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
18static 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 */
30static 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
70int 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}