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;
26 * Certain areas of memory on x86 require very specific protection flags,
27 * for example the BIOS area or kernel text. Callers don't always get this
28 * right (again, ioremap() on BIOS memory is not uncommon) so this function
29 * checks and fixes these known static required protection bits.
31 static inline pgprot_t static_protections(pgprot_t prot, unsigned long address)
33 pgprot_t forbidden = __pgprot(0);
36 * The BIOS area between 640k and 1Mb needs to be executable for
37 * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
39 if (within(__pa(address), BIOS_BEGIN, BIOS_END))
40 pgprot_val(forbidden) |= _PAGE_NX;
43 * The kernel text needs to be executable for obvious reasons
44 * Does not cover __inittext since that is gone later on
46 if (within(address, (unsigned long)_text, (unsigned long)_etext))
47 pgprot_val(forbidden) |= _PAGE_NX;
49 #ifdef CONFIG_DEBUG_RODATA
50 /* The .rodata section needs to be read-only */
51 if (within(address, (unsigned long)__start_rodata,
52 (unsigned long)__end_rodata))
53 pgprot_val(forbidden) |= _PAGE_RW;
56 prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));
61 pte_t *lookup_address(unsigned long address, int *level)
63 pgd_t *pgd = pgd_offset_k(address);
67 *level = PG_LEVEL_NONE;
71 pud = pud_offset(pgd, address);
74 pmd = pmd_offset(pud, address);
83 return pte_offset_kernel(pmd, address);
86 static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
89 set_pte_atomic(kpte, pte);
91 if (!SHARED_KERNEL_PMD) {
94 for (page = pgd_list; page; page = (struct page *)page->index) {
99 pgd = (pgd_t *)page_address(page) + pgd_index(address);
100 pud = pud_offset(pgd, address);
101 pmd = pmd_offset(pud, address);
102 set_pte_atomic((pte_t *)pmd, pte);
108 static int split_large_page(pte_t *kpte, unsigned long address)
110 pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
111 gfp_t gfp_flags = GFP_KERNEL;
118 #ifdef CONFIG_DEBUG_PAGEALLOC
119 gfp_flags = GFP_ATOMIC;
121 base = alloc_pages(gfp_flags, 0);
125 spin_lock_irqsave(&pgd_lock, flags);
127 * Check for races, another CPU might have split this page
130 tmp = lookup_address(address, &level);
136 address = __pa(address);
137 addr = address & LARGE_PAGE_MASK;
138 pbase = (pte_t *)page_address(base);
140 paravirt_alloc_pt(&init_mm, page_to_pfn(base));
143 for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
144 set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
147 * Install the new, split up pagetable. Important detail here:
149 * On Intel the NX bit of all levels must be cleared to make a
150 * page executable. See section 4.13.2 of Intel 64 and IA-32
151 * Architectures Software Developer's Manual).
153 ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
154 __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
158 spin_unlock_irqrestore(&pgd_lock, flags);
161 __free_pages(base, 0);
167 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot)
169 struct page *kpte_page;
174 BUG_ON(pfn > max_low_pfn);
178 kpte = lookup_address(address, &level);
182 kpte_page = virt_to_page(kpte);
183 BUG_ON(PageLRU(kpte_page));
184 BUG_ON(PageCompound(kpte_page));
186 prot = static_protections(prot, address);
188 if (level == PG_LEVEL_4K) {
189 set_pte_atomic(kpte, pfn_pte(pfn, canon_pgprot(prot)));
191 err = split_large_page(kpte, address);
199 * change_page_attr_addr - Change page table attributes in linear mapping
200 * @address: Virtual address in linear mapping.
201 * @numpages: Number of pages to change
202 * @prot: New page table attribute (PAGE_*)
204 * Change page attributes of a page in the direct mapping. This is a variant
205 * of change_page_attr() that also works on memory holes that do not have
206 * mem_map entry (pfn_valid() is false).
208 * See change_page_attr() documentation for more details.
210 * Modules and drivers should use the set_memory_* APIs instead.
213 static int change_page_attr_addr(unsigned long address, int numpages,
216 int err = 0, kernel_map = 0, i;
219 if (address >= __START_KERNEL_map &&
220 address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
222 address = (unsigned long)__va(__pa(address));
227 for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
228 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
230 if (!kernel_map || pte_present(pfn_pte(0, prot))) {
231 err = __change_page_attr(address, pfn, prot);
237 * Handle kernel mapping too which aliases part of
240 if (__pa(address) < KERNEL_TEXT_SIZE) {
244 addr2 = __START_KERNEL_map + __pa(address);
245 /* Make sure the kernel mappings stay executable */
246 prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
247 err = __change_page_attr(addr2, pfn, prot2);
256 * change_page_attr_set - Change page table attributes in the linear mapping.
257 * @addr: Virtual address in linear mapping.
258 * @numpages: Number of pages to change
259 * @prot: Protection/caching type bits to set (PAGE_*)
261 * Returns 0 on success, otherwise a negated errno.
263 * This should be used when a page is mapped with a different caching policy
264 * than write-back somewhere - some CPUs do not like it when mappings with
265 * different caching policies exist. This changes the page attributes of the
266 * in kernel linear mapping too.
268 * The caller needs to ensure that there are no conflicting mappings elsewhere
269 * (e.g. in user space) * This function only deals with the kernel linear map.
271 * This function is different from change_page_attr() in that only selected bits
272 * are impacted, all other bits remain as is.
274 static int change_page_attr_set(unsigned long addr, int numpages,
277 pgprot_t current_prot;
281 pte = lookup_address(addr, &level);
283 current_prot = pte_pgprot(*pte);
285 pgprot_val(current_prot) = 0;
287 pgprot_val(prot) = pgprot_val(current_prot) | pgprot_val(prot);
289 return change_page_attr_addr(addr, numpages, prot);
293 * change_page_attr_clear - Change page table attributes in the linear mapping.
294 * @addr: Virtual address in linear mapping.
295 * @numpages: Number of pages to change
296 * @prot: Protection/caching type bits to clear (PAGE_*)
298 * Returns 0 on success, otherwise a negated errno.
300 * This should be used when a page is mapped with a different caching policy
301 * than write-back somewhere - some CPUs do not like it when mappings with
302 * different caching policies exist. This changes the page attributes of the
303 * in kernel linear mapping too.
305 * The caller needs to ensure that there are no conflicting mappings elsewhere
306 * (e.g. in user space) * This function only deals with the kernel linear map.
308 * This function is different from change_page_attr() in that only selected bits
309 * are impacted, all other bits remain as is.
311 static int change_page_attr_clear(unsigned long addr, int numpages,
314 pgprot_t current_prot;
318 pte = lookup_address(addr, &level);
320 current_prot = pte_pgprot(*pte);
322 pgprot_val(current_prot) = 0;
324 pgprot_val(prot) = pgprot_val(current_prot) & ~pgprot_val(prot);
326 return change_page_attr_addr(addr, numpages, prot);
329 int set_memory_uc(unsigned long addr, int numpages)
333 pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
334 return change_page_attr_set(addr, numpages, uncached);
336 EXPORT_SYMBOL(set_memory_uc);
338 int set_memory_wb(unsigned long addr, int numpages)
342 pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
343 return change_page_attr_clear(addr, numpages, uncached);
345 EXPORT_SYMBOL(set_memory_wb);
347 int set_memory_x(unsigned long addr, int numpages)
351 pgprot_val(nx) = _PAGE_NX;
352 return change_page_attr_clear(addr, numpages, nx);
354 EXPORT_SYMBOL(set_memory_x);
356 int set_memory_nx(unsigned long addr, int numpages)
360 pgprot_val(nx) = _PAGE_NX;
361 return change_page_attr_set(addr, numpages, nx);
363 EXPORT_SYMBOL(set_memory_nx);
365 int set_memory_ro(unsigned long addr, int numpages)
369 pgprot_val(rw) = _PAGE_RW;
370 return change_page_attr_clear(addr, numpages, rw);
373 int set_memory_rw(unsigned long addr, int numpages)
377 pgprot_val(rw) = _PAGE_RW;
378 return change_page_attr_set(addr, numpages, rw);
381 int set_memory_np(unsigned long addr, int numpages)
385 pgprot_val(present) = _PAGE_PRESENT;
386 return change_page_attr_clear(addr, numpages, present);
389 int set_pages_uc(struct page *page, int numpages)
391 unsigned long addr = (unsigned long)page_address(page);
394 pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
395 return change_page_attr_set(addr, numpages, uncached);
397 EXPORT_SYMBOL(set_pages_uc);
399 int set_pages_wb(struct page *page, int numpages)
401 unsigned long addr = (unsigned long)page_address(page);
404 pgprot_val(uncached) = _PAGE_PCD | _PAGE_PWT;
405 return change_page_attr_clear(addr, numpages, uncached);
407 EXPORT_SYMBOL(set_pages_wb);
409 int set_pages_x(struct page *page, int numpages)
411 unsigned long addr = (unsigned long)page_address(page);
414 pgprot_val(nx) = _PAGE_NX;
415 return change_page_attr_clear(addr, numpages, nx);
417 EXPORT_SYMBOL(set_pages_x);
419 int set_pages_nx(struct page *page, int numpages)
421 unsigned long addr = (unsigned long)page_address(page);
424 pgprot_val(nx) = _PAGE_NX;
425 return change_page_attr_set(addr, numpages, nx);
427 EXPORT_SYMBOL(set_pages_nx);
429 int set_pages_ro(struct page *page, int numpages)
431 unsigned long addr = (unsigned long)page_address(page);
434 pgprot_val(rw) = _PAGE_RW;
435 return change_page_attr_clear(addr, numpages, rw);
438 int set_pages_rw(struct page *page, int numpages)
440 unsigned long addr = (unsigned long)page_address(page);
443 pgprot_val(rw) = _PAGE_RW;
444 return change_page_attr_set(addr, numpages, rw);
447 void clflush_cache_range(void *addr, int size)
451 for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
455 static void flush_kernel_map(void *arg)
458 * Flush all to work around Errata in early athlons regarding
459 * large page flushing.
463 if (boot_cpu_data.x86_model >= 4)
467 void global_flush_tlb(void)
469 BUG_ON(irqs_disabled());
471 on_each_cpu(flush_kernel_map, NULL, 1, 1);
473 EXPORT_SYMBOL(global_flush_tlb);
475 #ifdef CONFIG_DEBUG_PAGEALLOC
477 static int __set_pages_p(struct page *page, int numpages)
479 unsigned long addr = (unsigned long)page_address(page);
480 return change_page_attr_set(addr, numpages,
481 __pgprot(_PAGE_PRESENT | _PAGE_RW));
484 static int __set_pages_np(struct page *page, int numpages)
486 unsigned long addr = (unsigned long)page_address(page);
487 return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
490 void kernel_map_pages(struct page *page, int numpages, int enable)
492 if (PageHighMem(page))
495 debug_check_no_locks_freed(page_address(page),
496 numpages * PAGE_SIZE);
500 * If page allocator is not up yet then do not call c_p_a():
502 if (!debug_pagealloc_enabled)
506 * The return value is ignored - the calls cannot fail,
507 * large pages are disabled at boot time:
510 __set_pages_p(page, numpages);
512 __set_pages_np(page, numpages);
515 * We should perform an IPI and flush all tlbs,
516 * but that can deadlock->flush only current cpu:
523 * The testcases use internal knowledge of the implementation that shouldn't
524 * be exposed to the rest of the kernel. Include these directly here.
526 #ifdef CONFIG_CPA_DEBUG
527 #include "pageattr-test.c"