fix(errata): workaround for Neoverse-N2 erratum 2242415
Neoverse-N2 erratum 2242415 is a Cat B erratum that applies to
revision r0p0 of CPU. It is still open. The workaround
is to set CPUACTLR_EL1[22] to 1'b1. Setting CPUACTLR_EL1[22]
will cause CFP instruction to invalidate all branch predictor
resources regardless of context.
SDEN can be found here:
https://developer.arm.com/documentation/SDEN1982442/latest
Signed-off-by: nayanpatel-arm <nayankumar.patel@arm.com>
Change-Id: I442be81fbc32e21fed51a84f59584df17f845e96
diff --git a/lib/cpus/aarch64/neoverse_n2.S b/lib/cpus/aarch64/neoverse_n2.S
index 330cc59..c197590 100644
--- a/lib/cpus/aarch64/neoverse_n2.S
+++ b/lib/cpus/aarch64/neoverse_n2.S
@@ -184,6 +184,34 @@
endfunc check_errata_2138956
/* --------------------------------------------------
+ * Errata Workaround for Neoverse N2 Erratum 2242415.
+ * This applies to revision r0p0 of Neoverse N2. it is still open.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x1, x17
+ * --------------------------------------------------
+ */
+func errata_n2_2242415_wa
+ /* Check revision. */
+ mov x17, x30
+ bl check_errata_2242415
+ cbz x0, 1f
+
+ /* Apply instruction patching sequence */
+ mrs x1, NEOVERSE_N2_CPUACTLR_EL1
+ orr x1, x1, NEOVERSE_N2_CPUACTLR_EL1_BIT_22
+ msr NEOVERSE_N2_CPUACTLR_EL1, x1
+1:
+ ret x17
+endfunc errata_n2_2242415_wa
+
+func check_errata_2242415
+ /* Applies to r0p0 */
+ mov x1, #0x00
+ b cpu_rev_var_ls
+endfunc check_errata_2242415
+
+/* --------------------------------------------------
* Errata Workaround for Neoverse N2 Erratum 2138953.
* This applies to revision r0p0 of Neoverse N2. it is still open.
* Inputs:
@@ -258,6 +286,11 @@
bl errata_n2_2138953_wa
#endif
+#if ERRATA_N2_2242415
+ mov x0, x18
+ bl errata_n2_2242415_wa
+#endif
+
#if ENABLE_AMU
/* Make sure accesses from EL0/EL1 and EL2 are not trapped to EL3 */
mrs x0, cptr_el3
@@ -324,6 +357,7 @@
report_errata ERRATA_N2_2189731, neoverse_n2, 2189731
report_errata ERRATA_N2_2138956, neoverse_n2, 2138956
report_errata ERRATA_N2_2138953, neoverse_n2, 2138953
+ report_errata ERRATA_N2_2242415, neoverse_n2, 2242415
ldp x8, x30, [sp], #16
ret