[Lldb-commits] [lldb] 91c0ef6 - [lldb] [ObjectFileMachO] BSS segments are loadable segments (#96983)
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lldb-commits at lists.llvm.org
Mon Jul 1 21:56:37 PDT 2024
Author: Jason Molenda
Date: 2024-07-01T21:56:33-07:00
New Revision: 91c0ef6f67821eb7298cb05988045e92354ac77b
URL: https://github.com/llvm/llvm-project/commit/91c0ef6f67821eb7298cb05988045e92354ac77b
DIFF: https://github.com/llvm/llvm-project/commit/91c0ef6f67821eb7298cb05988045e92354ac77b.diff
LOG: [lldb] [ObjectFileMachO] BSS segments are loadable segments (#96983)
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
Added:
Modified:
lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
Removed:
################################################################################
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index 2979bf69bf762..0dcb1bed23548 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 +6214,33 @@ bool ObjectFileMachO::SetLoadAddress(Target &target, lldb::addr_t value,
// malformed.
const bool warn_multiple = true;
+ if (log) {
+ StreamString logmsg;
+ logmsg << "ObjectFileMachO::SetLoadAddress ";
+ if (GetFileSpec())
+ logmsg << "path='" << GetFileSpec().GetPath() << "' ";
+ if (GetUUID()) {
+ logmsg << "uuid=" << GetUUID().GetAsString();
+ }
+ LLDB_LOGF(log, "%s", logmsg.GetData());
+ }
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 +6255,10 @@ 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;
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