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4332 

Minimize memory footprint while running subx ELF binaries. We don't use
memory before address 0x08048000, so we don't need to allocate space for
it.
This commit is contained in:
Kartik Agaram 2018-07-09 22:43:40 -07:00
parent 8291833d08
commit 1ce67ba21b
2 changed files with 5 additions and 2 deletions
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1
subx/020elf.cc
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@ -7,6 +7,7 @@ if (is_equal(argv[1], "run")) {
reset();
cerr << std::hex;
initialize_mem();
Mem_offset = CODE_START;
load_elf(argv[2]);
while (EIP < End_of_program) // weak final-gasp termination check
run_one_instruction();

6
subx/021translate.cc
View File

@ -13,7 +13,8 @@ typedef void (*transform_fn)(const string& input, string& output);
vector<transform_fn> Transform;
:(before "End Includes")
const int START = 0x08048000;
const int CODE_START = 0x08048000;
const int CODE_SIZE = 0x1000;
:(before "End Main")
if (is_equal(argv[1], "translate")) {
assert(argc > 3);
@ -68,7 +69,7 @@ void dump_elf_header(ostream& out) {
// e_version
O(0x01); O(0x00); O(0x00); O(0x00);
// e_entry
int e_entry = START + /*size of ehdr*/52 + /*size of phdr*/32;
int e_entry = CODE_START + /*size of ehdr*/52 + /*size of phdr*/32;
emit(e_entry);
// e_phoff -- immediately after ELF header
int e_phoff = 52;
@ -108,6 +109,7 @@ void dump_elf_header(ostream& out) {
emit(e_entry);
// p_filesz
uint32_t size = End_of_program - /*we're not using location 0*/1;
assert(size < CODE_SIZE);
emit(size);
// p_memsz
emit(size);