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LibJS/JIT: Add patchable absolute references to basic blocks

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This commit is contained in:
Andreas Kling 2023-10-17 18:04:57 +02:00
parent 2e6c02f088
commit 3523f9f722
2 changed files with 23 additions and 7 deletions
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27
Userland/Libraries/LibJS/JIT/Compiler.cpp
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@ -234,8 +234,14 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable const& bytecode_
compiler.m_assembler.exit();
}
// Patch up all the jumps
auto* executable_memory = mmap(nullptr, compiler.m_output.size(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (executable_memory == MAP_FAILED) {
perror("mmap");
return nullptr;
}
for (auto& block : bytecode_executable.basic_blocks) {
// Patch up all the jumps
for (auto& jump : block->jumps_to_here) {
auto offset = block->offset - jump - 4;
compiler.m_output[jump + 0] = (offset >> 0) & 0xff;
@ -243,16 +249,23 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable const& bytecode_
compiler.m_output[jump + 2] = (offset >> 16) & 0xff;
compiler.m_output[jump + 3] = (offset >> 24) & 0xff;
}
// Patch up all the absolute references
for (auto& absolute_reference : block->absolute_references_to_here) {
auto offset = bit_cast<u64>(executable_memory) + block->offset;
compiler.m_output[absolute_reference + 0] = (offset >> 0) & 0xff;
compiler.m_output[absolute_reference + 1] = (offset >> 8) & 0xff;
compiler.m_output[absolute_reference + 2] = (offset >> 16) & 0xff;
compiler.m_output[absolute_reference + 3] = (offset >> 24) & 0xff;
compiler.m_output[absolute_reference + 4] = (offset >> 32) & 0xff;
compiler.m_output[absolute_reference + 5] = (offset >> 40) & 0xff;
compiler.m_output[absolute_reference + 6] = (offset >> 48) & 0xff;
compiler.m_output[absolute_reference + 7] = (offset >> 56) & 0xff;
}
}
write(STDOUT_FILENO, compiler.m_output.data(), compiler.m_output.size());
auto* executable_memory = mmap(nullptr, compiler.m_output.size(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
if (executable_memory == MAP_FAILED) {
perror("mmap");
return nullptr;
}
memcpy(executable_memory, compiler.m_output.data(), compiler.m_output.size());
mprotect(executable_memory, compiler.m_output.size(), PROT_READ | PROT_EXEC);
return make<NativeExecutable>(executable_memory, compiler.m_output.size());