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 __arm_gen_branch_thumb2(unsigned long pc, 7 unsigned long addr, bool link, 8 bool warn) 9 { 10 unsigned long s, j1, j2, i1, i2, imm10, imm11; 11 unsigned long first, second; 12 long offset; 13 14 offset = (long)addr - (long)(pc + 4); 15 if (offset < -16777216 || offset > 16777214) { 16 WARN_ON_ONCE(warn); 17 return 0; 18 } 19 20 s = (offset >> 24) & 0x1; 21 i1 = (offset >> 23) & 0x1; 22 i2 = (offset >> 22) & 0x1; 23 imm10 = (offset >> 12) & 0x3ff; 24 imm11 = (offset >> 1) & 0x7ff; 25 26 j1 = (!i1) ^ s; 27 j2 = (!i2) ^ s; 28 29 first = 0xf000 | (s << 10) | imm10; 30 second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11; 31 if (link) 32 second |= 1 << 14; 33 34 return __opcode_thumb32_compose(first, second); 35 } 36 37 static unsigned long __arm_gen_branch_arm(unsigned long pc, unsigned long addr, 38 bool link, bool warn) 39 { 40 unsigned long opcode = 0xea000000; 41 long offset; 42 43 if (link) 44 opcode |= 1 << 24; 45 46 offset = (long)addr - (long)(pc + 8); 47 if (unlikely(offset < -33554432 || offset > 33554428)) { 48 WARN_ON_ONCE(warn); 49 return 0; 50 } 51 52 offset = (offset >> 2) & 0x00ffffff; 53 54 return opcode | offset; 55 } 56 57 unsigned long 58 __arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn) 59 { 60 if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) 61 return __arm_gen_branch_thumb2(pc, addr, link, warn); 62 else 63 return __arm_gen_branch_arm(pc, addr, link, warn); 64 } 65