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, 23 insertions, 21 deletions

diff --git a/bl32/tsp/aarch64/tsp_entrypoint.S b/bl32/tsp/aarch64/tsp_entrypoint.S
index fd6b0fbc..1d3ec21a 100644
--- a/bl32/tsp/aarch64/tsp_entrypoint.S
+++ b/bl32/tsp/aarch64/tsp_entrypoint.S
@@ -129,22 +129,13 @@ func tsp_entrypoint _align=3
 	 */
 	bl	tsp_setup
 
-	/* ---------------------------------------------
-	 * Enable pointer authentication
-	 * ---------------------------------------------
-	 */
 #if ENABLE_PAUTH
-	mrs	x0, sctlr_el1
-	orr	x0, x0, #SCTLR_EnIA_BIT
-#if ENABLE_BTI
 	/* ---------------------------------------------
-	 * Enable PAC branch type compatibility
+	 * Program APIAKey_EL1
+	 * and enable pointer authentication
 	 * ---------------------------------------------
 	 */
-	bic	x0, x0, #(SCTLR_BT0_BIT | SCTLR_BT1_BIT)
-#endif	/* ENABLE_BTI */
-	msr	sctlr_el1, x0
-	isb
+	bl	pauth_init_enable_el1
 #endif /* ENABLE_PAUTH */
 
 	/* ---------------------------------------------
@@ -271,6 +262,15 @@ func tsp_cpu_on_entry
 	mov	x0, #0
 	bl	bl32_plat_enable_mmu
 
+#if ENABLE_PAUTH
+	/* ---------------------------------------------
+	 * Program APIAKey_EL1
+	 * and enable pointer authentication
+	 * ---------------------------------------------
+	 */
+	bl	pauth_init_enable_el1
+#endif /* ENABLE_PAUTH */
+
 	/* ---------------------------------------------
 	 * Enter C runtime to perform any remaining
 	 * book keeping
diff --git a/bl32/tsp/tsp_main.c b/bl32/tsp/tsp_main.c
index 0a817351..e1d961cc 100644
--- a/bl32/tsp/tsp_main.c
+++ b/bl32/tsp/tsp_main.c
@@ -4,14 +4,16 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#include <platform_def.h>
+#include <assert.h>
 
+#include <arch_features.h>
 #include <arch_helpers.h>
 #include <bl32/tsp/tsp.h>
 #include <common/bl_common.h>
 #include <common/debug.h>
 #include <lib/spinlock.h>
 #include <plat/common/platform.h>
+#include <platform_def.h>
 #include <platform_tsp.h>
 
 #include "tsp_private.h"
@@ -79,16 +81,16 @@ void tsp_setup(void)
 	/* Perform early platform-specific setup */
 	tsp_early_platform_setup();
 
-	/*
-	 * Update pointer authentication key before the MMU is enabled. It is
-	 * saved in the rodata section, that can be writen before enabling the
-	 * MMU. This function must be called after the console is initialized
-	 * in the early platform setup.
-	 */
-	bl_handle_pauth();
-
 	/* Perform late platform-specific setup */
 	tsp_plat_arch_setup();
+
+#if ENABLE_PAUTH
+	/*
+	 * Assert that the ARMv8.3-PAuth registers are present or an access
+	 * fault will be triggered when they are being saved or restored.
+	 */
+	assert(is_armv8_3_pauth_present());
+#endif /* ENABLE_PAUTH */
 }
 
 /*******************************************************************************