Workaround for Neoverse N1 erratum 1073348

Neoverse N1 erratum 1073348 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 disables static prediction.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.pjdoc-466751330-10325/index.html



Change-Id: I674126c0af6e068eecb379a190bcf7c75dcbca8e
Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>

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

@@ -226,6 +226,11 @@ For Cortex-A76, the following errata build flags are defined :
 -  ``ERRATA_A76_1275112``: This applies errata 1275112 workaround to Cortex-A76
    CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
 
+For Neoverse N1, the following errata build flags are defined :
+
+-  ``ERRATA_N1_1073348``: This applies errata 1073348 workaround to Neoverse-N1
+   CPU. This needs to be enabled only for revision r0p0 and r1p0 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.
 

include/lib/cpus/aarch64/neoverse_n1.h

@@ -33,6 +33,10 @@
 /*******************************************************************************
  * CPU Auxiliary Control register specific definitions.
  ******************************************************************************/
+#define NEOVERSE_N1_CPUACTLR_EL1	S3_0_C15_C1_0
+
+#define NEOVERSE_N1_CPUACTLR_EL1_BIT_6	(ULL(1) << 6)
+
 #define NEOVERSE_N1_CPUACTLR2_EL1	S3_0_C15_C1_1
 
 #define NEOVERSE_N1_CPUACTLR2_EL1_BIT_2		(ULL(1) << 2)

lib/cpus/aarch64/neoverse_n1.S

@@ -75,6 +75,33 @@ func neoverse_n1_disable_speculative_loads
 	ret
 endfunc neoverse_n1_disable_speculative_loads
 
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Errata #1073348
+ * This applies to revision r0p0 and r1p0 of Neoverse N1.
+ * Inputs:
+ * x0: variant[4:7] and revision[0:3] of current cpu.
+ * Shall clobber: x0-x17
+ * --------------------------------------------------
+ */
+func errata_n1_1073348_wa
+	/* Compare x0 against revision r1p0 */
+	mov	x17, x30
+	bl	check_errata_1073348
+	cbz	x0, 1f
+	mrs	x1, NEOVERSE_N1_CPUACTLR_EL1
+	orr	x1, x1, NEOVERSE_N1_CPUACTLR_EL1_BIT_6
+	msr	NEOVERSE_N1_CPUACTLR_EL1, x1
+	isb
+1:
+	ret	x17
+endfunc errata_n1_1073348_wa
+
+func check_errata_1073348
+	/* Applies to r0p0 and r1p0 */
+	mov	x1, #0x10
+	b	cpu_rev_var_ls
+endfunc check_errata_1073348
+
 /* --------------------------------------------------
  * Errata Workaround for Neoverse N1 Erratum 1315703.
  * This applies to revision <= r3p0 of Neoverse N1.
@@ -123,6 +150,11 @@ func neoverse_n1_reset_func
 	bl	errata_n1_1043202_wa
 #endif
 
+#if ERRATA_N1_1073348
+	mov	x0, x18
+	bl	errata_n1_1073348_wa
+#endif
+
 #if ERRATA_N1_1315703
 	mov	x0, x18
 	bl	errata_n1_1315703_wa
@@ -185,6 +217,7 @@ func neoverse_n1_errata_report
 	 * checking functions of each errata.
 	 */
 	report_errata ERRATA_N1_1043202, neoverse_n1, 1043202
+	report_errata ERRATA_N1_1073348, neoverse_n1, 1073348
 	report_errata ERRATA_N1_1315703, neoverse_n1, 1315703
 	report_errata ERRATA_DSU_936184, neoverse_n1, dsu_936184
 

lib/cpus/cpu-ops.mk

@@ -238,6 +238,10 @@ ERRATA_A76_1286807	?=0
 # only to r0p0 and r1p0 of the Neoverse N1 cpu.
 ERRATA_N1_1043202	?=1
 
+# Flag to apply erratum 1073348 workaround during reset. This erratum applies
+# only to revision r0p0 and r1p0 of the Neoverse N1 cpu.
+ERRATA_N1_1073348	?=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
@@ -431,6 +435,10 @@ $(eval $(call add_define,ERRATA_A76_1286807))
 $(eval $(call assert_boolean,ERRATA_N1_1043202))
 $(eval $(call add_define,ERRATA_N1_1043202))
 
+# Process ERRATA_N1_1073348 flag
+$(eval $(call assert_boolean,ERRATA_N1_1073348))
+$(eval $(call add_define,ERRATA_N1_1073348))
+
 # Process ERRATA_N1_1315703 flag
 $(eval $(call assert_boolean,ERRATA_N1_1315703))
 $(eval $(call add_define,ERRATA_N1_1315703))