1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * BPF JIT compiler for LoongArch 4 * 5 * Copyright (C) 2022 Loongson Technology Corporation Limited 6 */ 7 #include <linux/bitfield.h> 8 #include <linux/bpf.h> 9 #include <linux/filter.h> 10 #include <asm/cacheflush.h> 11 #include <asm/inst.h> 12 13 struct jit_ctx { 14 const struct bpf_prog *prog; 15 unsigned int idx; 16 unsigned int flags; 17 unsigned int epilogue_offset; 18 u32 *offset; 19 int num_exentries; 20 union loongarch_instruction *image; 21 u32 stack_size; 22 }; 23 24 struct jit_data { 25 struct bpf_binary_header *header; 26 u8 *image; 27 struct jit_ctx ctx; 28 }; 29 30 #define emit_insn(ctx, func, ...) \ 31 do { \ 32 if (ctx->image != NULL) { \ 33 union loongarch_instruction *insn = &ctx->image[ctx->idx]; \ 34 emit_##func(insn, ##__VA_ARGS__); \ 35 } \ 36 ctx->idx++; \ 37 } while (0) 38 39 #define is_signed_imm12(val) signed_imm_check(val, 12) 40 #define is_signed_imm14(val) signed_imm_check(val, 14) 41 #define is_signed_imm16(val) signed_imm_check(val, 16) 42 #define is_signed_imm26(val) signed_imm_check(val, 26) 43 #define is_signed_imm32(val) signed_imm_check(val, 32) 44 #define is_signed_imm52(val) signed_imm_check(val, 52) 45 #define is_unsigned_imm12(val) unsigned_imm_check(val, 12) 46 47 static inline int bpf2la_offset(int bpf_insn, int off, const struct jit_ctx *ctx) 48 { 49 /* BPF JMP offset is relative to the next instruction */ 50 bpf_insn++; 51 /* 52 * Whereas LoongArch branch instructions encode the offset 53 * from the branch itself, so we must subtract 1 from the 54 * instruction offset. 55 */ 56 return (ctx->offset[bpf_insn + off] - (ctx->offset[bpf_insn] - 1)); 57 } 58 59 static inline int epilogue_offset(const struct jit_ctx *ctx) 60 { 61 int from = ctx->idx; 62 int to = ctx->epilogue_offset; 63 64 return (to - from); 65 } 66 67 /* Zero-extend 32 bits into 64 bits */ 68 static inline void emit_zext_32(struct jit_ctx *ctx, enum loongarch_gpr reg, bool is32) 69 { 70 if (!is32) 71 return; 72 73 emit_insn(ctx, lu32id, reg, 0); 74 } 75 76 /* Signed-extend 32 bits into 64 bits */ 77 static inline void emit_sext_32(struct jit_ctx *ctx, enum loongarch_gpr reg, bool is32) 78 { 79 if (!is32) 80 return; 81 82 emit_insn(ctx, addiw, reg, reg, 0); 83 } 84 85 static inline void move_addr(struct jit_ctx *ctx, enum loongarch_gpr rd, u64 addr) 86 { 87 u64 imm_11_0, imm_31_12, imm_51_32, imm_63_52; 88 89 /* lu12iw rd, imm_31_12 */ 90 imm_31_12 = (addr >> 12) & 0xfffff; 91 emit_insn(ctx, lu12iw, rd, imm_31_12); 92 93 /* ori rd, rd, imm_11_0 */ 94 imm_11_0 = addr & 0xfff; 95 emit_insn(ctx, ori, rd, rd, imm_11_0); 96 97 /* lu32id rd, imm_51_32 */ 98 imm_51_32 = (addr >> 32) & 0xfffff; 99 emit_insn(ctx, lu32id, rd, imm_51_32); 100 101 /* lu52id rd, rd, imm_63_52 */ 102 imm_63_52 = (addr >> 52) & 0xfff; 103 emit_insn(ctx, lu52id, rd, rd, imm_63_52); 104 } 105 106 static inline void move_imm(struct jit_ctx *ctx, enum loongarch_gpr rd, long imm, bool is32) 107 { 108 long imm_11_0, imm_31_12, imm_51_32, imm_63_52, imm_51_0, imm_51_31; 109 110 /* or rd, $zero, $zero */ 111 if (imm == 0) { 112 emit_insn(ctx, or, rd, LOONGARCH_GPR_ZERO, LOONGARCH_GPR_ZERO); 113 return; 114 } 115 116 /* addiw rd, $zero, imm_11_0 */ 117 if (is_signed_imm12(imm)) { 118 emit_insn(ctx, addiw, rd, LOONGARCH_GPR_ZERO, imm); 119 goto zext; 120 } 121 122 /* ori rd, $zero, imm_11_0 */ 123 if (is_unsigned_imm12(imm)) { 124 emit_insn(ctx, ori, rd, LOONGARCH_GPR_ZERO, imm); 125 goto zext; 126 } 127 128 /* lu52id rd, $zero, imm_63_52 */ 129 imm_63_52 = (imm >> 52) & 0xfff; 130 imm_51_0 = imm & 0xfffffffffffff; 131 if (imm_63_52 != 0 && imm_51_0 == 0) { 132 emit_insn(ctx, lu52id, rd, LOONGARCH_GPR_ZERO, imm_63_52); 133 return; 134 } 135 136 /* lu12iw rd, imm_31_12 */ 137 imm_31_12 = (imm >> 12) & 0xfffff; 138 emit_insn(ctx, lu12iw, rd, imm_31_12); 139 140 /* ori rd, rd, imm_11_0 */ 141 imm_11_0 = imm & 0xfff; 142 if (imm_11_0 != 0) 143 emit_insn(ctx, ori, rd, rd, imm_11_0); 144 145 if (!is_signed_imm32(imm)) { 146 if (imm_51_0 != 0) { 147 /* 148 * If bit[51:31] is all 0 or all 1, 149 * it means bit[51:32] is sign extended by lu12iw, 150 * no need to call lu32id to do a new filled operation. 151 */ 152 imm_51_31 = (imm >> 31) & 0x1fffff; 153 if (imm_51_31 != 0 && imm_51_31 != 0x1fffff) { 154 /* lu32id rd, imm_51_32 */ 155 imm_51_32 = (imm >> 32) & 0xfffff; 156 emit_insn(ctx, lu32id, rd, imm_51_32); 157 } 158 } 159 160 /* lu52id rd, rd, imm_63_52 */ 161 if (!is_signed_imm52(imm)) 162 emit_insn(ctx, lu52id, rd, rd, imm_63_52); 163 } 164 165 zext: 166 emit_zext_32(ctx, rd, is32); 167 } 168 169 static inline void move_reg(struct jit_ctx *ctx, enum loongarch_gpr rd, 170 enum loongarch_gpr rj) 171 { 172 emit_insn(ctx, or, rd, rj, LOONGARCH_GPR_ZERO); 173 } 174 175 static inline int invert_jmp_cond(u8 cond) 176 { 177 switch (cond) { 178 case BPF_JEQ: 179 return BPF_JNE; 180 case BPF_JNE: 181 case BPF_JSET: 182 return BPF_JEQ; 183 case BPF_JGT: 184 return BPF_JLE; 185 case BPF_JGE: 186 return BPF_JLT; 187 case BPF_JLT: 188 return BPF_JGE; 189 case BPF_JLE: 190 return BPF_JGT; 191 case BPF_JSGT: 192 return BPF_JSLE; 193 case BPF_JSGE: 194 return BPF_JSLT; 195 case BPF_JSLT: 196 return BPF_JSGE; 197 case BPF_JSLE: 198 return BPF_JSGT; 199 } 200 return -1; 201 } 202 203 static inline void cond_jmp_offset(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj, 204 enum loongarch_gpr rd, int jmp_offset) 205 { 206 switch (cond) { 207 case BPF_JEQ: 208 /* PC += jmp_offset if rj == rd */ 209 emit_insn(ctx, beq, rj, rd, jmp_offset); 210 return; 211 case BPF_JNE: 212 case BPF_JSET: 213 /* PC += jmp_offset if rj != rd */ 214 emit_insn(ctx, bne, rj, rd, jmp_offset); 215 return; 216 case BPF_JGT: 217 /* PC += jmp_offset if rj > rd (unsigned) */ 218 emit_insn(ctx, bltu, rd, rj, jmp_offset); 219 return; 220 case BPF_JLT: 221 /* PC += jmp_offset if rj < rd (unsigned) */ 222 emit_insn(ctx, bltu, rj, rd, jmp_offset); 223 return; 224 case BPF_JGE: 225 /* PC += jmp_offset if rj >= rd (unsigned) */ 226 emit_insn(ctx, bgeu, rj, rd, jmp_offset); 227 return; 228 case BPF_JLE: 229 /* PC += jmp_offset if rj <= rd (unsigned) */ 230 emit_insn(ctx, bgeu, rd, rj, jmp_offset); 231 return; 232 case BPF_JSGT: 233 /* PC += jmp_offset if rj > rd (signed) */ 234 emit_insn(ctx, blt, rd, rj, jmp_offset); 235 return; 236 case BPF_JSLT: 237 /* PC += jmp_offset if rj < rd (signed) */ 238 emit_insn(ctx, blt, rj, rd, jmp_offset); 239 return; 240 case BPF_JSGE: 241 /* PC += jmp_offset if rj >= rd (signed) */ 242 emit_insn(ctx, bge, rj, rd, jmp_offset); 243 return; 244 case BPF_JSLE: 245 /* PC += jmp_offset if rj <= rd (signed) */ 246 emit_insn(ctx, bge, rd, rj, jmp_offset); 247 return; 248 } 249 } 250 251 static inline void cond_jmp_offs26(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj, 252 enum loongarch_gpr rd, int jmp_offset) 253 { 254 cond = invert_jmp_cond(cond); 255 cond_jmp_offset(ctx, cond, rj, rd, 2); 256 emit_insn(ctx, b, jmp_offset); 257 } 258 259 static inline void uncond_jmp_offs26(struct jit_ctx *ctx, int jmp_offset) 260 { 261 emit_insn(ctx, b, jmp_offset); 262 } 263 264 static inline int emit_cond_jmp(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj, 265 enum loongarch_gpr rd, int jmp_offset) 266 { 267 /* 268 * A large PC-relative jump offset may overflow the immediate field of 269 * the native conditional branch instruction, triggering a conversion 270 * to use an absolute jump instead, this jump sequence is particularly 271 * nasty. For now, use cond_jmp_offs26() directly to keep it simple. 272 * In the future, maybe we can add support for far branching, the branch 273 * relaxation requires more than two passes to converge, the code seems 274 * too complex to understand, not quite sure whether it is necessary and 275 * worth the extra pain. Anyway, just leave it as it is to enhance code 276 * readability now. 277 */ 278 if (is_signed_imm26(jmp_offset)) { 279 cond_jmp_offs26(ctx, cond, rj, rd, jmp_offset); 280 return 0; 281 } 282 283 return -EINVAL; 284 } 285 286 static inline int emit_uncond_jmp(struct jit_ctx *ctx, int jmp_offset) 287 { 288 if (is_signed_imm26(jmp_offset)) { 289 uncond_jmp_offs26(ctx, jmp_offset); 290 return 0; 291 } 292 293 return -EINVAL; 294 } 295 296 static inline int emit_tailcall_jmp(struct jit_ctx *ctx, u8 cond, enum loongarch_gpr rj, 297 enum loongarch_gpr rd, int jmp_offset) 298 { 299 if (is_signed_imm16(jmp_offset)) { 300 cond_jmp_offset(ctx, cond, rj, rd, jmp_offset); 301 return 0; 302 } 303 304 return -EINVAL; 305 } 306