https://github.com/jasonmolenda updated
https://github.com/llvm/llvm-project/pull/96983
>From 6bd566504355e8d50b9c922df9ebce18e07a726f Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmole...@apple.com>
Date: Thu, 27 Jun 2024 15:34:48 -0700
Subject: [PATCH 1/2] [lldb] [ObjectFileMachO] BSS segments are loadable
segments
ObjectFileMachO::SetLoadAddress sets the address of each segment
in a binary in a Target, but it ignores segments that are not loaded
in the virtual address space. It was marking segments that were
purely BSS -- having no content in the file, but in zero-initialized
memory when running in the virtual address space -- as not-loadable,
unless they were named "DATA". This works pretty well for typical
userland binaries, but in less Darwin environments, there may be
BSS segments with other names, that ARE loadable.
I looked at the origin of SectionIsLoadable's check for this, and
it was a cleanup by Greg in 2018 where we had three different
implementations of the idea in ObjectFileMachO and one of them
skipped zero-file-size segments (BSS), which made it into the
centralized SectionIsLoadable method.
Also add some logging to the DynamicLoader log channel when loading
a binary - it's the first place I look when debugging segment address
setting bugs, and it wasn't emitting anything.
rdar://129870649
---
.../ObjectFile/Mach-O/ObjectFileMachO.cpp | 31 ++++++++++++++++---
1 file changed, 26 insertions(+), 5 deletions(-)
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 2979bf69bf762..164c4409747e0 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -6159,10 +6159,6 @@ Section *ObjectFileMachO::GetMachHeaderSection() {
bool ObjectFileMachO::SectionIsLoadable(const Section *section) {
if (!section)
return false;
- const bool is_dsym = (m_header.filetype == MH_DSYM);
- if (section->GetFileSize() == 0 && !is_dsym &&
- section->GetName() != GetSegmentNameDATA())
- return false;
if (section->IsThreadSpecific())
return false;
if (GetModule().get() != section->GetModule().get())
@@ -6202,6 +6198,7 @@ lldb::addr_t
ObjectFileMachO::CalculateSectionLoadAddressForMemoryImage(
bool ObjectFileMachO::SetLoadAddress(Target &target, lldb::addr_t value,
bool value_is_offset) {
+ Log *log(GetLog(LLDBLog::DynamicLoader));
ModuleSP module_sp = GetModule();
if (!module_sp)
return false;
@@ -6217,17 +6214,37 @@ bool ObjectFileMachO::SetLoadAddress(Target &target,
lldb::addr_t value,
// malformed.
const bool warn_multiple = true;
+ if (log) {
+ std::string binary_description;
+ if (GetFileSpec()) {
+ binary_description += "path='";
+ binary_description += GetFileSpec().GetPath();
+ binary_description += "' ";
+ }
+ if (GetUUID()) {
+ binary_description += "uuid=";
+ binary_description += GetUUID().GetAsString();
+ }
+ LLDB_LOGF(log, "ObjectFileMachO::SetLoadAddress %s",
+ binary_description.c_str());
+ }
if (value_is_offset) {
// "value" is an offset to apply to each top level segment
for (size_t sect_idx = 0; sect_idx < num_sections; ++sect_idx) {
// Iterate through the object file sections to find all of the
// sections that size on disk (to avoid __PAGEZERO) and load them
SectionSP section_sp(section_list->GetSectionAtIndex(sect_idx));
- if (SectionIsLoadable(section_sp.get()))
+ if (SectionIsLoadable(section_sp.get())) {
+ LLDB_LOGF(log,
+ "ObjectFileMachO::SetLoadAddress segment '%s' load addr is "
+ "0x%" PRIx64,
+ section_sp->GetName().AsCString(),
+ section_sp->GetFileAddress() + value);
if (target.GetSectionLoadList().SetSectionLoadAddress(
section_sp, section_sp->GetFileAddress() + value,
warn_multiple))
++num_loaded_sections;
+ }
}
} else {
// "value" is the new base address of the mach_header, adjust each
@@ -6242,6 +6259,10 @@ bool ObjectFileMachO::SetLoadAddress(Target &target,
lldb::addr_t value,
CalculateSectionLoadAddressForMemoryImage(
value, mach_header_section, section_sp.get());
if (section_load_addr != LLDB_INVALID_ADDRESS) {
+ LLDB_LOGF(log,
+ "ObjectFileMachO::SetLoadAddress segment '%s' load addr is
"
+ "0x%" PRIx64,
+ section_sp->GetName().AsCString(), section_load_addr);
if (target.GetSectionLoadList().SetSectionLoadAddress(
section_sp, section_load_addr, warn_multiple))
++num_loaded_sections;
>From 2a7b154cbdffb75d763d3f8587266c9a7c0a0eb0 Mon Sep 17 00:00:00 2001
From: Jason Molenda <ja...@molenda.com>
Date: Mon, 1 Jul 2024 17:29:41 -0700
Subject: [PATCH 2/2] Build up the log message in a StreamString which is a
little more compact.
---
.../ObjectFile/Mach-O/ObjectFileMachO.cpp | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 164c4409747e0..0dcb1bed23548 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -6215,18 +6215,14 @@ bool ObjectFileMachO::SetLoadAddress(Target &target,
lldb::addr_t value,
const bool warn_multiple = true;
if (log) {
- std::string binary_description;
- if (GetFileSpec()) {
- binary_description += "path='";
- binary_description += GetFileSpec().GetPath();
- binary_description += "' ";
- }
+ StreamString logmsg;
+ logmsg << "ObjectFileMachO::SetLoadAddress ";
+ if (GetFileSpec())
+ logmsg << "path='" << GetFileSpec().GetPath() << "' ";
if (GetUUID()) {
- binary_description += "uuid=";
- binary_description += GetUUID().GetAsString();
+ logmsg << "uuid=" << GetUUID().GetAsString();
}
- LLDB_LOGF(log, "ObjectFileMachO::SetLoadAddress %s",
- binary_description.c_str());
+ LLDB_LOGF(log, "%s", logmsg.GetData());
}
if (value_is_offset) {
// "value" is an offset to apply to each top level segment
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