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 
pte_update_delta(pte_t * ptep,unsigned long addr,unsigned long old,unsigned long new)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  */
change_page_attr(pte_t * ptep,unsigned long addr,void * data)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 
change_memory_attr(unsigned long addr,int numpages,long action)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