Workaround for Neoverse N1 erratum 1262606

Neoverse N1 erratum 1262606 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: Idd980e9d5310232d38f0ce272862e1fb0f02ce9a
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 14dfe95807394803b9b82a56071149cf3201b330..1ed7cebe7f57d2392dc23d7b90a4c745c0cb502a 100644 (file)
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -246,6 +246,9 @@ For Neoverse N1, the following errata build flags are defined :
 -  ``ERRATA_N1_1257314``: This applies errata 1257314 workaround to Neoverse-N1
    CPU. This needs to be enabled only for revision <= r3p0 of the CPU.
 
+-  ``ERRATA_N1_1262606``: This applies errata 1262606 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/include/lib/cpus/aarch64/neoverse_n1.h b/include/lib/cpus/aarch64/neoverse_n1.h
index 0e9ddb8fe06f8d27388b1cad79a2f5097f0a0460..8f0ecf2b816e0dd7c03c0152a0736895b9ccaa8c 100644 (file)
--- a/include/lib/cpus/aarch64/neoverse_n1.h
+++ b/include/lib/cpus/aarch64/neoverse_n1.h
@@ -38,6 +38,7 @@
 #define NEOVERSE_N1_CPUACTLR_EL1       S3_0_C15_C1_0
 
 #define NEOVERSE_N1_CPUACTLR_EL1_BIT_6 (ULL(1) << 6)
+#define NEOVERSE_N1_CPUACTLR_EL1_BIT_13        (ULL(1) << 13)
 
 #define NEOVERSE_N1_CPUACTLR2_EL1      S3_0_C15_C1_1
 

diff --git a/lib/cpus/aarch64/neoverse_n1.S b/lib/cpus/aarch64/neoverse_n1.S
index 19b21a57e05d8e1785b8ee995dcab15fb791fae3..60045757307bc5e222ef29b1fbdeb06e296d68eb 100644 (file)
--- a/lib/cpus/aarch64/neoverse_n1.S
+++ b/lib/cpus/aarch64/neoverse_n1.S
@@ -238,6 +238,33 @@ func check_errata_1257314
        b       cpu_rev_var_ls
 endfunc check_errata_1257314
 
+/* --------------------------------------------------
+ * Errata Workaround for Neoverse N1 Errata #1262606
+ * 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_1262606_wa
+       /* Compare x0 against revision r3p0 */
+       mov     x17, x30
+       bl      check_errata_1262606
+       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_1262606_wa
+
+func check_errata_1262606
+       /* Applies to <=r3p0 */
+       mov     x1, #0x30
+       b       cpu_rev_var_ls
+endfunc check_errata_1262606
+
 /* --------------------------------------------------
  * Errata Workaround for Neoverse N1 Erratum 1315703.
  * This applies to revision <= r3p0 of Neoverse N1.
@@ -316,6 +343,11 @@ func neoverse_n1_reset_func
        bl      errata_n1_1257314_wa
 #endif
 
+#if ERRATA_N1_1262606
+       mov     x0, x18
+       bl      errata_n1_1262606_wa
+#endif
+
 #if ERRATA_N1_1315703
        mov     x0, x18
        bl      errata_n1_1315703_wa
@@ -384,6 +416,7 @@ func neoverse_n1_errata_report
        report_errata ERRATA_N1_1207823, neoverse_n1, 1207823
        report_errata ERRATA_N1_1220197, neoverse_n1, 1220197
        report_errata ERRATA_N1_1257314, neoverse_n1, 1257314
+       report_errata ERRATA_N1_1262606, neoverse_n1, 1262606
        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 c4769d9e776dd7b77288ad4221a71e54e3045c81..befb45eb0423a1a17f7c37c6b23996057ec628d9 100644 (file)
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -262,6 +262,10 @@ ERRATA_N1_1220197  ?=0
 # only to revision <= r3p0 of the Neoverse N1 cpu.
 ERRATA_N1_1257314      ?=0
 
+# Flag to apply erratum 1262606 workaround during reset. This erratum applies
+# only to revision <= r3p0 of the Neoverse N1 cpu.
+ERRATA_N1_1262606      ?=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
@@ -479,6 +483,10 @@ $(eval $(call add_define,ERRATA_N1_1220197))
 $(eval $(call assert_boolean,ERRATA_N1_1257314))
 $(eval $(call add_define,ERRATA_N1_1257314))
 
+# Process ERRATA_N1_1262606 flag
+$(eval $(call assert_boolean,ERRATA_N1_1262606))
+$(eval $(call add_define,ERRATA_N1_1262606))
+
 # Process ERRATA_N1_1315703 flag
 $(eval $(call assert_boolean,ERRATA_N1_1315703))
 $(eval $(call add_define,ERRATA_N1_1315703))