Neoverse N1: Introduce workaround for Neoverse N1 erratum 1315703
Neoverse N1 erratum 1315703 is a Cat A (rare) erratum [1], present in
older revisions of the Neoverse N1 processor core.
The workaround is to set a bit in the implementation defined CPUACTLR2_EL1
system register, which will disable the load-bypass-store feature.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdocpjdoc-466751330-1032/index.html
Change-Id: I5c708dbe0efa4daa0bcb6bd9622c5efe19c03af9
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 07983a9..6b524c2 100644
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -226,6 +226,9 @@
- ``ERRATA_A76_1275112``: This applies errata 1275112 workaround to Cortex-A76
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.
+
DSU Errata Workarounds
----------------------
diff --git a/include/lib/cpus/aarch64/neoverse_n1.h b/include/lib/cpus/aarch64/neoverse_n1.h
index ed5f136..b66aeb8 100644
--- a/include/lib/cpus/aarch64/neoverse_n1.h
+++ b/include/lib/cpus/aarch64/neoverse_n1.h
@@ -35,7 +35,8 @@
******************************************************************************/
#define NEOVERSE_N1_CPUACTLR2_EL1 S3_0_C15_C1_1
-#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_2 (ULL(1) << 2)
+#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_2 (ULL(1) << 2)
+#define NEOVERSE_N1_CPUACTLR2_EL1_BIT_16 (ULL(1) << 16)
/* Instruction patching registers */
#define CPUPSELR_EL3 S3_6_C15_C8_0
diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index a0babb0..3b8e8af 100644
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -16,7 +16,7 @@
#endif
/* --------------------------------------------------
- * Errata Workaround for Neoverse N1 Errata
+ * Errata Workaround for Neoverse N1 Erratum 1043202.
* This applies to revision r0p0 and r1p0 of Neoverse N1.
* Inputs:
* x0: variant[4:7] and revision[0:3] of current cpu.
@@ -70,6 +70,35 @@
ret
endfunc neoverse_n1_disable_speculative_loads
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Erratum 1315703.
+ * 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_1315703_wa
+ /* Compare x0 against revision r3p1 */
+ mov x17, x30
+ bl check_errata_1315703
+ cbz x0, 1f
+
+ mrs x0, NEOVERSE_N1_CPUACTLR2_EL1
+ orr x0, x0, #NEOVERSE_N1_CPUACTLR2_EL1_BIT_16
+ msr NEOVERSE_N1_CPUACTLR2_EL1, x0
+ isb
+
+1:
+ ret x17
+endfunc errata_n1_1315703_wa
+
+func check_errata_1315703
+ /* Applies to everything <= r3p0. */
+ mov x1, #0x30
+ b cpu_rev_var_ls
+endfunc check_errata_1315703
+
func neoverse_n1_reset_func
mov x19, x30
@@ -89,6 +118,11 @@
bl errata_n1_1043202_wa
#endif
+#if ERRATA_N1_1315703
+ mov x0, x18
+ bl errata_n1_1315703_wa
+#endif
+
#if ENABLE_AMU
/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
mrs x0, actlr_el3
@@ -141,6 +175,7 @@
* checking functions of each errata.
*/
report_errata ERRATA_N1_1043202, neoverse_n1, 1043202
+ report_errata ERRATA_N1_1315703, neoverse_n1, 1315703
ldp x8, x30, [sp], #16
ret
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 599e11e..db45375 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -238,6 +238,10 @@
# only to r0p0 and r1p0 of the Neoverse N1 cpu.
ERRATA_N1_1043202 ?=1
+# Flag to apply erratum 1315703 workaround during reset. This erratum applies
+# to revisions before r3p1 of the Neoverse N1 cpu.
+ERRATA_N1_1315703 ?=1
+
# Flag to apply DSU erratum 798953. This erratum applies to DSUs revision r0p0.
# Applying the workaround results in higher DSU power consumption on idle.
ERRATA_DSU_798953 ?=0
@@ -427,6 +431,10 @@
$(eval $(call assert_boolean,ERRATA_N1_1043202))
$(eval $(call add_define,ERRATA_N1_1043202))
+# Process ERRATA_N1_1315703 flag
+$(eval $(call assert_boolean,ERRATA_N1_1315703))
+$(eval $(call add_define,ERRATA_N1_1315703))
+
# Process ERRATA_DSU_798953 flag
$(eval $(call assert_boolean,ERRATA_DSU_798953))
$(eval $(call add_define,ERRATA_DSU_798953))