1 // SPDX-License-Identifier: GPL-2.0 2 3 /* 4 * MMU-generic set_memory implementation for powerpc 5 * 6 * Copyright 2019-2021, IBM Corporation. 7 */ 8 9 #include <linux/mm.h> 10 #include <linux/vmalloc.h> 11 #include <linux/set_memory.h> 12 13 #include <asm/mmu.h> 14 #include <asm/page.h> 15 #include <asm/pgtable.h> 16 17 18 static pte_basic_t pte_update_delta(pte_t *ptep, unsigned long addr, 19 unsigned long old, unsigned long new) 20 { 21 return pte_update(&init_mm, addr, ptep, old & ~new, new & ~old, 0); 22 } 23 24 /* 25 * Updates the attributes of a page atomically. 26 * 27 * This sequence is safe against concurrent updates, and also allows updating the 28 * attributes of a page currently being executed or accessed. 29 */ 30 static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) 31 { 32 long action = (long)data; 33 34 addr &= PAGE_MASK; 35 /* modify the PTE bits as desired */ 36 switch (action) { 37 case SET_MEMORY_RO: 38 /* Don't clear DIRTY bit */ 39 pte_update_delta(ptep, addr, _PAGE_KERNEL_RW & ~_PAGE_DIRTY, _PAGE_KERNEL_RO); 40 break; 41 case SET_MEMORY_RW: 42 pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_RW); 43 break; 44 case SET_MEMORY_NX: 45 pte_update_delta(ptep, addr, _PAGE_KERNEL_ROX, _PAGE_KERNEL_RO); 46 break; 47 case SET_MEMORY_X: 48 pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX); 49 break; 50 case SET_MEMORY_NP: 51 pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0); 52 break; 53 case SET_MEMORY_P: 54 pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0); 55 break; 56 default: 57 WARN_ON_ONCE(1); 58 break; 59 } 60 61 /* See ptesync comment in radix__set_pte_at() */ 62 if (radix_enabled()) 63 asm volatile("ptesync": : :"memory"); 64 65 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 66 67 return 0; 68 } 69 70 int change_memory_attr(unsigned long addr, int numpages, long action) 71 { 72 unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); 73 unsigned long size = numpages * PAGE_SIZE; 74 75 if (!numpages) 76 return 0; 77 78 if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) && 79 is_vm_area_hugepages((void *)addr))) 80 return -EINVAL; 81 82 #ifdef CONFIG_PPC_BOOK3S_64 83 /* 84 * On hash, the linear mapping is not in the Linux page table so 85 * apply_to_existing_page_range() will have no effect. If in the future 86 * the set_memory_* functions are used on the linear map this will need 87 * to be updated. 88 */ 89 if (!radix_enabled()) { 90 int region = get_region_id(addr); 91 92 if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID)) 93 return -EINVAL; 94 } 95 #endif 96 97 return apply_to_existing_page_range(&init_mm, start, size, 98 change_page_attr, (void *)action); 99 } 100