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>

2 files changed, 15 insertions, 16 deletions

diff --git a/plat/arm/common/aarch64/arm_pauth.c b/plat/arm/common/aarch64/arm_pauth.c
index a685c319..7cea8a0c 100644
--- a/plat/arm/common/aarch64/arm_pauth.c
+++ b/plat/arm/common/aarch64/arm_pauth.c
@@ -4,27 +4,25 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <arch_helpers.h>
 #include <cdefs.h>
 #include <stdint.h>
 
 /*
- * Instruction pointer authentication key A. The low 64-bit are at [0], and the
- * high bits at [1].
+ * This is only a toy implementation to generate a seemingly random
+ * 128-bit key from sp, x30 and cntpct_el0 values.
+ * A production system must re-implement this function to generate
+ * keys from a reliable randomness source.
  */
-uint64_t plat_apiakey[2];
-
-/*
- * This is only a toy implementation to generate a seemingly random 128-bit key
- * from sp and x30 values. A production system must re-implement this function
- * to generate keys from a reliable randomness source.
- */
-uint64_t *plat_init_apiakey(void)
+uint128_t plat_init_apkey(void)
 {
-	uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U);
-	uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U);
+	uint64_t return_addr = (uint64_t)__builtin_return_address(0U);
+	uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U);
+	uint64_t cntpct = read_cntpct_el0();
 
-	plat_apiakey[0] = (return_addr << 13) ^ frame_addr;
-	plat_apiakey[1] = (frame_addr << 15) ^ return_addr;
+	/* Generate 128-bit key */
+	uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct;
+	uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct;
 
-	return plat_apiakey;
+	return ((uint128_t)(key_hi) << 64) | key_lo;
 }
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 10b6e512..a4a29bf7 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -234,7 +234,8 @@ endif
 
 # Pointer Authentication sources
 ifeq (${ENABLE_PAUTH}, 1)
-PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c
+PLAT_BL_COMMON_SOURCES	+=	plat/arm/common/aarch64/arm_pauth.c	\
+				lib/extensions/pauth/pauth_helpers.S
 endif
 
 # SPM uses libfdt in Arm platforms