Author: jmolenda Date: Mon Jun 18 16:30:03 2018 New Revision: 334995 URL: http://llvm.org/viewvc/llvm-project?rev=334995&view=rev Log: Some NFC changes to how we scan of kexts & kernels in memory in the DynamicLoaderDarwinKernel plugin. Created a new function ReadMachHeader and instead of reading through the target cached memory reader, start by reading only a mach header sized chunk of memory, then check it for a valid mach-o magic # and use the size of the load commands to pre-fetch the entire load commands of the kext which is the only thing we're going to read, instead of letting the generic mach-o parser read it in 512 byte chunks.
Functionally this is doing exactly the same thing as before, but by cutting down on the # of packets going back and forth, even on a local connection it's close to a quarter faster than it was before. <rdar://problem/38570146> Modified: lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h Modified: lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp?rev=334995&r1=334994&r2=334995&view=diff ============================================================================== --- lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp (original) +++ lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp Mon Jun 18 16:30:03 2018 @@ -8,8 +8,6 @@ // //===----------------------------------------------------------------------===// -#include "lldb/Utility/SafeMachO.h" - #include "Plugins/Platform/MacOSX/PlatformDarwinKernel.h" #include "lldb/Breakpoint/StoppointCallbackContext.h" #include "lldb/Core/Debugger.h" @@ -368,46 +366,30 @@ lldb::addr_t DynamicLoaderDarwinKernel:: } //---------------------------------------------------------------------- -// Given an address in memory, look to see if there is a kernel image at that -// address. Returns a UUID; if a kernel was not found at that address, -// UUID.IsValid() will be false. +// Read the mach_header struct out of memory and return it. +// Returns true if the mach_header was successfully read, +// Returns false if there was a problem reading the header, or it was not +// a Mach-O header. //---------------------------------------------------------------------- -lldb_private::UUID -DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress(lldb::addr_t addr, - Process *process) { - Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER)); - if (addr == LLDB_INVALID_ADDRESS) - return UUID(); - - if (log) - log->Printf("DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress: " - "looking for kernel binary at 0x%" PRIx64, - addr); - - // First try a quick test -- read the first 4 bytes and see if there is a - // valid Mach-O magic field there (the first field of the - // mach_header/mach_header_64 struct). +bool +DynamicLoaderDarwinKernel::ReadMachHeader(addr_t addr, Process *process, llvm::MachO::mach_header &header) { Status read_error; - uint8_t magicbuf[4]; - if (process->ReadMemoryFromInferior (addr, magicbuf, sizeof (magicbuf), read_error) != sizeof (magicbuf)) - return UUID(); + + // Read the mach header and see whether it looks like a kernel + if (process->DoReadMemory (addr, &header, sizeof(header), read_error) != + sizeof(header)) + return false; const uint32_t magicks[] = { llvm::MachO::MH_MAGIC_64, llvm::MachO::MH_MAGIC, llvm::MachO::MH_CIGAM, llvm::MachO::MH_CIGAM_64}; bool found_matching_pattern = false; for (size_t i = 0; i < llvm::array_lengthof (magicks); i++) - if (::memcmp (magicbuf, &magicks[i], sizeof (magicbuf)) == 0) + if (::memcmp (&header.magic, &magicks[i], sizeof (uint32_t)) == 0) found_matching_pattern = true; if (found_matching_pattern == false) - return UUID(); - - // Read the mach header and see whether it looks like a kernel - llvm::MachO::mach_header header; - if (process->DoReadMemory(addr, &header, sizeof(header), read_error) != - sizeof(header)) - return UUID(); + return false; if (header.magic == llvm::MachO::MH_CIGAM || header.magic == llvm::MachO::MH_CIGAM_64) { @@ -420,6 +402,35 @@ DynamicLoaderDarwinKernel::CheckForKerne header.flags = llvm::ByteSwap_32(header.flags); } + return true; +} + +//---------------------------------------------------------------------- +// Given an address in memory, look to see if there is a kernel image at that +// address. +// Returns a UUID; if a kernel was not found at that address, UUID.IsValid() +// will be false. +//---------------------------------------------------------------------- +lldb_private::UUID +DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress(lldb::addr_t addr, + Process *process) { + Log *log(lldb_private::GetLogIfAnyCategoriesSet(LIBLLDB_LOG_DYNAMIC_LOADER)); + if (addr == LLDB_INVALID_ADDRESS) + return UUID(); + + if (log) + log->Printf("DynamicLoaderDarwinKernel::CheckForKernelImageAtAddress: " + "looking for kernel binary at 0x%" PRIx64, + addr); + + llvm::MachO::mach_header header; + + if (ReadMachHeader (addr, process, header) == false) + return UUID(); + + // First try a quick test -- read the first 4 bytes and see if there is a + // valid Mach-O magic field there + // (the first field of the mach_header/mach_header_64 struct). // A kernel is an executable which does not have the dynamic link object flag // set. if (header.filetype == llvm::MachO::MH_EXECUTE && @@ -639,8 +650,17 @@ bool DynamicLoaderDarwinKernel::KextImag FileSpec file_spec; file_spec.SetFile(m_name.c_str(), false, FileSpec::Style::native); + llvm::MachO::mach_header mh; + size_t size_to_read = 512; + if (ReadMachHeader (m_load_address, process, mh)) { + if (mh.magic == llvm::MachO::MH_CIGAM || llvm::MachO::MH_MAGIC) + size_to_read = sizeof (llvm::MachO::mach_header) + mh.sizeofcmds; + if (mh.magic == llvm::MachO::MH_CIGAM_64 || llvm::MachO::MH_MAGIC_64) + size_to_read = sizeof (llvm::MachO::mach_header_64) + mh.sizeofcmds; + } + ModuleSP memory_module_sp = - process->ReadModuleFromMemory(file_spec, m_load_address); + process->ReadModuleFromMemory(file_spec, m_load_address, size_to_read); if (memory_module_sp.get() == NULL) return false; Modified: lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h URL: http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h?rev=334995&r1=334994&r2=334995&view=diff ============================================================================== --- lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h (original) +++ lldb/trunk/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h Mon Jun 18 16:30:03 2018 @@ -17,6 +17,9 @@ #include <vector> // Other libraries and framework includes + +#include "lldb/Utility/SafeMachO.h" + // Project includes #include "lldb/Target/DynamicLoader.h" #include "lldb/Target/Process.h" @@ -284,6 +287,9 @@ protected: static lldb::addr_t SearchForKernelViaExhaustiveSearch(lldb_private::Process *process); + static bool + ReadMachHeader(lldb::addr_t addr, lldb_private::Process *process, llvm::MachO::mach_header &mh); + static lldb_private::UUID CheckForKernelImageAtAddress(lldb::addr_t addr, lldb_private::Process *process); _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits