1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/bug.h> 3 #include <linux/kernel.h> 4 #include <asm/opcodes.h> 5 6 static unsigned long 7 __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link) 8 { 9 unsigned long s, j1, j2, i1, i2, imm10, imm11; 10 unsigned long first, second; 11 long offset; 12 13 offset = (long)addr - (long)(pc + 4); 14 if (offset < -16777216 || offset > 16777214) { 15 WARN_ON_ONCE(1); 16 return 0; 17 } 18 19 s = (offset >> 24) & 0x1; 20 i1 = (offset >> 23) & 0x1; 21 i2 = (offset >> 22) & 0x1; 22 imm10 = (offset >> 12) & 0x3ff; 23 imm11 = (offset >> 1) & 0x7ff; 24 25 j1 = (!i1) ^ s; 26 j2 = (!i2) ^ s; 27 28 first = 0xf000 | (s << 10) | imm10; 29 second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11; 30 if (link) 31 second |= 1 << 14; 32 33 return __opcode_thumb32_compose(first, second); 34 } 35 36 static unsigned long 37 __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link) 38 { 39 unsigned long opcode = 0xea000000; 40 long offset; 41 42 if (link) 43 opcode |= 1 << 24; 44 45 offset = (long)addr - (long)(pc + 8); 46 if (unlikely(offset < -33554432 || offset > 33554428)) { 47 WARN_ON_ONCE(1); 48 return 0; 49 } 50 51 offset = (offset >> 2) & 0x00ffffff; 52 53 return opcode | offset; 54 } 55 56 unsigned long 57 __arm_gen_branch(unsigned long pc, unsigned long addr, bool link) 58 { 59 if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) 60 return __arm_gen_branch_thumb2(pc, addr, link); 61 else 62 return __arm_gen_branch_arm(pc, addr, link); 63 } 64