Access system registers directly in assembler

Instead of using the system register helper functions to read
or write system registers, assembler coded functions should
use MRS/MSR instructions. This results in faster and more
compact code.

This change replaces all usage of the helper functions with
direct register accesses.

Change-Id: I791d5f11f257010bb3e6a72c6c5ab8779f1982b3

8 files changed, 26 insertions, 34 deletions

diff --git a/bl1/aarch64/bl1_entrypoint.S b/bl1/aarch64/bl1_entrypoint.S
index e25386f7..c081af48 100644
--- a/bl1/aarch64/bl1_entrypoint.S
+++ b/bl1/aarch64/bl1_entrypoint.S
@@ -97,10 +97,10 @@ _wait_for_entrypoint:
 	 * their turn to be woken up
 	 * ---------------------------------------------
 	 */
-	bl	read_mpidr
+	mrs	x0, mpidr_el1
 	bl	platform_get_entrypoint
 	cbnz	x0, _do_warm_boot
-	bl	read_mpidr
+	mrs	x0, mpidr_el1
 	bl	platform_is_primary_cpu
 	cbnz	x0, _do_cold_boot
 
diff --git a/bl1/aarch64/bl1_exceptions.S b/bl1/aarch64/bl1_exceptions.S
index 71fd4cd7..a87b20f5 100644
--- a/bl1/aarch64/bl1_exceptions.S
+++ b/bl1/aarch64/bl1_exceptions.S
@@ -189,7 +189,7 @@ func process_exception
 	mov	x0, #SYNC_EXCEPTION_AARCH64
 	bl	plat_report_exception
 
-	bl	read_esr_el3
+	mrs	x0, esr_el3
 	ubfx	x1, x0, #ESR_EC_SHIFT, #ESR_EC_LENGTH
 	cmp	x1, #EC_AARCH64_SMC
 	b.ne	panic
@@ -201,10 +201,8 @@ func process_exception
 	mov	x2, x3
 	mov	x3, x4
 	bl	display_boot_progress
-	mov	x0, x20
-	bl	write_elr
-	mov	x0, x21
-	bl	write_spsr
+	msr	elr_el3, x20
+	msr	spsr_el3, x21
 	ubfx	x0, x21, #MODE_EL_SHIFT, #2
 	cmp	x0, #MODE_EL3
 	b.ne	skip_mmu_teardown
@@ -216,7 +214,7 @@ func process_exception
 	 * ---------------------------------------------
 	 */
 	bl	disable_mmu_icache_el3
-	bl	tlbialle3
+	tlbi	alle3
 skip_mmu_teardown:
 	ldp     x6, x7, [sp, #0x30]
 	ldp     x4, x5, [sp, #0x20]
diff --git a/bl2/aarch64/bl2_entrypoint.S b/bl2/aarch64/bl2_entrypoint.S
index cd07aa9d..4f7565f4 100644
--- a/bl2/aarch64/bl2_entrypoint.S
+++ b/bl2/aarch64/bl2_entrypoint.S
@@ -54,8 +54,7 @@ func bl2_entrypoint
 	 * So, make sure no secondary has lost its way.
 	 * ---------------------------------------------
 	 */
-	bl	read_mpidr
-	mov	x19, x0
+	mrs	x0, mpidr_el1
 	bl	platform_is_primary_cpu
 	cbz	x0, _panic
 
@@ -102,7 +101,7 @@ func bl2_entrypoint
 	 * ease the pain of initializing the MMU
 	 * --------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 
 	/* ---------------------------------------------
@@ -120,7 +119,7 @@ func bl2_entrypoint
 	 * -IS-WBWA memory
 	 * ---------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_stack
 
 	/* ---------------------------------------------
diff --git a/bl31/aarch64/bl31_entrypoint.S b/bl31/aarch64/bl31_entrypoint.S
index 1b79421d..13bd5b89 100644
--- a/bl31/aarch64/bl31_entrypoint.S
+++ b/bl31/aarch64/bl31_entrypoint.S
@@ -107,8 +107,7 @@ func bl31_entrypoint
 	 * So, make sure no secondary has lost its way.
 	 * ---------------------------------------------
 	 */
-	bl	read_mpidr
-	mov	x19, x0
+	mrs	x0, mpidr_el1
 	bl	platform_is_primary_cpu
 	cbz	x0, _panic
 
@@ -137,7 +136,7 @@ func bl31_entrypoint
 	 * ease the pain of initializing the MMU
 	 * --------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 
 	/* ---------------------------------------------
@@ -154,7 +153,7 @@ func bl31_entrypoint
 	 * -IS-WBWA memory
 	 * ---------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_stack
 
 	/* ---------------------------------------------
diff --git a/include/common/asm_macros.S b/include/common/asm_macros.S
index 6cf1a19f..a41b7297 100644
--- a/include/common/asm_macros.S
+++ b/include/common/asm_macros.S
@@ -58,7 +58,7 @@
 
 
 	.macro	smc_check  label
-	bl	read_esr
+	mrs	x0, esr_el3
 	ubfx	x0, x0, #ESR_EC_SHIFT, #ESR_EC_LENGTH
 	cmp	x0, #EC_AARCH64_SMC
 	b.ne	$label
diff --git a/lib/aarch64/cpu_helpers.S b/lib/aarch64/cpu_helpers.S
index 4e5eb5bd..abb996d6 100644
--- a/lib/aarch64/cpu_helpers.S
+++ b/lib/aarch64/cpu_helpers.S
@@ -35,13 +35,11 @@
 
 
 func cpu_reset_handler
-	mov	x19, x30 // lr
-
 	/* ---------------------------------------------
 	 * As a bare minimal enable the SMP bit.
 	 * ---------------------------------------------
 	 */
-	bl	read_midr
+	mrs	x0, midr_el1
 	lsr	x0, x0, #MIDR_PN_SHIFT
 	and	x0, x0, #MIDR_PN_MASK
 	cmp	x0, #MIDR_PN_A57
@@ -49,9 +47,9 @@ func cpu_reset_handler
 	cmp	x0, #MIDR_PN_A53
 	b.ne	smp_setup_end
 smp_setup_begin:
-	bl	read_cpuectlr
+	mrs	x0, CPUECTLR_EL1
 	orr	x0, x0, #CPUECTLR_SMP_BIT
-	bl	write_cpuectlr
+	msr	CPUECTLR_EL1, x0
 	isb
 smp_setup_end:
-	ret	x19
+	ret
diff --git a/plat/fvp/aarch64/bl1_plat_helpers.S b/plat/fvp/aarch64/bl1_plat_helpers.S
index 92075ea4..b4d44586 100644
--- a/plat/fvp/aarch64/bl1_plat_helpers.S
+++ b/plat/fvp/aarch64/bl1_plat_helpers.S
@@ -67,7 +67,7 @@ func plat_secondary_cold_boot_setup
 	 * loader zeroes out the zi section.
 	 * ---------------------------------------------
 	 */
-	bl	read_mpidr
+	mrs	x0, mpidr_el1
 	ldr	x1, =PWRC_BASE
 	str	w0, [x1, #PPOFFR_OFF]
 
@@ -173,8 +173,6 @@ func platform_mem_init
 func platform_cold_boot_init
 	mov	x20, x0
 	bl	platform_mem_init
-	bl	read_mpidr
-	mov	x19, x0
 
 	/* ---------------------------------------------
 	 * Give ourselves a small coherent stack to
@@ -182,6 +180,7 @@ func platform_cold_boot_init
 	 * CCI in assembler
 	 * ---------------------------------------------
 	 */
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 
 	/* ---------------------------------------------
@@ -200,7 +199,7 @@ func platform_cold_boot_init
 	 * -IS-WBWA memory
 	 * ---------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_stack
 
 	/* ---------------------------------------------
diff --git a/services/std_svc/psci/psci_entry.S b/services/std_svc/psci/psci_entry.S
index ec55a819..25adaa11 100644
--- a/services/std_svc/psci/psci_entry.S
+++ b/services/std_svc/psci/psci_entry.S
@@ -76,8 +76,7 @@ psci_aff_common_finish_entry:
 	 */
 	msr	spsel, #0
 
-	bl	read_mpidr
-	mov	x19, x0
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 
 	/* ---------------------------------------------
@@ -85,14 +84,14 @@ psci_aff_common_finish_entry:
 	 * level 0.
 	 * ---------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	get_power_on_target_afflvl
 	cmp	x0, xzr
 	b.lt	_panic
 	mov	x3, x23
 	mov	x2, x0
-	mov	x0, x19
 	mov	x1, #MPIDR_AFFLVL0
+	mrs	x0, mpidr_el1
 	blr	x22
 
 	/* --------------------------------------------
@@ -100,7 +99,7 @@ psci_aff_common_finish_entry:
 	 * -IS-WBWA memory
 	 * --------------------------------------------
 	 */
-	mov	x0, x19
+	mrs	x0, mpidr_el1
 	bl	platform_set_stack
 
 	zero_callee_saved_regs
@@ -119,7 +118,7 @@ func __psci_cpu_off
 	sub	sp, sp, #0x10
 	stp	x19, x20, [sp, #0]
 	mov	x19, sp
-	bl	read_mpidr
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 	bl	psci_cpu_off
 	mov	x1, #PSCI_E_SUCCESS
@@ -140,7 +139,7 @@ func __psci_cpu_suspend
 	mov	x20, x0
 	mov	x21, x1
 	mov	x22, x2
-	bl	read_mpidr
+	mrs	x0, mpidr_el1
 	bl	platform_set_coherent_stack
 	mov	x0, x20
 	mov	x1, x21