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1 /*
2 * linux/arch/arm/mm/nommu.c
3 *
4 * ARM uCLinux supporting functions.
5 */
6 #include <linux/module.h>
7 #include <linux/mm.h>
8 #include <linux/pagemap.h>
9 #include <linux/io.h>
10 #include <linux/memblock.h>
11 #include <linux/kernel.h>
12
13 #include <asm/cacheflush.h>
14 #include <asm/cp15.h>
15 #include <asm/sections.h>
16 #include <asm/page.h>
17 #include <asm/setup.h>
18 #include <asm/traps.h>
19 #include <asm/mach/arch.h>
20 #include <asm/cputype.h>
21 #include <asm/mpu.h>
22 #include <asm/procinfo.h>
23
24 #include "mm.h"
25
26 unsigned long vectors_base;
27
28 #ifdef CONFIG_ARM_MPU
29 struct mpu_rgn_info mpu_rgn_info;
30
31 /* Region number */
32 static void rgnr_write(u32 v)
33 {
34 asm("mcr p15, 0, %0, c6, c2, 0" : : "r" (v));
35 }
36
37 /* Data-side / unified region attributes */
38
39 /* Region access control register */
40 static void dracr_write(u32 v)
41 {
42 asm("mcr p15, 0, %0, c6, c1, 4" : : "r" (v));
43 }
44
45 /* Region size register */
46 static void drsr_write(u32 v)
47 {
48 asm("mcr p15, 0, %0, c6, c1, 2" : : "r" (v));
49 }
50
51 /* Region base address register */
52 static void drbar_write(u32 v)
53 {
54 asm("mcr p15, 0, %0, c6, c1, 0" : : "r" (v));
55 }
56
57 static u32 drbar_read(void)
58 {
59 u32 v;
60 asm("mrc p15, 0, %0, c6, c1, 0" : "=r" (v));
61 return v;
62 }
63 /* Optional instruction-side region attributes */
64
65 /* I-side Region access control register */
66 static void iracr_write(u32 v)
67 {
68 asm("mcr p15, 0, %0, c6, c1, 5" : : "r" (v));
69 }
70
71 /* I-side Region size register */
72 static void irsr_write(u32 v)
73 {
74 asm("mcr p15, 0, %0, c6, c1, 3" : : "r" (v));
75 }
76
77 /* I-side Region base address register */
78 static void irbar_write(u32 v)
79 {
80 asm("mcr p15, 0, %0, c6, c1, 1" : : "r" (v));
81 }
82
83 static unsigned long irbar_read(void)
84 {
85 unsigned long v;
86 asm("mrc p15, 0, %0, c6, c1, 1" : "=r" (v));
87 return v;
88 }
89
90 /* MPU initialisation functions */
91 void __init adjust_lowmem_bounds_mpu(void)
92 {
93 phys_addr_t phys_offset = PHYS_OFFSET;
94 phys_addr_t aligned_region_size, specified_mem_size, rounded_mem_size;
95 struct memblock_region *reg;
96 bool first = true;
97 phys_addr_t mem_start;
98 phys_addr_t mem_end;
99
100 for_each_memblock(memory, reg) {
101 if (first) {
102 /*
103 * Initially only use memory continuous from
104 * PHYS_OFFSET */
105 if (reg->base != phys_offset)
106 panic("First memory bank must be contiguous from PHYS_OFFSET");
107
108 mem_start = reg->base;
109 mem_end = reg->base + reg->size;
110 specified_mem_size = reg->size;
111 first = false;
112 } else {
113 /*
114 * memblock auto merges contiguous blocks, remove
115 * all blocks afterwards in one go (we can't remove
116 * blocks separately while iterating)
117 */
118 pr_notice("Ignoring RAM after %pa, memory at %pa ignored\n",
119 &mem_end, &reg->base);
120 memblock_remove(reg->base, 0 - reg->base);
121 break;
122 }
123 }
124
125 /*
126 * MPU has curious alignment requirements: Size must be power of 2, and
127 * region start must be aligned to the region size
128 */
129 if (phys_offset != 0)
130 pr_info("PHYS_OFFSET != 0 => MPU Region size constrained by alignment requirements\n");
131
132 /*
133 * Maximum aligned region might overflow phys_addr_t if phys_offset is
134 * 0. Hence we keep everything below 4G until we take the smaller of
135 * the aligned_region_size and rounded_mem_size, one of which is
136 * guaranteed to be smaller than the maximum physical address.
137 */
138 aligned_region_size = (phys_offset - 1) ^ (phys_offset);
139 /* Find the max power-of-two sized region that fits inside our bank */
140 rounded_mem_size = (1 << __fls(specified_mem_size)) - 1;
141
142 /* The actual region size is the smaller of the two */
143 aligned_region_size = aligned_region_size < rounded_mem_size
144 ? aligned_region_size + 1
145 : rounded_mem_size + 1;
146
147 if (aligned_region_size != specified_mem_size) {
148 pr_warn("Truncating memory from %pa to %pa (MPU region constraints)",
149 &specified_mem_size, &aligned_region_size);
150 memblock_remove(mem_start + aligned_region_size,
151 specified_mem_size - aligned_region_size);
152
153 mem_end = mem_start + aligned_region_size;
154 }
155
156 pr_debug("MPU Region from %pa size %pa (end %pa))\n",
157 &phys_offset, &aligned_region_size, &mem_end);
158
159 }
160
161 static int mpu_present(void)
162 {
163 return ((read_cpuid_ext(CPUID_EXT_MMFR0) & MMFR0_PMSA) == MMFR0_PMSAv7);
164 }
165
166 static int mpu_max_regions(void)
167 {
168 /*
169 * We don't support a different number of I/D side regions so if we
170 * have separate instruction and data memory maps then return
171 * whichever side has a smaller number of supported regions.
172 */
173 u32 dregions, iregions, mpuir;
174 mpuir = read_cpuid(CPUID_MPUIR);
175
176 dregions = iregions = (mpuir & MPUIR_DREGION_SZMASK) >> MPUIR_DREGION;
177
178 /* Check for separate d-side and i-side memory maps */
179 if (mpuir & MPUIR_nU)
180 iregions = (mpuir & MPUIR_IREGION_SZMASK) >> MPUIR_IREGION;
181
182 /* Use the smallest of the two maxima */
183 return min(dregions, iregions);
184 }
185
186 static int mpu_iside_independent(void)
187 {
188 /* MPUIR.nU specifies whether there is *not* a unified memory map */
189 return read_cpuid(CPUID_MPUIR) & MPUIR_nU;
190 }
191
192 static int mpu_min_region_order(void)
193 {
194 u32 drbar_result, irbar_result;
195 /* We've kept a region free for this probing */
196 rgnr_write(MPU_PROBE_REGION);
197 isb();
198 /*
199 * As per ARM ARM, write 0xFFFFFFFC to DRBAR to find the minimum
200 * region order
201 */
202 drbar_write(0xFFFFFFFC);
203 drbar_result = irbar_result = drbar_read();
204 drbar_write(0x0);
205 /* If the MPU is non-unified, we use the larger of the two minima*/
206 if (mpu_iside_independent()) {
207 irbar_write(0xFFFFFFFC);
208 irbar_result = irbar_read();
209 irbar_write(0x0);
210 }
211 isb(); /* Ensure that MPU region operations have completed */
212 /* Return whichever result is larger */
213 return __ffs(max(drbar_result, irbar_result));
214 }
215
216 static int mpu_setup_region(unsigned int number, phys_addr_t start,
217 unsigned int size_order, unsigned int properties)
218 {
219 u32 size_data;
220
221 /* We kept a region free for probing resolution of MPU regions*/
222 if (number > mpu_max_regions() || number == MPU_PROBE_REGION)
223 return -ENOENT;
224
225 if (size_order > 32)
226 return -ENOMEM;
227
228 if (size_order < mpu_min_region_order())
229 return -ENOMEM;
230
231 /* Writing N to bits 5:1 (RSR_SZ) specifies region size 2^N+1 */
232 size_data = ((size_order - 1) << MPU_RSR_SZ) | 1 << MPU_RSR_EN;
233
234 dsb(); /* Ensure all previous data accesses occur with old mappings */
235 rgnr_write(number);
236 isb();
237 drbar_write(start);
238 dracr_write(properties);
239 isb(); /* Propagate properties before enabling region */
240 drsr_write(size_data);
241
242 /* Check for independent I-side registers */
243 if (mpu_iside_independent()) {
244 irbar_write(start);
245 iracr_write(properties);
246 isb();
247 irsr_write(size_data);
248 }
249 isb();
250
251 /* Store region info (we treat i/d side the same, so only store d) */
252 mpu_rgn_info.rgns[number].dracr = properties;
253 mpu_rgn_info.rgns[number].drbar = start;
254 mpu_rgn_info.rgns[number].drsr = size_data;
255 return 0;
256 }
257
258 /*
259 * Set up default MPU regions, doing nothing if there is no MPU
260 */
261 void __init mpu_setup(void)
262 {
263 int region_err;
264 if (!mpu_present())
265 return;
266
267 region_err = mpu_setup_region(MPU_RAM_REGION, PHYS_OFFSET,
268 ilog2(memblock.memory.regions[0].size),
269 MPU_AP_PL1RW_PL0RW | MPU_RGN_NORMAL);
270 if (region_err) {
271 panic("MPU region initialization failure! %d", region_err);
272 } else {
273 pr_info("Using ARMv7 PMSA Compliant MPU. "
274 "Region independence: %s, Max regions: %d\n",
275 mpu_iside_independent() ? "Yes" : "No",
276 mpu_max_regions());
277 }
278 }
279 #else
280 static void adjust_lowmem_bounds_mpu(void) {}
281 static void __init mpu_setup(void) {}
282 #endif /* CONFIG_ARM_MPU */
283
284 #ifdef CONFIG_CPU_CP15
285 #ifdef CONFIG_CPU_HIGH_VECTOR
286 static unsigned long __init setup_vectors_base(void)
287 {
288 unsigned long reg = get_cr();
289
290 set_cr(reg | CR_V);
291 return 0xffff0000;
292 }
293 #else /* CONFIG_CPU_HIGH_VECTOR */
294 /* Write exception base address to VBAR */
295 static inline void set_vbar(unsigned long val)
296 {
297 asm("mcr p15, 0, %0, c12, c0, 0" : : "r" (val) : "cc");
298 }
299
300 /*
301 * Security extensions, bits[7:4], permitted values,
302 * 0b0000 - not implemented, 0b0001/0b0010 - implemented
303 */
304 static inline bool security_extensions_enabled(void)
305 {
306 return !!cpuid_feature_extract(CPUID_EXT_PFR1, 4);
307 }
308
309 static unsigned long __init setup_vectors_base(void)
310 {
311 unsigned long base = 0, reg = get_cr();
312
313 set_cr(reg & ~CR_V);
314 if (security_extensions_enabled()) {
315 if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM))
316 base = CONFIG_DRAM_BASE;
317 set_vbar(base);
318 } else if (IS_ENABLED(CONFIG_REMAP_VECTORS_TO_RAM)) {
319 if (CONFIG_DRAM_BASE != 0)
320 pr_err("Security extensions not enabled, vectors cannot be remapped to RAM, vectors base will be 0x00000000\n");
321 }
322
323 return base;
324 }
325 #endif /* CONFIG_CPU_HIGH_VECTOR */
326 #endif /* CONFIG_CPU_CP15 */
327
328 void __init arm_mm_memblock_reserve(void)
329 {
330 #ifndef CONFIG_CPU_V7M
331 vectors_base = IS_ENABLED(CONFIG_CPU_CP15) ? setup_vectors_base() : 0;
332 /*
333 * Register the exception vector page.
334 * some architectures which the DRAM is the exception vector to trap,
335 * alloc_page breaks with error, although it is not NULL, but "0."
336 */
337 memblock_reserve(vectors_base, 2 * PAGE_SIZE);
338 #else /* ifndef CONFIG_CPU_V7M */
339 /*
340 * There is no dedicated vector page on V7-M. So nothing needs to be
341 * reserved here.
342 */
343 #endif
344 }
345
346 void __init adjust_lowmem_bounds(void)
347 {
348 phys_addr_t end;
349 adjust_lowmem_bounds_mpu();
350 end = memblock_end_of_DRAM();
351 high_memory = __va(end - 1) + 1;
352 memblock_set_current_limit(end);
353 }
354
355 /*
356 * paging_init() sets up the page tables, initialises the zone memory
357 * maps, and sets up the zero page, bad page and bad page tables.
358 */
359 void __init paging_init(const struct machine_desc *mdesc)
360 {
361 early_trap_init((void *)vectors_base);
362 mpu_setup();
363 bootmem_init();
364 }
365
366 /*
367 * We don't need to do anything here for nommu machines.
368 */
369 void setup_mm_for_reboot(void)
370 {
371 }
372
373 void flush_dcache_page(struct page *page)
374 {
375 __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
376 }
377 EXPORT_SYMBOL(flush_dcache_page);
378
379 void flush_kernel_dcache_page(struct page *page)
380 {
381 __cpuc_flush_dcache_area(page_address(page), PAGE_SIZE);
382 }
383 EXPORT_SYMBOL(flush_kernel_dcache_page);
384
385 void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
386 unsigned long uaddr, void *dst, const void *src,
387 unsigned long len)
388 {
389 memcpy(dst, src, len);
390 if (vma->vm_flags & VM_EXEC)
391 __cpuc_coherent_user_range(uaddr, uaddr + len);
392 }
393
394 void __iomem *__arm_ioremap_pfn(unsigned long pfn, unsigned long offset,
395 size_t size, unsigned int mtype)
396 {
397 if (pfn >= (0x100000000ULL >> PAGE_SHIFT))
398 return NULL;
399 return (void __iomem *) (offset + (pfn << PAGE_SHIFT));
400 }
401 EXPORT_SYMBOL(__arm_ioremap_pfn);
402
403 void __iomem *__arm_ioremap_caller(phys_addr_t phys_addr, size_t size,
404 unsigned int mtype, void *caller)
405 {
406 return (void __iomem *)phys_addr;
407 }
408
409 void __iomem * (*arch_ioremap_caller)(phys_addr_t, size_t, unsigned int, void *);
410
411 void __iomem *ioremap(resource_size_t res_cookie, size_t size)
412 {
413 return __arm_ioremap_caller(res_cookie, size, MT_DEVICE,
414 __builtin_return_address(0));
415 }
416 EXPORT_SYMBOL(ioremap);
417
418 void __iomem *ioremap_cache(resource_size_t res_cookie, size_t size)
419 __alias(ioremap_cached);
420
421 void __iomem *ioremap_cached(resource_size_t res_cookie, size_t size)
422 {
423 return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_CACHED,
424 __builtin_return_address(0));
425 }
426 EXPORT_SYMBOL(ioremap_cache);
427 EXPORT_SYMBOL(ioremap_cached);
428
429 void __iomem *ioremap_wc(resource_size_t res_cookie, size_t size)
430 {
431 return __arm_ioremap_caller(res_cookie, size, MT_DEVICE_WC,
432 __builtin_return_address(0));
433 }
434 EXPORT_SYMBOL(ioremap_wc);
435
436 void *arch_memremap_wb(phys_addr_t phys_addr, size_t size)
437 {
438 return (void *)phys_addr;
439 }
440
441 void __iounmap(volatile void __iomem *addr)
442 {
443 }
444 EXPORT_SYMBOL(__iounmap);
445
446 void (*arch_iounmap)(volatile void __iomem *);
447
448 void iounmap(volatile void __iomem *addr)
449 {
450 }
451 EXPORT_SYMBOL(iounmap);