caio/clang-p2996
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[lldb/ELF] Fix IDs of synthetic eh_frame symbols

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The code used the total number of symbols to create a symbol ID for the
synthetic symbols. This is not correct because the IDs of real symbols
can be higher than their total number, as we do not add all symbols (and
in particular, we never add symbol zero, which is not a real symbol).

This meant we could have symbols with duplicate IDs, which caused
problems if some relocations were referring to the duplicated IDs. This
was the cause of the failure of the test D97786.

This patch fixes the code to use the ID of the highest (last) symbol
instead.
This commit is contained in:
Pavel Labath
2021-04-17 18:31:17 +02:00
parent 85740ee108
commit cd64273f5e
2 changed files with 50 additions and 16 deletions
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34
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
View File

@@ -2901,8 +2901,11 @@ void ObjectFileELF::ParseUnwindSymbols(Symtab *symbol_table,
// recalculate the index first.
std::vector<Symbol> new_symbols;
eh_frame->ForEachFDEEntries([this, symbol_table, section_list, &new_symbols](
lldb::addr_t file_addr, uint32_t size, dw_offset_t) {
size_t num_symbols = symbol_table->GetNumSymbols();
uint64_t last_symbol_id =
num_symbols ? symbol_table->SymbolAtIndex(num_symbols - 1)->GetID() : 0;
eh_frame->ForEachFDEEntries([&](lldb::addr_t file_addr, uint32_t size,
dw_offset_t) {
Symbol *symbol = symbol_table->FindSymbolAtFileAddress(file_addr);
if (symbol) {
if (!symbol->GetByteSizeIsValid()) {
@@ -2915,21 +2918,20 @@ void ObjectFileELF::ParseUnwindSymbols(Symtab *symbol_table,
if (section_sp) {
addr_t offset = file_addr - section_sp->GetFileAddress();
const char *symbol_name = GetNextSyntheticSymbolName().GetCString();
uint64_t symbol_id = symbol_table->GetNumSymbols();
Symbol eh_symbol(
symbol_id, // Symbol table index.
symbol_name, // Symbol name.
eSymbolTypeCode, // Type of this symbol.
true, // Is this globally visible?
false, // Is this symbol debug info?
false, // Is this symbol a trampoline?
true, // Is this symbol artificial?
section_sp, // Section in which this symbol is defined or null.
offset, // Offset in section or symbol value.
0, // Size: Don't specify the size as an FDE can
false, // Size is valid: cover multiple symbols.
false, // Contains linker annotations?
0); // Symbol flags.
++last_symbol_id, // Symbol table index.
symbol_name, // Symbol name.
eSymbolTypeCode, // Type of this symbol.
true, // Is this globally visible?
false, // Is this symbol debug info?
false, // Is this symbol a trampoline?
true, // Is this symbol artificial?
section_sp, // Section in which this symbol is defined or null.
offset, // Offset in section or symbol value.
0, // Size: Don't specify the size as an FDE can
false, // Size is valid: cover multiple symbols.
false, // Contains linker annotations?
0); // Symbol flags.
new_symbols.push_back(eh_symbol);
}
}

32
lldb/test/Shell/ObjectFile/ELF/eh_frame-symbols.yaml Normal file
View File

@@ -0,0 +1,32 @@
# RUN: yaml2obj %s >%t
# RUN: %lldb %t -o "image dump symtab" -b | FileCheck %s
# CHECK: Index UserID DSX Type File Address/Value Load Address Size Flags Name
# CHECK: [ 0] 1 SourceFile 0x0000000000000000 0x0000000000000000 0x00000004 -
# CHECK: [ 1] 2 SX Code 0x0000000000201180 0x0000000000000010 0x00000000 ___lldb_unnamed_symbol1$${{.*}}
# CHECK: [ 2] 3 SX Code 0x0000000000201190 0x0000000000000006 0x00000000 ___lldb_unnamed_symbol2$${{.*}}
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_EXEC
Machine: EM_X86_64
Sections:
- Name: .eh_frame
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Address: 0x200120
AddressAlign: 0x8
Content: 1400000000000000017A5200017810011B0C0708900100001C0000001C000000401000000600000000410E108602430D06410C07080000001C0000003C000000301000000600000000410E108602430D06410C070800000000000000
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x201180
AddressAlign: 0x10
Content: 554889E55DC3662E0F1F840000000000554889E55DC3
Symbols:
- Name: '-'
Type: STT_FILE
Index: SHN_ABS
...