LXR linux/arch/arm/kernel/insn.c

   1#include <linux/bug.h>
   2#include <linux/kernel.h>
   3#include <asm/opcodes.h>
   4
   5static unsigned long
   6__arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
   7{
   8        unsigned long s, j1, j2, i1, i2, imm10, imm11;
   9        unsigned long first, second;
  10        long offset;
  11
  12        offset = (long)addr - (long)(pc + 4);
  13        if (offset < -16777216 || offset > 16777214) {
  14                WARN_ON_ONCE(1);
  15                return 0;
  16        }
  17
  18        s       = (offset >> 24) & 0x1;
  19        i1      = (offset >> 23) & 0x1;
  20        i2      = (offset >> 22) & 0x1;
  21        imm10   = (offset >> 12) & 0x3ff;
  22        imm11   = (offset >>  1) & 0x7ff;
  23
  24        j1 = (!i1) ^ s;
  25        j2 = (!i2) ^ s;
  26
  27        first = 0xf000 | (s << 10) | imm10;
  28        second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
  29        if (link)
  30                second |= 1 << 14;
  31
  32        return __opcode_thumb32_compose(first, second);
  33}
  34
  35static unsigned long
  36__arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
  37{
  38        unsigned long opcode = 0xea000000;
  39        long offset;
  40
  41        if (link)
  42                opcode |= 1 << 24;
  43
  44        offset = (long)addr - (long)(pc + 8);
  45        if (unlikely(offset < -33554432 || offset > 33554428)) {
  46                WARN_ON_ONCE(1);
  47                return 0;
  48        }
  49
  50        offset = (offset >> 2) & 0x00ffffff;
  51
  52        return opcode | offset;
  53}
  54
  55unsigned long
  56__arm_gen_branch(unsigned long pc, unsigned long addr, bool link)
  57{
  58        if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
  59                return __arm_gen_branch_thumb2(pc, addr, link);
  60        else
  61                return __arm_gen_branch_arm(pc, addr, link);
  62}
  63