> However, looking at this > code, this is still not sufficient to find the *next* frame pointer on > the stack. are you sure about that? this code looks like it does just that: https://github.com/torvalds/linux/blob/master/arch/arm/kernel/stacktrace.c
On Wed, Sep 7, 2016 at 1:03 PM, Ard Biesheuvel <[email protected]> wrote: > On 7 September 2016 at 10:48, Michael Zimmermann > <[email protected]> wrote: > > nice, can we do this for ARM too? I usually need to add DEBUG((...))'s > all > > over the place for hours until I found the reason for a fault. > > > > This is going to be tricky. Unlike AARCH64, which unambiguously > describes in the AAPCS how to link the stack frames using x29, the > AAPCS for ARM does not standardise this, and so different compilers > may do different things, also depending on whether you are executing > in ARM or Thumb mode. For instance, the following prologue was snipped > from a BdsDxe.dll build using GCC5 in Thumb2 mode. > > 00000254 <_ModuleEntryPoint>: > 254: e96d 7e02 strd r7, lr, [sp, #-8]! > 258: b084 sub sp, #16 > 25a: af00 add r7, sp, #0 > > Googling around, i can indeed find sources that describe how GCC uses > r7 as the frame pointer for Thumb2 code. However, looking at this > code, this is still not sufficient to find the *next* frame pointer on > the stack. IOW, there is no standardised layout to find the next frame > pointer inside the stack frame. > > The only way to do this reliably is using unwind tables, but this is > *much* more complicated than the 20 line patch that enables it for > AArch64 > > Ard. > > > > On Wed, Sep 7, 2016 at 10:21 AM, Ard Biesheuvel < > [email protected]> > > wrote: > >> > >> When dumping the CPU state after an unhandled fault, walk the stack > >> frames and decode the return addresses so we can show a minimal > >> backtrace. Unfortunately, we do not have sufficient information to > >> show the function names, but at least we can see the modules and the > >> return addresses inside the modules. > >> > >> Contributed-under: TianoCore Contribution Agreement 1.0 > >> Signed-off-by: Ard Biesheuvel <[email protected]> > >> --- > >> > >> Example output: > >> > >> Synchronous Exception at 0x00000000F5EA4C8C > >> > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe/DEBUG/ > ArmVeNorFlashDxe.dll > >> loaded at 0x00000000F5E90000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe/DEBUG/ > ArmVeNorFlashDxe.dll > >> (0x00000000F5EA4AE8) loaded at 0x00000000F5E90000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe/DEBUG/ > ArmVeNorFlashDxe.dll > >> (0x00000000F5EA1BFC) loaded at 0x00000000F5E90000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashDxe/DEBUG/ > ArmVeNorFlashDxe.dll > >> (0x00000000F5EA23F4) loaded at 0x00000000F5E90000 > >> called from > >> /work/jenkins/workspace/ap-uefi-bin/EDK2_ARCH/ARM/EDK2_ > BINARY/FatPkg/label/sas-sw/Build/Fat/RELEASE_GCC49/ > AARCH64/FatPkg/EnhancedFatDxe/Fat/DEBUG/Fat.dll > >> (0x00000000FADC454C) loaded at 0x00000000FADC3000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll > >> (0x00000000FE47C868) loaded at 0x00000000FE471000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ > IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll > >> (0x00000000FAE2C50C) loaded at 0x00000000FAE01000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ > IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll > >> (0x00000000FAE2C674) loaded at 0x00000000FAE01000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ > IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll > >> (0x00000000FAE2C264) loaded at 0x00000000FAE01000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ > IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll > >> (0x00000000FAE36998) loaded at 0x00000000FAE01000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_GCC5/AARCH64/ > IntelFrameworkModulePkg/Universal/BdsDxe/BdsDxe/DEBUG/BdsDxe.dll > >> (0x00000000FAE03668) loaded at 0x00000000FAE01000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll > >> (0x00000000FE4733F0) loaded at 0x00000000FE471000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll > >> (0x00000000FE4724A0) loaded at 0x00000000FE471000 > >> called from > >> /home/ard/build/edk2/Build/ArmVExpress-FVP-AArch64/DEBUG_ > GCC5/AARCH64/MdeModulePkg/Core/Dxe/DxeMain/DEBUG/DxeCore.dll > >> (0x00000000FE472024) loaded at 0x00000000FE471000 > >> --- > >> .../AArch64/DefaultExceptionHandler.c | 21 > >> +++++++++++++++++++++ > >> 1 file changed, 21 insertions(+) > >> > >> diff --git > >> a/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/ > DefaultExceptionHandler.c > >> b/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/ > DefaultExceptionHandler.c > >> index 31fc936b21ff..84b442f2b6f4 100644 > >> --- > >> a/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/ > DefaultExceptionHandler.c > >> +++ > >> b/ArmPkg/Library/DefaultExceptionHandlerLib/AArch64/ > DefaultExceptionHandler.c > >> @@ -152,9 +152,30 @@ DefaultExceptionHandler ( > >> CHAR8 *Pdb; > >> UINTN ImageBase; > >> UINTN PeCoffSizeOfHeader; > >> + UINT64 *Fp; > >> + > >> Pdb = GetImageName (SystemContext.SystemContextAArch64->ELR, > >> &ImageBase, &PeCoffSizeOfHeader); > >> if (Pdb != NULL) { > >> DEBUG ((EFI_D_ERROR, "%a loaded at 0x%016lx \n", Pdb, > ImageBase)); > >> + > >> + Pdb = GetImageName (SystemContext.SystemContextAArch64->LR, > >> &ImageBase, > >> + &PeCoffSizeOfHeader); > >> + if (Pdb != NULL) { > >> + DEBUG ((EFI_D_ERROR, "called from %a (0x%016lx) loaded at > >> 0x%016lx \n", > >> + Pdb, SystemContext.SystemContextAArch64->LR, ImageBase)); > >> + } > >> + for (Fp = (UINT64 *)SystemContext.SystemContextAArch64->FP; > >> + *Fp != 0; > >> + Fp = (UINT64 *)Fp[0]) { > >> + if (Fp[1] == SystemContext.SystemContextAArch64->LR) { > >> + continue; > >> + } > >> + Pdb = GetImageName (Fp[1], &ImageBase, &PeCoffSizeOfHeader); > >> + if (Pdb != NULL) { > >> + DEBUG ((EFI_D_ERROR, "called from %a (0x%016lx) loaded at > >> 0x%016lx \n", > >> + Pdb, Fp[1], ImageBase)); > >> + } > >> + } > >> } > >> DEBUG_CODE_END (); > >> > >> -- > >> 2.7.4 > >> > >> _______________________________________________ > >> edk2-devel mailing list > >> [email protected] > >> https://lists.01.org/mailman/listinfo/edk2-devel > > > > > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
