1 // SPDX-License-Identifier: GPL-2.0
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
14 struct patch {
15 void *addr;
16 unsigned int insn;
17 };
18
19 static DEFINE_SPINLOCK(patch_lock);
20
patch_map(void * addr,int fixmap,unsigned long * flags)21 static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
22 __acquires(&patch_lock)
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 spin_lock_irqsave(&patch_lock, *flags);
37 else
38 __acquire(&patch_lock);
39
40 set_fixmap(fixmap, page_to_phys(page));
41
42 return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
43 }
44
patch_unmap(int fixmap,unsigned long * flags)45 static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
46 __releases(&patch_lock)
47 {
48 clear_fixmap(fixmap);
49
50 if (flags)
51 spin_unlock_irqrestore(&patch_lock, *flags);
52 else
53 __release(&patch_lock);
54 }
55
__patch_text_real(void * addr,unsigned int insn,bool remap)56 void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
57 {
58 bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
59 unsigned int uintaddr = (uintptr_t) addr;
60 bool twopage = false;
61 unsigned long flags;
62 void *waddr = addr;
63 int size;
64
65 if (remap)
66 waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
67 else
68 __acquire(&patch_lock);
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 } else
106 __release(&patch_lock);
107
108 flush_icache_range((uintptr_t)(addr),
109 (uintptr_t)(addr) + size);
110 }
111
patch_text_stop_machine(void * data)112 static int __kprobes patch_text_stop_machine(void *data)
113 {
114 struct patch *patch = data;
115
116 __patch_text(patch->addr, patch->insn);
117
118 return 0;
119 }
120
patch_text(void * addr,unsigned int insn)121 void __kprobes patch_text(void *addr, unsigned int insn)
122 {
123 struct patch patch = {
124 .addr = addr,
125 .insn = insn,
126 };
127
128 stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
129 }
130
