size)
428{
429 /* We don't currently support the first MEMBLOCK not mapping 0
430 * physical on those processors
431 */
432 BUG_ON(first_memblock_base != 0);
433
434 memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_256M));
435}
436
437void __init print_system_hash_info(void)
438{
439 pr_info("Hash_size = 0x%lx\n", Hash_size);
440 if (Hash_mask)
441 pr_info("Hash_mask = 0x%lx\n", Hash_mask);
442}
443
444void __init early_init_mmu(void)
445{
446}
447

source code of linux/arch/powerpc/mm/book3s32/mmu.c