Workaround for Cortex A76 erratum 1791580
Cortex A76 erratum 1791580 is a Cat B erratum present in earlier
revisions of the Cortex A76. The workaround is to set a bit in the
implementation defined CPUACTLR2 register, which forces atomic store
operations to write-back memory to be performed in the L1 data cache.
This errata is explained in this SDEN:
https://static.docs.arm.com/sden885749/g/Arm_Cortex_A76_MP052_Software_Developer_Errata_Notice_v20.pdf
Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: Iefd58159b3f2e2286138993317b98e57dc361925
diff --git a/lib/cpus/aarch64/cortex_a76.S b/lib/cpus/aarch64/cortex_a76.S
index baefa46..3a0139a 100644
--- a/lib/cpus/aarch64/cortex_a76.S
+++ b/lib/cpus/aarch64/cortex_a76.S
@@ -392,6 +392,33 @@
#endif
endfunc check_errata_1286807
+ /* --------------------------------------------------
+ * Errata workaround for Cortex A76 Errata #1791580.
+ * This applies to revisions <= r4p0 of Cortex A76.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_a76_1791580_wa
+ /* Compare x0 against revision r4p0 */
+ mov x17, x30
+ bl check_errata_1791580
+ cbz x0, 1f
+ mrs x1, CORTEX_A76_CPUACTLR2_EL1
+ orr x1, x1, CORTEX_A76_CPUACTLR2_EL1_BIT_2
+ msr CORTEX_A76_CPUACTLR2_EL1, x1
+ isb
+1:
+ ret x17
+endfunc errata_a76_1791580_wa
+
+func check_errata_1791580
+ /* Applies to everything <=r4p0. */
+ mov x1, #0x40
+ b cpu_rev_var_ls
+endfunc check_errata_1791580
+
func check_errata_cve_2018_3639
#if WORKAROUND_CVE_2018_3639
mov x0, #ERRATA_APPLIES
@@ -449,6 +476,11 @@
bl errata_a76_1262888_wa
#endif
+#if ERRATA_A76_1791580
+ mov x0, x18
+ bl errata_a76_1791580_wa
+#endif
+
#if WORKAROUND_CVE_2018_3639
/* If the PE implements SSBS, we don't need the dynamic workaround */
mrs x0, id_aa64pfr1_el1
@@ -529,6 +561,7 @@
report_errata ERRATA_A76_1262888, cortex_a76, 1262888
report_errata ERRATA_A76_1275112, cortex_a76, 1275112
report_errata ERRATA_A76_1286807, cortex_a76, 1286807
+ report_errata ERRATA_A76_1791580, cortex_a76, 1791580
report_errata WORKAROUND_CVE_2018_3639, cortex_a76, cve_2018_3639
report_errata ERRATA_DSU_798953, cortex_a76, dsu_798953
report_errata ERRATA_DSU_936184, cortex_a76, dsu_936184
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 1bc082d..97db734 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -250,6 +250,10 @@
# only to revision <= r3p0 of the Cortex A76 cpu.
ERRATA_A76_1286807 ?=0
+# Flag to apply erratum 1791580 workaround during reset. This erratum applies
+# only to revision <= r4p0 of the Cortex A76 cpu.
+ERRATA_A76_1791580 ?=0
+
# Flag to apply erratum 1688305 workaround during reset. This erratum applies
# to revisions r0p0 - r1p0 of the A78 cpu.
ERRATA_A78_1688305 ?=0
@@ -487,6 +491,10 @@
$(eval $(call assert_boolean,ERRATA_A76_1286807))
$(eval $(call add_define,ERRATA_A76_1286807))
+# Process ERRATA_A76_1791580 flag
+$(eval $(call assert_boolean,ERRATA_A76_1791580))
+$(eval $(call add_define,ERRATA_A76_1791580))
+
# Process ERRATA_A78_1688305 flag
$(eval $(call assert_boolean,ERRATA_A78_1688305))
$(eval $(call add_define,ERRATA_A78_1688305))