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1#include <linux/gfp.h>
2#include <linux/initrd.h>
3#include <linux/ioport.h>
4#include <linux/swap.h>
5#include <linux/memblock.h>
6
7#include <asm/cacheflush.h>
8#include <asm/e820.h>
9#include <asm/init.h>
10#include <asm/page.h>
11#include <asm/page_types.h>
12#include <asm/sections.h>
13#include <asm/setup.h>
14#include <asm/system.h>
15#include <asm/tlbflush.h>
16#include <asm/tlb.h>
17#include <asm/proto.h>
18
19unsigned long __initdata pgt_buf_start;
20unsigned long __meminitdata pgt_buf_end;
21unsigned long __meminitdata pgt_buf_top;
22
23int after_bootmem;
24
25int direct_gbpages
26#ifdef CONFIG_DIRECT_GBPAGES
27 = 1
28#endif
29;
30
31static void __init find_early_table_space(unsigned long end, int use_pse,
32 int use_gbpages)
33{
34 unsigned long puds, pmds, ptes, tables, start = 0, good_end = end;
35 phys_addr_t base;
36
37 puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
38 tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
39
40 if (use_gbpages) {
41 unsigned long extra;
42
43 extra = end - ((end>>PUD_SHIFT) << PUD_SHIFT);
44 pmds = (extra + PMD_SIZE - 1) >> PMD_SHIFT;
45 } else
46 pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
47
48 tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
49
50 if (use_pse) {
51 unsigned long extra;
52
53 extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
54#ifdef CONFIG_X86_32
55 extra += PMD_SIZE;
56#endif
57 ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
58 } else
59 ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
60
61 tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
62
63#ifdef CONFIG_X86_32
64 /* for fixmap */
65 tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
66#endif
67 good_end = max_pfn_mapped << PAGE_SHIFT;
68
69 base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
70 if (base == MEMBLOCK_ERROR)
71 panic("Cannot find space for the kernel page tables");
72
73 pgt_buf_start = base >> PAGE_SHIFT;
74 pgt_buf_end = pgt_buf_start;
75 pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
76
77 printk(KERN_DEBUG "kernel direct mapping tables up to %lx @ %lx-%lx\n",
78 end, pgt_buf_start << PAGE_SHIFT, pgt_buf_top << PAGE_SHIFT);
79}
80
81void __init native_pagetable_reserve(u64 start, u64 end)
82{
83 memblock_x86_reserve_range(start, end, "PGTABLE");
84}
85
86struct map_range {
87 unsigned long start;
88 unsigned long end;
89 unsigned page_size_mask;
90};
91
92#ifdef CONFIG_X86_32
93#define NR_RANGE_MR 3
94#else /* CONFIG_X86_64 */
95#define NR_RANGE_MR 5
96#endif
97
98static int __meminit save_mr(struct map_range *mr, int nr_range,
99 unsigned long start_pfn, unsigned long end_pfn,
100 unsigned long page_size_mask)
101{
102 if (start_pfn < end_pfn) {
103 if (nr_range >= NR_RANGE_MR)
104 panic("run out of range for init_memory_mapping\n");
105 mr[nr_range].start = start_pfn<<PAGE_SHIFT;
106 mr[nr_range].end = end_pfn<<PAGE_SHIFT;
107 mr[nr_range].page_size_mask = page_size_mask;
108 nr_range++;
109 }
110
111 return nr_range;
112}
113
114/*
115 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
116 * This runs before bootmem is initialized and gets pages directly from
117 * the physical memory. To access them they are temporarily mapped.
118 */
119unsigned long __init_refok init_memory_mapping(unsigned long start,
120 unsigned long end)
121{
122 unsigned long page_size_mask = 0;
123 unsigned long start_pfn, end_pfn;
124 unsigned long ret = 0;
125 unsigned long pos;
126
127 struct map_range mr[NR_RANGE_MR];
128 int nr_range, i;
129 int use_pse, use_gbpages;
130
131 printk(KERN_INFO "init_memory_mapping: %016lx-%016lx\n", start, end);
132
133#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KMEMCHECK)
134 /*
135 * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
136 * This will simplify cpa(), which otherwise needs to support splitting
137 * large pages into small in interrupt context, etc.
138 */
139 use_pse = use_gbpages = 0;
140#else
141 use_pse = cpu_has_pse;
142 use_gbpages = direct_gbpages;
143#endif
144
145 /* Enable PSE if available */
146 if (cpu_has_pse)
147 set_in_cr4(X86_CR4_PSE);
148
149 /* Enable PGE if available */
150 if (cpu_has_pge) {
151 set_in_cr4(X86_CR4_PGE);
152 __supported_pte_mask |= _PAGE_GLOBAL;
153 }
154
155 if (use_gbpages)
156 page_size_mask |= 1 << PG_LEVEL_1G;
157 if (use_pse)
158 page_size_mask |= 1 << PG_LEVEL_2M;
159
160 memset(mr, 0, sizeof(mr));
161 nr_range = 0;
162
163 /* head if not big page alignment ? */
164 start_pfn = start >> PAGE_SHIFT;
165 pos = start_pfn << PAGE_SHIFT;
166#ifdef CONFIG_X86_32
167 /*
168 * Don't use a large page for the first 2/4MB of memory
169 * because there are often fixed size MTRRs in there
170 * and overlapping MTRRs into large pages can cause
171 * slowdowns.
172 */
173 if (pos == 0)
174 end_pfn = 1<<(PMD_SHIFT - PAGE_SHIFT);
175 else
176 end_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
177 << (PMD_SHIFT - PAGE_SHIFT);
178#else /* CONFIG_X86_64 */
179 end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
180 << (PMD_SHIFT - PAGE_SHIFT);
181#endif
182 if (end_pfn > (end >> PAGE_SHIFT))
183 end_pfn = end >> PAGE_SHIFT;
184 if (start_pfn < end_pfn) {
185 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
186 pos = end_pfn << PAGE_SHIFT;
187 }
188
189 /* big page (2M) range */
190 start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
191 << (PMD_SHIFT - PAGE_SHIFT);
192#ifdef CONFIG_X86_32
193 end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
194#else /* CONFIG_X86_64 */
195 end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
196 << (PUD_SHIFT - PAGE_SHIFT);
197 if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
198 end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
199#endif
200
201 if (start_pfn < end_pfn) {
202 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
203 page_size_mask & (1<<PG_LEVEL_2M));
204 pos = end_pfn << PAGE_SHIFT;
205 }
206
207#ifdef CONFIG_X86_64
208 /* big page (1G) range */
209 start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
210 << (PUD_SHIFT - PAGE_SHIFT);
211 end_pfn = (end >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
212 if (start_pfn < end_pfn) {
213 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
214 page_size_mask &
215 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
216 pos = end_pfn << PAGE_SHIFT;
217 }
218
219 /* tail is not big page (1G) alignment */
220 start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
221 << (PMD_SHIFT - PAGE_SHIFT);
222 end_pfn = (end >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
223 if (start_pfn < end_pfn) {
224 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
225 page_size_mask & (1<<PG_LEVEL_2M));
226 pos = end_pfn << PAGE_SHIFT;
227 }
228#endif
229
230 /* tail is not big page (2M) alignment */
231 start_pfn = pos>>PAGE_SHIFT;
232 end_pfn = end>>PAGE_SHIFT;
233 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
234
235 /* try to merge same page size and continuous */
236 for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
237 unsigned long old_start;
238 if (mr[i].end != mr[i+1].start ||
239 mr[i].page_size_mask != mr[i+1].page_size_mask)
240 continue;
241 /* move it */
242 old_start = mr[i].start;
243 memmove(&mr[i], &mr[i+1],
244 (nr_range - 1 - i) * sizeof(struct map_range));
245 mr[i--].start = old_start;
246 nr_range--;
247 }
248
249 for (i = 0; i < nr_range; i++)
250 printk(KERN_DEBUG " %010lx - %010lx page %s\n",
251 mr[i].start, mr[i].end,
252 (mr[i].page_size_mask & (1<<PG_LEVEL_1G))?"1G":(
253 (mr[i].page_size_mask & (1<<PG_LEVEL_2M))?"2M":"4k"));
254
255 /*
256 * Find space for the kernel direct mapping tables.
257 *
258 * Later we should allocate these tables in the local node of the
259 * memory mapped. Unfortunately this is done currently before the
260 * nodes are discovered.
261 */
262 if (!after_bootmem)
263 find_early_table_space(end, use_pse, use_gbpages);
264
265 for (i = 0; i < nr_range; i++)
266 ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
267 mr[i].page_size_mask);
268
269#ifdef CONFIG_X86_32
270 early_ioremap_page_table_range_init();
271
272 load_cr3(swapper_pg_dir);
273#endif
274
275 __flush_tlb_all();
276
277 /*
278 * Reserve the kernel pagetable pages we used (pgt_buf_start -
279 * pgt_buf_end) and free the other ones (pgt_buf_end - pgt_buf_top)
280 * so that they can be reused for other purposes.
281 *
282 * On native it just means calling memblock_x86_reserve_range, on Xen it
283 * also means marking RW the pagetable pages that we allocated before
284 * but that haven't been used.
285 *
286 * In fact on xen we mark RO the whole range pgt_buf_start -
287 * pgt_buf_top, because we have to make sure that when
288 * init_memory_mapping reaches the pagetable pages area, it maps
289 * RO all the pagetable pages, including the ones that are beyond
290 * pgt_buf_end at that time.
291 */
292 if (!after_bootmem && pgt_buf_end > pgt_buf_start)
293 x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
294 PFN_PHYS(pgt_buf_end));
295
296 if (!after_bootmem)
297 early_memtest(start, end);
298
299 return ret >> PAGE_SHIFT;
300}
301
302
303/*
304 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
305 * is valid. The argument is a physical page number.
306 *
307 *
308 * On x86, access has to be given to the first megabyte of ram because that area
309 * contains bios code and data regions used by X and dosemu and similar apps.
310 * Access has to be given to non-kernel-ram areas as well, these contain the PCI
311 * mmio resources as well as potential bios/acpi data regions.
312 */
313int devmem_is_allowed(unsigned long pagenr)
314{
315 if (pagenr <= 256)
316 return 1;
317 if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
318 return 0;
319 if (!page_is_ram(pagenr))
320 return 1;
321 return 0;
322}
323
324void free_init_pages(char *what, unsigned long begin, unsigned long end)
325{
326 unsigned long addr;
327 unsigned long begin_aligned, end_aligned;
328
329 /* Make sure boundaries are page aligned */
330 begin_aligned = PAGE_ALIGN(begin);
331 end_aligned = end & PAGE_MASK;
332
333 if (WARN_ON(begin_aligned != begin || end_aligned != end)) {
334 begin = begin_aligned;
335 end = end_aligned;
336 }
337
338 if (begin >= end)
339 return;
340
341 addr = begin;
342
343 /*
344 * If debugging page accesses then do not free this memory but
345 * mark them not present - any buggy init-section access will
346 * create a kernel page fault:
347 */
348#ifdef CONFIG_DEBUG_PAGEALLOC
349 printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
350 begin, end);
351 set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
352#else
353 /*
354 * We just marked the kernel text read only above, now that
355 * we are going to free part of that, we need to make that
356 * writeable and non-executable first.
357 */
358 set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
359 set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
360
361 printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
362
363 for (; addr < end; addr += PAGE_SIZE) {
364 ClearPageReserved(virt_to_page(addr));
365 init_page_count(virt_to_page(addr));
366 memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
367 free_page(addr);
368 totalram_pages++;
369 }
370#endif
371}
372
373void free_initmem(void)
374{
375 free_init_pages("unused kernel memory",
376 (unsigned long)(&__init_begin),
377 (unsigned long)(&__init_end));
378}
379
380#ifdef CONFIG_BLK_DEV_INITRD
381void free_initrd_mem(unsigned long start, unsigned long end)
382{
383 /*
384 * end could be not aligned, and We can not align that,
385 * decompresser could be confused by aligned initrd_end
386 * We already reserve the end partial page before in
387 * - i386_start_kernel()
388 * - x86_64_start_kernel()
389 * - relocate_initrd()
390 * So here We can do PAGE_ALIGN() safely to get partial page to be freed
391 */
392 free_init_pages("initrd memory", start, PAGE_ALIGN(end));
393}
394#endif
1#include <linux/gfp.h>
2#include <linux/initrd.h>
3#include <linux/ioport.h>
4#include <linux/swap.h>
5#include <linux/memblock.h>
6#include <linux/bootmem.h> /* for max_low_pfn */
7
8#include <asm/set_memory.h>
9#include <asm/e820/api.h>
10#include <asm/init.h>
11#include <asm/page.h>
12#include <asm/page_types.h>
13#include <asm/sections.h>
14#include <asm/setup.h>
15#include <asm/tlbflush.h>
16#include <asm/tlb.h>
17#include <asm/proto.h>
18#include <asm/dma.h> /* for MAX_DMA_PFN */
19#include <asm/microcode.h>
20#include <asm/kaslr.h>
21#include <asm/hypervisor.h>
22#include <asm/cpufeature.h>
23#include <asm/pti.h>
24
25/*
26 * We need to define the tracepoints somewhere, and tlb.c
27 * is only compied when SMP=y.
28 */
29#define CREATE_TRACE_POINTS
30#include <trace/events/tlb.h>
31
32#include "mm_internal.h"
33
34/*
35 * Tables translating between page_cache_type_t and pte encoding.
36 *
37 * The default values are defined statically as minimal supported mode;
38 * WC and WT fall back to UC-. pat_init() updates these values to support
39 * more cache modes, WC and WT, when it is safe to do so. See pat_init()
40 * for the details. Note, __early_ioremap() used during early boot-time
41 * takes pgprot_t (pte encoding) and does not use these tables.
42 *
43 * Index into __cachemode2pte_tbl[] is the cachemode.
44 *
45 * Index into __pte2cachemode_tbl[] are the caching attribute bits of the pte
46 * (_PAGE_PWT, _PAGE_PCD, _PAGE_PAT) at index bit positions 0, 1, 2.
47 */
48uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = {
49 [_PAGE_CACHE_MODE_WB ] = 0 | 0 ,
50 [_PAGE_CACHE_MODE_WC ] = 0 | _PAGE_PCD,
51 [_PAGE_CACHE_MODE_UC_MINUS] = 0 | _PAGE_PCD,
52 [_PAGE_CACHE_MODE_UC ] = _PAGE_PWT | _PAGE_PCD,
53 [_PAGE_CACHE_MODE_WT ] = 0 | _PAGE_PCD,
54 [_PAGE_CACHE_MODE_WP ] = 0 | _PAGE_PCD,
55};
56EXPORT_SYMBOL(__cachemode2pte_tbl);
57
58uint8_t __pte2cachemode_tbl[8] = {
59 [__pte2cm_idx( 0 | 0 | 0 )] = _PAGE_CACHE_MODE_WB,
60 [__pte2cm_idx(_PAGE_PWT | 0 | 0 )] = _PAGE_CACHE_MODE_UC_MINUS,
61 [__pte2cm_idx( 0 | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC_MINUS,
62 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | 0 )] = _PAGE_CACHE_MODE_UC,
63 [__pte2cm_idx( 0 | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_WB,
64 [__pte2cm_idx(_PAGE_PWT | 0 | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS,
65 [__pte2cm_idx(0 | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC_MINUS,
66 [__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC,
67};
68EXPORT_SYMBOL(__pte2cachemode_tbl);
69
70static unsigned long __initdata pgt_buf_start;
71static unsigned long __initdata pgt_buf_end;
72static unsigned long __initdata pgt_buf_top;
73
74static unsigned long min_pfn_mapped;
75
76static bool __initdata can_use_brk_pgt = true;
77
78/*
79 * Pages returned are already directly mapped.
80 *
81 * Changing that is likely to break Xen, see commit:
82 *
83 * 279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve
84 *
85 * for detailed information.
86 */
87__ref void *alloc_low_pages(unsigned int num)
88{
89 unsigned long pfn;
90 int i;
91
92 if (after_bootmem) {
93 unsigned int order;
94
95 order = get_order((unsigned long)num << PAGE_SHIFT);
96 return (void *)__get_free_pages(GFP_ATOMIC | __GFP_ZERO, order);
97 }
98
99 if ((pgt_buf_end + num) > pgt_buf_top || !can_use_brk_pgt) {
100 unsigned long ret;
101 if (min_pfn_mapped >= max_pfn_mapped)
102 panic("alloc_low_pages: ran out of memory");
103 ret = memblock_find_in_range(min_pfn_mapped << PAGE_SHIFT,
104 max_pfn_mapped << PAGE_SHIFT,
105 PAGE_SIZE * num , PAGE_SIZE);
106 if (!ret)
107 panic("alloc_low_pages: can not alloc memory");
108 memblock_reserve(ret, PAGE_SIZE * num);
109 pfn = ret >> PAGE_SHIFT;
110 } else {
111 pfn = pgt_buf_end;
112 pgt_buf_end += num;
113 printk(KERN_DEBUG "BRK [%#010lx, %#010lx] PGTABLE\n",
114 pfn << PAGE_SHIFT, (pgt_buf_end << PAGE_SHIFT) - 1);
115 }
116
117 for (i = 0; i < num; i++) {
118 void *adr;
119
120 adr = __va((pfn + i) << PAGE_SHIFT);
121 clear_page(adr);
122 }
123
124 return __va(pfn << PAGE_SHIFT);
125}
126
127/*
128 * By default need 3 4k for initial PMD_SIZE, 3 4k for 0-ISA_END_ADDRESS.
129 * With KASLR memory randomization, depending on the machine e820 memory
130 * and the PUD alignment. We may need twice more pages when KASLR memory
131 * randomization is enabled.
132 */
133#ifndef CONFIG_RANDOMIZE_MEMORY
134#define INIT_PGD_PAGE_COUNT 6
135#else
136#define INIT_PGD_PAGE_COUNT 12
137#endif
138#define INIT_PGT_BUF_SIZE (INIT_PGD_PAGE_COUNT * PAGE_SIZE)
139RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE);
140void __init early_alloc_pgt_buf(void)
141{
142 unsigned long tables = INIT_PGT_BUF_SIZE;
143 phys_addr_t base;
144
145 base = __pa(extend_brk(tables, PAGE_SIZE));
146
147 pgt_buf_start = base >> PAGE_SHIFT;
148 pgt_buf_end = pgt_buf_start;
149 pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
150}
151
152int after_bootmem;
153
154early_param_on_off("gbpages", "nogbpages", direct_gbpages, CONFIG_X86_DIRECT_GBPAGES);
155
156struct map_range {
157 unsigned long start;
158 unsigned long end;
159 unsigned page_size_mask;
160};
161
162static int page_size_mask;
163
164static void __init probe_page_size_mask(void)
165{
166 /*
167 * For pagealloc debugging, identity mapping will use small pages.
168 * This will simplify cpa(), which otherwise needs to support splitting
169 * large pages into small in interrupt context, etc.
170 */
171 if (boot_cpu_has(X86_FEATURE_PSE) && !debug_pagealloc_enabled())
172 page_size_mask |= 1 << PG_LEVEL_2M;
173 else
174 direct_gbpages = 0;
175
176 /* Enable PSE if available */
177 if (boot_cpu_has(X86_FEATURE_PSE))
178 cr4_set_bits_and_update_boot(X86_CR4_PSE);
179
180 /* Enable PGE if available */
181 __supported_pte_mask &= ~_PAGE_GLOBAL;
182 if (boot_cpu_has(X86_FEATURE_PGE)) {
183 cr4_set_bits_and_update_boot(X86_CR4_PGE);
184 __supported_pte_mask |= _PAGE_GLOBAL;
185 }
186
187 /* By the default is everything supported: */
188 __default_kernel_pte_mask = __supported_pte_mask;
189 /* Except when with PTI where the kernel is mostly non-Global: */
190 if (cpu_feature_enabled(X86_FEATURE_PTI))
191 __default_kernel_pte_mask &= ~_PAGE_GLOBAL;
192
193 /* Enable 1 GB linear kernel mappings if available: */
194 if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) {
195 printk(KERN_INFO "Using GB pages for direct mapping\n");
196 page_size_mask |= 1 << PG_LEVEL_1G;
197 } else {
198 direct_gbpages = 0;
199 }
200}
201
202static void setup_pcid(void)
203{
204 if (!IS_ENABLED(CONFIG_X86_64))
205 return;
206
207 if (!boot_cpu_has(X86_FEATURE_PCID))
208 return;
209
210 if (boot_cpu_has(X86_FEATURE_PGE)) {
211 /*
212 * This can't be cr4_set_bits_and_update_boot() -- the
213 * trampoline code can't handle CR4.PCIDE and it wouldn't
214 * do any good anyway. Despite the name,
215 * cr4_set_bits_and_update_boot() doesn't actually cause
216 * the bits in question to remain set all the way through
217 * the secondary boot asm.
218 *
219 * Instead, we brute-force it and set CR4.PCIDE manually in
220 * start_secondary().
221 */
222 cr4_set_bits(X86_CR4_PCIDE);
223
224 /*
225 * INVPCID's single-context modes (2/3) only work if we set
226 * X86_CR4_PCIDE, *and* we INVPCID support. It's unusable
227 * on systems that have X86_CR4_PCIDE clear, or that have
228 * no INVPCID support at all.
229 */
230 if (boot_cpu_has(X86_FEATURE_INVPCID))
231 setup_force_cpu_cap(X86_FEATURE_INVPCID_SINGLE);
232 } else {
233 /*
234 * flush_tlb_all(), as currently implemented, won't work if
235 * PCID is on but PGE is not. Since that combination
236 * doesn't exist on real hardware, there's no reason to try
237 * to fully support it, but it's polite to avoid corrupting
238 * data if we're on an improperly configured VM.
239 */
240 setup_clear_cpu_cap(X86_FEATURE_PCID);
241 }
242}
243
244#ifdef CONFIG_X86_32
245#define NR_RANGE_MR 3
246#else /* CONFIG_X86_64 */
247#define NR_RANGE_MR 5
248#endif
249
250static int __meminit save_mr(struct map_range *mr, int nr_range,
251 unsigned long start_pfn, unsigned long end_pfn,
252 unsigned long page_size_mask)
253{
254 if (start_pfn < end_pfn) {
255 if (nr_range >= NR_RANGE_MR)
256 panic("run out of range for init_memory_mapping\n");
257 mr[nr_range].start = start_pfn<<PAGE_SHIFT;
258 mr[nr_range].end = end_pfn<<PAGE_SHIFT;
259 mr[nr_range].page_size_mask = page_size_mask;
260 nr_range++;
261 }
262
263 return nr_range;
264}
265
266/*
267 * adjust the page_size_mask for small range to go with
268 * big page size instead small one if nearby are ram too.
269 */
270static void __ref adjust_range_page_size_mask(struct map_range *mr,
271 int nr_range)
272{
273 int i;
274
275 for (i = 0; i < nr_range; i++) {
276 if ((page_size_mask & (1<<PG_LEVEL_2M)) &&
277 !(mr[i].page_size_mask & (1<<PG_LEVEL_2M))) {
278 unsigned long start = round_down(mr[i].start, PMD_SIZE);
279 unsigned long end = round_up(mr[i].end, PMD_SIZE);
280
281#ifdef CONFIG_X86_32
282 if ((end >> PAGE_SHIFT) > max_low_pfn)
283 continue;
284#endif
285
286 if (memblock_is_region_memory(start, end - start))
287 mr[i].page_size_mask |= 1<<PG_LEVEL_2M;
288 }
289 if ((page_size_mask & (1<<PG_LEVEL_1G)) &&
290 !(mr[i].page_size_mask & (1<<PG_LEVEL_1G))) {
291 unsigned long start = round_down(mr[i].start, PUD_SIZE);
292 unsigned long end = round_up(mr[i].end, PUD_SIZE);
293
294 if (memblock_is_region_memory(start, end - start))
295 mr[i].page_size_mask |= 1<<PG_LEVEL_1G;
296 }
297 }
298}
299
300static const char *page_size_string(struct map_range *mr)
301{
302 static const char str_1g[] = "1G";
303 static const char str_2m[] = "2M";
304 static const char str_4m[] = "4M";
305 static const char str_4k[] = "4k";
306
307 if (mr->page_size_mask & (1<<PG_LEVEL_1G))
308 return str_1g;
309 /*
310 * 32-bit without PAE has a 4M large page size.
311 * PG_LEVEL_2M is misnamed, but we can at least
312 * print out the right size in the string.
313 */
314 if (IS_ENABLED(CONFIG_X86_32) &&
315 !IS_ENABLED(CONFIG_X86_PAE) &&
316 mr->page_size_mask & (1<<PG_LEVEL_2M))
317 return str_4m;
318
319 if (mr->page_size_mask & (1<<PG_LEVEL_2M))
320 return str_2m;
321
322 return str_4k;
323}
324
325static int __meminit split_mem_range(struct map_range *mr, int nr_range,
326 unsigned long start,
327 unsigned long end)
328{
329 unsigned long start_pfn, end_pfn, limit_pfn;
330 unsigned long pfn;
331 int i;
332
333 limit_pfn = PFN_DOWN(end);
334
335 /* head if not big page alignment ? */
336 pfn = start_pfn = PFN_DOWN(start);
337#ifdef CONFIG_X86_32
338 /*
339 * Don't use a large page for the first 2/4MB of memory
340 * because there are often fixed size MTRRs in there
341 * and overlapping MTRRs into large pages can cause
342 * slowdowns.
343 */
344 if (pfn == 0)
345 end_pfn = PFN_DOWN(PMD_SIZE);
346 else
347 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
348#else /* CONFIG_X86_64 */
349 end_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
350#endif
351 if (end_pfn > limit_pfn)
352 end_pfn = limit_pfn;
353 if (start_pfn < end_pfn) {
354 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
355 pfn = end_pfn;
356 }
357
358 /* big page (2M) range */
359 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
360#ifdef CONFIG_X86_32
361 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
362#else /* CONFIG_X86_64 */
363 end_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
364 if (end_pfn > round_down(limit_pfn, PFN_DOWN(PMD_SIZE)))
365 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
366#endif
367
368 if (start_pfn < end_pfn) {
369 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
370 page_size_mask & (1<<PG_LEVEL_2M));
371 pfn = end_pfn;
372 }
373
374#ifdef CONFIG_X86_64
375 /* big page (1G) range */
376 start_pfn = round_up(pfn, PFN_DOWN(PUD_SIZE));
377 end_pfn = round_down(limit_pfn, PFN_DOWN(PUD_SIZE));
378 if (start_pfn < end_pfn) {
379 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
380 page_size_mask &
381 ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
382 pfn = end_pfn;
383 }
384
385 /* tail is not big page (1G) alignment */
386 start_pfn = round_up(pfn, PFN_DOWN(PMD_SIZE));
387 end_pfn = round_down(limit_pfn, PFN_DOWN(PMD_SIZE));
388 if (start_pfn < end_pfn) {
389 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
390 page_size_mask & (1<<PG_LEVEL_2M));
391 pfn = end_pfn;
392 }
393#endif
394
395 /* tail is not big page (2M) alignment */
396 start_pfn = pfn;
397 end_pfn = limit_pfn;
398 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
399
400 if (!after_bootmem)
401 adjust_range_page_size_mask(mr, nr_range);
402
403 /* try to merge same page size and continuous */
404 for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
405 unsigned long old_start;
406 if (mr[i].end != mr[i+1].start ||
407 mr[i].page_size_mask != mr[i+1].page_size_mask)
408 continue;
409 /* move it */
410 old_start = mr[i].start;
411 memmove(&mr[i], &mr[i+1],
412 (nr_range - 1 - i) * sizeof(struct map_range));
413 mr[i--].start = old_start;
414 nr_range--;
415 }
416
417 for (i = 0; i < nr_range; i++)
418 pr_debug(" [mem %#010lx-%#010lx] page %s\n",
419 mr[i].start, mr[i].end - 1,
420 page_size_string(&mr[i]));
421
422 return nr_range;
423}
424
425struct range pfn_mapped[E820_MAX_ENTRIES];
426int nr_pfn_mapped;
427
428static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn)
429{
430 nr_pfn_mapped = add_range_with_merge(pfn_mapped, E820_MAX_ENTRIES,
431 nr_pfn_mapped, start_pfn, end_pfn);
432 nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_MAX_ENTRIES);
433
434 max_pfn_mapped = max(max_pfn_mapped, end_pfn);
435
436 if (start_pfn < (1UL<<(32-PAGE_SHIFT)))
437 max_low_pfn_mapped = max(max_low_pfn_mapped,
438 min(end_pfn, 1UL<<(32-PAGE_SHIFT)));
439}
440
441bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn)
442{
443 int i;
444
445 for (i = 0; i < nr_pfn_mapped; i++)
446 if ((start_pfn >= pfn_mapped[i].start) &&
447 (end_pfn <= pfn_mapped[i].end))
448 return true;
449
450 return false;
451}
452
453/*
454 * Setup the direct mapping of the physical memory at PAGE_OFFSET.
455 * This runs before bootmem is initialized and gets pages directly from
456 * the physical memory. To access them they are temporarily mapped.
457 */
458unsigned long __ref init_memory_mapping(unsigned long start,
459 unsigned long end)
460{
461 struct map_range mr[NR_RANGE_MR];
462 unsigned long ret = 0;
463 int nr_range, i;
464
465 pr_debug("init_memory_mapping: [mem %#010lx-%#010lx]\n",
466 start, end - 1);
467
468 memset(mr, 0, sizeof(mr));
469 nr_range = split_mem_range(mr, 0, start, end);
470
471 for (i = 0; i < nr_range; i++)
472 ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
473 mr[i].page_size_mask);
474
475 add_pfn_range_mapped(start >> PAGE_SHIFT, ret >> PAGE_SHIFT);
476
477 return ret >> PAGE_SHIFT;
478}
479
480/*
481 * We need to iterate through the E820 memory map and create direct mappings
482 * for only E820_TYPE_RAM and E820_KERN_RESERVED regions. We cannot simply
483 * create direct mappings for all pfns from [0 to max_low_pfn) and
484 * [4GB to max_pfn) because of possible memory holes in high addresses
485 * that cannot be marked as UC by fixed/variable range MTRRs.
486 * Depending on the alignment of E820 ranges, this may possibly result
487 * in using smaller size (i.e. 4K instead of 2M or 1G) page tables.
488 *
489 * init_mem_mapping() calls init_range_memory_mapping() with big range.
490 * That range would have hole in the middle or ends, and only ram parts
491 * will be mapped in init_range_memory_mapping().
492 */
493static unsigned long __init init_range_memory_mapping(
494 unsigned long r_start,
495 unsigned long r_end)
496{
497 unsigned long start_pfn, end_pfn;
498 unsigned long mapped_ram_size = 0;
499 int i;
500
501 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
502 u64 start = clamp_val(PFN_PHYS(start_pfn), r_start, r_end);
503 u64 end = clamp_val(PFN_PHYS(end_pfn), r_start, r_end);
504 if (start >= end)
505 continue;
506
507 /*
508 * if it is overlapping with brk pgt, we need to
509 * alloc pgt buf from memblock instead.
510 */
511 can_use_brk_pgt = max(start, (u64)pgt_buf_end<<PAGE_SHIFT) >=
512 min(end, (u64)pgt_buf_top<<PAGE_SHIFT);
513 init_memory_mapping(start, end);
514 mapped_ram_size += end - start;
515 can_use_brk_pgt = true;
516 }
517
518 return mapped_ram_size;
519}
520
521static unsigned long __init get_new_step_size(unsigned long step_size)
522{
523 /*
524 * Initial mapped size is PMD_SIZE (2M).
525 * We can not set step_size to be PUD_SIZE (1G) yet.
526 * In worse case, when we cross the 1G boundary, and
527 * PG_LEVEL_2M is not set, we will need 1+1+512 pages (2M + 8k)
528 * to map 1G range with PTE. Hence we use one less than the
529 * difference of page table level shifts.
530 *
531 * Don't need to worry about overflow in the top-down case, on 32bit,
532 * when step_size is 0, round_down() returns 0 for start, and that
533 * turns it into 0x100000000ULL.
534 * In the bottom-up case, round_up(x, 0) returns 0 though too, which
535 * needs to be taken into consideration by the code below.
536 */
537 return step_size << (PMD_SHIFT - PAGE_SHIFT - 1);
538}
539
540/**
541 * memory_map_top_down - Map [map_start, map_end) top down
542 * @map_start: start address of the target memory range
543 * @map_end: end address of the target memory range
544 *
545 * This function will setup direct mapping for memory range
546 * [map_start, map_end) in top-down. That said, the page tables
547 * will be allocated at the end of the memory, and we map the
548 * memory in top-down.
549 */
550static void __init memory_map_top_down(unsigned long map_start,
551 unsigned long map_end)
552{
553 unsigned long real_end, start, last_start;
554 unsigned long step_size;
555 unsigned long addr;
556 unsigned long mapped_ram_size = 0;
557
558 /* xen has big range in reserved near end of ram, skip it at first.*/
559 addr = memblock_find_in_range(map_start, map_end, PMD_SIZE, PMD_SIZE);
560 real_end = addr + PMD_SIZE;
561
562 /* step_size need to be small so pgt_buf from BRK could cover it */
563 step_size = PMD_SIZE;
564 max_pfn_mapped = 0; /* will get exact value next */
565 min_pfn_mapped = real_end >> PAGE_SHIFT;
566 last_start = start = real_end;
567
568 /*
569 * We start from the top (end of memory) and go to the bottom.
570 * The memblock_find_in_range() gets us a block of RAM from the
571 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
572 * for page table.
573 */
574 while (last_start > map_start) {
575 if (last_start > step_size) {
576 start = round_down(last_start - 1, step_size);
577 if (start < map_start)
578 start = map_start;
579 } else
580 start = map_start;
581 mapped_ram_size += init_range_memory_mapping(start,
582 last_start);
583 last_start = start;
584 min_pfn_mapped = last_start >> PAGE_SHIFT;
585 if (mapped_ram_size >= step_size)
586 step_size = get_new_step_size(step_size);
587 }
588
589 if (real_end < map_end)
590 init_range_memory_mapping(real_end, map_end);
591}
592
593/**
594 * memory_map_bottom_up - Map [map_start, map_end) bottom up
595 * @map_start: start address of the target memory range
596 * @map_end: end address of the target memory range
597 *
598 * This function will setup direct mapping for memory range
599 * [map_start, map_end) in bottom-up. Since we have limited the
600 * bottom-up allocation above the kernel, the page tables will
601 * be allocated just above the kernel and we map the memory
602 * in [map_start, map_end) in bottom-up.
603 */
604static void __init memory_map_bottom_up(unsigned long map_start,
605 unsigned long map_end)
606{
607 unsigned long next, start;
608 unsigned long mapped_ram_size = 0;
609 /* step_size need to be small so pgt_buf from BRK could cover it */
610 unsigned long step_size = PMD_SIZE;
611
612 start = map_start;
613 min_pfn_mapped = start >> PAGE_SHIFT;
614
615 /*
616 * We start from the bottom (@map_start) and go to the top (@map_end).
617 * The memblock_find_in_range() gets us a block of RAM from the
618 * end of RAM in [min_pfn_mapped, max_pfn_mapped) used as new pages
619 * for page table.
620 */
621 while (start < map_end) {
622 if (step_size && map_end - start > step_size) {
623 next = round_up(start + 1, step_size);
624 if (next > map_end)
625 next = map_end;
626 } else {
627 next = map_end;
628 }
629
630 mapped_ram_size += init_range_memory_mapping(start, next);
631 start = next;
632
633 if (mapped_ram_size >= step_size)
634 step_size = get_new_step_size(step_size);
635 }
636}
637
638void __init init_mem_mapping(void)
639{
640 unsigned long end;
641
642 pti_check_boottime_disable();
643 probe_page_size_mask();
644 setup_pcid();
645
646#ifdef CONFIG_X86_64
647 end = max_pfn << PAGE_SHIFT;
648#else
649 end = max_low_pfn << PAGE_SHIFT;
650#endif
651
652 /* the ISA range is always mapped regardless of memory holes */
653 init_memory_mapping(0, ISA_END_ADDRESS);
654
655 /* Init the trampoline, possibly with KASLR memory offset */
656 init_trampoline();
657
658 /*
659 * If the allocation is in bottom-up direction, we setup direct mapping
660 * in bottom-up, otherwise we setup direct mapping in top-down.
661 */
662 if (memblock_bottom_up()) {
663 unsigned long kernel_end = __pa_symbol(_end);
664
665 /*
666 * we need two separate calls here. This is because we want to
667 * allocate page tables above the kernel. So we first map
668 * [kernel_end, end) to make memory above the kernel be mapped
669 * as soon as possible. And then use page tables allocated above
670 * the kernel to map [ISA_END_ADDRESS, kernel_end).
671 */
672 memory_map_bottom_up(kernel_end, end);
673 memory_map_bottom_up(ISA_END_ADDRESS, kernel_end);
674 } else {
675 memory_map_top_down(ISA_END_ADDRESS, end);
676 }
677
678#ifdef CONFIG_X86_64
679 if (max_pfn > max_low_pfn) {
680 /* can we preseve max_low_pfn ?*/
681 max_low_pfn = max_pfn;
682 }
683#else
684 early_ioremap_page_table_range_init();
685#endif
686
687 load_cr3(swapper_pg_dir);
688 __flush_tlb_all();
689
690 x86_init.hyper.init_mem_mapping();
691
692 early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
693}
694
695/*
696 * devmem_is_allowed() checks to see if /dev/mem access to a certain address
697 * is valid. The argument is a physical page number.
698 *
699 * On x86, access has to be given to the first megabyte of RAM because that
700 * area traditionally contains BIOS code and data regions used by X, dosemu,
701 * and similar apps. Since they map the entire memory range, the whole range
702 * must be allowed (for mapping), but any areas that would otherwise be
703 * disallowed are flagged as being "zero filled" instead of rejected.
704 * Access has to be given to non-kernel-ram areas as well, these contain the
705 * PCI mmio resources as well as potential bios/acpi data regions.
706 */
707int devmem_is_allowed(unsigned long pagenr)
708{
709 if (page_is_ram(pagenr)) {
710 /*
711 * For disallowed memory regions in the low 1MB range,
712 * request that the page be shown as all zeros.
713 */
714 if (pagenr < 256)
715 return 2;
716
717 return 0;
718 }
719
720 /*
721 * This must follow RAM test, since System RAM is considered a
722 * restricted resource under CONFIG_STRICT_IOMEM.
723 */
724 if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) {
725 /* Low 1MB bypasses iomem restrictions. */
726 if (pagenr < 256)
727 return 1;
728
729 return 0;
730 }
731
732 return 1;
733}
734
735void free_init_pages(char *what, unsigned long begin, unsigned long end)
736{
737 unsigned long begin_aligned, end_aligned;
738
739 /* Make sure boundaries are page aligned */
740 begin_aligned = PAGE_ALIGN(begin);
741 end_aligned = end & PAGE_MASK;
742
743 if (WARN_ON(begin_aligned != begin || end_aligned != end)) {
744 begin = begin_aligned;
745 end = end_aligned;
746 }
747
748 if (begin >= end)
749 return;
750
751 /*
752 * If debugging page accesses then do not free this memory but
753 * mark them not present - any buggy init-section access will
754 * create a kernel page fault:
755 */
756 if (debug_pagealloc_enabled()) {
757 pr_info("debug: unmapping init [mem %#010lx-%#010lx]\n",
758 begin, end - 1);
759 set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
760 } else {
761 /*
762 * We just marked the kernel text read only above, now that
763 * we are going to free part of that, we need to make that
764 * writeable and non-executable first.
765 */
766 set_memory_nx(begin, (end - begin) >> PAGE_SHIFT);
767 set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
768
769 free_reserved_area((void *)begin, (void *)end,
770 POISON_FREE_INITMEM, what);
771 }
772}
773
774void __ref free_initmem(void)
775{
776 e820__reallocate_tables();
777
778 free_init_pages("unused kernel",
779 (unsigned long)(&__init_begin),
780 (unsigned long)(&__init_end));
781}
782
783#ifdef CONFIG_BLK_DEV_INITRD
784void __init free_initrd_mem(unsigned long start, unsigned long end)
785{
786 /*
787 * end could be not aligned, and We can not align that,
788 * decompresser could be confused by aligned initrd_end
789 * We already reserve the end partial page before in
790 * - i386_start_kernel()
791 * - x86_64_start_kernel()
792 * - relocate_initrd()
793 * So here We can do PAGE_ALIGN() safely to get partial page to be freed
794 */
795 free_init_pages("initrd", start, PAGE_ALIGN(end));
796}
797#endif
798
799/*
800 * Calculate the precise size of the DMA zone (first 16 MB of RAM),
801 * and pass it to the MM layer - to help it set zone watermarks more
802 * accurately.
803 *
804 * Done on 64-bit systems only for the time being, although 32-bit systems
805 * might benefit from this as well.
806 */
807void __init memblock_find_dma_reserve(void)
808{
809#ifdef CONFIG_X86_64
810 u64 nr_pages = 0, nr_free_pages = 0;
811 unsigned long start_pfn, end_pfn;
812 phys_addr_t start_addr, end_addr;
813 int i;
814 u64 u;
815
816 /*
817 * Iterate over all memory ranges (free and reserved ones alike),
818 * to calculate the total number of pages in the first 16 MB of RAM:
819 */
820 nr_pages = 0;
821 for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) {
822 start_pfn = min(start_pfn, MAX_DMA_PFN);
823 end_pfn = min(end_pfn, MAX_DMA_PFN);
824
825 nr_pages += end_pfn - start_pfn;
826 }
827
828 /*
829 * Iterate over free memory ranges to calculate the number of free
830 * pages in the DMA zone, while not counting potential partial
831 * pages at the beginning or the end of the range:
832 */
833 nr_free_pages = 0;
834 for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) {
835 start_pfn = min_t(unsigned long, PFN_UP(start_addr), MAX_DMA_PFN);
836 end_pfn = min_t(unsigned long, PFN_DOWN(end_addr), MAX_DMA_PFN);
837
838 if (start_pfn < end_pfn)
839 nr_free_pages += end_pfn - start_pfn;
840 }
841
842 set_dma_reserve(nr_pages - nr_free_pages);
843#endif
844}
845
846void __init zone_sizes_init(void)
847{
848 unsigned long max_zone_pfns[MAX_NR_ZONES];
849
850 memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
851
852#ifdef CONFIG_ZONE_DMA
853 max_zone_pfns[ZONE_DMA] = min(MAX_DMA_PFN, max_low_pfn);
854#endif
855#ifdef CONFIG_ZONE_DMA32
856 max_zone_pfns[ZONE_DMA32] = min(MAX_DMA32_PFN, max_low_pfn);
857#endif
858 max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
859#ifdef CONFIG_HIGHMEM
860 max_zone_pfns[ZONE_HIGHMEM] = max_pfn;
861#endif
862
863 free_area_init_nodes(max_zone_pfns);
864}
865
866__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = {
867 .loaded_mm = &init_mm,
868 .next_asid = 1,
869 .cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */
870};
871EXPORT_PER_CPU_SYMBOL(cpu_tlbstate);
872
873void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache)
874{
875 /* entry 0 MUST be WB (hardwired to speed up translations) */
876 BUG_ON(!entry && cache != _PAGE_CACHE_MODE_WB);
877
878 __cachemode2pte_tbl[cache] = __cm_idx2pte(entry);
879 __pte2cachemode_tbl[entry] = cache;
880}