<rdar://problem/12491235>

Enhance lldb so it can search for a kernel in memory when attaching
to a remote system.  Remove some of the code that was doing this
from ProcessMachCore and ProcessGDBRemote and put it in
DynamicLoaderDarwinKernel.

I've added a new setting, plugin.dynamic-loader.darwin-kernel.scan-type
which can be set to

 none   - for environments where reading random memory can cause a
          device crash 
 basic  - look at one fixed location in memory for a kernel load address, 
          plus the contents of that address
 fast-scan - the default, tries "basic" and then looks for the kernel's
          mach header near the current pc value when lldb connects
 exhaustive-scan - on 32-bit targets, step through the entire range where
          the kernel can be loaded, looking for the kernel binary

I don't have the setting set up correctly right now, I'm getting back unexpected
values from the Property system, but I'll figure that out tomorrow and fix.
Besides that, all of the different communication methods / types of kernels 
appear to be working correctly with these changes.

llvm-svn: 173891

2 files changed, 1 insertions, 119 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index bdeb8671857..25dbdba98b6 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -64,7 +64,6 @@
 #include "ProcessGDBRemoteLog.h"
 #include "ThreadGDBRemote.h"
 
-#include "Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.h"
 
 namespace lldb
 {
@@ -204,7 +203,6 @@ ProcessGDBRemote::ProcessGDBRemote(Target& target, Listener &listener) :
     m_waiting_for_attach (false),
     m_destroy_tried_resuming (false),
     m_dyld_plugin_name(),
-    m_kernel_load_addr (LLDB_INVALID_ADDRESS),
     m_command_sp ()
 {
     m_async_broadcaster.SetEventName (eBroadcastBitAsyncThreadShouldExit,   "async thread should exit");
@@ -494,8 +492,6 @@ ProcessGDBRemote::DoConnectRemote (Stream *strm, const char *remote_url)
         return error;
     StartAsyncThread ();
 
-    CheckForKernel (strm);
-
     lldb::pid_t pid = m_gdb_comm.GetCurrentProcessID ();
     if (pid == LLDB_INVALID_PROCESS_ID)
     {
@@ -537,110 +533,6 @@ ProcessGDBRemote::DoConnectRemote (Stream *strm, const char *remote_url)
     return error;
 }
 
-// When we are establishing a connection to a remote system and we have no executable specified,
-// or the executable is a kernel, we may be looking at a KASLR situation (where the kernel has been
-// slid in memory.)
-//
-// This function tries to locate the kernel in memory if this is possibly a kernel debug session.
-//
-// If a kernel is found, return the address of the kernel in GetImageInfoAddress() -- the 
-// DynamicLoaderDarwinKernel plugin uses this address as the kernel load address and will load the
-// binary, if needed, along with all the kexts.
-
-void
-ProcessGDBRemote::CheckForKernel (Stream *strm)
-{
-    // early return if this isn't an "unknown" system (kernel debugging doesn't have a system type)
-    const ArchSpec &gdb_remote_arch = m_gdb_comm.GetHostArchitecture();
-    if (!gdb_remote_arch.IsValid() || gdb_remote_arch.GetTriple().getVendor() != llvm::Triple::UnknownVendor)
-        return;
-
-    Module *exe_module = GetTarget().GetExecutableModulePointer();
-    ObjectFile *exe_objfile = NULL;
-    if (exe_module)
-        exe_objfile = exe_module->GetObjectFile();
-
-    // early return if we have an executable and it is not a kernel--this is very unlikely to be a kernel debug session.
-    if (exe_objfile
-        && (exe_objfile->GetType() != ObjectFile::eTypeExecutable 
-            || exe_objfile->GetStrata() != ObjectFile::eStrataKernel))
-        return;
-
-    // See if the kernel is in memory at the File address (slide == 0) -- no work needed, if so.
-    if (exe_objfile && exe_objfile->GetHeaderAddress().IsValid())
-    {
-        ModuleSP memory_module_sp;
-        memory_module_sp = ReadModuleFromMemory (exe_module->GetFileSpec(), exe_objfile->GetHeaderAddress().GetFileAddress(), false, false);
-        if (memory_module_sp.get() 
-            && memory_module_sp->GetUUID().IsValid() 
-            && memory_module_sp->GetUUID() == exe_module->GetUUID())
-        {
-            m_kernel_load_addr = exe_objfile->GetHeaderAddress().GetFileAddress();
-            m_dyld_plugin_name = DynamicLoaderDarwinKernel::GetPluginNameStatic();
-            SetCanJIT(false);
-            return;
-        }
-    }
-
-    // See if the kernel's load address is stored in the kernel's low globals page; this is
-    // done when a debug boot-arg has been set.  
-
-    Error error;
-    uint8_t buf[24];
-    ModuleSP memory_module_sp;
-    addr_t kernel_addr = LLDB_INVALID_ADDRESS;
-    
-    // First try the 32-bit 
-    if (memory_module_sp.get() == NULL)
-    {
-        DataExtractor data4 (buf, sizeof(buf), gdb_remote_arch.GetByteOrder(), 4);
-        if (DoReadMemory (0xffff0110, buf, 4, error) == 4)
-        {
-            lldb::offset_t offset = 0;
-            kernel_addr = data4.GetU32(&offset);
-            memory_module_sp = ReadModuleFromMemory (FileSpec("mach_kernel", false), kernel_addr, false, false);
-            if (!memory_module_sp.get()
-                || !memory_module_sp->GetUUID().IsValid()
-                || memory_module_sp->GetObjectFile() == NULL
-                || memory_module_sp->GetObjectFile()->GetType() != ObjectFile::eTypeExecutable
-                || memory_module_sp->GetObjectFile()->GetStrata() != ObjectFile::eStrataKernel)
-            {
-                memory_module_sp.reset();
-            }
-        }
-    }
-
-    // Now try the 64-bit location
-    if (memory_module_sp.get() == NULL)
-    {
-        DataExtractor data8 (buf, sizeof(buf), gdb_remote_arch.GetByteOrder(), 8);
-        if (DoReadMemory (0xffffff8000002010ULL, buf, 8, error) == 8)
-        {   
-            lldb::offset_t offset = 0; 
-            kernel_addr = data8.GetU64(&offset);
-            memory_module_sp = ReadModuleFromMemory (FileSpec("mach_kernel", false), kernel_addr, false, false);
-            if (!memory_module_sp.get()
-                || !memory_module_sp->GetUUID().IsValid()
-                || memory_module_sp->GetObjectFile() == NULL
-                || memory_module_sp->GetObjectFile()->GetType() != ObjectFile::eTypeExecutable
-                || memory_module_sp->GetObjectFile()->GetStrata() != ObjectFile::eStrataKernel)
-            {
-                memory_module_sp.reset();
-            }
-        }
-    }
-
-    if (memory_module_sp.get() 
-        && memory_module_sp->GetArchitecture().IsValid() 
-        && memory_module_sp->GetArchitecture().GetTriple().getVendor() == llvm::Triple::Apple)
-    {
-        m_kernel_load_addr = kernel_addr;
-        m_dyld_plugin_name = DynamicLoaderDarwinKernel::GetPluginNameStatic();
-        SetCanJIT(false);
-        return;
-    }
-}
-
 Error
 ProcessGDBRemote::WillLaunchOrAttach ()
 {
@@ -2085,16 +1977,10 @@ ProcessGDBRemote::IsAlive ()
     return m_gdb_comm.IsConnected() && m_private_state.GetValue() != eStateExited;
 }
 
-// For kernel debugging, we return the load address of the kernel binary as the
-// ImageInfoAddress and we return the DynamicLoaderDarwinKernel as the GetDynamicLoader()
-// name so the correct DynamicLoader plugin is chosen.
 addr_t
 ProcessGDBRemote::GetImageInfoAddress()
 {
-    if (m_kernel_load_addr != LLDB_INVALID_ADDRESS)
-        return m_kernel_load_addr;
-    else
-        return m_gdb_comm.GetShlibInfoAddr();
+    return m_gdb_comm.GetShlibInfoAddr();
 }
 
 //------------------------------------------------------------------
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
index 520dfc44adc..7684607b7f7 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.h
@@ -297,9 +297,6 @@ protected:
         m_last_stop_packet = response;
     }
 
-    void
-    CheckForKernel (lldb_private::Stream *strm);
-
     //------------------------------------------------------------------
     /// Broadcaster event bits definitions.
     //------------------------------------------------------------------
@@ -342,7 +339,6 @@ protected:
     bool m_waiting_for_attach;
     bool m_destroy_tried_resuming;
     std::string m_dyld_plugin_name;
-    lldb::addr_t m_kernel_load_addr;
     lldb::CommandObjectSP m_command_sp;
     
     bool