On 20/01/2023 17:27, Srinath Parvathaneni via Gcc-patches wrote:
Hi,
This patch adds support for Arm frame unwinding instruction "0xb5" [1]. When
an exception is taken and "0xb5" instruction is encounter during runtime
stack-unwinding, we use effective vsp as modifier in pointer authentication.
On completion of stack unwinding if "0xb5" instruction is not encountered
then CFA will be used as modifier in pointer authentication.
[1] https://github.com/ARM-software/abi-aa/releases/download/2022Q3/ehabi32.pdf
Regression tested on arm-none-eabi target and found no regressions.
Ok for master?
Regards,
Srinath.
gcc/ChangeLog:
2022-11-09 Srinath Parvathaneni <srinath.parvathan...@arm.com>
* libgcc/config/arm/pr-support.c (__gnu_unwind_execute): Decode opcode
"0xb5".
############### Attachment also inlined for ease of reply ###############
diff --git a/libgcc/config/arm/pr-support.c b/libgcc/config/arm/pr-support.c
index
e48854587c667a959aa66ccc4982231f63333ecc..1fbc41e17c227c21af1937344ded2a7fd80e61df
100644
--- a/libgcc/config/arm/pr-support.c
+++ b/libgcc/config/arm/pr-support.c
@@ -107,7 +107,9 @@ __gnu_unwind_execute (_Unwind_Context * context,
__gnu_unwind_state * uws)
_uw op;
int set_pc;
int set_pac = 0;
+ int set_pac_sp = 0;
_uw reg;
+ _uw sp;
set_pc = 0;
for (;;)
@@ -124,10 +126,11 @@ __gnu_unwind_execute (_Unwind_Context * context,
__gnu_unwind_state * uws)
#if defined(TARGET_HAVE_PACBTI)
if (set_pac)
{
- _uw sp;
_uw lr;
_uw pac;
- _Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &sp);
+ if (!set_pac_sp)
+ _Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32,
+ &sp);
_Unwind_VRS_Get (context, _UVRSC_CORE, R_LR, _UVRSD_UINT32, &lr);
_Unwind_VRS_Get (context, _UVRSC_PAC, R_IP,
_UVRSD_UINT32, &pac);
@@ -259,6 +262,14 @@ __gnu_unwind_execute (_Unwind_Context * context,
__gnu_unwind_state * uws)
continue;
}
+ /* Use current VSP as modifier in PAC validation. */
+ if (op == 0xb5)
+ {
+ _Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &sp);
+ set_pac_sp = 1;
+ continue;
+ }
+
if ((op & 0xfc) == 0xb4) /* Obsolete FPA. */
return _URC_FAILURE;
OK.
R.