Re: [PATCH v2 9/9] gdb, mi: Add -shadow-stack-list-frames command

[Tom Tromey <tom@tromey.com>]

>>>>> Christina Schimpe <christina.schimpe@intel.com> writes:

> +void
> +mi_cmd_shadow_stack_list_frames (const char *command,
> +				 const char *const *argv,
> +				 int argc)

> +  /* Check if START_SSP points to a shadow stack memory range and use
> +     the returned range to determine when to stop unwinding.
> +     Note that a shadow stack memory range can change, due to shadow stack
> +     switches for instance on x86 for an inter-privilege far call or when
> +     calling an interrupt/exception handler at a higher privilege level.
> +     Shadow stack for userspace is supported for amd64 linux starting with
> +     Linux kernel v6.6.  However, shadow stack switches are not supported
> +     due to missing kernel space support.  We therefore implement this
> +     command without support for shadow stack switches for now.  */
> +  std::pair<CORE_ADDR, CORE_ADDR> range;
> +  if (!gdbarch_address_in_shadow_stack_memory_range (gdbarch, *start_ssp,
> +						     &range))
> +    {
> +      /* If START_SSP points off the shadow stack memory range, we cannot
> +	 print the shadow stack backtrace.  This is possible, for
> +	 instance, on x86 if NEW_SSP points to the end of RANGE which
> +	 means that the shadow stack is empty.  */
> +      return;
> +    }

It seems like more of this could be shared with the earlier patch.
Replicating a lot of the logic doesn't seem good.

The gdb_printfs in the other code can be handled by changing them to use
ui_out::text or ui_out::message instead.

> +  if (!curr.has_value ())
> +    error (_("-shadow-stack-list-frames: Not enough frames on the shadow "
> +	     "stack."));

For things like this maybe the API has to be changed a little but that
seems fine.

Tom