arm-trusted-firmware/lib/extensions/pauth/pauth_helpers.S
Alexei Fedorov ed108b5605 Refactor ARMv8.3 Pointer Authentication support code
This patch provides the following features and makes modifications
listed below:
- Individual APIAKey key generation for each CPU.
- New key generation on every BL31 warm boot and TSP CPU On event.
- Per-CPU storage of APIAKey added in percpu_data[]
  of cpu_data structure.
- `plat_init_apiakey()` function replaced with `plat_init_apkey()`
  which returns 128-bit value and uses Generic timer physical counter
  value to increase the randomness of the generated key.
  The new function can be used for generation of all ARMv8.3-PAuth keys
- ARMv8.3-PAuth specific code placed in `lib\extensions\pauth`.
- New `pauth_init_enable_el1()` and `pauth_init_enable_el3()` functions
  generate, program and enable APIAKey_EL1 for EL1 and EL3 respectively;
  pauth_disable_el1()` and `pauth_disable_el3()` functions disable
  PAuth for EL1 and EL3 respectively;
  `pauth_load_bl31_apiakey()` loads saved per-CPU APIAKey_EL1 from
  cpu-data structure.
- Combined `save_gp_pauth_registers()` function replaces calls to
  `save_gp_registers()` and `pauth_context_save()`;
  `restore_gp_pauth_registers()` replaces `pauth_context_restore()`
  and `restore_gp_registers()` calls.
- `restore_gp_registers_eret()` function removed with corresponding
  code placed in `el3_exit()`.
- Fixed the issue when `pauth_t pauth_ctx` structure allocated space
  for 12 uint64_t PAuth registers instead of 10 by removal of macro
  CTX_PACGAKEY_END from `include/lib/el3_runtime/aarch64/context.h`
  and assigning its value to CTX_PAUTH_REGS_END.
- Use of MODE_SP_ELX and MODE_SP_EL0 macro definitions
  in `msr	spsel`  instruction instead of hard-coded values.
- Changes in documentation related to ARMv8.3-PAuth and ARMv8.5-BTI.

Change-Id: Id18b81cc46f52a783a7e6a09b9f149b6ce803211
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
2019-09-13 14:11:59 +01:00

117 lines
2.9 KiB
ArmAsm

/*
* Copyright (c) 2019, Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <arch.h>
#include <asm_macros.S>
#include <lib/el3_runtime/cpu_data.h>
.global pauth_init_enable_el1
.global pauth_disable_el1
.global pauth_init_enable_el3
.global pauth_disable_el3
.globl pauth_load_bl31_apiakey
/* -------------------------------------------------------------
* Program APIAKey_EL1 and enable pointer authentication in EL1
* -------------------------------------------------------------
*/
func pauth_init_enable_el1
stp x29, x30, [sp, #-16]!
/* Initialize platform key */
bl plat_init_apkey
/* Program instruction key A used by the Trusted Firmware */
msr APIAKeyLo_EL1, x0
msr APIAKeyHi_EL1, x1
/* Enable pointer authentication */
mrs x0, sctlr_el1
orr x0, x0, #SCTLR_EnIA_BIT
#if ENABLE_BTI
/* Enable PAC branch type compatibility */
bic x0, x0, #(SCTLR_BT0_BIT | SCTLR_BT1_BIT)
#endif
msr sctlr_el1, x0
isb
ldp x29, x30, [sp], #16
ret
endfunc pauth_init_enable_el1
/* -------------------------------------------------------------
* Disable pointer authentication in EL3
* -------------------------------------------------------------
*/
func pauth_disable_el1
mrs x0, sctlr_el1
bic x0, x0, #SCTLR_EnIA_BIT
msr sctlr_el1, x0
isb
ret
endfunc pauth_disable_el1
/* -------------------------------------------------------------
* Program APIAKey_EL1 and enable pointer authentication in EL3
* -------------------------------------------------------------
*/
func pauth_init_enable_el3
stp x29, x30, [sp, #-16]!
/* Initialize platform key */
bl plat_init_apkey
/* Program instruction key A used by the Trusted Firmware */
msr APIAKeyLo_EL1, x0
msr APIAKeyHi_EL1, x1
/* Enable pointer authentication */
mrs x0, sctlr_el3
orr x0, x0, #SCTLR_EnIA_BIT
#if ENABLE_BTI
/* Enable PAC branch type compatibility */
bic x0, x0, #SCTLR_BT_BIT
#endif
msr sctlr_el3, x0
isb
ldp x29, x30, [sp], #16
ret
endfunc pauth_init_enable_el3
/* -------------------------------------------------------------
* Disable pointer authentication in EL3
* -------------------------------------------------------------
*/
func pauth_disable_el3
mrs x0, sctlr_el3
bic x0, x0, #SCTLR_EnIA_BIT
msr sctlr_el3, x0
isb
ret
endfunc pauth_disable_el3
/* -------------------------------------------------------------
* The following function strictly follows the AArch64 PCS
* to use x9-x17 (temporary caller-saved registers) to load
* the APIAKey_EL1 used by the firmware.
* -------------------------------------------------------------
*/
func pauth_load_bl31_apiakey
/* tpidr_el3 contains the address of cpu_data structure */
mrs x9, tpidr_el3
/* Load apiakey from cpu_data */
ldp x10, x11, [x9, #CPU_DATA_APIAKEY_OFFSET]
/* Program instruction key A */
msr APIAKeyLo_EL1, x10
msr APIAKeyHi_EL1, x11
isb
ret
endfunc pauth_load_bl31_apiakey