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