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[LLDB][ELF] Load both, .symtab and .dynsym sections

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Summary:
This change ensures that the .dynsym section will be parsed even when there's already is a .symtab.

It is motivated because of minidebuginfo (https://sourceware.org/gdb/current/onlinedocs/gdb/MiniDebugInfo.html#MiniDebugInfo).

There it says:

    Keep all the function symbols not already in the dynamic symbol table.

That means the .symtab embedded inside the .gnu_debugdata does NOT contain the symbols from .dynsym. But in order to put a breakpoint on all symbols we need to load both. I hope this makes sense.

My other patch D66791 implements support for minidebuginfo, that's why I need this change.

Reviewers: labath, espindola, alexshap

Subscribers: JDevlieghere, emaste, arichardson, MaskRay, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D67390

llvm-svn: 371599
This commit is contained in:
Konrad Kleine
2019-09-11 10:00:30 +00:00
parent 57256af307
commit 3a4781bbf4
6 changed files with 119 additions and 9 deletions
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26
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
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@@ -2647,21 +2647,31 @@ Symtab *ObjectFileELF::GetSymtab() {
// smaller version of the symtab that only contains global symbols. The
// information found in the dynsym is therefore also found in the symtab,
// while the reverse is not necessarily true.
// One exception to the above rule is when we have minidebuginfo embedded
// into a compressed .gnu_debugdata section. This section contains a .symtab
// from which all symbols already contained in the .dynsym are stripped.
Section *symtab =
section_list->FindSectionByType(eSectionTypeELFSymbolTable, true).get();
if (!symtab) {
// The symtab section is non-allocable and can be stripped, so if it
// doesn't exist then use the dynsym section which should always be
// there.
symtab =
section_list->FindSectionByType(eSectionTypeELFDynamicSymbols, true)
.get();
}
if (symtab) {
m_symtab_up.reset(new Symtab(symtab->GetObjectFile()));
symbol_id += ParseSymbolTable(m_symtab_up.get(), symbol_id, symtab);
}
// The symtab section is non-allocable and can be stripped, while the dynsym
// section which should always be always be there. If both exist we load
// both to support the minidebuginfo case. Otherwise we just load the dynsym
// section.
Section *dynsym =
section_list->FindSectionByType(eSectionTypeELFDynamicSymbols, true)
.get();
if (dynsym) {
if (!m_symtab_up) {
auto sec = symtab ? symtab : dynsym;
m_symtab_up.reset(new Symtab(sec->GetObjectFile()));
}
symbol_id += ParseSymbolTable(m_symtab_up.get(), symbol_id, dynsym);
}
// DT_JMPREL
// If present, this entry's d_ptr member holds the address of
// relocation