RE:[PATCH v4 00/13] Add new command to print the shadow stack backtrace

["Joos, Christina" <christina.joos@intel.com>]

Hi all,

I wanted to give you a heads-up that I will be out for at least half a year for personal reasons starting around late October.
Maybe there is still a chance to get the series in before I leave.

Kind Regards,
Christina

> -----Original Message-----
> From: Christina Schimpe <christina.schimpe@intel.com>
> Sent: Mittwoch, 8. Juli 2026 16:36
> To: gdb-patches@sourceware.org
> Cc: tom@tromey.com; thiago.bauermann@linaro.org
> Subject: [PATCH v4 00/13] Add new command to print the shadow stack
> backtrace
> 
> Hi all,
> 
> this is my v4 of the series
> "Add new command to print the shadow stack backtrace".
> 
> ***Diff of v4 to v3***:
> 
> - Minor fixup for ARM compilation
> - The commit
>   "gdb: Provide gdbarch hook to distinguish shadow stack backtrace elements."
>   was accidentially merged into the previous one
>   ("gdb: Add command option 'bt -shadow' to print the shadow stack
> backtrace.").
>   Isolate it again.
> 
> Other than that, I am keeping the full cover letter summarizing the changes for v3
> (diff of v3 to v2). It has not been reviewed yet, since I posted it just a couple days
> ago.
> 
> ***Diff of v3 to v2***:
> 
> It now includes:
> - the implementation of the -past-main command line option
> - support for inferior calls
> (printing of <function called from gdb> instead of the shadow stack element)
> - full support for signals
> (printing of <signal handler called> instead of the shadow stack element)
> 
> Due to this some larger refactoring was required; I summarized it here:
> https://sourceware.org/pipermail/gdb-patches/2026-May/227481.html
> 
> The refactoring mostly affected the following commits:
> "gdb: Provide gdbarch hook to distinguish shadow stack backtrace elements."
> "gdb: Add command option 'bt -shadow' to print the shadow stack backtrace."
> "gdb: Implement the hook 'is_no_return_shadow_stack_address' for amd64
> linux."
> I did not add any Reviewed-By or Approved-By tags for the 3 commits, since they
> changed significantly.
> 
> Furthermore, I addressed (hopefully all) the comments of Tom, Thiago and Eli:
> - Remove annotations
> - Some better code reuse (especially for the mi patch)
> - A new patch "aarch64: Implement gdbarch function
> top_addr_empty_shadow_stack."
>   This also allows to remove some target dependent GCS code in aarch64-*.c
> - Various smaller issues and nits
> - Fixes for check-gdbarch.py
> 
> And finally some smaller issues I noted myself (mostly for patch #1
> "gdb: Generalize handling of the shadow stack pointer."):
> - Remove unused gdbarch parameter in some of the introduced hooks
> - Changes in gdb/aarch64-tdep.c when calling shadow_stack_push, since some
> code for getting the shadow stack pointer and checking the enablement state was
> duplicated.
> 
> Opens:
> 1) Thiago suggested changing the frame numbering so that it always starts at #1,
> since for the shadow stack we don't have frame #0 printed by the normal
> backtrace.
> 2) Or, consider printing frame #0 similarly to what the normal backtrace does
> 3) Consider printing frame arguments (but I believe, if possible, this should better
> be added in a follow-up series)
> 4) Show the selected frame, for details see here:
> https://sourceware.org/pipermail/gdb-patches/2026-June/227720.html
> 
> This is an example for the output of 'bt -shadow' on amd64 linux:
> ~~~
> (gdb) bt -shadow
> #0  0x000055555555514a in call1 at amd64-shadow-stack.c:27
> #1  0x000055555555515f in main at amd64-shadow-stack.c:38 ~~~
> 
> Note that the normal backtrace includes one additional frame, since the shadow
> stack backtrace relies on return addresses of the shadow stack only.  But except
> the missing frame arguments and frame #0 of the normal backtrace, the
> backtrace is the same.
> ~~~
> (gdb) bt
> #0  call2 () at amd64-shadow-stack.c:21
> #1  0x000055555555514a in call1 () at amd64-shadow-stack.c:27
> #2  0x000055555555515f in main () at amd64-shadow-stack.c:38 ~~~
> 
> I am happy about your feedback!
> 
> Christina
> 
> v3: https://sourceware.org/pipermail/gdb-patches/2026-July/228440.html
> v2: https://sourceware.org/pipermail/gdb-patches/2026-January/224388.html
> v1: https://sourceware.org/pipermail/gdb-patches/2025-
> September/221141.html
> 
> Christina Schimpe (13):
>   gdb: Generalize handling of the shadow stack pointer.
>   aarch64: Implement gdbarch function top_addr_empty_shadow_stack.
>   gdb: Add get_main_func_start_pc to refactor frame.c:inside_main_func.
>   gdb: Refactor 'stack.c:print_frame'.
>   gdb: Introduce 'stack.c:print_pc' function without frame argument.
>   gdb: Refactor 'find_symbol_funname' and 'info_frame_command_core' in
>     stack.c.
>   gdb: Refactor 'stack.c:print_frame_info'.
>   gdb: Add command option 'bt -shadow' to print the shadow stack
>     backtrace.
>   gdb: Provide gdbarch hook to distinguish shadow stack backtrace
>     elements.
>   gdb: Implement the hook 'is_no_return_shadow_stack_address' for amd64
>     linux.
>   gdb: Enable inferior calls in the shadow stack backtrace.
>   gdb: Enable signal trampolines in the shadow stack backtrace.
>   gdb, mi: Add -shadow-stack-list-frames command
> 
>  gdb/Makefile.in                               |   2 +
>  gdb/NEWS                                      |  11 +
>  gdb/aarch64-linux-tdep.c                      |  51 +-
>  gdb/aarch64-tdep.c                            |  66 +-
>  gdb/amd64-linux-tdep.c                        | 211 ++---
>  gdb/amd64-tdep.c                              |  22 +
>  gdb/doc/gdb.texinfo                           |  95 +++
>  gdb/frame.c                                   |  37 +-
>  gdb/frame.h                                   |   6 +
>  gdb/gdbarch-gen.c                             | 190 ++++-
>  gdb/gdbarch-gen.h                             |  95 ++-
>  gdb/gdbarch.h                                 |   1 +
>  gdb/gdbarch_components.py                     | 124 ++-
>  gdb/infcall.c                                 |   4 +-
>  gdb/linux-tdep.c                              |   9 +-
>  gdb/mi/mi-cmd-stack.c                         | 100 +++
>  gdb/mi/mi-cmds.c                              |   2 +
>  gdb/mi/mi-cmds.h                              |   1 +
>  gdb/shadow-stack.c                            | 769 ++++++++++++++++++
>  gdb/shadow-stack.h                            | 182 +++++
>  gdb/stack.c                                   | 319 +++++---
>  gdb/stack.h                                   |  43 +
>  .../amd64-shadow-stack-backtrace-signal.exp   |  49 ++
>  .../gdb.arch/amd64-shadow-stack-cmds.exp      |  71 ++
>  .../gdb.arch/amd64-shadow-stack-signal.c      |  31 +
>  gdb/testsuite/gdb.base/options.exp            |   2 +-
>  .../gdb.mi/mi-shadow-stack-signal.exp         |  69 ++
>  gdb/testsuite/gdb.mi/mi-shadow-stack.exp      |  93 +++
>  28 files changed, 2247 insertions(+), 408 deletions(-)  create mode 100644
> gdb/shadow-stack.c  create mode 100644 gdb/shadow-stack.h  create mode
> 100644 gdb/testsuite/gdb.arch/amd64-shadow-stack-backtrace-signal.exp
>  create mode 100644 gdb/testsuite/gdb.arch/amd64-shadow-stack-signal.c
>  create mode 100644 gdb/testsuite/gdb.mi/mi-shadow-stack-signal.exp
>  create mode 100644 gdb/testsuite/gdb.mi/mi-shadow-stack.exp
> 
> --
> 2.34.1
> 
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