Re: [edk2-devel] [PATCH v1] EmulatorPkg: Fix Source Level Debug on Windows

["Michael D Kinney" <michael.d.kinney@intel.com>]

I have VS Code on Windows working today using the PDB based symbol file.

The following lines in the EmulatorPkg DSC file force 4KB alignment and the DLL export of the InitializeDriver symbol

https://github.com/tianocore/edk2/blob/bf0bdacdd6f6cdd2e9ac5db14b6daf19a5a5bd57/EmulatorPkg/EmulatorPkg.dsc#L497

  MSFT:*_*_*_DLINK_FLAGS     = /ALIGN:4096 /FILEALIGN:4096 /SUBSYSTEM:CONSOLE
  MSFT:DEBUG_*_*_DLINK_FLAGS = /EXPORT:InitializeDriver=$(IMAGE_ENTRY_POINT) /BASE:0x10000
  MSFT:NOOPT_*_*_DLINK_FLAGS = /EXPORT:InitializeDriver=$(IMAGE_ENTRY_POINT) /BASE:0x10000


I think this is why it is working for me without this change.

Are you suggesting that with this change these can be removed?

Mike

> -----Original Message-----
> From: Desimone, Nathaniel L <nathaniel.l.desimone@intel.com>
> Sent: Tuesday, September 26, 2023 1:32 PM
> To: Kinney, Michael D <michael.d.kinney@intel.com>;
> devel@edk2.groups.io
> Cc: Andrew Fish <afish@apple.com>; Ni, Ray <ray.ni@intel.com>; Chiu,
> Chasel <chasel.chiu@intel.com>
> Subject: RE: [PATCH v1] EmulatorPkg: Fix Source Level Debug on Windows
> 
> Hi Mike,
> 
> Source level debug with VS Code does indeed work today with gdb or
> lldb. This change makes the Visual Studio Windows debugger work as
> well.
> 
> You are correct that if the same DLL is loaded more than once that
> this method cannot perform source level debug on the second instance;
> but this change won't break that scenario either. If the same DLL
> occurs twice, then we will use the PE/COFF image loaded by either the
> PEI core or DXE core instead of the one loaded by Windows. This means
> that the second instance of the DLL will not be source level debug-
> able by Visual Studio; but PI-spec compliance is maintained. This
> behavior is unchanged from the original code.
> 
> Yes, this code enables PE/COFF images that do not have sections that
> are 4KB aligned. It will setup page protection for user mode. Without
> this change you must turn off the NX bit when using the Visual Studio
> Windows debugger.
> 
> Thanks,
> Nate
> 
> -----Original Message-----
> From: Kinney, Michael D <michael.d.kinney@intel.com>
> Sent: Tuesday, September 26, 2023 1:08 PM
> To: Desimone, Nathaniel L <nathaniel.l.desimone@intel.com>;
> devel@edk2.groups.io
> Cc: Andrew Fish <afish@apple.com>; Ni, Ray <ray.ni@intel.com>; Chiu,
> Chasel <chasel.chiu@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>
> Subject: RE: [PATCH v1] EmulatorPkg: Fix Source Level Debug on Windows
> 
> Hi Nate,
> 
> I am able to do source level debug of EmulatorPkg using VS Code today.
> 
> What scenarios are broken?
> 
> I do know that the DLL based approach would only allow a single
> instance of the module to be loaded and debugged.  If, for example, a
> driver is loaded more than once from the UEFI Shell in the EmulatorPkg
> env, the 2nd driver would use the first DLL which does not match the
> PI spec behavior.
> 
> It also appears that this change can support PE/COFF images that do
> not have sections that are 4KB aligned and handles the page protection
> settings for the user mode application env.  Is that correct?
> 
> Mike
> 
> > -----Original Message-----
> > From: Desimone, Nathaniel L <nathaniel.l.desimone@intel.com>
> > Sent: Friday, September 22, 2023 3:49 PM
> > To: devel@edk2.groups.io
> > Cc: Andrew Fish <afish@apple.com>; Ni, Ray <ray.ni@intel.com>;
> Kinney,
> > Michael D <michael.d.kinney@intel.com>; Chiu, Chasel
> > <chasel.chiu@intel.com>
> > Subject: [PATCH v1] EmulatorPkg: Fix Source Level Debug on Windows
> >
> > The Visual Studio Windows debugger will only load symbols for
> PE/COFF
> > images that Windows is aware of. Therefore, to enable source level
> > debugging, all PEI/DXE modules must be loaded via LoadLibrary() or
> > LoadLibraryEx() and the the instance in memory created by
> > LoadLibrary() must be the one that is actually executed.
> >
> > The current source level debug implementation in EmulatorPkg for
> > Windows is inherited from the old Nt32Pkg. This implementation makes
> > the assumption that all PEI/DXE modules have a DLL export tables
> with
> > a symbol named InitializeDriver. Therefore, this source level debug
> > implementation requires all modules to be linked in a non-PI spec
> > defined manner. Support for adding the InitializeDriver symbol was
> > removed in EmulatorPkg, which broke source level debugging.
> >
> > To fix this, the source level debugging implementation has been
> > modified to use the PE/COFF entry point directly. This brings the
> > implementation into compliance with the PI spec and should work with
> > any PEIM/DXE driver.
> > Implementing this requires parsing the in-memory instance of the
> > PE/COFF image created by Windows to find the entrypoint and since
> > PEIMs/DXE drivers are not garunteed to have 4KB aligned sections, it
> > also requires explicit configuration of the page table using
> > VirtualProtect().
> >
> > With this fix, the debugging experience is now so good it is
> > unprecedented!
> > In Visual Studio Code, add the following to launch.json:
> >
> > {
> >   "version": "0.2.0",
> >   "configurations": [
> >     {
> >       "name": "EmulatorPkg Launch",
> >       "type": "cppvsdbg",
> >       "request": "launch",
> >       "program":
> >
> "${workspaceFolder}/<path_to_build>/Build/EmulatorX64/DEBUG_<tool_chai
> > n>/X64/WinHost",
> >       "args": [],
> >       "stopAtEntry": false,
> >       "cwd":
> >
> "${workspaceFolder}/<path_to_build>/Build/EmulatorX64/DEBUG_<tool_chai
> > n>/X64/",
> >       "environment": [],
> >       "console": false,
> >     }
> >   ]
> > }
> >
> > Make modifications to the above template as nessesary and build
> > EmulatorPkg.
> > Now, just add breakpoints directly in Visual Studio Code the way you
> > would with any other software project. When you start the debugger,
> it
> > will halt at the breakpoint automatically without any extra
> > configuration required.
> >
> > Cc: Andrew Fish <afish@apple.com>
> > Cc: Ray Ni <ray.ni@intel.com>
> > Cc: Michael D Kinney <michael.d.kinney@intel.com>
> > Cc: Chasel Chiu <chasel.chiu@intel.com>
> > Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
> > ---
> >  EmulatorPkg/Win/Host/WinHost.c | 206 +++++++++++++++++++++++++++++-
> --
> > -
> >  1 file changed, 182 insertions(+), 24 deletions(-)
> >
> > diff --git a/EmulatorPkg/Win/Host/WinHost.c
> > b/EmulatorPkg/Win/Host/WinHost.c index 193a947fbd..e414da6c55 100644
> > --- a/EmulatorPkg/Win/Host/WinHost.c
> > +++ b/EmulatorPkg/Win/Host/WinHost.c
> > @@ -8,7 +8,7 @@
> >    This code produces 128 K of temporary memory for the SEC stack by
> > directly
> >    allocate memory space with ReadWrite and Execute attribute.
> >
> > -Copyright (c) 2006 - 2022, Intel Corporation. All rights
> > reserved.<BR>
> > +Copyright (c) 2006 - 2023, Intel Corporation. All rights
> > reserved.<BR>
> >  (C) Copyright 2016-2020 Hewlett Packard Enterprise Development
> LP<BR>
> >  SPDX-License-Identifier: BSD-2-Clause-Patent  **/ @@ -977,7 +977,7
> @@
> > AddModHandle (
> >    for (Index = 0; Index < mPdbNameModHandleArraySize; Index++,
> > Array++) {
> >      if (Array->PdbPointer == NULL) {
> >        //
> > -      // Make a copy of the stirng and store the ModHandle
> > +      // Make a copy of the string and store the ModHandle
> >        //
> >        Handle            = GetProcessHeap ();
> >        Size              = AsciiStrLen (ImageContext->PdbPointer) +
> 1;
> > @@ -1056,26 +1056,45 @@ RemoveModHandle (
> >    return NULL;
> >  }
> >
> > +typedef struct {
> > +  UINTN   Base;
> > +  UINT32  Size;
> > +  UINT32  Flags;
> > +} IMAGE_SECTION_DATA;
> > +
> >  VOID
> >  EFIAPI
> >  PeCoffLoaderRelocateImageExtraAction (
> >    IN OUT PE_COFF_LOADER_IMAGE_CONTEXT  *ImageContext
> >    )
> >  {
> > -  EFI_STATUS  Status;
> > -  VOID        *DllEntryPoint;
> > -  CHAR16      *DllFileName;
> > -  HMODULE     Library;
> > -  UINTN       Index;
> > +  EFI_STATUS                          Status;
> > +  VOID                                *DllEntryPoint;
> > +  CHAR16                              *DllFileName;
> > +  HMODULE                             Library;
> > +  UINTN                               Index;
> > +  PE_COFF_LOADER_IMAGE_CONTEXT        PeCoffImageContext;
> > +  EFI_IMAGE_OPTIONAL_HEADER_PTR_UNION Hdr;
> > +  EFI_IMAGE_SECTION_HEADER            *FirstSection;
> > +  EFI_IMAGE_SECTION_HEADER            *Section;
> > +  IMAGE_SECTION_DATA                  *SectionData;
> > +  UINTN                               NumberOfSections;
> > +  UINTN                               Base;
> > +  UINTN                               End;
> > +  UINTN                               RegionBase;
> > +  UINTN                               RegionSize;
> > +  UINT32                              Flags;
> > +  DWORD                               NewProtection;
> > +  DWORD                               OldProtection;
> >
> >    ASSERT (ImageContext != NULL);
> >    //
> > -  // If we load our own PE COFF images the Windows debugger can not
> > source
> > -  //  level debug our code. If a valid PDB pointer exists use it to
> > load
> > -  //  the *.dll file as a library using Windows* APIs. This allows
> > -  //  source level debug. The image is still loaded and relocated
> > -  //  in the Framework memory space like on a real system (by the
> > code above),
> > -  //  but the entry point points into the DLL loaded by the code
> > below.
> > +  // If we load our own PE/COFF images the Windows debugger can not
> > source
> > +  // level debug our code. If a valid PDB pointer exists use it to
> > load
> > +  // the *.dll file as a library using Windows* APIs. This allows
> //
> > + source level debug. The image is still loaded and relocated  // in
> > + the Framework memory space like on a real system (by the code
> > above),
> > +  // but the entry point points into the DLL loaded by the code
> > below.
> >    //
> >
> >    DllEntryPoint = NULL;
> > @@ -1106,27 +1125,166 @@ PeCoffLoaderRelocateImageExtraAction (
> >      }
> >
> >      //
> > -    // Replace .PDB with .DLL on the filename
> > +    // Replace .PDB with .DLL in the filename
> >      //
> >      DllFileName[Index - 3] = 'D';
> >      DllFileName[Index - 2] = 'L';
> >      DllFileName[Index - 1] = 'L';
> >
> >      //
> > -    // Load the .DLL file into the user process's address space for
> > source
> > -    // level debug
> > +    // Load the .DLL file into the process's address space for
> source
> > level
> > +    // debug.
> > +    //
> > +    // EFI modules use the PE32 entry point for a different purpose
> > than
> > +    // Windows. For Windows DLLs, the PE entry point is used for
> the
> > DllMain()
> > +    // function. DllMain() has a very specific purpose; it
> > initializes runtime
> > +    // libraries, instance data, and thread local storage.
> > LoadLibrary()/
> > +    // LoadLibraryEx() will run the PE32 entry point and assume it
> to
> > be a
> > +    // DllMain() implementation by default. By passing the
> > +    // DONT_RESOLVE_DLL_REFERENCES argument to LoadLibraryEx(), the
> > execution
> > +    // of the entry point as a DllMain() function will be
> suppressed.
> > This
> > +    // also prevents other modules that are referenced by the DLL
> > from being
> > +    // loaded. We use LoadLibraryEx() to create a copy of the PE32
> > +    // image that the OS (and therefore the debugger) is aware of.
> > +    // Source level debugging is the only reason to do this.
> >      //
> >      Library = LoadLibraryEx (DllFileName, NULL,
> > DONT_RESOLVE_DLL_REFERENCES);
> >      if (Library != NULL) {
> >        //
> > -      // InitializeDriver is the entry point we put in all our EFI
> > DLL's. The
> > -      // DONT_RESOLVE_DLL_REFERENCES argument to LoadLIbraryEx()
> > suppresses the
> > -      // normal DLL entry point of DllMain, and prevents other
> > modules that are
> > -      // referenced in side the DllFileName from being loaded.
> There
> > is no error
> > -      // checking as the we can point to the PE32 image loaded by
> > Tiano. This
> > -      // step is only needed for source level debugging
> > +      // Parse the PE32 image loaded by the OS and find the entry
> > point
> >        //
> > -      DllEntryPoint = (VOID *)(UINTN)GetProcAddress (Library,
> > "InitializeDriver");
> > +      ZeroMem (&PeCoffImageContext, sizeof (PeCoffImageContext));
> > +      PeCoffImageContext.Handle = Library;
> > +      PeCoffImageContext.ImageRead =
> PeCoffLoaderImageReadFromMemory;
> > +      Status = PeCoffLoaderGetImageInfo (&PeCoffImageContext);
> > +      if (EFI_ERROR (Status) || (PeCoffImageContext.ImageError !=
> > IMAGE_ERROR_SUCCESS)) {
> > +        SecPrint ("DLL is not a valid PE/COFF image.\n\r");
> > +        FreeLibrary (Library);
> > +        Library = NULL;
> > +      } else {
> > +        Hdr.Pe32 = (EFI_IMAGE_NT_HEADERS32 *)((UINTN)Library +
> > (UINTN)PeCoffImageContext.PeCoffHeaderOffset);
> > +        if (Hdr.Pe32->OptionalHeader.Magic ==
> > EFI_IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
> > +          //
> > +          // Use PE32 offset
> > +          //
> > +          DllEntryPoint = (VOID *) ((UINTN)Library +
> (UINTN)Hdr.Pe32-
> > >OptionalHeader.AddressOfEntryPoint);
> > +        } else {
> > +          //
> > +          // Use PE32+ offset
> > +          //
> > +          DllEntryPoint = (VOID *) ((UINTN)Library +
> > (UINTN)Hdr.Pe32Plus->OptionalHeader.AddressOfEntryPoint);
> > +        }
> > +        //
> > +        // Now we need to configure memory access for the copy of
> the
> > PE32 image
> > +        // loaded by the OS.
> > +        //
> > +        // Most Windows DLLs are linked with sections 4KB aligned
> but
> > EFI
> > +        // modules are not to reduce size. Because of this we need
> to
> > compute
> > +        // the union of memory access attributes and explicitly
> > configure
> > +        // each page.
> > +        //
> > +        FirstSection = (EFI_IMAGE_SECTION_HEADER *)(
> > +                                            (UINTN)Library +
> > +
> > PeCoffImageContext.PeCoffHeaderOffset +
> > +                                            sizeof (UINT32) +
> > +                                            sizeof
> > (EFI_IMAGE_FILE_HEADER) +
> > +                                            Hdr.Pe32-
> > >FileHeader.SizeOfOptionalHeader
> > +                                            );
> > +        NumberOfSections = (UINTN)(Hdr.Pe32-
> > >FileHeader.NumberOfSections);
> > +        Section = FirstSection;
> > +        SectionData = malloc (NumberOfSections * sizeof
> > (IMAGE_SECTION_DATA));
> > +        if (SectionData == NULL) {
> > +          FreeLibrary (Library);
> > +          Library = NULL;
> > +          DllEntryPoint = NULL;
> > +        }
> > +        ZeroMem (SectionData, NumberOfSections * sizeof
> > (IMAGE_SECTION_DATA));
> > +        //
> > +        // Extract the section data from the PE32 image
> > +        //
> > +        for (Index = 0; Index < NumberOfSections; Index++) {
> > +          SectionData[Index].Base = (UINTN)Library + Section-
> > >VirtualAddress;
> > +          SectionData[Index].Size = Section->Misc.VirtualSize;
> > +          if (SectionData[Index].Size == 0) {
> > +            SectionData[Index].Size = Section->SizeOfRawData;
> > +          }
> > +          SectionData[Index].Flags = (Section->Characteristics &
> > +                                      (EFI_IMAGE_SCN_MEM_EXECUTE |
> > EFI_IMAGE_SCN_MEM_WRITE));
> > +          Section += 1;
> > +        }
> > +        //
> > +        // Loop over every DWORD in memory and compute the union of
> > the memory
> > +        // access bits.
> > +        //
> > +        End = (UINTN)Library + (UINTN)PeCoffImageContext.ImageSize;
> > +        RegionBase = (UINTN)Library;
> > +        RegionSize = 0;
> > +        Flags = 0;
> > +        for (Base = (UINTN)Library + sizeof (UINT32); Base < End;
> > Base += sizeof (UINT32)) {
> > +          for (Index = 0; Index < NumberOfSections; Index++) {
> > +            if (SectionData[Index].Base <= Base &&
> > +                (SectionData[Index].Base + SectionData[Index].Size)
> >
> > Base) {
> > +              Flags |= SectionData[Index].Flags;
> > +            }
> > +          }
> > +          //
> > +          // When a new page is reached configure the memory access
> > for the
> > +          // previous page.
> > +          //
> > +          if (Base % SIZE_4KB == 0) {
> > +            RegionSize += SIZE_4KB;
> > +            if ((Flags & EFI_IMAGE_SCN_MEM_WRITE) ==
> > EFI_IMAGE_SCN_MEM_WRITE) {
> > +              if ((Flags & EFI_IMAGE_SCN_MEM_EXECUTE) ==
> > EFI_IMAGE_SCN_MEM_EXECUTE) {
> > +                NewProtection = PAGE_EXECUTE_READWRITE;
> > +              } else {
> > +                NewProtection = PAGE_READWRITE;
> > +              }
> > +            } else {
> > +              if ((Flags & EFI_IMAGE_SCN_MEM_EXECUTE) ==
> > EFI_IMAGE_SCN_MEM_EXECUTE) {
> > +                NewProtection = PAGE_EXECUTE_READ;
> > +              } else {
> > +                NewProtection = PAGE_READONLY;
> > +              }
> > +            }
> > +            if (!VirtualProtect ((LPVOID)RegionBase, (SIZE_T)
> > RegionSize, NewProtection, &OldProtection)) {
> > +              SecPrint ("Setting PE32 Section Access Failed\n\r");
> > +              FreeLibrary (Library);
> > +              free (SectionData);
> > +              Library = NULL;
> > +              DllEntryPoint = NULL;
> > +              break;
> > +            }
> > +            Flags = 0;
> > +            RegionBase = Base;
> > +            RegionSize = 0;
> > +          }
> > +        }
> > +        free (SectionData);
> > +        //
> > +        // Configure the last partial page
> > +        //
> > +        if (Library != NULL && (End - RegionBase) > 0) {
> > +          if ((Flags & EFI_IMAGE_SCN_MEM_WRITE) ==
> > EFI_IMAGE_SCN_MEM_WRITE) {
> > +            if ((Flags & EFI_IMAGE_SCN_MEM_EXECUTE) ==
> > EFI_IMAGE_SCN_MEM_EXECUTE) {
> > +              NewProtection = PAGE_EXECUTE_READWRITE;
> > +            } else {
> > +              NewProtection = PAGE_READWRITE;
> > +            }
> > +          } else {
> > +            if ((Flags & EFI_IMAGE_SCN_MEM_EXECUTE) ==
> > EFI_IMAGE_SCN_MEM_EXECUTE) {
> > +              NewProtection = PAGE_EXECUTE_READ;
> > +            } else {
> > +              NewProtection = PAGE_READONLY;
> > +            }
> > +          }
> > +          if (!VirtualProtect ((LPVOID)RegionBase, (SIZE_T) (End -
> > RegionBase), NewProtection, &OldProtection)) {
> > +            SecPrint ("Setting PE32 Section Access Failed\n\r");
> > +            FreeLibrary (Library);
> > +            Library = NULL;
> > +            DllEntryPoint = NULL;
> > +          }
> > +        }
> > +      }
> >      }
> >
> >      if ((Library != NULL) && (DllEntryPoint != NULL)) { @@ -1142,7
> > +1300,7 @@ PeCoffLoaderRelocateImageExtraAction (
> >          // This DLL is not already loaded, so source level
> debugging
> > is supported.
> >          //
> >          ImageContext->EntryPoint =
> > (EFI_PHYSICAL_ADDRESS)(UINTN)DllEntryPoint;
> > -        SecPrint ("LoadLibraryEx (\n\r  %S,\n\r  NULL,
> > DONT_RESOLVE_DLL_REFERENCES)\n\r", DllFileName);
> > +        SecPrint ("LoadLibraryEx (\n\r  %S,\n\r  NULL,
> > DONT_RESOLVE_DLL_REFERENCES) @ 0x%X\n\r", DllFileName, (int) (UINTN)
> > Library);
> >        }
> >      } else {
> >        SecPrint ("WARNING: No source level debug %S. \n\r",
> > DllFileName);
> > --
> > 2.39.2.windows.1



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