Re: [kvm-unit-tests PATCH v3 0/6] arm64: improve debuggability

Andrew Jones
2023-07-01T12:20:05Z

On Wed, Jun 28, 2023 at 12:13:49AM +0000, Nadav Amit wrote:
> From: Nadav Amit <namit@vmware.com>
>
> My recent experience in debugging ARM64 tests on EFI was not as fun as I
> expected it to be.
>
> There were several reasons for that besides the questionable definition
> of "fun":
>
> 1. ARM64 is not compiled with frame pointers and there is no stack
> unwinder when the stack is dumped.
>
> 2. Building an EFI drops the debug information.
>
> 3. The addresses that are printed on dump_stack() and the use of GDB
> are hard because taking code relocation into account is non trivial.
>
> The patches help both ARM64 and EFI for this matter. The image address
> is printed when EFI is used to allow the use of GDB. Symbols are emitted
> into a separate debug file. The frame pointer is included and special
> entry is added upon an exception to allow backtracing across
> exceptions.
>
> [ PowerPC: Please ack patches 1,2 ]
> [ x86: Please ack patches 1,2,5 ]
>
> v2->v3:
> * Consider PowerPC for reloc and related fixes [Andrew]
>
> v1->v2:
> * Andrew comments [see in individual patches]
> * Few cleanups
>
> Nadav Amit (6):
> efi: keep efi debug information in a separate file
> lib/stack: print base addresses on relocation setups
> arm64: enable frame pointer and support stack unwinding
> arm64: stack: update trace stack on exception
> efi: print address of image
> arm64: dump stack on bad exception
>
> .gitignore | 1 +
> Makefile | 2 +-
> arm/Makefile.arm | 3 --
> arm/Makefile.arm64 | 2 ++
> arm/Makefile.common | 8 +++++-
> arm/cstart64.S | 13 +++++++++
> lib/arm64/asm-offsets.c | 6 +++-
> lib/arm64/asm/stack.h | 3 ++
> lib/arm64/processor.c | 1 +
> lib/arm64/stack.c | 62 +++++++++++++++++++++++++++++++++++++++++
> lib/efi.c | 4 +++
> lib/stack.c | 31 +++++++++++++++++++--
> powerpc/Makefile.common | 1 +
> x86/Makefile.common | 5 +++-
> 14 files changed, 133 insertions(+), 9 deletions(-)
> create mode 100644 lib/arm64/stack.c
>
> --
> 2.34.1
>

Merged. arm64 backtraces will be really nice to have!

Thanks, Nadav!

drew