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Profanity
Copyright (C) 2012 - 2015 James Booth <boothj5@gmail.com>

Profanity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Profanity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Profanity.  If not, see <http://www.gnu.org/licenses/>.

There is an additional exception from the author permitting linking
with OpenSSL:

As copyright holder, I give permission for profanity to be linked to
the OpenSSL libraries. This includes permission for profanity
binaries to be distributed linked against the OpenSSL libraries.
All other obligations under the GPL v3 remain intact.
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-07-07 16:41:05 +0000
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//: Global variables.
//:
//: Global variables are just labels in the data segment.
//: However, they can only be used in imm32 and not disp32 arguments. And they
//: can't be used with jump and call instructions.
//:
//: This layer has much the same structure as rewriting labels.

:(code)
void test_global_variable() {
  run(
      "== code 0x1\n"
      "b9  x/imm32\n"
      "== data 0x2000\n"
      "x:\n"
      "  00 00 00 00\n"
  );
  CHECK_TRACE_CONTENTS(
      "transform: global variable 'x' is at address 0x00002000\n"
  );
}

:(before "End Transforms")
Transform.push_back(rewrite_global_variables);
:(code)
void rewrite_global_variables(program& p) {
  trace(3, "transform") << "-- rewrite global variables" << end();
  // Begin rewrite_global_variables
  map<string, uint32_t> address;
  compute_addresses_for_global_variables(p, address);
  if (trace_contains_errors()) return;
  drop_global_variables(p);
  replace_global_variables_with_addresses(p, address);
}

void compute_addresses_for_global_variables(const program& p, map<string, uint32_t>& address) {
  for (int i = 0;  i < SIZE(p.segments);  ++i) {
    if (p.segments.at(i).name != "code")
      compute_addresses_for_global_variables(p.segments.at(i), address);
  }
}

void compute_addresses_for_global_variables(const segment& s, map<string, uint32_t>& address) {
  int current_address = s.start;
  for (int i = 0;  i < SIZE(s.lines);  ++i) {
    const line& inst = s.lines.at(i);
    for (int j = 0;  j < SIZE(inst.words);  ++j) {
      const word& curr = inst.words.at(j);
      if (*curr.data.rbegin() != ':') {
        current_address += size_of(curr);
      }
      else {
        string variable = drop_last(curr.data);
        // ensure variables look sufficiently different from raw hex
        check_valid_name(variable);
        if (trace_contains_errors()) return;
        if (j > 0)
          raise << "'" << to_string(inst) << "': global variable names can only be the first word in a line.\n" << end();
        if (Labels_file.is_open())
          Labels_file << "0x" << HEXWORD << current_address << ' ' << variable << '\n';
        if (contains_key(address, variable)) {
          raise << "duplicate global '" << variable << "'\n" << end();
          return;
        }
        put(address, variable, current_address);
        trace(99, "transform") << "global variable '" << variable << "' is at address 0x" << HEXWORD << current_address << end();
        // no modifying current_address; global variable definitions won't be in the final binary
      }
    }
  }
}

void drop_global_variables(program& p) {
  for (int i = 0;  i < SIZE(p.segments);  ++i) {
    if (p.segments.at(i).name != "code")
      drop_labels(p.segments.at(i));
  }
}

void replace_global_variables_with_addresses(program& p, const map<string, uint32_t>& address) {
  if (p.segments.empty()) return;
  for (int i = 0;  i < SIZE(p.segments);  ++i) {
    segment& curr = p.segments.at(i);
    if (curr.name == "code")
      replace_global_variables_in_code_segment(curr, address);
    else
      replace_global_variables_in_data_segment(curr, address);
  }
}

void replace_global_variables_in_code_segment(segment& code, const map<string, uint32_t>& address) {
  for (int i = 0;  i < SIZE(code.lines);  ++i) {
    line& inst = code.lines.at(i);
    line new_inst;
    for (int j = 0;  j < SIZE(inst.words);  ++j) {
      const word& curr = inst.words.at(j);
      if (!contains_key(address, curr.data)) {
        if (!looks_like_hex_int(curr.data))
          raise << "missing reference to global '" << curr.data << "'\n" << end();
        new_inst.words.push_back(curr);
        continue;
      }
      if (!valid_use_of_global_variable(curr)) {
        raise << "'" << to_string(inst) << "': can't refer to global variable '" << curr.data << "'\n" << end();
        return;
      }
      emit_hex_bytes(new_inst, get(address, curr.data), 4);
    }
    inst.words.swap(new_inst.words);
    trace(99, "transform") << "instruction after transform: '" << data_to_string(inst) << "'" << end();
  }
}

void replace_global_variables_in_data_segment(segment& data, const map<string, uint32_t>& address) {
  for (int i = 0;  i < SIZE(data.lines);  ++i) {
    line& l = data.lines.at(i);
    line new_l;
    for (int j = 0;  j < SIZE(l.words);  ++j) {
      const word& curr = l.words.at(j);
      if (!contains_key(address, curr.data)) {
        if (looks_like_hex_int(curr.data)) {
          if (has_argument_metadata(curr, "imm32"))
            emit_hex_bytes(new_l, curr, 4);
          else if (has_argument_metadata(curr, "imm16"))
            emit_hex_bytes(new_l, curr, 2);
          else if (has_argument_metadata(curr, "imm8"))
            emit_hex_bytes(new_l, curr, 1);
          else if (has_argument_metadata(curr, "disp8"))
            raise << "can't use /disp8 in a non-code segment\n" << end();
          else if (has_argument_metadata(curr, "disp16"))
            raise << "can't use /disp16 in a non-code segment\n" << end();
          else if (has_argument_metadata(curr, "disp32"))
            raise << "can't use /disp32 in a non-code segment\n" << end();
          else
            new_l.words.push_back(curr);
        }
        else {
          raise << "missing reference to global '" << curr.data << "'\n" << end();
          new_l.words.push_back(curr);
        }
        continue;
      }
      trace(99, "transform") << curr.data << " maps to " << HEXWORD << get(address, curr.data) << end();
      emit_hex_bytes(new_l, get(address, curr.data), 4);
    }
    l.words.swap(new_l.words);
    trace(99, "transform") << "after transform: '" << data_to_string(l) << "'" << end();
  }
}

bool valid_use_of_global_variable(const word& curr) {
  if (has_argument_metadata(curr, "imm32")) return true;
  // End Valid Uses Of Global Variable(curr)
  return false;
}

//:: a more complex sanity check for how we use global variables
//: requires first saving some data early before we pack arguments

:(after "Begin Transforms")
Transform.push_back(correlate_disp32_with_mod);
:(code)
void correlate_disp32_with_mod(program& p) {
  if (p.segments.empty()) return;
  segment& code = *find(p, "code");
  for (int i = 0;  i < SIZE(code.lines);  ++i) {
    line& inst = code.lines.at(i);
    for (int j = 0;  j < SIZE(inst.words);  ++j) {
      word& curr = inst.words.at(j);
      if (has_argument_metadata(curr, "disp32")
          && has_argument_metadata(inst, "mod"))
        curr.metadata.push_back("has_mod");
    }
  }
}

:(before "End Valid Uses Of Global Variable(curr)")
if (has_argument_metadata(curr, "disp32"))
  return has_metadata(curr, "has_mod");
// todo: more sophisticated check, to ensure we don't use global variable
// addresses as a real displacement added to other arguments.

:(code)
bool has_metadata(const word& w, const string& m) {
  for (int i = 0;  i < SIZE(w.metadata);  ++i)
    if (w.metadata.at(i) == m) return true;
  return false;
}

void test_global_variable_disallowed_in_jump() {
  Hide_errors = true;
  run(
      "== code 0x1\n"
      "eb/jump  x/disp8\n"
      "== data 0x2000\n"
      "x:\n"
      "  00 00 00 00\n"
  );
  CHECK_TRACE_CONTENTS(
      "error: 'eb/jump x/disp8': can't refer to global variable 'x'\n"
      // sub-optimal error message; should be
//?       "error: can't jump to data (variable 'x')\n"
  );
}

void test_global_variable_disallowed_in_call() {
  Hide_errors = true;
  run(
      "== code 0x1\n"
      "e8/call  x/disp32\n"
      "== data 0x2000\n"
      "x:\n"
      "  00 00 00 00\n"
  );
  CHECK_TRACE_CONTENTS(
      "error: 'e8/call x/disp32': can't refer to global variable 'x'\n"
      // sub-optimal error message; should be
//?       "error: can't call to the data segment ('x')\n"
  );
}

void test_global_variable_in_data_segment() {
  run(
      "== code 0x1\n"
      "b9  x/imm32\n"
      "== data 0x2000\n"
      "x:\n"
      "  y/imm32\n"
      "y:\n"
      "  00 00 00 00\n"
  );
  // check that we loaded 'x' with the address of 'y'
  CHECK_TRACE_CONTENTS(
      "load: 0x00002000 -> 04\n"
      "load: 0x00002001 -> 20\n"
      "load: 0x00002002 -> 00\n"
      "load: 0x00002003 -> 00\n"
  );
  CHECK_TRACE_COUNT("error", 0);
}

void test_raw_number_with_imm32_in_data_segment() {
  run(
      "== code 0x1\n"
      "b9  x/imm32\n"
      "== data 0x2000\n"
      "x:\n"
      "  1/imm32\n"
  );
  // check that we loaded 'x' with the address of 1
  CHECK_TRACE_CONTENTS(
      "load: 0x00002000 -> 01\n"
      "load: 0x00002001 -> 00\n"
      "load: 0x00002002 -> 00\n"
      "load: 0x00002003 -> 00\n"
  );
  CHECK_TRACE_COUNT("error", 0);
}

void test_duplicate_global_variable() {
  Hide_errors = true;
  run(
      "== code 0x1\n"
      "40/increment-EAX\n"
      "== data 0x2000\n"
      "x:\n"
      "x:\n"
      "  00\n"
  );
  CHECK_TRACE_CONTENTS(
      "error: duplicate global 'x'\n"
  );
}

void test_global_variable_disp32_with_modrm() {
  run(
      "== code 0x1\n"
      "8b/copy 0/mod/indirect 5/rm32/.disp32 2/r32/EDX x/disp32\n"
      "== data 0x2000\n"
      "x:\n"
      "  00 00 00 00\n"
  );
  CHECK_TRACE_COUNT("error", 0);
}

void test_global_variable_disp32_with_call() {
  transform(
      "== code 0x1\n"
      "foo:\n"
      "  e8/call bar/disp32\n"
      "bar:\n"
  );
  CHECK_TRACE_COUNT("error", 0);
}

string to_full_string(const line& in) {
  ostringstream out;
  for (int i = 0;  i < SIZE(in.words);  ++i) {
    if (i > 0) out << ' ';
    out << in.words.at(i).data;
    for (int j = 0;  j < SIZE(in.words.at(i).metadata);  ++j)
      out << '/' << in.words.at(i).metadata.at(j);
  }
  return out.str();
}
generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-07-07 16:41:01 +0000