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/code-patching.h>
29 #include <asm/sections.h>
30
31 #include <mm/mmu_decl.h>
32
33 u8 __initdata early_hash[SZ_256K] __aligned(SZ_256K) = {0};
34
35 static struct hash_pte __initdata *Hash = (struct hash_pte *)early_hash;
36 static unsigned long __initdata Hash_size, Hash_mask;
37 static unsigned int __initdata hash_mb, hash_mb2;
38 unsigned long __initdata _SDR1;
39
40 struct ppc_bat BATS[8][2]; /* 8 pairs of IBAT, DBAT */
41
42 static 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
49 unsigned long mmu_hash_lock;
50 #endif
51
52 /*
53 * Return PA for this VA if it is mapped by a BAT, or 0
54 */
v_block_mapped(unsigned long va)55 phys_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 */
p_block_mapped(phys_addr_t pa)67 unsigned 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
find_free_bat(void)78 int __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 */
bat_block_size(unsigned long base,unsigned long top)102 unsigned 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(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 */
setibat(int index,unsigned long virt,phys_addr_t phys,unsigned int size,pgprot_t prot)116 static 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 (flags & _PAGE_USER)
131 bat[0].batu |= 1; /* Vp = 1 */
132 }
133
clearibat(int index)134 static 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
__mmu_mapin_ram(unsigned long base,unsigned long top)142 static 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
mmu_mapin_ram(unsigned long base,unsigned long top)158 unsigned 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(0, PAGE_OFFSET, 0, size, 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, border);
179 if (done != border)
180 return done;
181
182 return __mmu_mapin_ram(border, top);
183 }
184
is_module_segment(unsigned long addr)185 static bool is_module_segment(unsigned long addr)
186 {
187 if (!IS_ENABLED(CONFIG_MODULES))
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
mmu_mark_initmem_nx(void)196 void 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(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT);
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(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT);
219 base += size;
220 }
221 for (; i < nb; i++)
222 clearibat(i);
223
224 update_bats();
225
226 for (i = TASK_SIZE >> 28; i < 16; i++) {
227 /* Do not set NX on VM space for modules */
228 if (is_module_segment(i << 28))
229 continue;
230
231 mtsr(mfsr(i << 28) | 0x10000000, i << 28);
232 }
233 }
234
mmu_mark_rodata_ro(void)235 void mmu_mark_rodata_ro(void)
236 {
237 int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
238 int i;
239
240 for (i = 0; i < nb; i++) {
241 struct ppc_bat *bat = BATS[i];
242
243 if (bat_addrs[i].start < (unsigned long)__end_rodata)
244 bat[1].batl = (bat[1].batl & ~BPP_RW) | BPP_RX;
245 }
246
247 update_bats();
248 }
249
250 /*
251 * Set up one of the D BAT (block address translation) register pairs.
252 * The parameters are not checked; in particular size must be a power
253 * of 2 between 128k and 256M.
254 */
setbat(int index,unsigned long virt,phys_addr_t phys,unsigned int size,pgprot_t prot)255 void __init setbat(int index, unsigned long virt, phys_addr_t phys,
256 unsigned int size, pgprot_t prot)
257 {
258 unsigned int bl;
259 int wimgxpp;
260 struct ppc_bat *bat;
261 unsigned long flags = pgprot_val(prot);
262
263 if (index == -1)
264 index = find_free_bat();
265 if (index == -1) {
266 pr_err("%s: no BAT available for mapping 0x%llx\n", __func__,
267 (unsigned long long)phys);
268 return;
269 }
270 bat = BATS[index];
271
272 if ((flags & _PAGE_NO_CACHE) ||
273 (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0))
274 flags &= ~_PAGE_COHERENT;
275
276 bl = (size >> 17) - 1;
277 /* Do DBAT first */
278 wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
279 | _PAGE_COHERENT | _PAGE_GUARDED);
280 wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX;
281 bat[1].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
282 bat[1].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
283 if (flags & _PAGE_USER)
284 bat[1].batu |= 1; /* Vp = 1 */
285 if (flags & _PAGE_GUARDED) {
286 /* G bit must be zero in IBATs */
287 flags &= ~_PAGE_EXEC;
288 }
289
290 bat_addrs[index].start = virt;
291 bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
292 bat_addrs[index].phys = phys;
293 }
294
295 /*
296 * Preload a translation in the hash table
297 */
hash_preload(struct mm_struct * mm,unsigned long ea)298 static void hash_preload(struct mm_struct *mm, unsigned long ea)
299 {
300 pmd_t *pmd;
301
302 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
303 return;
304 pmd = pmd_off(mm, ea);
305 if (!pmd_none(*pmd))
306 add_hash_page(mm->context.id, ea, pmd_val(*pmd));
307 }
308
309 /*
310 * This is called at the end of handling a user page fault, when the
311 * fault has been handled by updating a PTE in the linux page tables.
312 * We use it to preload an HPTE into the hash table corresponding to
313 * the updated linux PTE.
314 *
315 * This must always be called with the pte lock held.
316 */
__update_mmu_cache(struct vm_area_struct * vma,unsigned long address,pte_t * ptep)317 void __update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
318 pte_t *ptep)
319 {
320 /*
321 * We don't need to worry about _PAGE_PRESENT here because we are
322 * called with either mm->page_table_lock held or ptl lock held
323 */
324
325 /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
326 if (!pte_young(*ptep) || address >= TASK_SIZE)
327 return;
328
329 /* We have to test for regs NULL since init will get here first thing at boot */
330 if (!current->thread.regs)
331 return;
332
333 /* We also avoid filling the hash if not coming from a fault */
334 if (TRAP(current->thread.regs) != 0x300 && TRAP(current->thread.regs) != 0x400)
335 return;
336
337 hash_preload(vma->vm_mm, address);
338 }
339
340 /*
341 * Initialize the hash table and patch the instructions in hashtable.S.
342 */
MMU_init_hw(void)343 void __init MMU_init_hw(void)
344 {
345 unsigned int n_hpteg, lg_n_hpteg;
346
347 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
348 return;
349
350 if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);
351
352 #define LG_HPTEG_SIZE 6 /* 64 bytes per HPTEG */
353 #define SDR1_LOW_BITS ((n_hpteg - 1) >> 10)
354 #define MIN_N_HPTEG 1024 /* min 64kB hash table */
355
356 /*
357 * Allow 1 HPTE (1/8 HPTEG) for each page of memory.
358 * This is less than the recommended amount, but then
359 * Linux ain't AIX.
360 */
361 n_hpteg = total_memory / (PAGE_SIZE * 8);
362 if (n_hpteg < MIN_N_HPTEG)
363 n_hpteg = MIN_N_HPTEG;
364 lg_n_hpteg = __ilog2(n_hpteg);
365 if (n_hpteg & (n_hpteg - 1)) {
366 ++lg_n_hpteg; /* round up if not power of 2 */
367 n_hpteg = 1 << lg_n_hpteg;
368 }
369 Hash_size = n_hpteg << LG_HPTEG_SIZE;
370
371 /*
372 * Find some memory for the hash table.
373 */
374 if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
375 Hash = memblock_alloc(Hash_size, Hash_size);
376 if (!Hash)
377 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
378 __func__, Hash_size, Hash_size);
379 _SDR1 = __pa(Hash) | SDR1_LOW_BITS;
380
381 pr_info("Total memory = %lldMB; using %ldkB for hash table\n",
382 (unsigned long long)(total_memory >> 20), Hash_size >> 10);
383
384
385 Hash_mask = n_hpteg - 1;
386 hash_mb2 = hash_mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
387 if (lg_n_hpteg > 16)
388 hash_mb2 = 16 - LG_HPTEG_SIZE;
389 }
390
MMU_init_hw_patch(void)391 void __init MMU_init_hw_patch(void)
392 {
393 unsigned int hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
394 unsigned int hash = (unsigned int)Hash - PAGE_OFFSET;
395
396 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
397 return;
398
399 if (ppc_md.progress)
400 ppc_md.progress("hash:patch", 0x345);
401 if (ppc_md.progress)
402 ppc_md.progress("hash:done", 0x205);
403
404 /* WARNING: Make sure nothing can trigger a KASAN check past this point */
405
406 /*
407 * Patch up the instructions in hashtable.S:create_hpte
408 */
409 modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16);
410 modify_instruction_site(&patch__hash_page_A1, 0x7c0, hash_mb << 6);
411 modify_instruction_site(&patch__hash_page_A2, 0x7c0, hash_mb2 << 6);
412 modify_instruction_site(&patch__hash_page_B, 0xffff, hmask);
413 modify_instruction_site(&patch__hash_page_C, 0xffff, hmask);
414
415 /*
416 * Patch up the instructions in hashtable.S:flush_hash_page
417 */
418 modify_instruction_site(&patch__flush_hash_A0, 0xffff, hash >> 16);
419 modify_instruction_site(&patch__flush_hash_A1, 0x7c0, hash_mb << 6);
420 modify_instruction_site(&patch__flush_hash_A2, 0x7c0, hash_mb2 << 6);
421 modify_instruction_site(&patch__flush_hash_B, 0xffff, hmask);
422 }
423
setup_initial_memory_limit(phys_addr_t first_memblock_base,phys_addr_t first_memblock_size)424 void setup_initial_memory_limit(phys_addr_t first_memblock_base,
425 phys_addr_t first_memblock_size)
426 {
427 /* We don't currently support the first MEMBLOCK not mapping 0
428 * physical on those processors
429 */
430 BUG_ON(first_memblock_base != 0);
431
432 memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_256M));
433 }
434
print_system_hash_info(void)435 void __init print_system_hash_info(void)
436 {
437 pr_info("Hash_size = 0x%lx\n", Hash_size);
438 if (Hash_mask)
439 pr_info("Hash_mask = 0x%lx\n", Hash_mask);
440 }
441
early_init_mmu(void)442 void __init early_init_mmu(void)
443 {
444 }
445