Re: [PATCH 09/12] gdb, gdbarch: Enable inferior calls for shadow stack support.

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

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

> diff --git a/gdb/infcall.c b/gdb/infcall.c
> index 6399278c6ae..3a4f1e35a2f 100644
> --- a/gdb/infcall.c
> +++ b/gdb/infcall.c
> @@ -1453,6 +1453,12 @@ call_function_by_hand_dummy (struct value *function,
>  				bp_addr, args.size (), args.data (),
>  				sp, return_method, struct_addr);
>
> +  /* Push the return address of the inferior (bp_addr) on the shadow stack
> +     and update the shadow stack pointer.  As we don't execute a call
> +     instruction to start the inferior we need to handle this manually.  */
> +  if (gdbarch_shadow_stack_push_p (gdbarch))
> +    gdbarch_shadow_stack_push (gdbarch, bp_addr);
> +

For AArch64's Guarded Control Stack, instead of adding a new gdbarch
method I added this change to aarch64_push_dummy_call:

  if (aarch64_gcs_is_enabled (regcache))
    aarch64_push_gcs_entry (regcache, bp_addr);

To implement aarch64_gcs_is_enabled I did add a new method to
aarch64_gdbarch_tdep so that OS-independent code in aarch64-tdep.c could call
Linux-specific logic in aarch64-linux-tdep.c:

static bool
aarch64_gcs_is_enabled (regcache *regs)
{
  gdbarch *arch = regs->arch ();
  aarch64_gdbarch_tdep *tdep = gdbarch_tdep<aarch64_gdbarch_tdep> (arch);

  if (tdep->gcs_is_enabled == nullptr)
    return false;

  return tdep->gcs_is_enabled (regs);
}

Wouldn't a similar approach work for amd64?

--
Thiago