1
2#include <linux/kernel.h>
3#include <linux/spinlock.h>
4#include <linux/kprobes.h>
5#include <linux/mm.h>
6#include <linux/stop_machine.h>
7
8#include <asm/cacheflush.h>
9#include <asm/fixmap.h>
10#include <asm/smp_plat.h>
11#include <asm/opcodes.h>
12#include <asm/patch.h>
13
14struct patch {
15 void *addr;
16 unsigned int insn;
17};
18
19#ifdef CONFIG_MMU
20static DEFINE_RAW_SPINLOCK(patch_lock);
21
22static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
23{
24 unsigned int uintaddr = (uintptr_t) addr;
25 bool module = !core_kernel_text(uintaddr);
26 struct page *page;
27
28 if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
29 page = vmalloc_to_page(addr);
30 else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
31 page = virt_to_page(addr);
32 else
33 return addr;
34
35 if (flags)
36 raw_spin_lock_irqsave(&patch_lock, *flags);
37
38 set_fixmap(fixmap, page_to_phys(page));
39
40 return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
41}
42
43static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
44{
45 clear_fixmap(fixmap);
46
47 if (flags)
48 raw_spin_unlock_irqrestore(&patch_lock, *flags);
49}
50#else
51static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
52{
53 return addr;
54}
55static void __kprobes patch_unmap(int fixmap, unsigned long *flags) { }
56#endif
57
58void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
59{
60 bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
61 unsigned int uintaddr = (uintptr_t) addr;
62 bool twopage = false;
63 unsigned long flags;
64 void *waddr = addr;
65 int size;
66
67 if (remap)
68 waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
69
70 if (thumb2 && __opcode_is_thumb16(insn)) {
71 *(u16 *)waddr = __opcode_to_mem_thumb16(insn);
72 size = sizeof(u16);
73 } else if (thumb2 && (uintaddr & 2)) {
74 u16 first = __opcode_thumb32_first(insn);
75 u16 second = __opcode_thumb32_second(insn);
76 u16 *addrh0 = waddr;
77 u16 *addrh1 = waddr + 2;
78
79 twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
80 if (twopage && remap)
81 addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
82
83 *addrh0 = __opcode_to_mem_thumb16(first);
84 *addrh1 = __opcode_to_mem_thumb16(second);
85
86 if (twopage && addrh1 != addr + 2) {
87 flush_kernel_vmap_range(addrh1, 2);
88 patch_unmap(FIX_TEXT_POKE1, NULL);
89 }
90
91 size = sizeof(u32);
92 } else {
93 if (thumb2)
94 insn = __opcode_to_mem_thumb32(insn);
95 else
96 insn = __opcode_to_mem_arm(insn);
97
98 *(u32 *)waddr = insn;
99 size = sizeof(u32);
100 }
101
102 if (waddr != addr) {
103 flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
104 patch_unmap(FIX_TEXT_POKE0, &flags);
105 }
106
107 flush_icache_range((uintptr_t)(addr),
108 (uintptr_t)(addr) + size);
109}
110
111static int __kprobes patch_text_stop_machine(void *data)
112{
113 struct patch *patch = data;
114
115 __patch_text(patch->addr, patch->insn);
116
117 return 0;
118}
119
120void __kprobes patch_text(void *addr, unsigned int insn)
121{
122 struct patch patch = {
123 .addr = addr,
124 .insn = insn,
125 };
126
127 stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
128}
129
