When setting up the stack in the startup code and jumping into C code for the first time, ensure that the frame pointer register is cleared so that backtraces terminate correctly. Otherwise, output like the below is shown when encountering an exception on a DEBUG build:
Synchronous Exception at 0x0000000078A14780 PC 0x000078A14780 (0x000078A00000+0x00014780) [ 0] ArmVeNorFlashDxe.dll PC 0x000078A10634 (0x000078A00000+0x00010634) [ 0] ArmVeNorFlashDxe.dll PC 0x000078A11CF0 (0x000078A00000+0x00011CF0) [ 0] ArmVeNorFlashDxe.dll PC 0x000078A11DD0 (0x000078A00000+0x00011DD0) [ 0] ArmVeNorFlashDxe.dll PC 0x00007BC9D87C (0x00007BC98000+0x0000587C) [ 1] PartitionDxe.dll PC 0x00007BC99B3C (0x00007BC98000+0x00001B3C) [ 1] PartitionDxe.dll PC 0x00007F362F50 (0x00007F359000+0x00009F50) [ 2] DxeCore.dll PC 0x00007BD63BB0 (0x00007BD5B000+0x00008BB0) [ 3] BdsDxe.dll PC 0x00007BD6EE00 (0x00007BD5B000+0x00013E00) [ 3] BdsDxe.dll PC 0x00007BD67C70 (0x00007BD5B000+0x0000CC70) [ 3] BdsDxe.dll PC 0x00007F3724F0 (0x00007F359000+0x000194F0) [ 4] DxeCore.dll PC 0x00004008FC30 PC 0x000040090130 PC 0x5800F6025800F5E1 Recursive exception occurred while dumping the CPU state which is rather unhelpful, given that this prevent the remaining debug output from being printed (register dump, stack dump, fault related system registers etc) Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <[email protected]> --- ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S | 3 +++ 1 file changed, 3 insertions(+) diff --git a/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S b/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S index 891cf1fcab40..86b9fbee6e67 100644 --- a/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S +++ b/ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S @@ -121,6 +121,9 @@ _GetStackBase: mov x1, x21 mov x2, x22 + // Set the frame pointer to 0x0 so any backtraces terminate here + mov x29, xzr + // Jump to PrePiCore C code // x0 = MpId // x1 = UefiMemoryBase -- 2.17.1 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
