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recomp.cpp
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recomp.cpp
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#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <map>
#include <set>
#include <vector>
#include <string>
#include <capstone/capstone.h>
#include "elf.h"
#define INSPECT_FUNCTION_POINTERS 0 // set this to 1 when testing a new program, to verify that no false function pointers are found
#ifndef TRACE
#define TRACE 0
#endif
#ifndef ugen53
#define ugen53 0
#endif
#define LABELS_64_BIT 1
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define u32be(x) (uint32_t)(((x & 0xff) << 24) + ((x & 0xff00) << 8) + ((x & 0xff0000) >> 8) + ((uint32_t)(x) >> 24))
#define u16be(x) (uint16_t)(((x & 0xff) << 8) + ((x & 0xff00) >> 8))
#define read_u32_be(buf) (uint32_t)(((buf)[0] << 24) + ((buf)[1] << 16) + ((buf)[2] << 8) + ((buf)[3]))
using namespace std;
struct Edge {
uint32_t i;
uint8_t function_entry: 1;
uint8_t function_exit: 1;
uint8_t extern_function: 1;
uint8_t function_pointer: 1;
};
struct Insn {
uint32_t id;
uint8_t op_count;
string mnemonic;
string op_str;
cs_mips_op operands[8];
uint8_t is_jump: 1;
uint8_t is_global_got_memop: 1;
uint8_t no_following_successor: 1;
int linked_insn;
union {
uint32_t linked_value;
float linked_float;
};
uint32_t jtbl_addr;
uint32_t num_cases;
mips_reg index_reg;
vector<Edge> successors;
vector<Edge> predecessors;
uint64_t b_liveout;
uint64_t b_livein;
uint64_t f_livein;
uint64_t f_liveout;
};
struct Function {
vector<uint32_t> returns; //points to delay slots
uint32_t end_addr; //address after end
uint32_t nargs;
uint32_t nret;
bool v0_in;
bool referenced_by_function_pointer;
};
static csh handle;
static const uint8_t *text_section;
static uint32_t text_section_len;
static uint32_t text_vaddr;
static const uint8_t *rodata_section;
static uint32_t rodata_section_len;
static uint32_t rodata_vaddr;
static const uint8_t *data_section;
static uint32_t data_section_len;
static uint32_t data_vaddr;
static uint32_t bss_section_len;
static uint32_t bss_vaddr;
static vector<Insn> insns;
static set<uint32_t> label_addresses;
static vector<uint32_t> got_globals;
static vector<uint32_t> got_locals;
static uint32_t gp_value;
static uint32_t gp_value_adj;
static map<uint32_t, string> symbol_names;
static vector<pair<uint32_t, uint32_t>> data_function_pointers;
static set<uint32_t> li_function_pointers;
static map<uint32_t, Function> functions;
static uint32_t main_addr;
static uint32_t mcount_addr;
static uint32_t procedure_table_start;
static uint32_t procedure_table_len;
#define FLAG_NO_MEM 1
#define FLAG_VARARG 2
static const struct {
const char *name;
const char *params;
int flags;
} extern_functions[] = {
{"exit", "vi"}, // override exit from application
{"abort", "v"},
{"sbrk", "pi"},
{"malloc", "pu"},
{"calloc", "puu"},
{"realloc", "ppu"},
{"free", "vp"},
{"fscanf", "ipp", FLAG_VARARG},
{"printf", "ip", FLAG_VARARG},
{"sprintf", "ipp", FLAG_VARARG},
{"fprintf", "ipp", FLAG_VARARG},
{"_doprnt", "ippp"},
{"strlen", "up"},
{"open", "ipii"},
{"creat", "ipi"},
{"access", "ipi"},
{"rename", "ipp"},
{"utime", "ipp"},
{"flock", "iii"},
{"chmod", "ipu"},
{"umask", "ii", FLAG_NO_MEM},
{"ecvt", "pdipp"},
{"fcvt", "pdipp"},
{"sqrt", "dd", FLAG_NO_MEM},
{"sqrtf", "ff", FLAG_NO_MEM},
{"atoi", "ip"},
{"atol", "ip"},
{"atof", "dp"},
{"strtol", "ippi"},
{"strtoul", "uppi"},
{"strtod", "dpp"},
{"strchr", "ppi"},
{"strrchr", "ppi"},
{"strcspn", "upp"},
{"strpbrk", "ppp"},
{"fstat", "iip"},
{"stat", "ipp"},
{"ftruncate", "iii"},
{"bcopy", "vppu"},
{"memcpy", "pppu"},
{"memccpy", "pppiu"},
{"read", "iipu"},
{"write", "iipu"},
{"fopen", "ppp"},
{"freopen", "pppp"},
{"fclose", "ip"},
{"ftell", "ip"},
{"rewind", "ip"},
{"fseek", "ipii"},
{"lseek", "iiii"},
{"fflush", "ip"},
{"dup", "ii"},
{"dup2", "iii"},
{"pipe", "ip"},
{"perror", "vp"},
{"fdopen", "iip"},
{"memset", "ppiu"},
{"bcmp", "ippu"},
{"memcmp", "ippu"},
{"getpid", "i", FLAG_NO_MEM},
{"getpgrp", "i"},
{"remove", "ip"},
{"unlink", "ip"},
{"close", "ii"},
{"strcmp", "ipp"},
{"strncmp", "ippu"},
{"strcpy", "ppp"},
{"strncpy", "pppu"},
{"strcat", "ppp"},
{"strncat", "pppu"},
{"strtok", "ppp"},
{"strstr", "ppp"},
{"strdup", "pp"},
{"toupper", "ii", FLAG_NO_MEM},
{"tolower", "ii", FLAG_NO_MEM},
{"gethostname", "ipu"},
{"isatty", "ii"},
{"strftime", "upupp"},
{"times", "ip"},
{"clock", "i", FLAG_NO_MEM},
{"ctime", "pp"},
{"localtime", "pp"},
{"setvbuf", "ippiu"},
{"__semgetc", "ip"},
{"__semputc", "iip"},
{"fgetc", "ip"},
{"fgets", "ipip"},
{"__filbuf", "ip"},
{"__flsbuf", "iip"},
{"ungetc", "iip"},
{"gets", "pp"},
{"fread", "upuup"},
{"fwrite", "upuup"},
{"fputs", "ipp"},
{"puts", "ip"},
{"getcwd", "ppu"},
{"time", "ip"},
{"bzero", "vpu"},
{"fp_class_d", "id", FLAG_NO_MEM},
{"ldexp", "ddi", FLAG_NO_MEM},
{"__ll_mul", "lll", FLAG_NO_MEM},
{"__ll_div", "lll", FLAG_NO_MEM},
{"__ll_rem", "ljl", FLAG_NO_MEM},
{"__ll_lshift", "llj", FLAG_NO_MEM},
{"__ll_rshift", "llj", FLAG_NO_MEM},
{"__ull_div", "jjj", FLAG_NO_MEM},
{"__ull_rem", "jjj", FLAG_NO_MEM},
{"__ull_rshift", "jjj", FLAG_NO_MEM},
{"__d_to_ull", "jd", FLAG_NO_MEM},
{"__d_to_ll", "ld", FLAG_NO_MEM},
{"__f_to_ull", "jf", FLAG_NO_MEM},
{"__f_to_ll", "lf", FLAG_NO_MEM},
{"__ull_to_f", "fj", FLAG_NO_MEM},
{"__ll_to_f", "fl", FLAG_NO_MEM},
{"__ull_to_d", "dj", FLAG_NO_MEM},
{"__ll_to_d", "dl", FLAG_NO_MEM},
{"_exit", "vi"},
{"_cleanup", "v"},
{"_rld_new_interface", "pu", FLAG_VARARG},
{"_exithandle", "v"},
{"_prctl", "ii", FLAG_VARARG},
{"_atod", "dpii"},
{"pathconf", "ipi"},
{"getenv", "pp"},
{"gettxt", "ppp"},
{"setlocale", "pip"},
{"mmap", "ppuiiii"},
{"munmap", "ipu"},
{"mprotect", "ipui"},
{"sysconf", "ii"},
{"getpagesize", "i"},
{"strerror", "pi"},
{"ioctl", "iiu", FLAG_VARARG},
{"fcntl", "iii", FLAG_VARARG},
{"signal", "pit"},
{"sigset", "pit"},
{"get_fpc_csr", "i"},
{"set_fpc_csr", "ii"},
{"setjmp", "ip"},
{"longjmp", "vpi"},
{"tempnam", "ppp"},
{"tmpnam", "pp"},
{"mktemp", "pp"},
{"mkstemp", "ip"},
{"tmpfile", "p"},
{"wait", "ip"},
{"kill", "iii"},
{"execlp", "ip", FLAG_VARARG},
{"execv", "ipp"},
{"execvp", "ipp"},
{"fork", "i"},
{"system", "ip"},
{"tsearch", "pppp"},
{"tfind", "pppp"},
{"qsort", "vpuut"},
{"regcmp", "pp", FLAG_VARARG},
{"regex", "ppp", FLAG_VARARG},
{"__assert", "vppi"},
};
static void disassemble(void) {
csh handle;
cs_insn *disasm;
static size_t disasm_size;
assert(cs_open(CS_ARCH_MIPS, (cs_mode)(CS_MODE_MIPS64 | CS_MODE_BIG_ENDIAN), &handle) == CS_ERR_OK);
cs_option(handle, CS_OPT_DETAIL, CS_OPT_ON);
disasm_size = cs_disasm(handle, text_section, text_section_len, text_vaddr, 0, &disasm);
for (size_t i = 0; i < disasm_size; i++) {
insns.push_back(Insn());
Insn& insn = insns.back();
insn.id = disasm[i].id;
insn.mnemonic = disasm[i].mnemonic;
insn.op_str = disasm[i].op_str;
if (disasm[i].detail != nullptr && disasm[i].detail->mips.op_count > 0) {
insn.op_count = disasm[i].detail->mips.op_count;
memcpy(insn.operands, disasm[i].detail->mips.operands, sizeof(insn.operands));
}
insn.is_jump = cs_insn_group(handle, &disasm[i], MIPS_GRP_JUMP) || insn.id == MIPS_INS_JAL || insn.id == MIPS_INS_BAL || insn.id == MIPS_INS_JALR;
insn.linked_insn = -1;
}
cs_free(disasm, disasm_size);
cs_close(&handle);
{
// Add dummy instruction to avoid out of bounds
insns.push_back(Insn());
Insn& insn = insns.back();
insn.id = MIPS_INS_NOP;
insn.mnemonic = "nop";
insn.no_following_successor = true;
}
}
static void add_function(uint32_t addr) {
if (addr >= text_vaddr && addr < text_vaddr + text_section_len) {
functions[addr];
}
}
static map<uint32_t, Function>::iterator find_function(uint32_t addr) {
if (functions.size() == 0) {
return functions.end();
}
auto it = functions.upper_bound(addr);
if (it == functions.begin()) {
return functions.end();
}
--it;
return it;
}
// try to find a matching LUI for a given register
static void link_with_lui(int offset, uint32_t reg, int mem_imm)
{
#define MAX_LOOKBACK 128
// don't attempt to compute addresses for zero offset
// end search after some sane max number of instructions
int end_search = MAX(0, offset - MAX_LOOKBACK);
for (int search = offset - 1; search >= end_search; search--) {
// use an `if` instead of `case` block to allow breaking out of the `for` loop
if (insns[search].id == MIPS_INS_LUI) {
uint32_t rd = insns[search].operands[0].reg;
if (reg == rd) {
break;
}
} else if (insns[search].id == MIPS_INS_LW ||
insns[search].id == MIPS_INS_LD ||
insns[search].id == MIPS_INS_ADDIU ||
//insns[search].id == MIPS_INS_ADDU || used in jump tables for offset
insns[search].id == MIPS_INS_ADD ||
insns[search].id == MIPS_INS_SUB ||
insns[search].id == MIPS_INS_SUBU) {
uint32_t rd = insns[search].operands[0].reg;
if (reg == rd) {
if (insns[search].id == MIPS_INS_LW && insns[search].operands[1].mem.base == MIPS_REG_GP) {
int mem_imm0 = (int)insns[search].operands[1].mem.disp;
uint32_t got_entry = (mem_imm0 + gp_value_adj) / sizeof(uint32_t);
if (got_entry < got_locals.size()) {
// used for static functions
char buf[32];
uint32_t addr = got_locals[got_entry] + mem_imm;
insns[search].linked_insn = offset;
insns[search].linked_value = addr;
insns[offset].linked_insn = search;
insns[offset].linked_value = addr;
//vaddr_references[addr].insert(text_vaddr + offset * 4);
insns[search].id = MIPS_INS_LI;
insns[search].mnemonic = "li";
sprintf(buf, "$%s, 0x%x", cs_reg_name(handle, rd), addr);
insns[search].op_str = buf;
insns[search].operands[1].type = MIPS_OP_IMM;
insns[search].operands[1].imm = addr;
switch (insns[offset].id) {
case MIPS_INS_ADDIU:
insns[offset].id = MIPS_INS_MOVE;
insns[offset].operands[1].type = MIPS_OP_REG;
insns[offset].mnemonic = "move";
sprintf(buf, "$%s, $%s", cs_reg_name(handle, insns[offset].operands[0].reg), cs_reg_name(handle, rd));
insns[offset].op_str = buf;
if (addr >= text_vaddr && addr < text_vaddr + text_section_len) {
add_function(addr);
}
break;
case MIPS_INS_LB:
case MIPS_INS_LBU:
case MIPS_INS_SB:
case MIPS_INS_LH:
case MIPS_INS_LHU:
case MIPS_INS_SH:
case MIPS_INS_LW:
case MIPS_INS_SW:
case MIPS_INS_LDC1:
case MIPS_INS_LWC1:
case MIPS_INS_SWC1:
insns[offset].operands[1].mem.disp = 0;
sprintf(buf, "$%s, ($%s)", cs_reg_name(handle, insns[offset].operands[0].reg), cs_reg_name(handle, rd));
insns[offset].op_str = buf;
break;
default:
assert(0);
}
}
break;
} else {
// ignore: reg is pointer, offset is probably struct data member
break;
}
}
} else if (insns[search].id == MIPS_INS_JR &&
insns[search].operands[0].reg == MIPS_REG_RA && offset - search >= 2) {
// stop looking when previous `jr ra` is hit,
// but ignore if `offset` is branch delay slot for this `jr ra`
break;
}
}
}
// for a given `jalr t9`, find the matching t9 load
static void link_with_jalr(int offset)
{
// end search after some sane max number of instructions
int end_search = MAX(0, offset - MAX_LOOKBACK);
for (int search = offset - 1; search >= end_search; search--) {
if (insns[search].operands[0].reg == MIPS_REG_T9) {
if (insns[search].id == MIPS_INS_LW || insns[search].id == MIPS_INS_LI) {
if (insns[search].is_global_got_memop || insns[search].id == MIPS_INS_LI) {
char buf[32];
sprintf(buf, "0x%x", insns[search].linked_value);
insns[search].linked_insn = offset;
insns[offset].linked_insn = search;
insns[offset].linked_value = insns[search].linked_value;
//insns[offset].label = insns[search].label;
//function_entry_points.insert(insns[search].linked_value);
insns[offset].id = MIPS_INS_JAL;
insns[offset].mnemonic = "jal";
insns[offset].op_str = buf;
insns[offset].operands[0].type = MIPS_OP_IMM;
insns[offset].operands[0].imm = insns[search].linked_value;
insns[search].id = MIPS_INS_NOP;
insns[search].mnemonic = "nop";
insns[search].op_str = "";
insns[search].is_global_got_memop = false;
add_function(insns[search].linked_value);
}
break;
} else if (insns[search].id == MIPS_INS_ADDIU) {
if (insns[search].linked_insn != -1) {
//function_entry_points.insert(insns[search].linked_value);
uint32_t first = insns[search].linked_insn;
insns[search].linked_insn = offset;
insns[offset].linked_insn = first;
insns[offset].linked_value = insns[search].linked_value;
}
break;
} else if (insns[search].id == MIPS_INS_LI) {
if (insns[search].linked_insn != -1) {
//function_entry_points.insert(insns[search].linked_value);
uint32_t first = insns[search].linked_insn;
insns[search].linked_insn = offset;
insns[offset].linked_insn = first;
insns[offset].linked_value = insns[search].linked_value;
insns[search].id = MIPS_INS_NOP;
insns[search].mnemonic = "nop";
insns[search].op_str = "";
}
break;
} else if (insns[search].id == MIPS_INS_LD ||
insns[search].id == MIPS_INS_ADDU ||
insns[search].id == MIPS_INS_ADD ||
insns[search].id == MIPS_INS_SUB ||
insns[search].id == MIPS_INS_SUBU) {
break;
}
} else if (insns[search].id == MIPS_INS_JR &&
insns[search].operands[0].reg == MIPS_REG_RA)
{
// stop looking when previous `jr ra` is hit
break;
}
}
}
static void pass1(void) {
for (size_t i = 0; i < insns.size(); i++) {
Insn& insn = insns[i];
if (insn.id == MIPS_INS_BAL) {
insn.id = MIPS_INS_JAL;
insn.mnemonic = "jal";
}
if (insn.is_jump) {
if (insn.id == MIPS_INS_JAL || insn.id == MIPS_INS_J) {
uint32_t target = (uint32_t)insn.operands[0].imm;
label_addresses.insert(target);
add_function(target);
} else if (insn.id == MIPS_INS_JR) {
// sltiu $at, $ty, z
// sw $reg, offset($sp) (very seldom, one or more, usually in func entry)
// lw $gp, offset($sp) (if PIC, and very seldom)
// beqz $at, .L
// some other instruction (not always)
// lui $at, %hi(jtbl)
// sll $tx, $ty, 2
// addu $at, $at, $tx
// lw $tx, %lo(jtbl)($at)
// nop (code compiled with 5.3)
// addu $tx, $tx, $gp (if PIC)
// jr $tx
// IDO 7.1:
//lw at,offset(gp)
//andi t9,t8,0x3f
//sll t9,t9,0x2
//addu at,at,t9
//lw t9,offset(at)
//addu t9,t9,gp
//jr t9
// IDO 5.3:
//lw at,offset(gp)
//andi t3,t2,0x3f
//sll t3,t3,0x2
//addu at,at,t3
//something
//lw t3,offset(at)
//something
//addu t3,t3,gp
//jr t3
if (i >= 7 && rodata_section != NULL) {
bool is_pic = insns[i - 1].id == MIPS_INS_ADDU && insns[i - 1].operands[2].reg == MIPS_REG_GP;
bool has_nop = insns[i - is_pic - 1].id == MIPS_INS_NOP;
bool has_extra = insns[i - is_pic - has_nop - 5].id != MIPS_INS_BEQZ;
int lw = i - is_pic - has_nop - 1;
if (insns[lw].id != MIPS_INS_LW) {
--lw;
}
if (insns[lw].id == MIPS_INS_LW && insns[lw].linked_insn != -1) {
int sltiu_index = -1;
int andi_index = -1;
uint32_t addu_index = lw - 1;
uint32_t num_cases;
bool found = false;
bool and_variant = false;
int end = 14;
if (insns[addu_index].id != MIPS_INS_ADDU) {
--addu_index;
}
mips_reg index_reg = (mips_reg)insns[addu_index - 1].operands[1].reg;
if (insns[addu_index].id != MIPS_INS_ADDU) {
goto skip;
}
if (insns[addu_index - 1].id != MIPS_INS_SLL) {
goto skip;
}
if (insns[addu_index - 1].operands[0].reg != insn.operands[0].reg) {
goto skip;
}
for (int j = 3; j <= 4; j++) {
if (insns[lw - j].id == MIPS_INS_ANDI) {
andi_index = lw - j;
break;
}
}
if (i == 368393) {
// In copt
end = 18;
}
for (int j = 5; j <= end; j++) {
if (insns[lw - has_extra - j].id == MIPS_INS_SLTIU &&
insns[lw - has_extra - j].operands[0].reg == MIPS_REG_AT)
{
sltiu_index = j;
break;
}
if (insns[lw - has_extra - j].id == MIPS_INS_JR) {
// Prevent going into a previous switch
break;
}
}
if (sltiu_index != -1) {
andi_index = -1;
}
if (sltiu_index != -1 && insns[lw - has_extra - sltiu_index].id == MIPS_INS_SLTIU) {
num_cases = insns[lw - has_extra - sltiu_index].operands[2].imm;
found = true;
} else if (andi_index != -1) {
num_cases = insns[andi_index].operands[2].imm + 1;
found = true;
and_variant = true;
} else if (i == 219382) {
// Special hard case in copt where the initial sltiu is in another basic block
found = true;
num_cases = 13;
} else if (i == 370995) {
// Special hard case in copt where the initial sltiu is in another basic block
found = true;
num_cases = 12;
}
if (found) {
uint32_t jtbl_addr = insns[lw].linked_value;
if (is_pic) {
insns[i - 1].id = MIPS_INS_NOP;
}
//printf("jump table at %08x, size %u\n", jtbl_addr, num_cases);
insn.jtbl_addr = jtbl_addr;
insn.num_cases = num_cases;
insn.index_reg = index_reg;
insns[lw].id = MIPS_INS_NOP;
insns[addu_index].id = MIPS_INS_NOP;
insns[addu_index - 1].id = MIPS_INS_NOP;
if (!and_variant) {
insns[addu_index - 2].id = MIPS_INS_NOP;
}
if (jtbl_addr < rodata_vaddr || jtbl_addr + num_cases * sizeof(uint32_t) > rodata_vaddr + rodata_section_len) {
fprintf(stderr, "jump table outside rodata\n");
exit(EXIT_FAILURE);
}
for (uint32_t i = 0; i < num_cases; i++) {
uint32_t target_addr = read_u32_be(rodata_section + (jtbl_addr - rodata_vaddr) + i * sizeof(uint32_t));
target_addr += gp_value;
//printf("%08X\n", target_addr);
label_addresses.insert(target_addr);
}
}
skip:;
}
}
} else {
for (int j = 0; j < insn.op_count; j++) {
if (insn.operands[j].type == MIPS_OP_IMM) {
uint32_t target = (uint32_t)insn.operands[j].imm;
label_addresses.insert(target);
}
}
}
}
switch (insns[i].id) {
// find floating point LI
case MIPS_INS_MTC1:
{
unsigned int rt = insns[i].operands[0].reg;
for (int s = i - 1; s >= 0; s--) {
if (insns[s].id == MIPS_INS_LUI && insns[s].operands[0].reg == rt) {
float f;
uint32_t lui_imm = (uint32_t)(insns[s].operands[1].imm << 16);
memcpy(&f, &lui_imm, sizeof(f));
insns[s].operands[1].imm <<= 16;
// link up the LUI with this instruction and the float
insns[s].linked_insn = i;
insns[s].linked_float = f;
// rewrite LUI instruction to be LI
insns[s].id = MIPS_INS_LI;
insns[s].mnemonic = "li";
break;
} else if (insns[s].id == MIPS_INS_LW ||
insns[s].id == MIPS_INS_LD ||
insns[s].id == MIPS_INS_LH ||
insns[s].id == MIPS_INS_LHU ||
insns[s].id == MIPS_INS_LB ||
insns[s].id == MIPS_INS_LBU ||
insns[s].id == MIPS_INS_ADDIU ||
insns[s].id == MIPS_INS_ADD ||
insns[s].id == MIPS_INS_SUB ||
insns[s].id == MIPS_INS_SUBU) {
unsigned int rd = insns[s].operands[0].reg;
if (rt == rd) {
break;
}
} else if (insns[s].id == MIPS_INS_JR &&
insns[s].operands[0].reg == MIPS_REG_RA) {
// stop looking when previous `jr ra` is hit
break;
}
}
break;
}
case MIPS_INS_SD:
case MIPS_INS_SW:
case MIPS_INS_SH:
case MIPS_INS_SB:
case MIPS_INS_LB:
case MIPS_INS_LBU:
case MIPS_INS_LD:
case MIPS_INS_LDL:
case MIPS_INS_LDR:
case MIPS_INS_LH:
case MIPS_INS_LHU:
case MIPS_INS_LW:
case MIPS_INS_LWU:
case MIPS_INS_LDC1:
case MIPS_INS_LWC1:
case MIPS_INS_LWC2:
case MIPS_INS_LWC3:
case MIPS_INS_SWC1:
case MIPS_INS_SWC2:
case MIPS_INS_SWC3:
{
unsigned int mem_rs = insns[i].operands[1].mem.base;
int mem_imm = (int)insns[i].operands[1].mem.disp;
if (mem_rs == MIPS_REG_GP) {
unsigned int got_entry = (mem_imm + gp_value_adj) / sizeof(unsigned int);
if (got_entry >= got_locals.size()) {
got_entry -= got_locals.size();
if (got_entry < got_globals.size()) {
assert(insn.id == MIPS_INS_LW);
//printf("gp 0x%08x %s\n", mem_imm, got_globals[got_entry].name);
unsigned int dest_vaddr = got_globals[got_entry];
insns[i].is_global_got_memop = true;
insns[i].linked_value = dest_vaddr;
//insns[i].label = got_globals[got_entry].name;
//vaddr_references[dest_vaddr].insert(vaddr + i * 4);
//disasm_add_data_addr(state, dest_vaddr);
insns[i].id = MIPS_INS_LI;
insns[i].operands[1].imm = dest_vaddr;
char buf[32];
sprintf(buf, "$%s, 0x%x", cs_reg_name(handle, insn.operands[0].reg), dest_vaddr);
insns[i].op_str = buf;
}
}
} else {
link_with_lui(i, mem_rs, mem_imm);
}
break;
}
case MIPS_INS_ADDIU:
case MIPS_INS_ORI:
{
unsigned int rd = insns[i].operands[0].reg;
unsigned int rs = insns[i].operands[1].reg;
int64_t imm = insns[i].operands[2].imm;
if (rs == MIPS_REG_ZERO) { // becomes LI
char buf[32];
insns[i].id = MIPS_INS_LI;
insns[i].operands[1].imm = imm;
insns[i].mnemonic = "li";
sprintf(buf, "$%s, %" PRIi64, cs_reg_name(handle, rd), imm);
insns[i].op_str = buf;
} else if (/*rd == rs &&*/ rd != MIPS_REG_GP) { // only look for LUI if rd and rs are the same
link_with_lui(i, rs, (int)imm);
}
break;
}
case MIPS_INS_JALR:
{
unsigned int r = insn.operands[0].reg;
if (r == MIPS_REG_T9) {
link_with_jalr(i);
if (insn.linked_insn != -1) {
char buf[32];
sprintf(buf, "0x%x", insn.linked_value);
insn.id = MIPS_INS_JAL;
insn.mnemonic = "jal";
insn.op_str = buf;
insn.operands[0].type = MIPS_OP_IMM;
insn.operands[0].imm = insn.linked_value;
label_addresses.insert(insn.linked_value);
add_function(insn.linked_value);
}
}
break;
}
}
if (insn.id == MIPS_INS_ADDU && insn.operands[0].reg == MIPS_REG_GP && insn.operands[1].reg == MIPS_REG_GP && insn.operands[2].reg == MIPS_REG_T9 && i >= 2) {
//state->function_entry_points.insert(vaddr + (i - 2) * 4);
for (int j = i - 2; j <= i; j++) {
insns[j].id = MIPS_INS_NOP;
insns[j].mnemonic = "nop";
insns[j].op_str = "";
}
}
}
}
static uint32_t addr_to_i(uint32_t addr) {
return (addr - text_vaddr) / 4;
}
static void pass2(void) {
// Find returns in each function
for (size_t i = 0; i < insns.size(); i++) {
uint32_t addr = text_vaddr + i * 4;
Insn& insn = insns[i];
if (insn.id == MIPS_INS_JR && insn.operands[0].reg == MIPS_REG_RA) {
auto it = find_function(addr);
assert(it != functions.end());
it->second.returns.push_back(addr + 4);
}
if (insn.is_global_got_memop && text_vaddr <= insn.operands[1].imm && insn.operands[1].imm < text_vaddr + text_section_len) {
uint32_t faddr = insn.operands[1].imm;
li_function_pointers.insert(faddr);
functions[faddr].referenced_by_function_pointer = true;
#if INSPECT_FUNCTION_POINTERS
fprintf(stderr, "li function pointer: 0x%x at 0x%x\n", faddr, addr);
#endif
}
}
for (auto it = functions.begin(); it != functions.end(); ++it) {
if (it->second.returns.size() == 0) {
uint32_t i = addr_to_i(it->first);
auto str_it = symbol_names.find(it->first);
if (str_it != symbol_names.end() && str_it->second == "__start") {
} else if (str_it != symbol_names.end() && str_it->second == "xmalloc") {
// orig 5.3:
/*
496bf4: 3c1c0fb9 lui gp,0xfb9
496bf8: 279c366c addiu gp,gp,13932
496bfc: 0399e021 addu gp,gp,t9
496c00: 27bdffd8 addiu sp,sp,-40
496c04: 8f858de8 lw a1,-29208(gp)
496c08: 10000006 b 496c24 <alloc_new+0x14>
496c0c: afbf0020 sw ra,32(sp)
*/
// jal alloc_new
// lui $a1, malloc_scb
// jr $ra
// nop
uint32_t alloc_new_addr = text_vaddr + (i + 7) * 4;
insns[i].id = MIPS_INS_JAL;
insns[i].op_count = 1;
insns[i].mnemonic = "jal";
insns[i].op_str = "alloc_new";
insns[i].operands[0].imm = alloc_new_addr;
assert(symbol_names.count(alloc_new_addr) && symbol_names[alloc_new_addr] == "alloc_new");
i++;
if (insns[i + 5].id == MIPS_INS_LI) {
// 7.1
insns[i] = insns[i + 5];
} else {
// 5.3
insns[i] = insns[i + 3];
}
i++;
insns[i].id = MIPS_INS_JR;
insns[i].op_count = 1;
insns[i].mnemonic = "jr";
insns[i].op_str = "$ra";
insns[i].operands[0].reg = MIPS_REG_RA;
it->second.returns.push_back(text_vaddr + i * 4 + 4);
i++;
for (uint32_t j = 0; j < 4; j++) {
insns[i].id = MIPS_INS_NOP;
insns[i].op_count = 0;
insns[i].mnemonic = "nop";
i++;
}
} else if (str_it != symbol_names.end() && str_it->second == "xfree") {
// jal alloc_dispose
// lui $a1, malloc_scb
// jr $ra
// nop
uint32_t alloc_dispose_addr = text_vaddr + (i + 4) * 4;
if (symbol_names.count(alloc_dispose_addr + 4) && symbol_names[alloc_dispose_addr + 4] == "alloc_dispose") {
alloc_dispose_addr += 4;
}
insns[i].id = MIPS_INS_JAL;
insns[i].op_count = 1;
insns[i].mnemonic = "jal";
insns[i].op_str = "alloc_dispose";
insns[i].operands[0].imm = alloc_dispose_addr;
assert(symbol_names.count(alloc_dispose_addr) && symbol_names[alloc_dispose_addr] == "alloc_dispose");
i++;
insns[i] = insns[i + 2];
i++;
insns[i].id = MIPS_INS_JR;
insns[i].op_count = 1;
insns[i].mnemonic = "jr";
insns[i].op_str = "$ra";
insns[i].operands[0].reg = MIPS_REG_RA;
it->second.returns.push_back(text_vaddr + i * 4 + 4);
i++;
insns[i].id = MIPS_INS_NOP;
insns[i].op_count = 0;
insns[i].mnemonic = "nop";
} else if (insns[i].id == MIPS_INS_LW && insns[i + 1].id == MIPS_INS_MOVE && insns[i + 2].id == MIPS_INS_JALR) {
/*
408f50: 8f998010 lw t9,-32752(gp)
408f54: 03e07821 move t7,ra
408f58: 0320f809 jalr t9
*/
} else if (it->first > mcount_addr) {
fprintf(stderr, "no ret: 0x%x\n", it->first);
abort();
}
}
auto next = it;
++next;
if (next == functions.end()) {
it->second.end_addr = text_vaddr + text_section_len;
} else {
it->second.end_addr = next->first;
}
}
}
static void add_edge(uint32_t from, uint32_t to, bool function_entry = false, bool function_exit = false, bool extern_function = false, bool function_pointer = false) {
Edge fe = Edge(), be = Edge();
fe.i = to;
be.i = from;
fe.function_entry = function_entry;
be.function_entry = function_entry;
fe.function_exit = function_exit;
be.function_exit = function_exit;
fe.extern_function = extern_function;
be.extern_function = extern_function;
fe.function_pointer = function_pointer;
be.function_pointer = function_pointer;
insns[from].successors.push_back(fe);
insns[to].predecessors.push_back(be);
}
static void pass3(void) {
// Build graph
for (size_t i = 0; i < insns.size(); i++) {
uint32_t addr = text_vaddr + i * 4;
Insn& insn = insns[i];
if (insn.no_following_successor) {
continue;
}
switch (insn.id) {
case MIPS_INS_BEQ:
case MIPS_INS_BGEZ:
case MIPS_INS_BGTZ:
case MIPS_INS_BLEZ:
case MIPS_INS_BLTZ:
case MIPS_INS_BNE:
case MIPS_INS_BEQZ:
case MIPS_INS_BNEZ:
case MIPS_INS_BC1F:
case MIPS_INS_BC1T:
add_edge(i, i + 1);
add_edge(i + 1, addr_to_i((uint32_t)insn.operands[insn.op_count - 1].imm));
break;
case MIPS_INS_BEQL:
case MIPS_INS_BGEZL:
case MIPS_INS_BGTZL:
case MIPS_INS_BLEZL:
case MIPS_INS_BLTZL:
case MIPS_INS_BNEL:
case MIPS_INS_BC1FL:
case MIPS_INS_BC1TL:
add_edge(i, i + 1);
add_edge(i, i + 2);
add_edge(i + 1, addr_to_i((uint32_t)insn.operands[insn.op_count - 1].imm));
insns[i + 1].no_following_successor = true; // don't inspect delay slot
break;
case MIPS_INS_B:
case MIPS_INS_J:
add_edge(i, i + 1);
add_edge(i + 1, addr_to_i((uint32_t)insn.operands[0].imm));
insns[i + 1].no_following_successor = true; // don't inspect delay slot
break;
case MIPS_INS_JR: {
add_edge(i, i + 1);
if (insn.jtbl_addr != 0) {
uint32_t jtbl_pos = insn.jtbl_addr - rodata_vaddr;
assert(jtbl_pos < rodata_section_len && jtbl_pos + insn.num_cases * 4 <= rodata_section_len);
for (uint32_t j = 0; j < insn.num_cases; j++) {
uint32_t dest_addr = read_u32_be(rodata_section + jtbl_pos + j * 4) + gp_value;
add_edge(i + 1, addr_to_i(dest_addr));
}
} else {
assert(insn.operands[0].reg == MIPS_REG_RA && "jump to address in register not supported");
}
insns[i + 1].no_following_successor = true; // don't inspect delay slot
break;
}
case MIPS_INS_JAL: {
add_edge(i, i + 1);
uint32_t dest = (uint32_t)insn.operands[0].imm;
if (dest > mcount_addr && dest >= text_vaddr && dest < text_vaddr + text_section_len) {
add_edge(i + 1, addr_to_i(dest), true);
auto it = functions.find(dest);
assert(it != functions.end());
for (uint32_t ret_instr : it->second.returns) {
add_edge(addr_to_i(ret_instr), i + 2, false, true);
}
} else {
add_edge(i + 1, i + 2, false, false, true);
}
insns[i + 1].no_following_successor = true; // don't inspect delay slot
break;
}
case MIPS_INS_JALR:
// function pointer
add_edge(i, i + 1);
add_edge(i + 1, i + 2, false, false, false, true);
insns[i + 1].no_following_successor = true; // don't inspect delay slot
break;