309 lines
11 KiB
C++
309 lines
11 KiB
C++
//: Labels are defined by ending names with a ':'. This layer will compute
|
|
//: displacements for labels, and compute the offset for instructions using them.
|
|
//:
|
|
//: We won't check this, but our convention will be that jump targets will
|
|
//: start with a '$', while functions will not. Function names will never be
|
|
//: jumped to, and jump targets will never be called.
|
|
|
|
//: We're introducing non-number names for the first time, so it's worth
|
|
//: laying down some ground rules all transforms will follow, so things don't
|
|
//: get too confusing:
|
|
//: - if it starts with a digit, it's treated as a number. If it can't be
|
|
//: parsed as hex it will raise an error.
|
|
//: - if it starts with '-' it's treated as a number.
|
|
//: - if it starts with '0x' it's treated as a number.
|
|
//: - if it's two characters long, it can't be a name. Either it's a hex
|
|
//: byte, or it raises an error.
|
|
//: That's it. Names can start with any non-digit that isn't a dash. They can
|
|
//: be a single character long. 'a' is not a hex number, it's a variable.
|
|
//: Later layers may add more conventions partitioning the space of names. But
|
|
//: the above rules will remain inviolate.
|
|
|
|
//: One special label: the address to start running the program at.
|
|
|
|
:(scenario entry_label)
|
|
== 0x1
|
|
05 0x0d0c0b0a/imm32
|
|
Entry:
|
|
05 0x0d0c0b0a/imm32
|
|
+run: inst: 0x00000006
|
|
-run: inst: 0x00000001
|
|
|
|
:(before "End Globals")
|
|
uint32_t Entry_address = 0;
|
|
:(before "End Reset")
|
|
Entry_address = 0;
|
|
:(before "End Initialize EIP")
|
|
if (Entry_address) EIP = Entry_address;
|
|
:(after "Override e_entry")
|
|
if (Entry_address) e_entry = Entry_address;
|
|
|
|
:(before "End looks_like_hex_int(s) Detectors")
|
|
if (SIZE(s) == 2) return true;
|
|
|
|
:(scenarios transform)
|
|
:(scenario pack_immediate_ignores_single_byte_nondigit_operand)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
b9/copy a/imm32
|
|
+transform: packing instruction 'b9/copy a/imm32'
|
|
# no change (we're just not printing metadata to the trace)
|
|
+transform: instruction after packing: 'b9 a'
|
|
|
|
:(scenario pack_immediate_ignores_3_hex_digit_operand)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
b9/copy aaa/imm32
|
|
+transform: packing instruction 'b9/copy aaa/imm32'
|
|
# no change (we're just not printing metadata to the trace)
|
|
+transform: instruction after packing: 'b9 aaa'
|
|
|
|
:(scenario pack_immediate_ignores_non_hex_operand)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
b9/copy xxx/imm32
|
|
+transform: packing instruction 'b9/copy xxx/imm32'
|
|
# no change (we're just not printing metadata to the trace)
|
|
+transform: instruction after packing: 'b9 xxx'
|
|
|
|
//: a helper we'll find handy later
|
|
:(code)
|
|
void check_valid_name(const string& s) {
|
|
if (s.empty()) {
|
|
raise << "empty name!\n" << end();
|
|
return;
|
|
}
|
|
if (s.at(0) == '-')
|
|
raise << "'" << s << "' starts with '-', which can be confused with a negative number; use a different name\n" << end();
|
|
if (s.substr(0, 2) == "0x") {
|
|
raise << "'" << s << "' looks like a hex number; use a different name\n" << end();
|
|
return;
|
|
}
|
|
if (isdigit(s.at(0)))
|
|
raise << "'" << s << "' starts with a digit, and so can be confused with a negative number; use a different name.\n" << end();
|
|
if (SIZE(s) == 2)
|
|
raise << "'" << s << "' is two characters long which can look like raw hex bytes at a glance; use a different name\n" << end();
|
|
}
|
|
|
|
//: Now that that's done, let's start using names as labels.
|
|
|
|
:(scenario map_label)
|
|
== 0x1
|
|
loop:
|
|
05 0x0d0c0b0a/imm32
|
|
+transform: label 'loop' is at address 1
|
|
|
|
:(before "End Level-2 Transforms")
|
|
Transform.push_back(rewrite_labels);
|
|
:(code)
|
|
void rewrite_labels(program& p) {
|
|
trace(99, "transform") << "-- rewrite labels" << end();
|
|
if (p.segments.empty()) return;
|
|
segment& code = p.segments.at(0);
|
|
map<string, int32_t> byte_index; // values are unsigned, but we're going to do subtractions on them so they need to fit in 31 bits
|
|
compute_byte_indices_for_labels(code, byte_index);
|
|
if (trace_contains_errors()) return;
|
|
drop_labels(code);
|
|
if (trace_contains_errors()) return;
|
|
replace_labels_with_displacements(code, byte_index);
|
|
if (contains_key(byte_index, "Entry"))
|
|
Entry_address = code.start + get(byte_index, "Entry");
|
|
}
|
|
|
|
void compute_byte_indices_for_labels(const segment& code, map<string, int32_t>& byte_index) {
|
|
int current_byte = 0;
|
|
for (int i = 0; i < SIZE(code.lines); ++i) {
|
|
const line& inst = code.lines.at(i);
|
|
for (int j = 0; j < SIZE(inst.words); ++j) {
|
|
const word& curr = inst.words.at(j);
|
|
// hack: if we have any operand metadata left after previous transforms,
|
|
// deduce its size
|
|
// Maybe we should just move this transform to before instruction
|
|
// packing, and deduce the size of *all* operands. But then we'll also
|
|
// have to deal with bitfields.
|
|
if (has_operand_metadata(curr, "disp32") || has_operand_metadata(curr, "imm32")) {
|
|
if (*curr.data.rbegin() == ':')
|
|
raise << "'" << to_string(inst) << "': don't use ':' when jumping to labels\n" << end();
|
|
current_byte += 4;
|
|
}
|
|
else if (has_operand_metadata(curr, "disp16")) {
|
|
if (*curr.data.rbegin() == ':')
|
|
raise << "'" << to_string(inst) << "': don't use ':' when jumping to labels\n" << end();
|
|
current_byte += 2;
|
|
}
|
|
// automatically handle /disp8 and /imm8 here
|
|
else if (*curr.data.rbegin() != ':') {
|
|
++current_byte;
|
|
}
|
|
else {
|
|
string label = drop_last(curr.data);
|
|
// ensure labels look sufficiently different from raw hex
|
|
check_valid_name(label);
|
|
if (trace_contains_errors()) return;
|
|
if (contains_any_operand_metadata(curr))
|
|
raise << "'" << to_string(inst) << "': label definition (':') not allowed in operand\n" << end();
|
|
if (j > 0)
|
|
raise << "'" << to_string(inst) << "': labels can only be the first word in a line.\n" << end();
|
|
if (Map_file.is_open())
|
|
Map_file << "0x" << HEXWORD << (code.start + current_byte) << ' ' << label << '\n';
|
|
if (contains_key(byte_index, label) && label != "Entry") {
|
|
raise << "duplicate label '" << label << "'\n" << end();
|
|
return;
|
|
}
|
|
put(byte_index, label, current_byte);
|
|
trace(99, "transform") << "label '" << label << "' is at address " << (current_byte+code.start) << end();
|
|
// no modifying current_byte; label definitions won't be in the final binary
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
:(before "End Globals")
|
|
bool Dump_map = false; // currently used only by 'subx translate'
|
|
ofstream Map_file;
|
|
:(before "End Commandline Options")
|
|
else if (is_equal(*arg, "--map")) {
|
|
Dump_map = true;
|
|
// End --map Settings
|
|
}
|
|
//: wait to open "map" for writing until we're sure we aren't trying to read it
|
|
:(after "Begin subx translate")
|
|
if (Dump_map)
|
|
Map_file.open("map");
|
|
:(before "End subx translate")
|
|
if (Dump_map)
|
|
Map_file.close();
|
|
|
|
:(code)
|
|
void drop_labels(segment& code) {
|
|
for (int i = 0; i < SIZE(code.lines); ++i) {
|
|
line& inst = code.lines.at(i);
|
|
vector<word>::iterator new_end = remove_if(inst.words.begin(), inst.words.end(), is_label);
|
|
inst.words.erase(new_end, inst.words.end());
|
|
}
|
|
}
|
|
|
|
bool is_label(const word& w) {
|
|
return *w.data.rbegin() == ':';
|
|
}
|
|
|
|
void replace_labels_with_displacements(segment& code, const map<string, int32_t>& byte_index) {
|
|
int32_t byte_index_next_instruction_starts_at = 0;
|
|
for (int i = 0; i < SIZE(code.lines); ++i) {
|
|
line& inst = code.lines.at(i);
|
|
byte_index_next_instruction_starts_at += num_bytes(inst);
|
|
line new_inst;
|
|
for (int j = 0; j < SIZE(inst.words); ++j) {
|
|
const word& curr = inst.words.at(j);
|
|
if (contains_key(byte_index, curr.data)) {
|
|
int32_t displacement = static_cast<int32_t>(get(byte_index, curr.data)) - byte_index_next_instruction_starts_at;
|
|
if (has_operand_metadata(curr, "disp8")) {
|
|
if (displacement > 0xff || displacement < -0x7f)
|
|
raise << "'" << to_string(inst) << "': label too far away for displacement " << std::hex << displacement << " to fit in 8 bits\n" << end();
|
|
else
|
|
emit_hex_bytes(new_inst, displacement, 1);
|
|
}
|
|
else if (has_operand_metadata(curr, "disp16")) {
|
|
if (displacement > 0xffff || displacement < -0x7fff)
|
|
raise << "'" << to_string(inst) << "': label too far away for displacement " << std::hex << displacement << " to fit in 16 bits\n" << end();
|
|
else
|
|
emit_hex_bytes(new_inst, displacement, 2);
|
|
}
|
|
else if (has_operand_metadata(curr, "disp32")) {
|
|
emit_hex_bytes(new_inst, displacement, 4);
|
|
}
|
|
}
|
|
else {
|
|
new_inst.words.push_back(curr);
|
|
}
|
|
}
|
|
inst.words.swap(new_inst.words);
|
|
trace(99, "transform") << "instruction after transform: '" << data_to_string(inst) << "'" << end();
|
|
}
|
|
}
|
|
|
|
string data_to_string(const line& inst) {
|
|
ostringstream out;
|
|
for (int i = 0; i < SIZE(inst.words); ++i) {
|
|
if (i > 0) out << ' ';
|
|
out << inst.words.at(i).data;
|
|
}
|
|
return out.str();
|
|
}
|
|
|
|
string drop_last(const string& s) {
|
|
return string(s.begin(), --s.end());
|
|
}
|
|
|
|
//: Label definitions must be the first word on a line. No jumping inside
|
|
//: instructions.
|
|
//: They should also be the only word on a line.
|
|
//: However, you can absolutely have multiple labels map to the same address,
|
|
//: as long as they're on separate lines.
|
|
|
|
:(scenario multiple_labels_at)
|
|
== 0x1
|
|
# address 1
|
|
loop:
|
|
$loop2:
|
|
# address 1 (labels take up no space)
|
|
05 0x0d0c0b0a/imm32
|
|
# address 6
|
|
eb $loop2/disp8
|
|
# address 8
|
|
eb $loop3/disp8
|
|
# address 0xa
|
|
$loop3:
|
|
+transform: label 'loop' is at address 1
|
|
+transform: label '$loop2' is at address 1
|
|
+transform: label '$loop3' is at address a
|
|
# first jump is to -7
|
|
+transform: instruction after transform: 'eb f9'
|
|
# second jump is to 0 (fall through)
|
|
+transform: instruction after transform: 'eb 00'
|
|
|
|
:(scenario duplicate_label)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
loop:
|
|
loop:
|
|
05 0x0d0c0b0a/imm32
|
|
+error: duplicate label 'loop'
|
|
|
|
:(scenario label_too_short)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
xz:
|
|
05 0x0d0c0b0a/imm32
|
|
+error: 'xz' is two characters long which can look like raw hex bytes at a glance; use a different name
|
|
|
|
:(scenario label_hex)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
0xab:
|
|
05 0x0d0c0b0a/imm32
|
|
+error: '0xab' looks like a hex number; use a different name
|
|
|
|
:(scenario label_negative_hex)
|
|
% Hide_errors = true;
|
|
== 0x1
|
|
-a: # indent to avoid looking like a trace_should_not_contain command for this scenario
|
|
05 0x0d0c0b0a/imm32
|
|
+error: '-a' starts with '-', which can be confused with a negative number; use a different name
|
|
|
|
//: now that we have labels, we need to adjust segment size computation to
|
|
//: ignore them.
|
|
|
|
:(scenario segment_size_ignores_labels)
|
|
== code # 0x09000074
|
|
05/add 0x0d0c0b0a/imm32 # 5 bytes
|
|
foo: # 0 bytes
|
|
== data # 0x0a000079
|
|
bar:
|
|
00
|
|
+transform: segment 1 begins at address 0x0a000079
|
|
|
|
:(before "End size_of(word w) Special-cases")
|
|
else if (is_label(w))
|
|
return 0;
|