LXR linux/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
  11struct patch {
  12        void *addr;
  13        unsigned int insn;
  14};
  15
  16void __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
  47static 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
  56void __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}
  76