RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-07-26 08:57:34 +00:00
Code Issues Activity Actions

LibELF: Refactor how arch-specific dynamic relocation types are handled

Browse source 
We currently expect that the relocation type numbers are unique across
all architectures. But RISC-V and x86_64 use the same numbers for
different relocation types (R_X86_64_COPY = R_RISCV_JUMP_SLOT = 5).

So create a generic reloc type enum which maps to the arch-specific
reloc types instead of checking for all arch reloc types individually
everywhere.
This commit is contained in:
Sönke Holz 2024-02-10 20:43:07 +01:00 • committed by Andrew Kaster
parent c216e7439f
commit f8628f94b8
6 changed files with 98 additions and 23 deletions
Download patch file Download diff file Expand all files Collapse all files

38
Userland/Libraries/LibELF/DynamicLoader.cpp
View file

@ -11,6 +11,7 @@
#include <AK/Optional.h>
#include <AK/QuickSort.h>
#include <AK/StringBuilder.h>
#include <LibELF/Arch/GenericDynamicRelocationType.h>
#include <LibELF/DynamicLinker.h>
#include <LibELF/DynamicLoader.h>
#include <LibELF/Hashes.h>
@ -228,17 +229,17 @@ void DynamicLoader::do_main_relocations()
// If the object is position-independent, the pointer to the PLT trampoline needs to be relocated.
auto fixup_trampoline_pointer = [&](DynamicObject::Relocation const& relocation) {
VERIFY(relocation.type() == R_X86_64_JUMP_SLOT || relocation.type() == R_AARCH64_JUMP_SLOT);
VERIFY(static_cast<GenericDynamicRelocationType>(relocation.type()) == GenericDynamicRelocationType::JUMP_SLOT);
if (image().is_dynamic())
*((FlatPtr*)relocation.address().as_ptr()) += m_dynamic_object->base_address().get();
};
m_dynamic_object->plt_relocation_section().for_each_relocation([&](DynamicObject::Relocation const& relocation) {
if (relocation.type() == R_X86_64_IRELATIVE || relocation.type() == R_AARCH64_IRELATIVE) {
if (static_cast<GenericDynamicRelocationType>(relocation.type()) == GenericDynamicRelocationType::IRELATIVE) {
m_direct_ifunc_relocations.append(relocation);
return;
}
if (relocation.type() == R_X86_64_TLSDESC || relocation.type() == R_AARCH64_TLSDESC) {
if (static_cast<GenericDynamicRelocationType>(relocation.type()) == GenericDynamicRelocationType::TLSDESC) {
// GNU ld for some reason puts TLSDESC relocations into .rela.plt
// https://sourceware.org/bugzilla/show_bug.cgi?id=28387
@ -574,14 +575,14 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
return ResolvedTLSSymbol { *res.value().dynamic_object, res.value().value };
};
switch (relocation.type()) {
using enum GenericDynamicRelocationType;
switch (static_cast<GenericDynamicRelocationType>(relocation.type())) {
case R_X86_64_NONE:
case NONE:
// Apparently most loaders will just skip these?
// Seems if the 'link editor' generates one something is funky with your code
break;
case R_AARCH64_ABS64:
case R_X86_64_64: {
case ABSOLUTE: {
auto symbol = relocation.symbol();
auto res = lookup_symbol(symbol);
if (!res.has_value()) {
@ -602,8 +603,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
*patch_ptr = call_ifunc_resolver(VirtualAddress { *patch_ptr }).get();
break;
}
case R_AARCH64_GLOB_DAT:
case R_X86_64_GLOB_DAT: {
case GLOB_DAT: {
auto symbol = relocation.symbol();
auto res = lookup_symbol(symbol);
VirtualAddress symbol_location;
@ -633,8 +633,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
*patch_ptr = symbol_location.get();
break;
}
case R_AARCH64_RELATIVE:
case R_X86_64_RELATIVE: {
case RELATIVE: {
if (!image().is_dynamic())
break;
// FIXME: According to the spec, R_386_relative ones must be done first.
@ -646,8 +645,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
*patch_ptr += m_dynamic_object->base_address().get();
break;
}
case R_AARCH64_TLS_TPREL:
case R_X86_64_TPOFF64: {
case TLS_TPREL: {
auto maybe_resolution = resolve_tls_symbol(relocation);
if (!maybe_resolution.has_value())
break;
@ -660,7 +658,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
VERIFY(static_cast<ssize_t>(*patch_ptr) < 0);
break;
}
case R_X86_64_DTPMOD64: {
case TLS_DTPMOD: {
auto maybe_resolution = resolve_tls_symbol(relocation);
if (!maybe_resolution.has_value())
break;
@ -670,7 +668,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
*patch_ptr = maybe_resolution->dynamic_object.tls_offset().value();
break;
}
case R_X86_64_DTPOFF64: {
case TLS_DTPREL: {
auto maybe_resolution = resolve_tls_symbol(relocation);
if (!maybe_resolution.has_value())
break;
@ -680,7 +678,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
break;
}
#ifdef HAS_TLSDESC_SUPPORT
case R_AARCH64_TLSDESC: {
case TLSDESC: {
auto maybe_resolution = resolve_tls_symbol(relocation);
if (!maybe_resolution.has_value())
break;
@ -693,8 +691,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
break;
}
#endif
case R_AARCH64_IRELATIVE:
case R_X86_64_IRELATIVE: {
case IRELATIVE: {
if (should_call_ifunc_resolver == ShouldCallIfuncResolver::No)
return RelocationResult::CallIfuncResolver;
VirtualAddress resolver;
@ -711,8 +708,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
*patch_ptr = call_ifunc_resolver(resolver).get();
break;
}
case R_AARCH64_JUMP_SLOT:
case R_X86_64_JUMP_SLOT:
case JUMP_SLOT:
VERIFY_NOT_REACHED(); // PLT relocations are handled by do_plt_relocation.
default:
// Raise the alarm! Someone needs to implement this relocation type
@ -724,7 +720,7 @@ DynamicLoader::RelocationResult DynamicLoader::do_direct_relocation(DynamicObjec
DynamicLoader::RelocationResult DynamicLoader::do_plt_relocation(DynamicObject::Relocation const& relocation, ShouldCallIfuncResolver should_call_ifunc_resolver)
{
VERIFY(relocation.type() == R_X86_64_JUMP_SLOT || relocation.type() == R_AARCH64_JUMP_SLOT);
VERIFY(static_cast<GenericDynamicRelocationType>(relocation.type()) == GenericDynamicRelocationType::JUMP_SLOT);
auto symbol = relocation.symbol();
auto* relocation_address = (FlatPtr*)relocation.address().as_ptr();