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#include <mm/mmu_decl.h>
18
19static pte_basic_t pte_update_delta(pte_t *ptep, unsigned long addr,
20 unsigned long old, unsigned long new)
21{
22 return pte_update(&init_mm, addr, ptep, old & ~new, new & ~old, 0);
23}
24
25/*
26 * Updates the attributes of a page atomically.
27 *
28 * This sequence is safe against concurrent updates, and also allows updating the
29 * attributes of a page currently being executed or accessed.
30 */
31static int change_page_attr(pte_t *ptep, unsigned long addr, void *data)
32{
33 long action = (long)data;
34
35 addr &= PAGE_MASK;
36 /* modify the PTE bits as desired */
37 switch (action) {
38 case SET_MEMORY_RO:
39 /* Don't clear DIRTY bit */
40 pte_update_delta(ptep, addr, _PAGE_KERNEL_RW & ~_PAGE_DIRTY, _PAGE_KERNEL_RO);
41 break;
42 case SET_MEMORY_ROX:
43 /* Don't clear DIRTY bit */
44 pte_update_delta(ptep, addr, _PAGE_KERNEL_RW & ~_PAGE_DIRTY, _PAGE_KERNEL_ROX);
45 break;
46 case SET_MEMORY_RW:
47 pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_RW);
48 break;
49 case SET_MEMORY_NX:
50 pte_update_delta(ptep, addr, _PAGE_KERNEL_ROX, _PAGE_KERNEL_RO);
51 break;
52 case SET_MEMORY_X:
53 pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX);
54 break;
55 case SET_MEMORY_NP:
56 pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0);
57 break;
58 case SET_MEMORY_P:
59 pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0);
60 break;
61 default:
62 WARN_ON_ONCE(1);
63 break;
64 }
65
66 /* See ptesync comment in radix__set_pte_at() */
67 if (radix_enabled())
68 asm volatile("ptesync": : :"memory");
69
70 flush_tlb_kernel_range(start: addr, end: addr + PAGE_SIZE);
71
72 return 0;
73}
74
75int change_memory_attr(unsigned long addr, int numpages, long action)
76{
77 unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);
78 unsigned long size = numpages * PAGE_SIZE;
79
80 if (!numpages)
81 return 0;
82
83 if (WARN_ON_ONCE(is_vmalloc_or_module_addr((void *)addr) &&
84 is_vm_area_hugepages((void *)addr)))
85 return -EINVAL;
86
87#ifdef CONFIG_PPC_BOOK3S_64
88 /*
89 * On hash, the linear mapping is not in the Linux page table so
90 * apply_to_existing_page_range() will have no effect. If in the future
91 * the set_memory_* functions are used on the linear map this will need
92 * to be updated.
93 */
94 if (!radix_enabled()) {
95 int region = get_region_id(addr);
96
97 if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
98 return -EINVAL;
99 }
100#endif
101
102 return apply_to_existing_page_range(mm: &init_mm, address: start, size,
103 fn: change_page_attr, data: (void *)action);
104}
105
106#if defined(CONFIG_DEBUG_PAGEALLOC) || defined(CONFIG_KFENCE)
107#ifdef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
108void __kernel_map_pages(struct page *page, int numpages, int enable)
109{
110 int err;
111 unsigned long addr = (unsigned long)page_address(page);
112
113 if (PageHighMem(page))
114 return;
115
116 if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !radix_enabled())
117 err = hash__kernel_map_pages(page, numpages, enable);
118 else if (enable)
119 err = set_memory_p(addr, numpages);
120 else
121 err = set_memory_np(addr, numpages);
122
123 if (err)
124 panic(fmt: "%s: changing memory protections failed\n", __func__);
125}
126#endif
127#endif
128

source code of linux/arch/powerpc/mm/pageattr.c