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This commit is contained in:
Antoni Piasecki
2026-03-01 11:22:44 +01:00
parent a8573689d3
commit 71743552ec
2 changed files with 275 additions and 28 deletions
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295
riscv64.c
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@@ -63,6 +63,7 @@ static const char *const REGS[32] = {
typedef struct {
size_t offset;
size_t size;
size_t entrypoint;
} Section;
typedef struct {
@@ -85,6 +86,12 @@ Section riscv64_get_code_section(uint8_t *exe_bytes, size_t exe_size) {
exit(1);
}
GElf_Ehdr ehdr;
if (gelf_getehdr(elf, &ehdr) == 0) {
fprintf(stderr, "gelf_getehdr failed: %s\n", elf_errmsg(-1));
exit(1);
}
Elf_Scn *section = NULL;
while ((section = elf_nextscn(elf, section)) != NULL) {
GElf_Shdr header;
@@ -94,7 +101,10 @@ Section riscv64_get_code_section(uint8_t *exe_bytes, size_t exe_size) {
const char *name = elf_strptr(elf, str_table_index, header.sh_name);
if (name && strcmp(name, ".text") == 0) {
elf_end(elf);
return (Section){.offset = header.sh_offset, .size = header.sh_size};
return (Section){.offset = header.sh_offset,
.size = header.sh_size,
.entrypoint =
ehdr.e_entry - header.sh_addr + header.sh_offset};
}
}
@@ -140,7 +150,8 @@ void riscv64_disassemble_one(const RISCV64 *r) {
printf("blt %s, %s, %d\n", REGS[rs1], REGS[rs2], imm);
} else if (funct3 == 0b101) {
printf("bge %s, %s, %d\n", REGS[rs1], REGS[rs2], imm);
break;
} else if (funct3 == 0b110) {
printf("bltu %s, %s, %d\n", REGS[rs1], REGS[rs2], imm);
} else {
fprintf(stderr, "B-type: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -152,7 +163,36 @@ void riscv64_disassemble_one(const RISCV64 *r) {
if (funct3 == 0b000) {
printf("addi %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else if (funct3 == 0b001) {
printf("slli %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
uint32_t shamt = (ins >> 20) & 0b111111;
uint32_t funct6 = (ins >> 26) & 0b111111;
if (funct6 == 0b000000) {
printf("slli %s, %s, %d\n", REGS[rd], REGS[rs1], shamt);
} else {
fprintf(stderr, "I-type 1: funct3=001: unrecognized funct6: %b\n",
funct6);
exit(1);
}
} else if (funct3 == 0b011) {
printf("sltiu %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else if (funct3 == 0b100) {
printf("xori %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else if (funct3 == 0b101) {
// of course this one just has to be different
uint32_t shamt = (ins >> 20) & 0b111111;
uint32_t funct6 = (ins >> 26) & 0b111111;
if (funct6 == 0b000000) {
printf("srli %s, %s, %d\n", REGS[rd], REGS[rs1], shamt);
} else if (funct6 == 0b010000) {
printf("srai %s, %s, %d\n", REGS[rd], REGS[rs1], shamt);
} else {
fprintf(stderr, "I-type 1: funct3=101: unrecognized funct6: %b\n",
funct6);
exit(1);
}
} else if (funct3 == 0b111) {
printf("andi %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else {
fprintf(stderr, "I-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -163,8 +203,14 @@ void riscv64_disassemble_one(const RISCV64 *r) {
if (funct3 == 0b000) {
printf("lb %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else if (funct3 == 0b001) {
printf("lh %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else if (funct3 == 0b010) {
printf("lw %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else if (funct3 == 0b011) {
printf("ld %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else if (funct3 == 0b100) {
printf("lbu %s, %d(%s)\n", REGS[rd], imm, REGS[rs1]);
} else {
fprintf(stderr, "I-type 2: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -184,7 +230,6 @@ void riscv64_disassemble_one(const RISCV64 *r) {
fprintf(stderr, "I-type 4: funct3=000 unrecognized imm: %b\n", imm);
exit(1);
}
break;
} else {
fprintf(stderr, "I-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -208,6 +253,60 @@ void riscv64_disassemble_one(const RISCV64 *r) {
funct7);
exit(1);
}
} else if (funct3 == 0b001) {
if (funct7 == 0b0000001) {
printf("mulh %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b001: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b010) {
if (funct7 == 0b0000000) {
printf("slt %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b010: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b011) {
if (funct7 == 0b0000000) {
printf("sltu %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else if (funct7 == 0b0000001) {
printf("mulhu %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b011: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b100) {
if (funct7 == 0b0000000) {
printf("xor %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else if (funct7 == 0b0000001) {
printf("div %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b100: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b110) {
if (funct7 == 0b0000001) {
printf("rem %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else if (funct7 == 0b0000000) {
printf("or %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b110: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b111) {
if (funct7 == 0b000) {
printf("and %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 1: funct3=0b111: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else {
fprintf(stderr, "R-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -218,7 +317,19 @@ void riscv64_disassemble_one(const RISCV64 *r) {
exit(1);
case 0b0111011: {
PARSE_R_INS(ins);
if (funct3 == 0b101) {
if (funct3 == 0b000) {
if (funct7 == 0b0000000) {
printf("addw %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else if (funct7 == 0b0100000) {
printf("subw %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else if (funct7 == 0b0000001) {
printf("mulw %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
fprintf(stderr, "R-type 3: funct3=000: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b101) {
if (funct7 == 0b0000001) {
printf("divuw %s, %s, %s\n", REGS[rd], REGS[rs1], REGS[rs2]);
} else {
@@ -238,6 +349,9 @@ void riscv64_disassemble_one(const RISCV64 *r) {
if (funct3 == 0b000) {
PARSE_I_INS(ins);
printf("addiw %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else if (funct3 == 0b001) {
PARSE_I_INS(ins);
printf("slliw %s, %s, %d\n", REGS[rd], REGS[rs1], imm);
} else {
fprintf(stderr, "R-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -248,6 +362,10 @@ void riscv64_disassemble_one(const RISCV64 *r) {
if (funct3 == 0b000) {
printf("sb %s, %d(%s)\n", REGS[rs2], imm, REGS[rs1]);
} else if (funct3 == 0b001) {
printf("sh %s, %d(%s)\n", REGS[rs2], imm, REGS[rs1]);
} else if (funct3 == 0b010) {
printf("sw %s, %d(%s)\n", REGS[rs2], imm, REGS[rs1]);
} else if (funct3 == 0b011) {
printf("sd %s, %d(%s)\n", REGS[rs2], imm, REGS[rs1]);
} else {
@@ -270,7 +388,7 @@ void riscv64_disassemble_one(const RISCV64 *r) {
}
void riscv64_execute(RISCV64 *r) {
r->pc = r->code_section.offset;
r->pc = r->code_section.entrypoint;
r->regs[2] = (20 * 1024 * 1024) - 1; // set the stack pointer
@@ -307,6 +425,11 @@ void riscv64_execute(RISCV64 *r) {
r->pc += imm;
continue;
}
} else if (funct3 == 0b110) { // bltu
if ((uint64_t)r->regs[rs1] < (uint64_t)r->regs[rs2]) {
r->pc += imm;
continue;
}
} else {
fprintf(stderr, "B-type: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -318,7 +441,36 @@ void riscv64_execute(RISCV64 *r) {
if (funct3 == 0b000) { // addi
r->regs[rd] = r->regs[rs1] + imm;
} else if (funct3 == 0b001) { // slli
r->regs[rd] = r->regs[rs1] << (imm & 0b111111);
uint32_t shamt = (ins >> 20) & 0b111111;
uint32_t funct6 = (ins >> 26) & 0b111111;
if (funct6 == 0b000000) {
r->regs[rd] = r->regs[rs1] << shamt;
} else {
fprintf(stderr, "I-type 1: funct3=001: unrecognized funct6: %b\n",
funct6);
exit(1);
}
} else if (funct3 == 0b011) { // sltiu
r->regs[rd] = (r->regs[rs1] < (uint64_t)(int64_t)imm) ? 1 : 0;
} else if (funct3 == 0b100) { // xori
r->regs[rd] = r->regs[rs1] ^ imm;
} else if (funct3 == 0b101) {
// of course this one just has to be different
uint32_t shamt = (ins >> 20) & 0b111111;
uint32_t funct6 = (ins >> 26) & 0b111111;
if (funct6 == 0b000000) { // srli
r->regs[rd] = r->regs[rs1] >> shamt;
} else if (funct6 == 0b010000) { // srai
r->regs[rd] = (int32_t)r->regs[rs1] >> shamt;
} else {
fprintf(stderr, "I-type 1: funct3=101: unrecognized funct6: %b\n",
funct6);
exit(1);
}
} else if (funct3 == 0b111) {
r->regs[rd] = r->regs[rs1] & imm;
} else {
fprintf(stderr, "I-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -328,9 +480,15 @@ void riscv64_execute(RISCV64 *r) {
PARSE_I_INS(ins);
if (funct3 == 0b000) { // lb
r->regs[rd] = r->memory[r->regs[rs1] + imm];
r->regs[rd] = (int8_t)r->memory[r->regs[rs1] + imm];
} else if (funct3 == 0b001) { // lh
r->regs[rd] = *(int16_t *)&r->memory[r->regs[rs1] + imm];
} else if (funct3 == 0b010) { // lw
r->regs[rd] = *(int32_t *)&r->memory[r->regs[rs1] + imm];
} else if (funct3 == 0b011) { // ld
r->regs[rd] = *(uint64_t *)&r->memory[r->regs[rs1] + imm];
} else if (funct3 == 0b100) { // lbu
r->regs[rd] = r->memory[r->regs[rs1] + imm];
} else {
fprintf(stderr, "I-type 2: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -338,7 +496,7 @@ void riscv64_execute(RISCV64 *r) {
}; break;
case 0b1100111: { // jalr
PARSE_I_INS(ins);
uint32_t target = (r->regs[rs1] + imm) & ~1;
size_t target = (r->regs[rs1] + imm) & ~(size_t)1;
r->regs[rd] = r->pc + 4;
r->pc = target;
continue;
@@ -432,18 +590,86 @@ void riscv64_execute(RISCV64 *r) {
if (funct3 == 0b000) {
if (funct7 == 0b0000000) { // add
r->regs[rd] = r->regs[rs1] + r->regs[rs2];
break;
} else if (funct7 == 0b0100000) { // sub
r->regs[rd] = r->regs[rs1] - r->regs[rs2];
break;
} else if (funct7 == 0b0000001) { // mul
r->regs[rd] = r->regs[rs1] * r->regs[rs2];
break;
} else {
fprintf(stderr, "R-type 1: funct3=0b000: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b001) {
if (funct7 == 0b0000001) { // mulh
int64_t a_hi = r->regs[rs1] >> 32;
int64_t b_hi = r->regs[rs2] >> 32;
uint64_t a_lo = (uint32_t)r->regs[rs1];
uint64_t b_lo = (uint32_t)r->regs[rs2];
uint64_t p0 = a_lo * b_lo;
int64_t p1 = a_hi * b_lo;
int64_t p2 = b_hi * a_lo;
int64_t p3 = a_hi * b_hi;
int64_t carry = (p0 >> 32);
int64_t mid = p1 + p2 + carry;
r->regs[rd] = p3 + (mid >> 32);
} else {
fprintf(stderr, "R-type 1: funct3=0b001: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b010) {
if (funct7 == 0b0000000) { // slt
r->regs[rd] = ((int64_t)r->regs[rs1] < (int64_t)r->regs[rs2]) ? 1 : 0;
} else {
fprintf(stderr, "R-type 1: funct3=0b010: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b011) {
if (funct7 == 0b0000000) { // sltu
r->regs[rd] =
((uint64_t)r->regs[rs1] < (uint64_t)r->regs[rs2]) ? 1 : 0;
} else {
fprintf(stderr, "R-type 1: funct3=0b011: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b100) {
if (funct7 == 0b0000000) { // xor
r->regs[rd] = r->regs[rs1] ^ r->regs[rs2];
} else if (funct7 == 0b0000001) { // div
if (r->regs[rs2] == 0) {
r->regs[rd] = -1;
} else {
r->regs[rd] = (int64_t)r->regs[rs1] / (int64_t)r->regs[rs2];
}
} else {
fprintf(stderr, "R-type 1: funct3=0b100: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b110) {
if (funct7 == 0b0000001) { // rem
if (r->regs[rs2] == 0) {
r->regs[rd] = r->regs[rs1];
} else {
r->regs[rd] = (int64_t)r->regs[rs1] % (int64_t)r->regs[rs2];
}
} else if (funct7 == 0b0000000) { // or
r->regs[rd] = r->regs[rs1] | r->regs[rs2];
} else {
fprintf(stderr, "R-type 1: funct3=0b110: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b111) {
if (funct7 == 0b000) { // and
r->regs[rd] = r->regs[rs1] & r->regs[rs2];
} else {
fprintf(stderr, "R-type 1: funct3=0b111: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else {
fprintf(stderr, "R-type 1: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -451,23 +677,37 @@ void riscv64_execute(RISCV64 *r) {
}; break;
case 0b0111011: {
PARSE_R_INS(ins);
if (funct3 == 0b101) {
if (funct7 == 0b0000001) {
if (funct3 == 0b000) {
if (funct7 == 0b0000000) { // addw
r->regs[rd] = (int32_t)(r->regs[rs1] + r->regs[rs2]);
} else if (funct7 == 0b0100000) { // subw
r->regs[rd] = (int32_t)(r->regs[rs1] - r->regs[rs2]);
} else if (funct7 == 0b0000001) { // mulw
r->regs[rd] = (int32_t)(r->regs[rs1] * r->regs[rs2]);
} else {
fprintf(stderr, "R-type 3: funct3=000: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b101) {
if (funct7 == 0b0000001) { // divuw
if (r->regs[rs2] == 0) {
r->regs[rd] = -1LL;
} else {
r->regs[rd] = (int32_t)(r->regs[rs1] / r->regs[rs2]);
r->regs[rd] =
(int32_t)((uint32_t)r->regs[rs1] / (uint32_t)r->regs[rs2]);
}
} else {
fprintf(stderr, "R-type 3: funct3=101: unrecognized funct7: %b\n",
funct7);
exit(1);
}
} else if (funct3 == 0b111) {
} else if (funct3 == 0b111) { // remuw
if (r->regs[rs2] == 0) {
r->regs[rd] = (int32_t)r->regs[rs1];
} else {
r->regs[rd] = (int32_t)(r->regs[rs1] % r->regs[rs2]);
r->regs[rd] =
(int32_t)((uint32_t)r->regs[rs1] % (uint32_t)r->regs[rs2]);
}
} else {
fprintf(stderr, "R-type 3: unrecognized funct3: %03b\n", funct3);
@@ -475,11 +715,12 @@ void riscv64_execute(RISCV64 *r) {
}
}; break;
case 0b0011011: {
uint8_t funct3 = (ins >> 12) & 0b111;
if (funct3 == 0b000) {
PARSE_I_INS(ins);
int32_t result = r->regs[rs1] + imm;
r->regs[rd] = result;
PARSE_I_INS(ins);
if (funct3 == 0b000) { // addiw
r->regs[rd] = (int32_t)r->regs[rs1] + (int32_t)imm;
} else if (funct3 == 0b001) {
uint32_t shamt = (ins >> 20) & 0b11111;
r->regs[rd] = (int32_t)r->regs[rs1] << shamt;
} else {
fprintf(stderr, "R-type 4: unrecognized funct3: %03b\n", funct3);
exit(1);
@@ -491,6 +732,12 @@ void riscv64_execute(RISCV64 *r) {
if (funct3 == 0b000) { // sb
size_t addr = r->regs[rs1] + imm;
r->memory[addr] = r->regs[rs2];
} else if (funct3 == 0b001) { // sh
size_t addr = r->regs[rs1] + imm;
*(uint16_t *)(&r->memory[addr]) = r->regs[rs2];
} else if (funct3 == 0b010) { // sw
size_t addr = r->regs[rs1] + imm;
*(uint32_t *)(&r->memory[addr]) = r->regs[rs2];
} else if (funct3 == 0b011) { // sd
size_t addr = r->regs[rs1] + imm;
// take this rust
@@ -502,11 +749,11 @@ void riscv64_execute(RISCV64 *r) {
}; break;
case 0b0110111: { // lui
PARSE_U_INS(ins);
r->regs[rd] = imm << 12;
r->regs[rd] = (int64_t)imm << 12;
}; break;
case 0b0010111: { // auipc
PARSE_U_INS(ins);
r->regs[rd] = r->pc + (imm << 12);
r->regs[rd] = r->pc + ((int64_t)imm << 12);
}; break;
default:
fprintf(stderr, "Unrecognized opcode: %07b\n", opcode);