Linux Kernel  3.7.1
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patch.c
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1 #include <linux/kernel.h>
2 #include <linux/kprobes.h>
3 #include <linux/stop_machine.h>
4 
5 #include <asm/cacheflush.h>
6 #include <asm/smp_plat.h>
7 #include <asm/opcodes.h>
8 
9 #include "patch.h"
10 
11 struct patch {
12  void *addr;
13  unsigned int insn;
14 };
15 
16 void __kprobes __patch_text(void *addr, unsigned int insn)
17 {
18  bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
19  int size;
20 
21  if (thumb2 && __opcode_is_thumb16(insn)) {
22  *(u16 *)addr = __opcode_to_mem_thumb16(insn);
23  size = sizeof(u16);
24  } else if (thumb2 && ((uintptr_t)addr & 2)) {
27  u16 *addrh = addr;
28 
29  addrh[0] = __opcode_to_mem_thumb16(first);
30  addrh[1] = __opcode_to_mem_thumb16(second);
31 
32  size = sizeof(u32);
33  } else {
34  if (thumb2)
35  insn = __opcode_to_mem_thumb32(insn);
36  else
37  insn = __opcode_to_mem_arm(insn);
38 
39  *(u32 *)addr = insn;
40  size = sizeof(u32);
41  }
42 
44  (uintptr_t)(addr) + size);
45 }
46 
47 static int __kprobes patch_text_stop_machine(void *data)
48 {
49  struct patch *patch = data;
50 
51  __patch_text(patch->addr, patch->insn);
52 
53  return 0;
54 }
55 
56 void __kprobes patch_text(void *addr, unsigned int insn)
57 {
58  struct patch patch = {
59  .addr = addr,
60  .insn = insn,
61  };
62 
64  stop_machine(patch_text_stop_machine, &patch, cpu_online_mask);
65  } else {
66  bool straddles_word = IS_ENABLED(CONFIG_THUMB2_KERNEL)
67  && __opcode_is_thumb32(insn)
68  && ((uintptr_t)addr & 2);
69 
70  if (straddles_word)
71  stop_machine(patch_text_stop_machine, &patch, NULL);
72  else
73  __patch_text(addr, insn);
74  }
75 }