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disasm: For ELF inputs, pass an ELFSymbolProvider to disassembler

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This lets disasm output contain the symbol names of call and jump
destinations:

    8048111:	e8 88 38 01 00       	call   805b99e <__cxa_atexit>
    ...
    8048150:	74 15                	je     8048167 <_start+0x4c>

The latter (the symbol of the current function with an offset) is
arguably more distracting than useful because you usually want to look
at the instruction at the absolute offset in this case, but the former
is very nice to have.

For reasons I do not understand, this cuts the time to run
`disasm /bin/id` in half, from ~1s to ~0.5s.
This commit is contained in:
Nico Weber 2020-08-16 12:39:06 -04:00 • committed by Andreas Kling
parent fd73de684e
commit f025204dfe
1 changed files with 8 additions and 2 deletions
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10
Userland/disasm.cpp
View file

@ -31,6 +31,7 @@
#include <LibCore/ArgsParser.h>
#include <LibELF/Loader.h>
#include <LibX86/Disassembler.h>
#include <LibX86/ELFSymbolProvider.h>
#include <stdio.h>
#include <string.h>
@ -66,8 +67,13 @@ int main(int argc, char** argv)
size_t asm_size = file.size();
size_t file_offset = 0;
Vector<Symbol>::Iterator current_symbol = symbols.begin();
RefPtr<ELF::Loader> elf;
OwnPtr<X86::ELFSymbolProvider> symbol_provider; // nullptr for non-ELF disassembly.
if (asm_size >= 4 && strncmp((const char*)asm_data, "\u007fELF", 4) == 0) {
if (auto elf = ELF::Loader::create(asm_data, asm_size)) {
NonnullRefPtr<ELF::Loader> elf_loader = ELF::Loader::create(asm_data, asm_size);
if (elf_loader->image().is_valid()) {
elf = elf_loader;
symbol_provider = new X86::ELFSymbolProvider(*elf);
elf->image().for_each_section_of_type(SHT_PROGBITS, [&](const ELF::Image::Section& section) {
// FIXME: Disassemble all SHT_PROGBITS sections, not just .text.
if (section.name() != ".text")
@ -141,7 +147,7 @@ int main(int argc, char** argv)
is_first_symbol = false;
}
out() << String::format("%08x", virtual_offset) << " " << insn.value().to_string(virtual_offset);
out() << String::format("%08x", virtual_offset) << " " << insn.value().to_string(virtual_offset, symbol_provider);
}
return 0;