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>

3 files changed, 43 insertions, 51 deletions

diff --git a/bl2/aarch64/bl2_el3_entrypoint.S b/bl2/aarch64/bl2_el3_entrypoint.S
index 261d2957..6fe2dd92 100644
--- a/bl2/aarch64/bl2_el3_entrypoint.S
+++ b/bl2/aarch64/bl2_el3_entrypoint.S
@@ -43,22 +43,12 @@ func bl2_entrypoint
 	 */
 	bl	bl2_el3_setup
 
-	/* ---------------------------------------------
-	 * Enable pointer authentication
-	 * ---------------------------------------------
-	 */
 #if ENABLE_PAUTH
-	mrs	x0, sctlr_el3
-	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_BT_BIT
-#endif	/* ENABLE_BTI */
-	msr	sctlr_el3, x0
-	isb
+	bl	pauth_init_enable_el3
 #endif /* ENABLE_PAUTH */
 
 	/* ---------------------------------------------
@@ -87,16 +77,13 @@ func bl2_run_next_image
 	tlbi	alle3
 	bl	bl2_el3_plat_prepare_exit
 
+#if ENABLE_PAUTH
 	/* ---------------------------------------------
-	 * Disable pointer authentication before jumping to BL31 or that will
-	 * cause an authentication failure during the early platform init.
+	 * Disable pointer authentication before jumping
+	 * to next boot image.
 	 * ---------------------------------------------
 	 */
-#if ENABLE_PAUTH
-	mrs	x0, sctlr_el3
-	bic	x0, x0, #SCTLR_EnIA_BIT
-	msr	sctlr_el3, x0
-	isb
+	bl	pauth_disable_el3
 #endif /* ENABLE_PAUTH */
 
 	ldp	x0, x1, [x20, #ENTRY_POINT_INFO_PC_OFFSET]
diff --git a/bl2/aarch64/bl2_entrypoint.S b/bl2/aarch64/bl2_entrypoint.S
index 5e5b83b1..a021e424 100644
--- a/bl2/aarch64/bl2_entrypoint.S
+++ b/bl2/aarch64/bl2_entrypoint.S
@@ -117,22 +117,13 @@ func bl2_entrypoint
 	mov	x3, x23
 	bl	bl2_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 */
 
 	/* ---------------------------------------------
diff --git a/bl2/bl2_main.c b/bl2/bl2_main.c
index 79b0e717..802c1746 100644
--- a/bl2/bl2_main.c
+++ b/bl2/bl2_main.c
@@ -4,13 +4,17 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
+#include <assert.h>
+
 #include <arch_helpers.h>
+#include <arch_features.h>
 #include <bl1/bl1.h>
 #include <bl2/bl2.h>
 #include <common/bl_common.h>
 #include <common/debug.h>
 #include <drivers/auth/auth_mod.h>
 #include <drivers/console.h>
+#include <lib/extensions/pauth.h>
 #include <plat/common/platform.h>
 
 #include "bl2_private.h"
@@ -31,18 +35,16 @@ void bl2_setup(u_register_t arg0, u_register_t arg1, u_register_t arg2,
 	/* Perform early platform-specific setup */
 	bl2_early_platform_setup2(arg0, arg1, arg2, arg3);
 
-#ifdef __aarch64__
-	/*
-	 * 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();
-#endif /* __aarch64__ */
-
 	/* Perform late platform-specific setup */
 	bl2_plat_arch_setup();
+
+#if CTX_INCLUDE_PAUTH_REGS
+	/*
+	 * 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 /* CTX_INCLUDE_PAUTH_REGS */
 }
 
 #else /* if BL2_AT_EL3 */
@@ -55,18 +57,16 @@ void bl2_el3_setup(u_register_t arg0, u_register_t arg1, u_register_t arg2,
 	/* Perform early platform-specific setup */
 	bl2_el3_early_platform_setup(arg0, arg1, arg2, arg3);
 
-#ifdef __aarch64__
-	/*
-	 * 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();
-#endif /* __aarch64__ */
-
 	/* Perform late platform-specific setup */
 	bl2_el3_plat_arch_setup();
+
+#if CTX_INCLUDE_PAUTH_REGS
+	/*
+	 * 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 /* CTX_INCLUDE_PAUTH_REGS */
 }
 #endif /* BL2_AT_EL3 */
 
@@ -108,6 +108,13 @@ void bl2_main(void)
 
 	console_flush();
 
+#if ENABLE_PAUTH
+	/*
+	 * Disable pointer authentication before running next boot image
+	 */
+	pauth_disable_el1();
+#endif /* ENABLE_PAUTH */
+
 	/*
 	 * Run next BL image via an SMC to BL1. Information on how to pass
 	 * control to the BL32 (if present) and BL33 software images will
@@ -119,6 +126,13 @@ void bl2_main(void)
 	print_entry_point_info(next_bl_ep_info);
 	console_flush();
 
+#if ENABLE_PAUTH
+	/*
+	 * Disable pointer authentication before running next boot image
+	 */
+	pauth_disable_el3();
+#endif /* ENABLE_PAUTH */
+
 	bl2_run_next_image(next_bl_ep_info);
 #endif /* BL2_AT_EL3 */
 }