arch/arm/kernel/patch.c

   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)) {
  25                 u16 first = __opcode_thumb32_first(insn);
  26                 u16 second = __opcode_thumb32_second(insn);
  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
  43         flush_icache_range((uintptr_t)(addr),
  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
  63         if (cache_ops_need_broadcast()) {
  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 }