2 * Copyright 2002 Andi Kleen, SuSE Labs.
3 * Thanks to Ben LaHaise for precious feedback.
5 #include <linux/highmem.h>
6 #include <linux/bootmem.h>
7 #include <linux/module.h>
8 #include <linux/sched.h>
9 #include <linux/slab.h>
13 #include <asm/processor.h>
14 #include <asm/tlbflush.h>
15 #include <asm/sections.h>
16 #include <asm/uaccess.h>
17 #include <asm/pgalloc.h>
20 within(unsigned long addr, unsigned long start, unsigned long end)
22 return addr >= start && addr < end;
28 void clflush_cache_range(void *addr, int size)
32 for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
36 static void flush_kernel_map(void *arg)
39 * Flush all to work around Errata in early athlons regarding
40 * large page flushing.
44 if (boot_cpu_data.x86_model >= 4)
48 static void global_flush_tlb(void)
50 BUG_ON(irqs_disabled());
52 on_each_cpu(flush_kernel_map, NULL, 1, 1);
56 * Certain areas of memory on x86 require very specific protection flags,
57 * for example the BIOS area or kernel text. Callers don't always get this
58 * right (again, ioremap() on BIOS memory is not uncommon) so this function
59 * checks and fixes these known static required protection bits.
61 static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
63 pgprot_t forbidden = __pgprot(0);
66 * The BIOS area between 640k and 1Mb needs to be executable for
67 * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
69 if (within(__pa(address), BIOS_BEGIN, BIOS_END))
70 pgprot_val(forbidden) |= _PAGE_NX;
73 * The kernel text needs to be executable for obvious reasons
74 * Does not cover __inittext since that is gone later on
76 if (within(address, (unsigned long)_text, (unsigned long)_etext))
77 pgprot_val(forbidden) |= _PAGE_NX;
79 #ifdef CONFIG_DEBUG_RODATA
80 /* The .rodata section needs to be read-only */
81 if (within(address, (unsigned long)__start_rodata,
82 (unsigned long)__end_rodata))
83 pgprot_val(forbidden) |= _PAGE_RW;
86 prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
91 pte_t *lookup_address(unsigned long address, int *level)
93 pgd_t *pgd = pgd_offset_k(address);
97 *level = PG_LEVEL_NONE;
101 pud = pud_offset(pgd, address);
104 pmd = pmd_offset(pud, address);
108 *level = PG_LEVEL_2M;
112 *level = PG_LEVEL_4K;
113 return pte_offset_kernel(pmd, address);
116 static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
119 set_pte_atomic(kpte, pte);
121 if (!SHARED_KERNEL_PMD) {
124 for (page = pgd_list; page; page = (struct page *)page->index) {
129 pgd = (pgd_t *)page_address(page) + pgd_index(address);
130 pud = pud_offset(pgd, address);
131 pmd = pmd_offset(pud, address);
132 set_pte_atomic((pte_t *)pmd, pte);
138 static int split_large_page(pte_t *kpte, unsigned long address)
140 pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
141 gfp_t gfp_flags = GFP_KERNEL;
148 #ifdef CONFIG_DEBUG_PAGEALLOC
149 gfp_flags = GFP_ATOMIC;
151 base = alloc_pages(gfp_flags, 0);
155 spin_lock_irqsave(&pgd_lock, flags);
157 * Check for races, another CPU might have split this page
160 tmp = lookup_address(address, &level);
166 address = __pa(address);
167 addr = address & LARGE_PAGE_MASK;
168 pbase = (pte_t *)page_address(base);
170 paravirt_alloc_pt(&init_mm, page_to_pfn(base));
173 for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
174 set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
177 * Install the new, split up pagetable. Important detail here:
179 * On Intel the NX bit of all levels must be cleared to make a
180 * page executable. See section 4.13.2 of Intel 64 and IA-32
181 * Architectures Software Developer's Manual).
183 ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
184 __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
188 spin_unlock_irqrestore(&pgd_lock, flags);
191 __free_pages(base, 0);
197 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot)
199 struct page *kpte_page;
204 BUG_ON(pfn > max_low_pfn);
208 kpte = lookup_address(address, &level);
212 kpte_page = virt_to_page(kpte);
213 BUG_ON(PageLRU(kpte_page));
214 BUG_ON(PageCompound(kpte_page));
216 prot = static_protections(prot, address);
218 if (level == PG_LEVEL_4K) {
219 set_pte_atomic(kpte, pfn_pte(pfn, canon_pgprot(prot)));
221 err = split_large_page(kpte, address);
229 * change_page_attr_addr - Change page table attributes in linear mapping
230 * @address: Virtual address in linear mapping.
231 * @prot: New page table attribute (PAGE_*)
233 * Change page attributes of a page in the direct mapping. This is a variant
234 * of change_page_attr() that also works on memory holes that do not have
235 * mem_map entry (pfn_valid() is false).
237 * See change_page_attr() documentation for more details.
239 * Modules and drivers should use the set_memory_* APIs instead.
242 static int change_page_attr_addr(unsigned long address, pgprot_t prot)
244 int err = 0, kernel_map = 0;
245 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
248 if (address >= __START_KERNEL_map &&
249 address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
251 address = (unsigned long)__va(__pa(address));
256 if (!kernel_map || pte_present(pfn_pte(0, prot))) {
257 err = __change_page_attr(address, pfn, prot);
264 * Handle kernel mapping too which aliases part of
267 if (__pa(address) < KERNEL_TEXT_SIZE) {
271 addr2 = __START_KERNEL_map + __pa(address);
272 /* Make sure the kernel mappings stay executable */
273 prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
274 err = __change_page_attr(addr2, pfn, prot2);
282 * change_page_attr_set - Change page table attributes in the linear mapping.
283 * @addr: Virtual address in linear mapping.
284 * @numpages: Number of pages to change
285 * @prot: Protection/caching type bits to set (PAGE_*)
287 * Returns 0 on success, otherwise a negated errno.
289 * This should be used when a page is mapped with a different caching policy
290 * than write-back somewhere - some CPUs do not like it when mappings with
291 * different caching policies exist. This changes the page attributes of the
292 * in kernel linear mapping too.
294 * The caller needs to ensure that there are no conflicting mappings elsewhere
295 * (e.g. in user space) * This function only deals with the kernel linear map.
297 * This function is different from change_page_attr() in that only selected bits
298 * are impacted, all other bits remain as is.
300 static int change_page_attr_set(unsigned long addr, int numpages,
303 pgprot_t current_prot;
308 for (i = 0; i < numpages ; i++) {
310 pte = lookup_address(addr, &level);
312 current_prot = pte_pgprot(*pte);
314 pgprot_val(current_prot) = 0;
316 pgprot_val(prot) = pgprot_val(current_prot) | pgprot_val(prot);
318 ret = change_page_attr_addr(addr, prot);
327 * change_page_attr_clear - Change page table attributes in the linear mapping.
328 * @addr: Virtual address in linear mapping.
329 * @numpages: Number of pages to change
330 * @prot: Protection/caching type bits to clear (PAGE_*)
332 * Returns 0 on success, otherwise a negated errno.
334 * This should be used when a page is mapped with a different caching policy
335 * than write-back somewhere - some CPUs do not like it when mappings with
336 * different caching policies exist. This changes the page attributes of the
337 * in kernel linear mapping too.
339 * The caller needs to ensure that there are no conflicting mappings elsewhere
340 * (e.g. in user space) * This function only deals with the kernel linear map.
342 * This function is different from change_page_attr() in that only selected bits
343 * are impacted, all other bits remain as is.
345 static int change_page_attr_clear(unsigned long addr, int numpages,
348 pgprot_t current_prot;
353 for (i = 0; i < numpages; i++) {
354 pte = lookup_address(addr, &level);
356 current_prot = pte_pgprot(*pte);
358 pgprot_val(current_prot) = 0;
361 pgprot_val(current_prot) & ~pgprot_val(prot);
363 ret = change_page_attr_addr(addr, prot);
371 int set_memory_uc(unsigned long addr, int numpages)
375 err = change_page_attr_set(addr, numpages,
376 __pgprot(_PAGE_PCD | _PAGE_PWT));
380 EXPORT_SYMBOL(set_memory_uc);
382 int set_memory_wb(unsigned long addr, int numpages)
386 err = change_page_attr_clear(addr, numpages,
387 __pgprot(_PAGE_PCD | _PAGE_PWT));
391 EXPORT_SYMBOL(set_memory_wb);
393 int set_memory_x(unsigned long addr, int numpages)
397 err = change_page_attr_clear(addr, numpages,
402 EXPORT_SYMBOL(set_memory_x);
404 int set_memory_nx(unsigned long addr, int numpages)
408 err = change_page_attr_set(addr, numpages,
413 EXPORT_SYMBOL(set_memory_nx);
415 int set_memory_ro(unsigned long addr, int numpages)
419 err = change_page_attr_clear(addr, numpages,
425 int set_memory_rw(unsigned long addr, int numpages)
429 err = change_page_attr_set(addr, numpages,
435 int set_memory_np(unsigned long addr, int numpages)
439 err = change_page_attr_clear(addr, numpages,
440 __pgprot(_PAGE_PRESENT));
445 int set_pages_uc(struct page *page, int numpages)
447 unsigned long addr = (unsigned long)page_address(page);
449 return set_memory_uc(addr, numpages);
451 EXPORT_SYMBOL(set_pages_uc);
453 int set_pages_wb(struct page *page, int numpages)
455 unsigned long addr = (unsigned long)page_address(page);
457 return set_memory_wb(addr, numpages);
459 EXPORT_SYMBOL(set_pages_wb);
461 int set_pages_x(struct page *page, int numpages)
463 unsigned long addr = (unsigned long)page_address(page);
465 return set_memory_x(addr, numpages);
467 EXPORT_SYMBOL(set_pages_x);
469 int set_pages_nx(struct page *page, int numpages)
471 unsigned long addr = (unsigned long)page_address(page);
473 return set_memory_nx(addr, numpages);
475 EXPORT_SYMBOL(set_pages_nx);
477 int set_pages_ro(struct page *page, int numpages)
479 unsigned long addr = (unsigned long)page_address(page);
481 return set_memory_ro(addr, numpages);
484 int set_pages_rw(struct page *page, int numpages)
486 unsigned long addr = (unsigned long)page_address(page);
488 return set_memory_rw(addr, numpages);
492 #ifdef CONFIG_DEBUG_PAGEALLOC
494 static int __set_pages_p(struct page *page, int numpages)
496 unsigned long addr = (unsigned long)page_address(page);
497 return change_page_attr_set(addr, numpages,
498 __pgprot(_PAGE_PRESENT | _PAGE_RW));
501 static int __set_pages_np(struct page *page, int numpages)
503 unsigned long addr = (unsigned long)page_address(page);
504 return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
507 void kernel_map_pages(struct page *page, int numpages, int enable)
509 if (PageHighMem(page))
512 debug_check_no_locks_freed(page_address(page),
513 numpages * PAGE_SIZE);
517 * If page allocator is not up yet then do not call c_p_a():
519 if (!debug_pagealloc_enabled)
523 * The return value is ignored - the calls cannot fail,
524 * large pages are disabled at boot time:
527 __set_pages_p(page, numpages);
529 __set_pages_np(page, numpages);
532 * We should perform an IPI and flush all tlbs,
533 * but that can deadlock->flush only current cpu:
540 * The testcases use internal knowledge of the implementation that shouldn't
541 * be exposed to the rest of the kernel. Include these directly here.
543 #ifdef CONFIG_CPA_DEBUG
544 #include "pageattr-test.c"