lib/cpu: Workaround for Cortex A77 erratum 1946167

Cortex A77 erratum 1946167 is a Cat B erratum that applies to revisions
<= r1p1. This erratum is avoided by inserting a DMB ST before acquire
atomic instructions without release semantics through a series of
writes to implementation defined system registers.

SDEN can be found here:
https://documentation-service.arm.com/static/600057a29b9c2d1bb22cd1be?token=

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: I53e3b4fb7e7575ec83d75c2f132eda5ae0b4f01f

docs/design/cpu-specific-build-macros.rst

@@ -260,6 +260,9 @@ For Cortex-A77, the following errata build flags are defined :
 -  ``ERRATA_A77_1925769``: This applies errata 1925769 workaround to Cortex-A77
    CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
 
+-  ``ERRATA_A77_1946167``: This applies errata 1946167 workaround to Cortex-A77
+   CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
+
 For Cortex-A78, the following errata build flags are defined :
 
 -  ``ERRATA_A78_1688305``: This applies errata 1688305 workaround to Cortex-A78
@@ -385,7 +388,7 @@ architecture that can be enabled by the platform as desired.
 
 --------------
 
-*Copyright (c) 2014-2020, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2014-2021, Arm Limited and Contributors. All rights reserved.*
 
 .. _CVE-2017-5715: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-5715
 .. _CVE-2018-3639: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-3639

lib/cpus/aarch64/cortex_a77.S

 /*
- * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -114,6 +114,58 @@ func check_errata_1925769
 	b	cpu_rev_var_ls
 endfunc check_errata_1925769
 
+	/* --------------------------------------------------
+	 * Errata Workaround for Cortex A77 Errata #1946167.
+	 * This applies to revision <= r1p1 of Cortex A77.
+	 * Inputs:
+	 * x0: variant[4:7] and revision[0:3] of current cpu.
+	 * Shall clobber: x0-x17
+	 * --------------------------------------------------
+	 */
+func errata_a77_1946167_wa
+	/* Compare x0 against revision <= r1p1 */
+	mov	x17, x30
+	bl	check_errata_1946167
+	cbz	x0, 1f
+
+	ldr	x0,=0x4
+	msr	CORTEX_A77_CPUPSELR_EL3,x0
+	ldr	x0,=0x10E3900002
+	msr	CORTEX_A77_CPUPOR_EL3,x0
+	ldr	x0,=0x10FFF00083
+	msr	CORTEX_A77_CPUPMR_EL3,x0
+	ldr	x0,=0x2001003FF
+	msr	CORTEX_A77_CPUPCR_EL3,x0
+
+	ldr	x0,=0x5
+	msr	CORTEX_A77_CPUPSELR_EL3,x0
+	ldr	x0,=0x10E3800082
+	msr	CORTEX_A77_CPUPOR_EL3,x0
+	ldr	x0,=0x10FFF00083
+	msr	CORTEX_A77_CPUPMR_EL3,x0
+	ldr	x0,=0x2001003FF
+	msr	CORTEX_A77_CPUPCR_EL3,x0
+
+	ldr	x0,=0x6
+	msr	CORTEX_A77_CPUPSELR_EL3,x0
+	ldr	x0,=0x10E3800200
+	msr	CORTEX_A77_CPUPOR_EL3,x0
+	ldr	x0,=0x10FFF003E0
+	msr	CORTEX_A77_CPUPMR_EL3,x0
+	ldr	x0,=0x2001003FF
+	msr	CORTEX_A77_CPUPCR_EL3,x0
+
+	isb
+1:
+	ret	x17
+endfunc errata_a77_1946167_wa
+
+func check_errata_1946167
+	/* Applies to everything <= r1p1 */
+	mov	x1, #0x11
+	b	cpu_rev_var_ls
+endfunc check_errata_1946167
+
 	/* -------------------------------------------------
 	 * The CPU Ops reset function for Cortex-A77.
 	 * Shall clobber: x0-x19
@@ -134,6 +186,11 @@ func cortex_a77_reset_func
 	bl	errata_a77_1925769_wa
 #endif
 
+#if ERRATA_A77_1946167
+	mov	x0, x18
+	bl	errata_a77_1946167_wa
+#endif
+
 	ret	x19
 endfunc cortex_a77_reset_func
 
@@ -169,6 +226,7 @@ func cortex_a77_errata_report
 	 */
 	report_errata ERRATA_A77_1508412, cortex_a77, 1508412
 	report_errata ERRATA_A77_1925769, cortex_a77, 1925769
+	report_errata ERRATA_A77_1946167, cortex_a77, 1946167
 
 	ldp	x8, x30, [sp], #16
 	ret

lib/cpus/cpu-ops.mk

@@ -290,6 +290,10 @@ ERRATA_A77_1508412	?=0
 # only to revision <= r1p1 of the Cortex A77 cpu.
 ERRATA_A77_1925769	?=0
 
+# Flag to apply erratum 1946167 workaround during reset. This erratum applies
+# only to revision <= r1p1 of the Cortex A77 cpu.
+ERRATA_A77_1946167	?=0
+
 # Flag to apply erratum 1688305 workaround during reset. This erratum applies
 # to revisions r0p0 - r1p0 of the A78 cpu.
 ERRATA_A78_1688305	?=0
@@ -585,6 +589,10 @@ $(eval $(call add_define,ERRATA_A77_1508412))
 $(eval $(call assert_boolean,ERRATA_A77_1925769))
 $(eval $(call add_define,ERRATA_A77_1925769))
 
+# Process ERRATA_A77_1946167 flag
+$(eval $(call assert_boolean,ERRATA_A77_1946167))
+$(eval $(call add_define,ERRATA_A77_1946167))
+
 # Process ERRATA_A78_1688305 flag
 $(eval $(call assert_boolean,ERRATA_A78_1688305))
 $(eval $(call add_define,ERRATA_A78_1688305))