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(addr, 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(&init_mm, start, size,
103					    change_page_attr, (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("%s: changing memory protections failed\n", __func__);
125}
126#endif
127#endif
128