Workaround for Neoverse N1 erratum 1275112
Neoverse N1 erratum 1275112 is a Cat B erratum [1],
present in older revisions of the Neoverse N1 processor core.
The workaround is to set a bit in the implementation defined
CPUACTLR_EL1 system register, which delays instruction fetch after
branch misprediction.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html
Change-Id: If7fe55fe92e656fa6aea12327ab297f2e6119833
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 91032c4..d3fe89d 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -252,6 +252,9 @@
- ``ERRATA_N1_1262888``: This applies errata 1262888 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
+- ``ERRATA_N1_1275112``: This applies errata 1275112 workaround to Neoverse-N1
+ CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
+
- ``ERRATA_N1_1315703``: This applies errata 1315703 workaround to Neoverse-N1
CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index d5f2247..cffdf9e 100644
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -293,6 +293,33 @@
endfunc check_errata_1262888
/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Errata #1275112
+ * This applies to revision <=r3p0 of Neoverse N1.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_n1_1275112_wa
+ /* Compare x0 against revision r3p0 */
+ mov x17, x30
+ bl check_errata_1275112
+ cbz x0, 1f
+ mrs x1, NEOVERSE_N1_CPUACTLR_EL1
+ orr x1, x1, NEOVERSE_N1_CPUACTLR_EL1_BIT_13
+ msr NEOVERSE_N1_CPUACTLR_EL1, x1
+ isb
+1:
+ ret x17
+endfunc errata_n1_1275112_wa
+
+func check_errata_1275112
+ /* Applies to <=r3p0 */
+ mov x1, #0x30
+ b cpu_rev_var_ls
+endfunc check_errata_1275112
+
+/* --------------------------------------------------
* Errata Workaround for Neoverse N1 Erratum 1315703.
* This applies to revision <= r3p0 of Neoverse N1.
* Inputs:
@@ -380,6 +407,11 @@
bl errata_n1_1262888_wa
#endif
+#if ERRATA_N1_1275112
+ mov x0, x18
+ bl errata_n1_1275112_wa
+#endif
+
#if ERRATA_N1_1315703
mov x0, x18
bl errata_n1_1315703_wa
@@ -450,6 +482,7 @@
report_errata ERRATA_N1_1257314, neoverse_n1, 1257314
report_errata ERRATA_N1_1262606, neoverse_n1, 1262606
report_errata ERRATA_N1_1262888, neoverse_n1, 1262888
+ report_errata ERRATA_N1_1275112, neoverse_n1, 1275112
report_errata ERRATA_N1_1315703, neoverse_n1, 1315703
report_errata ERRATA_DSU_936184, neoverse_n1, dsu_936184
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 2f13696..2604023 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -270,6 +270,10 @@
# only to revision <= r3p0 of the Neoverse N1 cpu.
ERRATA_N1_1262888 ?=0
+# Flag to apply erratum 1275112 workaround during reset. This erratum applies
+# only to revision <= r3p0 of the Neoverse N1 cpu.
+ERRATA_N1_1275112 ?=0
+
# Flag to apply erratum 1315703 workaround during reset. This erratum applies
# to revisions before r3p1 of the Neoverse N1 cpu.
ERRATA_N1_1315703 ?=1
@@ -495,6 +499,10 @@
$(eval $(call assert_boolean,ERRATA_N1_1262888))
$(eval $(call add_define,ERRATA_N1_1262888))
+# Process ERRATA_N1_1275112 flag
+$(eval $(call assert_boolean,ERRATA_N1_1275112))
+$(eval $(call add_define,ERRATA_N1_1275112))
+
# Process ERRATA_N1_1315703 flag
$(eval $(call assert_boolean,ERRATA_N1_1315703))
$(eval $(call add_define,ERRATA_N1_1315703))