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arm: Add support for new frame unwinding instruction "0xb5".

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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

libgcc/ChangeLog:

2022-11-09  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	* config/arm/pr-support.c (__gnu_unwind_execute): Decode opcode
	"0xb5".
This commit is contained in:
Srinath Parvathaneni 2023-01-23 11:13:18 +00:00
parent 273874e925
commit 55a2d8096a
1 changed files with 13 additions and 2 deletions
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15
libgcc/config/arm/pr-support.c
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@ -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;