Re: [RFC 1/1] UefiCpuPkg/CpuExceptionHandlerLib/X64: Add stack trace support

[Andrew Fish <afish@apple.com>]

Paulo,

Cool feature. How does this code deal with VC++ that code does not store the frame pointer and requires symbols to unwind. 

Also on the page fault you can print the fault address since it is in CR2. 

It should be possible to post process the text file and make a symbolicated backtrace. 

Thanks,

Andrew Fish

> On Nov 14, 2017, at 4:47 AM, Paulo Alcantara <pcacjr@zytor.com> wrote:
> 
> This patch adds stack trace support during a X64 CPU exception.
> 
> It will dump out back trace, stack contents as well as image module
> names that were part of the call stack.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Cc: Eric Dong <eric.dong@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: Paulo Alcantara <pcacjr@zytor.com>
> ---
> UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c | 344 +++++++++++++++++++-
> 1 file changed, 342 insertions(+), 2 deletions(-)
> 
> diff --git a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> index 65f0cff680..7048247be3 100644
> --- a/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> +++ b/UefiCpuPkg/Library/CpuExceptionHandlerLib/X64/ArchExceptionHandler.c
> @@ -14,6 +14,11 @@
> 
> #include "CpuExceptionCommon.h"
> 
> +//
> +// Unknown PDB file name
> +//
> +GLOBAL_REMOVE_IF_UNREFERENCED CONST CHAR8 *mUnknownPdbFileName = "????";
> +
> /**
>   Return address map of exception handler template so that C code can generate
>   exception tables.
> @@ -243,6 +248,325 @@ DumpCpuContext (
> }
> 
> /**
> +  Dump stack contents.
> +
> +  @param[in]  ImageBase            Base address of PE/COFF image.
> +  @param[out] PdbAbsoluteFilePath  Absolute path of PDB file.
> +  @param[out] PdbFileName          File name of PDB file.
> +**/
> +STATIC
> +VOID
> +GetPdbFileName (
> +  IN  UINTN    ImageBase,
> +  OUT CHAR8    **PdbAbsoluteFilePath,
> +  OUT CHAR8    **PdbFileName
> +  )
> +{
> +  VOID   *PdbPointer;
> +  CHAR8  *Str;
> +
> +  //
> +  // Get PDB file name from PE/COFF image
> +  //
> +  PdbPointer = PeCoffLoaderGetPdbPointer ((VOID *)ImageBase);
> +  if (PdbPointer == NULL) {
> +    //
> +    // No PDB file name found. Set it to an unknown file name.
> +    //
> +    *PdbFileName = (CHAR8 *)mUnknownPdbFileName;
> +    if (PdbAbsoluteFilePath != NULL) {
> +      *PdbAbsoluteFilePath = NULL;
> +    }
> +  } else {
> +    //
> +    // Get file name portion out of PDB file in PE/COFF image
> +    //
> +    Str = (CHAR8 *)((UINTN)PdbPointer +
> +                    AsciiStrLen ((CHAR8 *)PdbPointer) - sizeof *Str);
> +    for (; *Str != '/' && *Str != '\\'; Str--) {
> +      ;
> +    }
> +
> +    //
> +    // Set PDB file name (also skip trailing path separator: '/' or '\\')
> +    //
> +    *PdbFileName = Str + 1;
> +
> +    if (PdbAbsoluteFilePath != NULL) {
> +      //
> +      // Set absolute file path of PDB file
> +      //
> +      *PdbAbsoluteFilePath = PdbPointer;
> +    }
> +  }
> +}
> +
> +/**
> +  Dump stack contents.
> +
> +  @param[in]  CurrentRsp         Current stack pointer address.
> +  @param[in]  UnwondStacksCount  Count of unwond stack frames.
> +**/
> +STATIC
> +VOID
> +DumpStackContents (
> +  IN UINT64  CurrentRsp,
> +  IN INTN    UnwondStacksCount
> +  )
> +{
> +  if (UnwondStacksCount == 0) {
> +    return;
> +  }
> +
> +  //
> +  // Dump out stack contents
> +  //
> +  InternalPrintMessage ("\nStack dump:\n");
> +  while (UnwondStacksCount-- > 0) {
> +    InternalPrintMessage (
> +      "0x%016lx: %016lx %016lx\n",
> +      CurrentRsp,
> +      *(UINT64 *)CurrentRsp,
> +      *(UINT64 *)((UINTN)CurrentRsp + 8)
> +      );
> +
> +    //
> +    // As per Microsoft x64 ABI, the stack pointer must be aligned on a 16 byte
> +    // boundary.
> +    //
> +    CurrentRsp = CurrentRsp + 16;
> +  }
> +}
> +
> +/**
> +  Dump all image module names from call stack.
> +
> +  @param[in]  SystemContext  Pointer to EFI_SYSTEM_CONTEXT.
> +**/
> +STATIC
> +VOID
> +DumpImageModuleNames (
> +  IN EFI_SYSTEM_CONTEXT   SystemContext
> +  )
> +{
> +  EFI_STATUS  Status;
> +  UINT64      Rip;
> +  UINTN       ImageBase;
> +  VOID        *EntryPoint;
> +  CHAR8       *PdbAbsoluteFilePath;
> +  CHAR8       *PdbFileName;
> +  UINT64      Rbp;
> +
> +  //
> +  // Set current RIP address
> +  //
> +  Rip = SystemContext.SystemContextX64->Rip;
> +
> +  //
> +  // Set current frame pointer address
> +  //
> +  Rbp = SystemContext.SystemContextX64->Rbp;
> +
> +  //
> +  // Get initial PE/COFF image base address from current RIP
> +  //
> +  ImageBase = PeCoffSearchImageBase (Rip);
> +  if (ImageBase == 0) {
> +    InternalPrintMessage ("!!!! Could not find image module names. !!!!");
> +    return;
> +  }
> +
> +  //
> +  // Get initial PE/COFF image's entry point
> +  //
> +  Status = PeCoffLoaderGetEntryPoint ((VOID *)ImageBase, &EntryPoint);
> +  if (EFI_ERROR (Status)) {
> +    EntryPoint = NULL;
> +  }
> +
> +  //
> +  // Get file name and absolute path of initial PDB file
> +  //
> +  GetPdbFileName (ImageBase, &PdbAbsoluteFilePath, &PdbFileName);
> +
> +  //
> +  // Print out initial image module name (if any)
> +  //
> +  if (PdbAbsoluteFilePath != NULL) {
> +    InternalPrintMessage (
> +      "\n%a (ImageBase=0x%016lx, EntryPoint=0x%016lx):\n",
> +      PdbFileName,
> +      ImageBase,
> +      (UINTN)EntryPoint
> +      );
> +    InternalPrintMessage ("%a\n", PdbAbsoluteFilePath);
> +  }
> +
> +  //
> +  // Walk through call stack and find next module names
> +  //
> +  for (;;) {
> +    //
> +    // Set RIP with return address from current stack frame
> +    //
> +    Rip = *(UINT64 *)((UINTN)Rbp + 8);
> +
> +    //
> +    // Check if RIP is within another PE/COFF image base address
> +    //
> +    if (Rip < ImageBase) {
> +      //
> +      // Search for the respective PE/COFF image based on RIP
> +      //
> +      ImageBase = PeCoffSearchImageBase (Rip);
> +      if (ImageBase == 0) {
> +        //
> +        // Stop stack trace
> +        //
> +        break;
> +      }
> +
> +      //
> +      // Get PE/COFF image's entry point
> +      //
> +      Status = PeCoffLoaderGetEntryPoint ((VOID *)ImageBase, &EntryPoint);
> +      if (EFI_ERROR (Status)) {
> +        EntryPoint = NULL;
> +      }
> +
> +      //
> +      // Get file name and absolute path of PDB file
> +      //
> +      GetPdbFileName (ImageBase, &PdbAbsoluteFilePath, &PdbFileName);
> +
> +      //
> +      // Print out image module name (if any)
> +      //
> +      if (PdbAbsoluteFilePath != NULL) {
> +        InternalPrintMessage (
> +          "%a (ImageBase=0x%016lx, EntryPoint=0x%016lx):\n",
> +          PdbFileName,
> +          ImageBase,
> +          (UINTN)EntryPoint
> +          );
> +        InternalPrintMessage ("%a\n", PdbAbsoluteFilePath);
> +      }
> +    }
> +
> +    //
> +    // Unwind the stack
> +    //
> +    Rbp = *(UINT64 *)(UINTN)Rbp;
> +  }
> +}
> +
> +/**
> +  Dump stack trace.
> +
> +  @param[in]  SystemContext      Pointer to EFI_SYSTEM_CONTEXT.
> +  @param[out] UnwondStacksCount  Count of unwond stack frames.
> +**/
> +STATIC
> +VOID
> +DumpStackTrace (
> +  IN  EFI_SYSTEM_CONTEXT   SystemContext,
> +  OUT INTN                 *UnwondStacksCount
> +  )
> +{
> +  UINT64  Rip;
> +  UINT64  Rbp;
> +  UINTN   ImageBase;
> +  CHAR8   *PdbFileName;
> +
> +  //
> +  // Initialize count of unwond stacks
> +  //
> +  *UnwondStacksCount = 0;
> +
> +  //
> +  // Set current RIP address
> +  //
> +  Rip = SystemContext.SystemContextX64->Rip;
> +
> +  //
> +  // Set current frame pointer address
> +  //
> +  Rbp = SystemContext.SystemContextX64->Rbp;
> +
> +  //
> +  // Get initial PE/COFF image base address from current RIP
> +  //
> +  ImageBase = PeCoffSearchImageBase (Rip);
> +  if (ImageBase == 0) {
> +    InternalPrintMessage ("!!!! Could not find backtrace information. !!!!");
> +    return;
> +  }
> +
> +  //
> +  // Get PDB file name from initial PE/COFF image
> +  //
> +  GetPdbFileName (ImageBase, NULL, &PdbFileName);
> +
> +  //
> +  // Print out back trace
> +  //
> +  InternalPrintMessage ("\nBack trace:\n");
> +
> +  for (;;) {
> +    //
> +    // Print stack frame in the following format:
> +    //
> +    // # <RIP> @ <ImageBase>+<RelOffset> (RBP) in [<ModuleName> | ????]
> +    //
> +    InternalPrintMessage (
> +      "%d 0x%016lx @ 0x%016lx+0x%x (0x%016lx) in %a\n",
> +      *UnwondStacksCount,
> +      Rip,
> +      ImageBase,
> +      Rip - ImageBase - 1,
> +      Rbp,
> +      PdbFileName
> +      );
> +
> +    //
> +    // Set RIP with return address from current stack frame
> +    //
> +    Rip = *(UINT64 *)((UINTN)Rbp + 8);
> +
> +    //
> +    // Check if RIP is within another PE/COFF image base address
> +    //
> +    if (Rip < ImageBase) {
> +      //
> +      // Search for the respective PE/COFF image based on RIP
> +      //
> +      ImageBase = PeCoffSearchImageBase (Rip);
> +      if (ImageBase == 0) {
> +        //
> +        // Stop stack trace
> +        //
> +        break;
> +      }
> +
> +      //
> +      // Get PDB file name
> +      //
> +      GetPdbFileName (ImageBase, NULL, &PdbFileName);
> +    }
> +
> +    //
> +    // Unwind the stack
> +    //
> +    Rbp = *(UINT64 *)(UINTN)Rbp;
> +
> +    //
> +    // Increment count of unwond stacks
> +    //
> +    (*UnwondStacksCount)++;
> +  }
> +}
> +
> +/**
>   Display CPU information.
> 
>   @param ExceptionType  Exception type.
> @@ -254,9 +578,25 @@ DumpImageAndCpuContent (
>   IN EFI_SYSTEM_CONTEXT   SystemContext
>   )
> {
> +  INTN UnwondStacksCount;
> +
> +  //
> +  // Dump CPU context
> +  //
>   DumpCpuContext (ExceptionType, SystemContext);
> +
> +  //
> +  // Dump stack trace
> +  //
> +  DumpStackTrace (SystemContext, &UnwondStacksCount);
> +
> +  //
> +  // Dump image module names
> +  //
> +  DumpImageModuleNames (SystemContext);
> +
>   //
> -  // Dump module image base and module entry point by RIP
> +  // Dump stack contents
>   //
> -  DumpModuleImageInfo (SystemContext.SystemContextX64->Rip);
> +  DumpStackContents (SystemContext.SystemContextX64->Rsp, UnwondStacksCount);
> }
> -- 
> 2.11.0
> 
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