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This is currently only preventing that outdated information is provided to user space. A concurrent split of huge/large pages does modify the kernel page tables, however either the huge/large mapping is reported or the split area is being walked. This "fixes" also only a potential future bug, since split pages could also be merged again if page permissions are the same for larger memory areas. Reviewed-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
362 lines
8.5 KiB
C
362 lines
8.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/hugetlb.h>
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#include <linux/mm.h>
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#include <asm/cacheflush.h>
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#include <asm/facility.h>
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#include <asm/pgalloc.h>
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#include <asm/page.h>
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#include <asm/set_memory.h>
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static inline unsigned long sske_frame(unsigned long addr, unsigned char skey)
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{
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asm volatile(".insn rrf,0xb22b0000,%[skey],%[addr],1,0"
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: [addr] "+a" (addr) : [skey] "d" (skey));
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return addr;
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}
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void __storage_key_init_range(unsigned long start, unsigned long end)
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{
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unsigned long boundary, size;
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while (start < end) {
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if (MACHINE_HAS_EDAT1) {
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/* set storage keys for a 1MB frame */
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size = 1UL << 20;
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boundary = (start + size) & ~(size - 1);
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if (boundary <= end) {
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do {
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start = sske_frame(start, PAGE_DEFAULT_KEY);
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} while (start < boundary);
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continue;
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}
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}
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page_set_storage_key(start, PAGE_DEFAULT_KEY, 1);
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start += PAGE_SIZE;
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}
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}
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#ifdef CONFIG_PROC_FS
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atomic_long_t direct_pages_count[PG_DIRECT_MAP_MAX];
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void arch_report_meminfo(struct seq_file *m)
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{
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seq_printf(m, "DirectMap4k: %8lu kB\n",
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atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_4K]) << 2);
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seq_printf(m, "DirectMap1M: %8lu kB\n",
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atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_1M]) << 10);
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seq_printf(m, "DirectMap2G: %8lu kB\n",
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atomic_long_read(&direct_pages_count[PG_DIRECT_MAP_2G]) << 21);
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}
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#endif /* CONFIG_PROC_FS */
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static void pgt_set(unsigned long *old, unsigned long new, unsigned long addr,
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unsigned long dtt)
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{
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unsigned long table, mask;
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mask = 0;
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if (MACHINE_HAS_EDAT2) {
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switch (dtt) {
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case CRDTE_DTT_REGION3:
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mask = ~(PTRS_PER_PUD * sizeof(pud_t) - 1);
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break;
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case CRDTE_DTT_SEGMENT:
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mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
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break;
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case CRDTE_DTT_PAGE:
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mask = ~(PTRS_PER_PTE * sizeof(pte_t) - 1);
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break;
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}
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table = (unsigned long)old & mask;
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crdte(*old, new, table, dtt, addr, S390_lowcore.kernel_asce);
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} else if (MACHINE_HAS_IDTE) {
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cspg(old, *old, new);
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} else {
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csp((unsigned int *)old + 1, *old, new);
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}
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}
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static int walk_pte_level(pmd_t *pmdp, unsigned long addr, unsigned long end,
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unsigned long flags)
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{
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pte_t *ptep, new;
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ptep = pte_offset_kernel(pmdp, addr);
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do {
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new = *ptep;
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if (pte_none(new))
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return -EINVAL;
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if (flags & SET_MEMORY_RO)
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new = pte_wrprotect(new);
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else if (flags & SET_MEMORY_RW)
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new = pte_mkwrite(pte_mkdirty(new));
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if (flags & SET_MEMORY_NX)
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pte_val(new) |= _PAGE_NOEXEC;
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else if (flags & SET_MEMORY_X)
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pte_val(new) &= ~_PAGE_NOEXEC;
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pgt_set((unsigned long *)ptep, pte_val(new), addr, CRDTE_DTT_PAGE);
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ptep++;
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addr += PAGE_SIZE;
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cond_resched();
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} while (addr < end);
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return 0;
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}
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static int split_pmd_page(pmd_t *pmdp, unsigned long addr)
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{
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unsigned long pte_addr, prot;
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pte_t *pt_dir, *ptep;
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pmd_t new;
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int i, ro, nx;
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pt_dir = vmem_pte_alloc();
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if (!pt_dir)
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return -ENOMEM;
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pte_addr = pmd_pfn(*pmdp) << PAGE_SHIFT;
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ro = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT);
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nx = !!(pmd_val(*pmdp) & _SEGMENT_ENTRY_NOEXEC);
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prot = pgprot_val(ro ? PAGE_KERNEL_RO : PAGE_KERNEL);
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if (!nx)
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prot &= ~_PAGE_NOEXEC;
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ptep = pt_dir;
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for (i = 0; i < PTRS_PER_PTE; i++) {
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pte_val(*ptep) = pte_addr | prot;
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pte_addr += PAGE_SIZE;
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ptep++;
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}
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pmd_val(new) = __pa(pt_dir) | _SEGMENT_ENTRY;
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pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
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update_page_count(PG_DIRECT_MAP_4K, PTRS_PER_PTE);
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update_page_count(PG_DIRECT_MAP_1M, -1);
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return 0;
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}
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static void modify_pmd_page(pmd_t *pmdp, unsigned long addr,
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unsigned long flags)
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{
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pmd_t new = *pmdp;
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if (flags & SET_MEMORY_RO)
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new = pmd_wrprotect(new);
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else if (flags & SET_MEMORY_RW)
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new = pmd_mkwrite(pmd_mkdirty(new));
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if (flags & SET_MEMORY_NX)
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pmd_val(new) |= _SEGMENT_ENTRY_NOEXEC;
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else if (flags & SET_MEMORY_X)
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pmd_val(new) &= ~_SEGMENT_ENTRY_NOEXEC;
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pgt_set((unsigned long *)pmdp, pmd_val(new), addr, CRDTE_DTT_SEGMENT);
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}
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static int walk_pmd_level(pud_t *pudp, unsigned long addr, unsigned long end,
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unsigned long flags)
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{
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unsigned long next;
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pmd_t *pmdp;
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int rc = 0;
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pmdp = pmd_offset(pudp, addr);
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do {
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if (pmd_none(*pmdp))
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return -EINVAL;
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next = pmd_addr_end(addr, end);
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if (pmd_large(*pmdp)) {
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if (addr & ~PMD_MASK || addr + PMD_SIZE > next) {
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rc = split_pmd_page(pmdp, addr);
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if (rc)
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return rc;
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continue;
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}
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modify_pmd_page(pmdp, addr, flags);
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} else {
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rc = walk_pte_level(pmdp, addr, next, flags);
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if (rc)
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return rc;
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}
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pmdp++;
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addr = next;
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cond_resched();
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} while (addr < end);
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return rc;
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}
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static int split_pud_page(pud_t *pudp, unsigned long addr)
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{
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unsigned long pmd_addr, prot;
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pmd_t *pm_dir, *pmdp;
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pud_t new;
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int i, ro, nx;
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pm_dir = vmem_crst_alloc(_SEGMENT_ENTRY_EMPTY);
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if (!pm_dir)
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return -ENOMEM;
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pmd_addr = pud_pfn(*pudp) << PAGE_SHIFT;
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ro = !!(pud_val(*pudp) & _REGION_ENTRY_PROTECT);
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nx = !!(pud_val(*pudp) & _REGION_ENTRY_NOEXEC);
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prot = pgprot_val(ro ? SEGMENT_KERNEL_RO : SEGMENT_KERNEL);
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if (!nx)
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prot &= ~_SEGMENT_ENTRY_NOEXEC;
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pmdp = pm_dir;
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for (i = 0; i < PTRS_PER_PMD; i++) {
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pmd_val(*pmdp) = pmd_addr | prot;
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pmd_addr += PMD_SIZE;
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pmdp++;
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}
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pud_val(new) = __pa(pm_dir) | _REGION3_ENTRY;
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pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
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update_page_count(PG_DIRECT_MAP_1M, PTRS_PER_PMD);
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update_page_count(PG_DIRECT_MAP_2G, -1);
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return 0;
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}
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static void modify_pud_page(pud_t *pudp, unsigned long addr,
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unsigned long flags)
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{
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pud_t new = *pudp;
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if (flags & SET_MEMORY_RO)
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new = pud_wrprotect(new);
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else if (flags & SET_MEMORY_RW)
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new = pud_mkwrite(pud_mkdirty(new));
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if (flags & SET_MEMORY_NX)
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pud_val(new) |= _REGION_ENTRY_NOEXEC;
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else if (flags & SET_MEMORY_X)
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pud_val(new) &= ~_REGION_ENTRY_NOEXEC;
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pgt_set((unsigned long *)pudp, pud_val(new), addr, CRDTE_DTT_REGION3);
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}
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static int walk_pud_level(p4d_t *p4d, unsigned long addr, unsigned long end,
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unsigned long flags)
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{
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unsigned long next;
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pud_t *pudp;
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int rc = 0;
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pudp = pud_offset(p4d, addr);
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do {
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if (pud_none(*pudp))
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return -EINVAL;
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next = pud_addr_end(addr, end);
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if (pud_large(*pudp)) {
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if (addr & ~PUD_MASK || addr + PUD_SIZE > next) {
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rc = split_pud_page(pudp, addr);
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if (rc)
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break;
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continue;
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}
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modify_pud_page(pudp, addr, flags);
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} else {
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rc = walk_pmd_level(pudp, addr, next, flags);
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}
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pudp++;
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addr = next;
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cond_resched();
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} while (addr < end && !rc);
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return rc;
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}
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static int walk_p4d_level(pgd_t *pgd, unsigned long addr, unsigned long end,
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unsigned long flags)
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{
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unsigned long next;
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p4d_t *p4dp;
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int rc = 0;
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p4dp = p4d_offset(pgd, addr);
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do {
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if (p4d_none(*p4dp))
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return -EINVAL;
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next = p4d_addr_end(addr, end);
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rc = walk_pud_level(p4dp, addr, next, flags);
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p4dp++;
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addr = next;
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cond_resched();
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} while (addr < end && !rc);
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return rc;
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}
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DEFINE_MUTEX(cpa_mutex);
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static int change_page_attr(unsigned long addr, unsigned long end,
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unsigned long flags)
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{
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unsigned long next;
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int rc = -EINVAL;
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pgd_t *pgdp;
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if (addr == end)
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return 0;
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if (end >= MODULES_END)
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return -EINVAL;
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mutex_lock(&cpa_mutex);
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pgdp = pgd_offset_k(addr);
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do {
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if (pgd_none(*pgdp))
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break;
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next = pgd_addr_end(addr, end);
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rc = walk_p4d_level(pgdp, addr, next, flags);
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if (rc)
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break;
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cond_resched();
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} while (pgdp++, addr = next, addr < end && !rc);
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mutex_unlock(&cpa_mutex);
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return rc;
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}
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int __set_memory(unsigned long addr, int numpages, unsigned long flags)
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{
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if (!MACHINE_HAS_NX)
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flags &= ~(SET_MEMORY_NX | SET_MEMORY_X);
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if (!flags)
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return 0;
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addr &= PAGE_MASK;
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return change_page_attr(addr, addr + numpages * PAGE_SIZE, flags);
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}
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#ifdef CONFIG_DEBUG_PAGEALLOC
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static void ipte_range(pte_t *pte, unsigned long address, int nr)
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{
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int i;
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if (test_facility(13)) {
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__ptep_ipte_range(address, nr - 1, pte, IPTE_GLOBAL);
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return;
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}
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for (i = 0; i < nr; i++) {
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__ptep_ipte(address, pte, 0, 0, IPTE_GLOBAL);
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address += PAGE_SIZE;
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pte++;
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}
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}
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void __kernel_map_pages(struct page *page, int numpages, int enable)
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{
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unsigned long address;
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int nr, i, j;
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pte_t *pte;
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for (i = 0; i < numpages;) {
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address = page_to_phys(page + i);
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pte = virt_to_kpte(address);
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nr = (unsigned long)pte >> ilog2(sizeof(long));
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nr = PTRS_PER_PTE - (nr & (PTRS_PER_PTE - 1));
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nr = min(numpages - i, nr);
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if (enable) {
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for (j = 0; j < nr; j++) {
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pte_val(*pte) &= ~_PAGE_INVALID;
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address += PAGE_SIZE;
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pte++;
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}
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} else {
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ipte_range(pte, address, nr);
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}
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i += nr;
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}
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}
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#endif /* CONFIG_DEBUG_PAGEALLOC */
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