DWARF stuff...
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static struct mi_registers
get_process_registers(struct mi_process proc)
{
struct user_regs_struct regs = { 0 };
struct iovec iov = { &regs, sizeof(regs) };
struct mi_registers result = { 0 };
ptrace(PTRACE_GETREGSET, proc.pid, NT_PRSTATUS, &iov);
result.rax = regs.rax;
result.rip = regs.rip;
result.rbp = regs.rbp;
result.rbx = regs.rbx;
result.rcx = regs.rcx;
result.rdx = regs.rdx;
result.rsi = regs.rsi;
result.rdi = regs.rdi;
result.rsp = regs.rsp;
result._sys = regs;
return(result);
}
static void
set_process_registers(struct mi_process proc, struct mi_registers regs)
{
regs._sys.rax = regs.rax;
regs._sys.rip = regs.rip;
regs._sys.rbp = regs.rbp;
regs._sys.rbx = regs.rbx;
regs._sys.rcx = regs.rcx;
regs._sys.rdx = regs.rdx;
regs._sys.rsi = regs.rsi;
regs._sys.rdi = regs.rdi;
regs._sys.rsp = regs.rsp;
struct iovec iov = { &regs._sys, sizeof(regs._sys) };
ptrace(PTRACE_SETREGSET, proc.pid, NT_PRSTATUS, &iov);
}
static int
is_call_instruction(long word)
{
// It's a call if:
// first byte == 0xe8
// first byte == 0xff AND "reg field" (bit 3-5 in next byte) == 2 or 3
// REX.W + 0xff/3 ????? TODO TODO TODO
u8 first_byte = word & 0xFF;
if (first_byte == 0xE8) {
return 1;
} else if (first_byte == 0xFF) {
u8 second_byte = word & 0xFF00UL;
u8 reg = second_byte & 0x38; // 111000 (to extract bits 3-5)
if (reg == 2 || reg == 3) {
return 1;
}
}
return 0;
}
static long
place_breakpoint_at(struct mi_process proc, u64 address)
{
long saved_instruction = ptrace(PTRACE_PEEKDATA, proc.pid, address, NULL);
long int3_byte = 0x000000000000CC;
long int3_word = (saved_instruction & 0xFFFFFFFFFFFFFF00) | int3_byte;
/* write 0xcc */
ptrace(PTRACE_POKEDATA, proc.pid, address, int3_word);
return(saved_instruction);
}
static void
run_until_breakpoint_and_restore(struct mi_process proc, u64 address, long saved_instruction)
{
/* wait till child hits the interrupt */
ptrace(PTRACE_CONT, proc.pid, 0, 0);
waitpid(proc.pid, 0, 0);
/* restore original instrucion */
ptrace(PTRACE_POKEDATA, proc.pid, address, saved_instruction);
/* step back to original instruction */
struct mi_registers regs = get_process_registers(proc);
regs.rip -= 1;
set_process_registers(proc, regs);
}
static u64
get_address_of_subroutine(struct mi_process proc, char *sr)
{
for (int i = 0; i < proc.debug.func_count; ++i) {
struct mi_function *func = proc.debug.functions + i;
if (0 == strcmp(func->name, sr)) {
return(func->low_pc);
}
}
return(0);
}
static struct mi_sourcepoint *
pc_to_sourcepoint(struct mi_process proc, u64 pc, int *comp_unit)
{
// NOTE: find first point BIGGER that pc, return the sourcepoint just before that
// TODO: binary search
for (int c = 0; c < proc.debug.cu_count; ++c) {
struct mi_compunit unit = proc.debug.compilation_units[c];
if (unit.low_pc <= pc && pc < unit.high_pc) {
for (int i = 0; i < unit.source.sp_count; ++i) {
struct mi_sourcepoint *point = unit.source.sp_table + i;
if (point->pc > pc) {
*comp_unit = c;
return(unit.source.sp_table + i - 1);
}
}
break;
}
}
return(0);
}
static struct mi_buffer
read_file_mmap(char *path)
{
struct mi_buffer result = { 0 };
struct stat s;
int fd = open(path, O_RDONLY);
if (fd == -1) {
printf("File not found: %s\n", path);
DIE("open() failed\n");
}
fstat(fd, &s);
result.data = mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
result.size = s.st_size;
printf("mmap()-ed %ld bytes (%s)\n", result.size, path);
close(fd);
return(result);
}
static void
print_sourcepoint(struct mi_process proc, int comp_unit, struct mi_sourcepoint *sp)
{
if (!sp) {
printf("Unknown location\n");
return;
}
struct mi_compunit unit = proc.debug.compilation_units[comp_unit];
// NOTE: sourcepoint file indices are 1-based
if (unit.source.source_files[sp->file - 1].file.data == 0) {
char *file_filename = unit.source.source_files[sp->file - 1].filename;
char *file_dirname = unit.source.source_files[sp->file - 1].dir;
char *comp_dir = unit.source.comp_dir;
char full_path[512] = { 0 };
snprintf(full_path, 511, "%s/%s/%s", comp_dir, file_dirname, file_filename);
struct mi_buffer file = read_file_mmap(full_path);
unit.source.source_files[sp->file - 1].file = file;
}
struct mi_buffer file = unit.source.source_files[sp->file - 1].file;
char *source = (char *) file.data;
u64 size = file.size;
int current_line = 1;
for (u32 i = 0; i < size; ++i) {
if (current_line == sp->line) {
int len = 0;
int start = 0;
int leading = 1;
for (u32 j = i; j < size; ++j) {
if (leading && (source[j] == '\t' || source[j] == ' ')) {
++start;
} else {
leading = 0;
}
if (source[j] == '\n') {
break;
}
++len;
}
printf("%.*s\n", len - start, source + i + start);
return;
}
if (source[i] == '\n') {
current_line++;
}
}
}
static struct mi_process
process_create(char *path)
{
struct mi_process result = { 0 };
/* disable ASLR */
syscall(SYS_personality, ADDR_NO_RANDOMIZE);
pid_t pid = fork();
if (pid == -1) {
DIE("fork error\n");
}
if (pid == 0) {
int rt = ptrace(PTRACE_TRACEME, 0, 0, 0);
assert(rt == 0);
char *args[] = { path, NULL };
rt = execvp(path, args);
if (rt == -1) {
DIE("exevp error\n");
}
}
struct mi_buffer file = read_file_mmap(path);
result.elf = file.data;
result.elf_size = file.size;
result.pid = pid;
return(result);
}
static struct mi_function *
get_function_around_pc(struct mi_process proc, u64 pc)
{
struct mi_debuginfo debug = proc.debug;
for (int c = 0; c < debug.cu_count; ++c) {
struct mi_compunit *unit = debug.compilation_units + c;
if (unit->low_pc <= pc && pc < unit->high_pc) {
for (int f = 0; f < unit->functions_count; ++f) {
struct mi_function *func = debug.functions + unit->functions_from + f;
if (func->low_pc <= pc && pc < func->high_pc) {
return(func);
}
}
break;
}
}
return(0);
}
static struct mi_variable *
get_variable(struct mi_process proc, char *name, int length, u64 pc)
{
struct mi_debuginfo debug = proc.debug;
for (int c = 0; c < debug.cu_count; ++c) {
struct mi_compunit *unit = debug.compilation_units + c;
if (unit->low_pc <= pc && pc < unit->high_pc) {
for (int f = 0; f < unit->functions_count; ++f) {
struct mi_function *func = debug.functions + unit->functions_from + f;
if (func->low_pc <= pc && pc < func->high_pc) {
for (int v = 0; v < func->variables_count; ++v) {
struct mi_variable *variable = debug.variables + func->variables_from + v;
if (0 == strncmp(name, variable->name, length)) {
return(variable);
}
}
return(0);
}
}
break;
}
}
return(0);
}
static u64
get_cfa_at_pc(struct mi_process proc, u64 pc)
{
struct dwarf_fde fde = eh_frame_find_fde(proc, pc);
if (!fde.length) {
printf("Could not find FDE for pc %#lx\n", pc);
return(0);
}
struct mi_registers regs = get_process_registers(proc);
struct dwarf_regset regset = eh_frame_init_registers(regs, fde.cie);
regset = eh_frame_find_pc(fde, regset, pc);
return(regset.cfa);
}