1 #include <linux/bug.h>
2 #include <linux/kernel.h>
3 #include <asm/opcodes.h>
4
5 static unsigned long
__arm_gen_branch_thumb2(unsigned long pc,unsigned long addr,bool link)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
35 static unsigned long
__arm_gen_branch_arm(unsigned long pc,unsigned long addr,bool link)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
55 unsigned long
__arm_gen_branch(unsigned long pc,unsigned long addr,bool link)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