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Ignore mapping symbols on aarch64 

ELF symbol tables on aarch64 may contains some mapping symbols. They
provide information about the underlying data but interfere with symbol
look-up of lldb. They are already ignored on arm32. With this CL they
will be ignored on aarch64 also.

Differential revision: http://reviews.llvm.org/D8776

llvm-svn: 234307
This commit is contained in:
Tamas Berghammer 2015-04-07 10:43:50 +00:00
parent 303c3ac925
commit 83544cf660
2 changed files with 83 additions and 51 deletions
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129
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
View File

@ -895,25 +895,18 @@ ObjectFileELF::GetAddressClass (addr_t file_addr)
if (res != eAddressClassCode)
return res;
ArchSpec arch_spec;
GetArchitecture(arch_spec);
if (arch_spec.GetMachine() != llvm::Triple::arm)
return res;
auto ub = m_address_class_map.upper_bound(file_addr);
if (ub == m_address_class_map.begin())
{
// No entry in the address class map before the address. Return
// default address class for an address in a code section.
return eAddressClassCode;
}
auto symtab = GetSymtab();
if (symtab == nullptr)
return res;
// Move iterator to the address class entry preceding address
--ub;
auto symbol = symtab->FindSymbolContainingFileAddress(file_addr);
if (symbol == nullptr)
return res;
// Thumb symbols have the lower bit set in the flags field so we just check
// for that.
if (symbol->GetFlags() & ARM_ELF_SYM_IS_THUMB)
res = eAddressClassCodeAlternateISA;
return res;
return ub->second;
}
size_t
@ -1872,45 +1865,79 @@ ObjectFileELF::ParseSymbols (Symtab *symtab,
}
}
ArchSpec arch;
int64_t symbol_value_offset = 0;
uint32_t additional_flags = 0;
if (GetArchitecture(arch) &&
arch.GetMachine() == llvm::Triple::arm)
ArchSpec arch;
if (GetArchitecture(arch))
{
// ELF symbol tables may contain some mapping symbols. They provide
// information about the underlying data. There are three of them
// currently defined:
// $a[.<any>]* - marks an ARM instruction sequence
// $t[.<any>]* - marks a THUMB instruction sequence
// $d[.<any>]* - marks a data item sequence (e.g. lit pool)
// These symbols interfere with normal debugger operations and we
// don't need them. We can drop them here.
static const llvm::StringRef g_armelf_arm_marker("$a");
static const llvm::StringRef g_armelf_thumb_marker("$t");
static const llvm::StringRef g_armelf_data_marker("$d");
llvm::StringRef symbol_name_ref(symbol_name);
if (symbol_name &&
(symbol_name_ref.startswith(g_armelf_arm_marker) ||
symbol_name_ref.startswith(g_armelf_thumb_marker) ||
symbol_name_ref.startswith(g_armelf_data_marker)))
continue;
// THUMB functions have the lower bit of their address set. Fixup
// the actual address and mark the symbol as THUMB.
if (symbol_type == eSymbolTypeCode && symbol.st_value & 1)
if (arch.GetMachine() == llvm::Triple::arm)
{
// Substracting 1 from the address effectively unsets
// the low order bit, which results in the address
// actually pointing to the beginning of the symbol.
// This delta will be used below in conjuction with
// symbol.st_value to produce the final symbol_value
// that we store in the symtab.
symbol_value_offset = -1;
additional_flags = ARM_ELF_SYM_IS_THUMB;
if (symbol.getBinding() == STB_LOCAL && symbol_name && symbol_name[0] == '$')
{
// These are reserved for the specification (e.g.: mapping
// symbols). We don't want to add them to the symbol table.
llvm::StringRef symbol_name_ref(symbol_name);
if (symbol_name_ref == "$a" || symbol_name_ref.startswith("$a."))
{
// $a[.<any>]* - marks an ARM instruction sequence
m_address_class_map[symbol.st_value] = eAddressClassCode;
}
else if (symbol_name_ref == "$b" || symbol_name_ref.startswith("$b.") ||
symbol_name_ref == "$t" || symbol_name_ref.startswith("$t."))
{
// $b[.<any>]* - marks a THUMB BL instruction sequence
// $t[.<any>]* - marks a THUMB instruction sequence
m_address_class_map[symbol.st_value] = eAddressClassCodeAlternateISA;
}
else if (symbol_name_ref == "$d" || symbol_name_ref.startswith("$d."))
{
// $d[.<any>]* - marks a data item sequence (e.g. lit pool)
m_address_class_map[symbol.st_value] = eAddressClassData;
}
continue;
}
}
else if (arch.GetMachine() == llvm::Triple::aarch64)
{
if (symbol.getBinding() == STB_LOCAL && symbol_name && symbol_name[0] == '$')
{
// These are reserved for the specification (e.g.: mapping
// symbols). We don't want to add them to the symbol table.
llvm::StringRef symbol_name_ref(symbol_name);
if (symbol_name_ref == "$x" || symbol_name_ref.startswith("$x."))
{
// $x[.<any>]* - marks an A64 instruction sequence
m_address_class_map[symbol.st_value] = eAddressClassCode;
}
else if (symbol_name_ref == "$d" || symbol_name_ref.startswith("$d."))
{
// $d[.<any>]* - marks a data item sequence (e.g. lit pool)
m_address_class_map[symbol.st_value] = eAddressClassData;
}
continue;
}
}
if (arch.GetMachine() == llvm::Triple::arm)
{
// THUMB functions have the lower bit of their address set. Fixup
// the actual address and mark the symbol as THUMB.
if (symbol_type == eSymbolTypeCode && symbol.st_value & 1)
{
// Substracting 1 from the address effectively unsets
// the low order bit, which results in the address
// actually pointing to the beginning of the symbol.
// This delta will be used below in conjuction with
// symbol.st_value to produce the final symbol_value
// that we store in the symtab.
symbol_value_offset = -1;
additional_flags = ARM_ELF_SYM_IS_THUMB;
}
}
}

5
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.h
View File

@ -219,6 +219,8 @@ private:
typedef DynamicSymbolColl::iterator DynamicSymbolCollIter;
typedef DynamicSymbolColl::const_iterator DynamicSymbolCollConstIter;
typedef std::map<lldb::addr_t, lldb::AddressClass> FileAddressToAddressClassMap;
/// Version of this reader common to all plugins based on this class.
static const uint32_t m_plugin_version = 1;
static const uint32_t g_core_uuid_magic;
@ -252,6 +254,9 @@ private:
/// The architecture detected from parsing elf file contents.
lldb_private::ArchSpec m_arch_spec;
/// The address class for each symbol in the elf file
FileAddressToAddressClassMap m_address_class_map;
/// Returns a 1 based index of the given section header.
size_t
SectionIndex(const SectionHeaderCollIter &I);