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, 9 insertions, 31 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 */
 
 	/* ---------------------------------------------