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 /* 19 * Updates the attributes of a page in three steps: 20 * 21 * 1. take the page_table_lock 22 * 2. install the new entry with the updated attributes 23 * 3. flush the TLB 24 * 25 * This sequence is safe against concurrent updates, and also allows updating the 26 * attributes of a page currently being executed or accessed. 27 */ 28 static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) 29 { 30 long action = (long)data; 31 pte_t pte; 32 33 spin_lock(&init_mm.page_table_lock); 34 35 pte = ptep_get(ptep); 36 37 /* modify the PTE bits as desired, then apply */ 38 switch (action) { 39 case SET_MEMORY_RO: 40 pte = pte_wrprotect(pte); 41 break; 42 case SET_MEMORY_RW: 43 pte = pte_mkwrite(pte_mkdirty(pte)); 44 break; 45 case SET_MEMORY_NX: 46 pte = pte_exprotect(pte); 47 break; 48 case SET_MEMORY_X: 49 pte = pte_mkexec(pte); 50 break; 51 default: 52 WARN_ON_ONCE(1); 53 break; 54 } 55 56 pte_update(&init_mm, addr, ptep, ~0UL, pte_val(pte), 0); 57 58 /* See ptesync comment in radix__set_pte_at() */ 59 if (radix_enabled()) 60 asm volatile("ptesync": : :"memory"); 61 62 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 63 64 spin_unlock(&init_mm.page_table_lock); 65 66 return 0; 67 } 68 69 int change_memory_attr(unsigned long addr, int numpages, long action) 70 { 71 unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); 72 unsigned long size = numpages * PAGE_SIZE; 73 74 if (!numpages) 75 return 0; 76 77 if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) && 78 is_vm_area_hugepages((void *)addr))) 79 return -EINVAL; 80 81 #ifdef CONFIG_PPC_BOOK3S_64 82 /* 83 * On hash, the linear mapping is not in the Linux page table so 84 * apply_to_existing_page_range() will have no effect. If in the future 85 * the set_memory_* functions are used on the linear map this will need 86 * to be updated. 87 */ 88 if (!radix_enabled()) { 89 int region = get_region_id(addr); 90 91 if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID)) 92 return -EINVAL; 93 } 94 #endif 95 96 return apply_to_existing_page_range(&init_mm, start, size, 97 change_page_attr, (void *)action); 98 } 99 100 /* 101 * Set the attributes of a page: 102 * 103 * This function is used by PPC32 at the end of init to set final kernel memory 104 * protection. It includes changing the maping of the page it is executing from 105 * and data pages it is using. 106 */ 107 static int set_page_attr(pte_t *ptep, unsigned long addr, void *data) 108 { 109 pgprot_t prot = __pgprot((unsigned long)data); 110 111 spin_lock(&init_mm.page_table_lock); 112 113 set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot)); 114 flush_tlb_kernel_range(addr, addr + PAGE_SIZE); 115 116 spin_unlock(&init_mm.page_table_lock); 117 118 return 0; 119 } 120 121 int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot) 122 { 123 unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); 124 unsigned long sz = numpages * PAGE_SIZE; 125 126 if (numpages <= 0) 127 return 0; 128 129 return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr, 130 (void *)pgprot_val(prot)); 131 } 132