1 /* 2 * Utility for QEMU MIPS to generate it's simple bootloader 3 * 4 * Instructions used here are carefully selected to keep compatibility with 5 * MIPS Release 6. 6 * 7 * Copyright (C) 2020 Jiaxun Yang <jiaxun.yang@flygoat.com> 8 * 9 * SPDX-License-Identifier: GPL-2.0-or-later 10 */ 11 12 #include "qemu/osdep.h" 13 #include "qemu/bitops.h" 14 #include "cpu.h" 15 #include "hw/mips/bootloader.h" 16 17 typedef enum bl_reg { 18 BL_REG_ZERO = 0, 19 BL_REG_AT = 1, 20 BL_REG_V0 = 2, 21 BL_REG_V1 = 3, 22 BL_REG_A0 = 4, 23 BL_REG_A1 = 5, 24 BL_REG_A2 = 6, 25 BL_REG_A3 = 7, 26 BL_REG_T0 = 8, 27 BL_REG_T1 = 9, 28 BL_REG_T2 = 10, 29 BL_REG_T3 = 11, 30 BL_REG_T4 = 12, 31 BL_REG_T5 = 13, 32 BL_REG_T6 = 14, 33 BL_REG_T7 = 15, 34 BL_REG_S0 = 16, 35 BL_REG_S1 = 17, 36 BL_REG_S2 = 18, 37 BL_REG_S3 = 19, 38 BL_REG_S4 = 20, 39 BL_REG_S5 = 21, 40 BL_REG_S6 = 22, 41 BL_REG_S7 = 23, 42 BL_REG_T8 = 24, 43 BL_REG_T9 = 25, 44 BL_REG_K0 = 26, 45 BL_REG_K1 = 27, 46 BL_REG_GP = 28, 47 BL_REG_SP = 29, 48 BL_REG_FP = 30, 49 BL_REG_RA = 31, 50 } bl_reg; 51 52 static bool bootcpu_supports_isa(uint64_t isa_mask) 53 { 54 return cpu_supports_isa(&MIPS_CPU(first_cpu)->env, isa_mask); 55 } 56 57 /* Base types */ 58 static void bl_gen_nop(uint32_t **p) 59 { 60 stl_p(*p, 0); 61 *p = *p + 1; 62 } 63 64 static void bl_gen_r_type(uint32_t **p, uint8_t opcode, 65 bl_reg rs, bl_reg rt, bl_reg rd, 66 uint8_t shift, uint8_t funct) 67 { 68 uint32_t insn = 0; 69 70 insn = deposit32(insn, 26, 6, opcode); 71 insn = deposit32(insn, 21, 5, rs); 72 insn = deposit32(insn, 16, 5, rt); 73 insn = deposit32(insn, 11, 5, rd); 74 insn = deposit32(insn, 6, 5, shift); 75 insn = deposit32(insn, 0, 6, funct); 76 77 stl_p(*p, insn); 78 *p = *p + 1; 79 } 80 81 static void bl_gen_i_type(uint32_t **p, uint8_t opcode, 82 bl_reg rs, bl_reg rt, uint16_t imm) 83 { 84 uint32_t insn = 0; 85 86 insn = deposit32(insn, 26, 6, opcode); 87 insn = deposit32(insn, 21, 5, rs); 88 insn = deposit32(insn, 16, 5, rt); 89 insn = deposit32(insn, 0, 16, imm); 90 91 stl_p(*p, insn); 92 *p = *p + 1; 93 } 94 95 /* Single instructions */ 96 static void bl_gen_dsll(uint32_t **p, bl_reg rd, bl_reg rt, uint8_t sa) 97 { 98 if (bootcpu_supports_isa(ISA_MIPS3)) { 99 bl_gen_r_type(p, 0, 0, rt, rd, sa, 0x38); 100 } else { 101 g_assert_not_reached(); /* unsupported */ 102 } 103 } 104 105 static void bl_gen_jalr(uint32_t **p, bl_reg rs) 106 { 107 bl_gen_r_type(p, 0, rs, 0, BL_REG_RA, 0, 0x09); 108 } 109 110 static void bl_gen_lui(uint32_t **p, bl_reg rt, uint16_t imm) 111 { 112 /* R6: It's a alias of AUI with RS = 0 */ 113 bl_gen_i_type(p, 0x0f, 0, rt, imm); 114 } 115 116 static void bl_gen_ori(uint32_t **p, bl_reg rt, bl_reg rs, uint16_t imm) 117 { 118 bl_gen_i_type(p, 0x0d, rs, rt, imm); 119 } 120 121 static void bl_gen_sw(uint32_t **p, bl_reg rt, uint8_t base, uint16_t offset) 122 { 123 bl_gen_i_type(p, 0x2b, base, rt, offset); 124 } 125 126 static void bl_gen_sd(uint32_t **p, bl_reg rt, uint8_t base, uint16_t offset) 127 { 128 if (bootcpu_supports_isa(ISA_MIPS3)) { 129 bl_gen_i_type(p, 0x3f, base, rt, offset); 130 } else { 131 g_assert_not_reached(); /* unsupported */ 132 } 133 } 134 135 /* Pseudo instructions */ 136 static void bl_gen_li(uint32_t **p, bl_reg rt, uint32_t imm) 137 { 138 bl_gen_lui(p, rt, extract32(imm, 16, 16)); 139 bl_gen_ori(p, rt, rt, extract32(imm, 0, 16)); 140 } 141 142 static void bl_gen_dli(uint32_t **p, bl_reg rt, uint64_t imm) 143 { 144 bl_gen_li(p, rt, extract64(imm, 32, 32)); 145 bl_gen_dsll(p, rt, rt, 16); 146 bl_gen_ori(p, rt, rt, extract64(imm, 16, 16)); 147 bl_gen_dsll(p, rt, rt, 16); 148 bl_gen_ori(p, rt, rt, extract64(imm, 0, 16)); 149 } 150 151 static void bl_gen_load_ulong(uint32_t **p, bl_reg rt, target_ulong imm) 152 { 153 if (bootcpu_supports_isa(ISA_MIPS3)) { 154 bl_gen_dli(p, rt, imm); /* 64bit */ 155 } else { 156 bl_gen_li(p, rt, imm); /* 32bit */ 157 } 158 } 159 160 /* Helpers */ 161 void bl_gen_jump_to(uint32_t **p, target_ulong jump_addr) 162 { 163 bl_gen_load_ulong(p, BL_REG_T9, jump_addr); 164 bl_gen_jalr(p, BL_REG_T9); 165 bl_gen_nop(p); /* delay slot */ 166 } 167 168 void bl_gen_jump_kernel(uint32_t **p, 169 bool set_sp, target_ulong sp, 170 bool set_a0, target_ulong a0, 171 bool set_a1, target_ulong a1, 172 bool set_a2, target_ulong a2, 173 bool set_a3, target_ulong a3, 174 target_ulong kernel_addr) 175 { 176 if (set_sp) { 177 bl_gen_load_ulong(p, BL_REG_SP, sp); 178 } 179 if (set_a0) { 180 bl_gen_load_ulong(p, BL_REG_A0, a0); 181 } 182 if (set_a1) { 183 bl_gen_load_ulong(p, BL_REG_A1, a1); 184 } 185 if (set_a2) { 186 bl_gen_load_ulong(p, BL_REG_A2, a2); 187 } 188 if (set_a3) { 189 bl_gen_load_ulong(p, BL_REG_A3, a3); 190 } 191 192 bl_gen_jump_to(p, kernel_addr); 193 } 194 195 void bl_gen_write_ulong(uint32_t **p, target_ulong addr, target_ulong val) 196 { 197 bl_gen_load_ulong(p, BL_REG_K0, val); 198 bl_gen_load_ulong(p, BL_REG_K1, addr); 199 if (bootcpu_supports_isa(ISA_MIPS3)) { 200 bl_gen_sd(p, BL_REG_K0, BL_REG_K1, 0x0); 201 } else { 202 bl_gen_sw(p, BL_REG_K0, BL_REG_K1, 0x0); 203 } 204 } 205 206 void bl_gen_write_u32(uint32_t **p, target_ulong addr, uint32_t val) 207 { 208 bl_gen_li(p, BL_REG_K0, val); 209 bl_gen_load_ulong(p, BL_REG_K1, addr); 210 bl_gen_sw(p, BL_REG_K0, BL_REG_K1, 0x0); 211 } 212 213 void bl_gen_write_u64(uint32_t **p, target_ulong addr, uint64_t val) 214 { 215 bl_gen_dli(p, BL_REG_K0, val); 216 bl_gen_load_ulong(p, BL_REG_K1, addr); 217 bl_gen_sd(p, BL_REG_K0, BL_REG_K1, 0x0); 218 } 219