1 // SPDX-License-Identifier: GPL-2.0 1
2 /*
3 * functions to patch RO kernel text during r
4 *
5 * Copyright (c) 2019 Sven Schnelle <svens@st
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/spinlock.h>
10 #include <linux/kprobes.h>
11 #include <linux/mm.h>
12 #include <linux/stop_machine.h>
13
14 #include <asm/cacheflush.h>
15 #include <asm/fixmap.h>
16 #include <asm/patch.h>
17
18 struct patch {
19 void *addr;
20 u32 *insn;
21 unsigned int len;
22 };
23
24 static DEFINE_RAW_SPINLOCK(patch_lock);
25
26 static void __kprobes *patch_map(void *addr, i
27 int *need_unm
28 {
29 unsigned long uintaddr = (uintptr_t) a
30 bool module = !core_kernel_text(uintad
31 struct page *page;
32
33 *need_unmap = 0;
34 if (module && IS_ENABLED(CONFIG_STRICT
35 page = vmalloc_to_page(addr);
36 else if (!module && IS_ENABLED(CONFIG_
37 page = virt_to_page(addr);
38 else
39 return addr;
40
41 *need_unmap = 1;
42 set_fixmap(fixmap, page_to_phys(page))
43 raw_spin_lock_irqsave(&patch_lock, *fl
44
45 return (void *) (__fix_to_virt(fixmap)
46 }
47
48 static void __kprobes patch_unmap(int fixmap,
49 {
50 clear_fixmap(fixmap);
51
52 raw_spin_unlock_irqrestore(&patch_lock
53 }
54
55 void __kprobes __patch_text_multiple(void *add
56 {
57 unsigned long start = (unsigned long)a
58 unsigned long end = (unsigned long)add
59 unsigned long flags;
60 u32 *p, *fixmap;
61 int mapped;
62
63 /* Make sure we don't have any aliases
64 flush_kernel_dcache_range_asm(start, e
65 flush_kernel_icache_range_asm(start, e
66 flush_tlb_kernel_range(start, end);
67
68 p = fixmap = patch_map(addr, FIX_TEXT_
69
70 while (len >= 4) {
71 *p++ = *insn++;
72 addr += sizeof(u32);
73 len -= sizeof(u32);
74 if (len && offset_in_page(addr
75 /*
76 * We're crossing a pa
77 * need to remap
78 */
79 flush_kernel_dcache_ra
80
81 flush_tlb_kernel_range
82
83 if (mapped)
84 patch_unmap(FI
85 p = fixmap = patch_map
86
87 }
88 }
89
90 flush_kernel_dcache_range_asm((unsigne
91 flush_tlb_kernel_range((unsigned long)
92 if (mapped)
93 patch_unmap(FIX_TEXT_POKE0, &f
94 }
95
96 void __kprobes __patch_text(void *addr, u32 in
97 {
98 __patch_text_multiple(addr, &insn, siz
99 }
100
101 static int __kprobes patch_text_stop_machine(v
102 {
103 struct patch *patch = data;
104
105 __patch_text_multiple(patch->addr, pat
106 return 0;
107 }
108
109 void __kprobes patch_text(void *addr, unsigned
110 {
111 struct patch patch = {
112 .addr = addr,
113 .insn = &insn,
114 .len = sizeof(insn),
115 };
116
117 stop_machine_cpuslocked(patch_text_sto
118 }
119
120 void __kprobes patch_text_multiple(void *addr,
121 {
122
123 struct patch patch = {
124 .addr = addr,
125 .insn = insn,
126 .len = len
127 };
128
129 stop_machine_cpuslocked(patch_text_sto
130 }
131
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