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Use two LC_NOTE load commands for identifying the main binary that 

lldb should use when given a corefile.

This uses an LC_NOTE "main bin spec" or an LC_NOTE "kern ver str"
if they are present in a Mach-O core file.

Core files may have multiple different binaries -- different kernels,
or a mix of user process and kernel binaries -- and it can be
difficult for lldb to detect the correct one to use simply by looking
at the pages of memory.  These two new LC_NOTE load commands allow
for the correct binary to be recorded unambiguously.

<rdar://problem/20878266> 

llvm-svn: 300138
This commit is contained in:
Jason Molenda 2017-04-12 23:33:30 +00:00
parent 75999dff93
commit 9b7fcdcb57
4 changed files with 156 additions and 10 deletions
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27
lldb/include/lldb/Symbol/ObjectFile.h
View File

@ -18,6 +18,7 @@
#include "lldb/Utility/DataExtractor.h"
#include "lldb/Utility/Endian.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/UUID.h"
#include "lldb/lldb-private.h"
namespace lldb_private {
@ -576,6 +577,32 @@ public:
return std::string();
}
//------------------------------------------------------------------
/// When the ObjectFile is a core file, lldb needs to locate the
/// "binary" in the core file. lldb can iterate over the pages looking
/// for a valid binary, but some core files may have metadata
/// describing where the main binary is exactly which removes ambiguity
/// when there are multiple binaries present in the captured memory pages.
///
/// @param[out] address
/// If the address of the binary is specified, this will be set.
/// This is an address is the virtual address space of the core file
/// memory segments; it is not an offset into the object file.
/// If no address is available, will be set to LLDB_INVALID_ADDRESS.
///
/// @param[out] uuid
/// If the uuid of the binary is specified, this will be set.
/// If no UUID is available, will be cleared.
///
/// @return
/// Returns true if either address or uuid has been set.
//------------------------------------------------------------------
virtual bool GetCorefileMainBinaryInfo (lldb::addr_t &address, UUID &uuid) {
address = LLDB_INVALID_ADDRESS;
uuid.Clear();
return false;
}
virtual lldb::RegisterContextSP
GetThreadContextAtIndex(uint32_t idx, lldb_private::Thread &thread) {
return lldb::RegisterContextSP();

111
lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
View File

@ -60,6 +60,8 @@
#ifndef __APPLE__
#include "Utility/UuidCompatibility.h"
#else
#include <uuid/uuid.h>
#endif
#define THUMB_ADDRESS_BIT_MASK 0xfffffffffffffffeull
@ -5354,23 +5356,67 @@ uint32_t ObjectFileMachO::GetNumThreadContexts() {
return m_thread_context_offsets.GetSize();
}
// The LC_IDENT load command has been obsoleted for a very
// long time and it should not occur in Mach-O files. But
// if it is there, it may contain a hint about where to find
// the main binary in a core file, so we'll use it.
std::string ObjectFileMachO::GetIdentifierString() {
std::string result;
ModuleSP module_sp(GetModule());
if (module_sp) {
std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
// First, look over the load commands for an LC_NOTE load command
// with data_owner string "kern ver str" & use that if found.
lldb::offset_t offset = MachHeaderSizeFromMagic(m_header.magic);
for (uint32_t i = 0; i < m_header.ncmds; ++i) {
const uint32_t cmd_offset = offset;
load_command lc;
if (m_data.GetU32(&offset, &lc.cmd, 2) == NULL)
break;
if (lc.cmd == LC_NOTE)
{
char data_owner[17];
m_data.CopyData (offset, 16, data_owner);
data_owner[16] = '\0';
offset += 16;
uint64_t fileoff = m_data.GetU64_unchecked (&offset);
uint64_t size = m_data.GetU64_unchecked (&offset);
// "kern ver str" has a uint32_t version and then a
// nul terminated c-string.
if (strcmp ("kern ver str", data_owner) == 0)
{
offset = fileoff;
uint32_t version;
if (m_data.GetU32 (&offset, &version, 1) != nullptr)
{
if (version == 1)
{
uint32_t strsize = size - sizeof (uint32_t);
char *buf = (char*) malloc (strsize);
if (buf)
{
m_data.CopyData (offset, strsize, buf);
buf[strsize - 1] = '\0';
result = buf;
if (buf)
free (buf);
return result;
}
}
}
}
}
offset = cmd_offset + lc.cmdsize;
}
// Second, make a pass over the load commands looking for an
// obsolete LC_IDENT load command.
offset = MachHeaderSizeFromMagic(m_header.magic);
for (uint32_t i = 0; i < m_header.ncmds; ++i) {
const uint32_t cmd_offset = offset;
struct ident_command ident_command;
if (m_data.GetU32(&offset, &ident_command, 2) == NULL)
break;
if (ident_command.cmd == LC_IDENT && ident_command.cmdsize != 0) {
char *buf = (char *)malloc (ident_command.cmdsize);
char *buf = (char *) malloc (ident_command.cmdsize);
if (buf != nullptr
&& m_data.CopyData (offset, ident_command.cmdsize, buf) == ident_command.cmdsize) {
buf[ident_command.cmdsize - 1] = '\0';
@ -5381,10 +5427,65 @@ std::string ObjectFileMachO::GetIdentifierString() {
}
offset = cmd_offset + ident_command.cmdsize;
}
}
return result;
}
bool ObjectFileMachO::GetCorefileMainBinaryInfo (addr_t &address, UUID &uuid) {
address = LLDB_INVALID_ADDRESS;
uuid.Clear();
ModuleSP module_sp(GetModule());
if (module_sp) {
std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
lldb::offset_t offset = MachHeaderSizeFromMagic(m_header.magic);
for (uint32_t i = 0; i < m_header.ncmds; ++i) {
const uint32_t cmd_offset = offset;
load_command lc;
if (m_data.GetU32(&offset, &lc.cmd, 2) == NULL)
break;
if (lc.cmd == LC_NOTE)
{
char data_owner[17];
memset (data_owner, 0, sizeof (data_owner));
m_data.CopyData (offset, 16, data_owner);
offset += 16;
uint64_t fileoff = m_data.GetU64_unchecked (&offset);
uint64_t size = m_data.GetU64_unchecked (&offset);
// "main bin spec" (main binary specification) data payload is formatted:
// uint32_t version [currently 1]
// uint32_t type [0 == unspecified, 1 == kernel, 2 == user process]
// uint64_t address [ UINT64_MAX if address not specified ]
// uuid_t uuid [ all zero's if uuid not specified ]
// uint32_t log2_pagesize [ process page size in log base 2, e.g. 4k pages are 12. 0 for unspecified ]
if (strcmp ("main bin spec", data_owner) == 0 && size >= 32)
{
offset = fileoff;
uint32_t version;
if (m_data.GetU32 (&offset, &version, 1) != nullptr && version == 1)
{
uint32_t type = 0;
uuid_t raw_uuid;
uuid_clear (raw_uuid);
if (m_data.GetU32 (&offset, &type, 1)
&& m_data.GetU64 (&offset, &address, 1)
&& m_data.CopyData (offset, sizeof (uuid_t), raw_uuid) != 0
&& uuid.SetBytes (raw_uuid, sizeof (uuid_t)))
{
return true;
}
}
}
}
offset = cmd_offset + lc.cmdsize;
}
}
return false;
}
lldb::RegisterContextSP
ObjectFileMachO::GetThreadContextAtIndex(uint32_t idx,
lldb_private::Thread &thread) {

3
lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.h
View File

@ -20,6 +20,7 @@
#include "lldb/Symbol/ObjectFile.h"
#include "lldb/Utility/FileSpec.h"
#include "lldb/Utility/SafeMachO.h"
#include "lldb/Utility/UUID.h"
//----------------------------------------------------------------------
// This class needs to be hidden as eventually belongs in a plugin that
@ -113,6 +114,8 @@ public:
std::string GetIdentifierString() override;
bool GetCorefileMainBinaryInfo (lldb::addr_t &address, lldb_private::UUID &uuid) override;
lldb::RegisterContextSP
GetThreadContextAtIndex(uint32_t idx, lldb_private::Thread &thread) override;

25
lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
View File

@ -294,11 +294,26 @@ Error ProcessMachCore::DoLoadCore() {
bool found_main_binary_definitively = false;
addr_t objfile_binary_addr;
UUID objfile_binary_uuid;
if (core_objfile->GetCorefileMainBinaryInfo (objfile_binary_addr, objfile_binary_uuid))
{
if (objfile_binary_addr != LLDB_INVALID_ADDRESS)
{
m_mach_kernel_addr = objfile_binary_addr;
found_main_binary_definitively = true;
if (log)
log->Printf ("ProcessMachCore::DoLoadCore: using kernel address 0x%" PRIx64
" from LC_NOTE 'main bin spec' load command.", m_mach_kernel_addr);
}
}
// This checks for the presence of an LC_IDENT string in a core file;
// LC_IDENT is very obsolete and should not be used in new code, but
// if the load command is present, let's use the contents.
std::string corefile_identifier = core_objfile->GetIdentifierString();
if (corefile_identifier.find("Darwin Kernel") != std::string::npos) {
if (found_main_binary_definitively == false
&& corefile_identifier.find("Darwin Kernel") != std::string::npos) {
UUID uuid;
addr_t addr = LLDB_INVALID_ADDRESS;
if (corefile_identifier.find("UUID=") != std::string::npos) {
@ -320,13 +335,13 @@ Error ProcessMachCore::DoLoadCore() {
found_main_binary_definitively = true;
if (log)
log->Printf("ProcessMachCore::DoLoadCore: Using the kernel address 0x%" PRIx64
"from LC_IDENT string '%s'", addr, corefile_identifier.c_str());
" from LC_IDENT/LC_NOTE 'kern ver str' string: '%s'", addr, corefile_identifier.c_str());
}
}
if (found_main_binary_definitively == false &&
(m_dyld_addr == LLDB_INVALID_ADDRESS ||
m_mach_kernel_addr == LLDB_INVALID_ADDRESS)) {
if (found_main_binary_definitively == false
&& (m_dyld_addr == LLDB_INVALID_ADDRESS
|| m_mach_kernel_addr == LLDB_INVALID_ADDRESS)) {
// We need to locate the main executable in the memory ranges
// we have in the core file. We need to search for both a user-process dyld
// binary