Workaround for Cortex A77 erratum 1925769

Cortex A77 erratum 1925769 is a Cat B erratum, present in older
revisions of the Cortex A77 processor core.  The workaround is to
set bit 8 in the ECTLR_EL1 register, there is a small performance cost
(<0.5%) for setting this bit.

SDEN can be found here:
https://documentation-service.arm.com/static/5f7c35d0d3be967f7be46d33

Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I9cf0e0b5dc1e3e32e24279d2632c759cc7bd7ce9

diff --git a/docs/design/cpu-specific-build-macros.rst b/docs/design/cpu-specific-build-macros.rst
index 8152c00d588d14601fa515ab0e9714938af38028..c976b8b3a9aee8bdf19a881e6aeeb13b722511f4 100644 (file)
--- a/docs/design/cpu-specific-build-macros.rst
+++ b/docs/design/cpu-specific-build-macros.rst
@@ -260,6 +260,9 @@ For Cortex-A77, the following errata build flags are defined :
 -  ``ERRATA_A77_1800714``: This applies errata 1800714 workaround to Cortex-A77
    CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
 
+-  ``ERRATA_A77_1925769``: This applies errata 1925769 workaround to Cortex-A77
+   CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
+
 For Cortex-A78, the following errata build flags are defined :
 
 -  ``ERRATA_A78_1688305``: This applies errata 1688305 workaround to Cortex-A78

diff --git a/include/lib/cpus/aarch64/cortex_a77.h b/include/lib/cpus/aarch64/cortex_a77.h
index 41aced8d289478ffee6572ab034b0daef017359d..ed84c0f4a17112cdfe047d7d871607cbaf24e189 100644 (file)
--- a/include/lib/cpus/aarch64/cortex_a77.h
+++ b/include/lib/cpus/aarch64/cortex_a77.h
@@ -16,6 +16,7 @@
  * CPU Extended Control register specific definitions.
  ******************************************************************************/
 #define CORTEX_A77_CPUECTLR_EL1                                S3_0_C15_C1_4
+#define CORTEX_A77_CPUECTLR_EL1_BIT_8                  (ULL(1) << 8)
 #define CORTEX_A77_CPUECTLR_EL1_BIT_53                 (ULL(1) << 53)
 
 /*******************************************************************************

diff --git a/lib/cpus/aarch64/cortex_a77.S b/lib/cpus/aarch64/cortex_a77.S
index ea219998f4c408fc4cdc076439d01bc1929821c2..04a610e495ed7d9b70757447c1290be27ee00290 100644 (file)
--- a/lib/cpus/aarch64/cortex_a77.S
+++ b/lib/cpus/aarch64/cortex_a77.S
@@ -114,6 +114,35 @@ func check_errata_1800714
        b       cpu_rev_var_ls
 endfunc check_errata_1800714
 
+       /* --------------------------------------------------
+        * Errata Workaround for Cortex A77 Errata #1925769.
+        * This applies to revision <= r1p1 of Cortex A77.
+        * Inputs:
+        * x0: variant[4:7] and revision[0:3] of current cpu.
+        * Shall clobber: x0-x17
+        * --------------------------------------------------
+        */
+func errata_a77_1925769_wa
+       /* Compare x0 against revision <= r1p1 */
+       mov     x17, x30
+       bl      check_errata_1925769
+       cbz     x0, 1f
+
+       /* Set bit 8 in ECTLR_EL1 */
+       mrs     x1, CORTEX_A77_CPUECTLR_EL1
+       orr     x1, x1, #CORTEX_A77_CPUECTLR_EL1_BIT_8
+       msr     CORTEX_A77_CPUECTLR_EL1, x1
+       isb
+1:
+       ret     x17
+endfunc errata_a77_1925769_wa
+
+func check_errata_1925769
+       /* Applies to everything <= r1p1 */
+       mov     x1, #0x11
+       b       cpu_rev_var_ls
+endfunc check_errata_1925769
+
        /* -------------------------------------------------
         * The CPU Ops reset function for Cortex-A77.
         * Shall clobber: x0-x19
@@ -134,6 +163,11 @@ func cortex_a77_reset_func
        bl      errata_a77_1800714_wa
 #endif
 
+#if ERRATA_A77_1925769
+       mov     x0, x18
+       bl      errata_a77_1925769_wa
+#endif
+
        ret     x19
 endfunc cortex_a77_reset_func
 
@@ -169,6 +203,7 @@ func cortex_a77_errata_report
         */
        report_errata ERRATA_A77_1508412, cortex_a77, 1508412
        report_errata ERRATA_A77_1800714, cortex_a77, 1800714
+       report_errata ERRATA_A77_1925769, cortex_a77, 1925769
 
        ldp     x8, x30, [sp], #16
        ret

diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 925ed5f08ac561b8eafee03b439d34cfe87262e0..12105388ffd20f341abd69478f8dfd3c07498fc6 100644 (file)
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -290,6 +290,10 @@ ERRATA_A77_1508412 ?=0
 # only to revision <= r1p1 of the Cortex A77 cpu.
 ERRATA_A77_1800714     ?=0
 
+# Flag to apply erratum 1925769 workaround during reset. This erratum applies
+# only to revision <= r1p1 of the Cortex A77 cpu.
+ERRATA_A77_1925769     ?=0
+
 # Flag to apply erratum 1688305 workaround during reset. This erratum applies
 # to revisions r0p0 - r1p0 of the A78 cpu.
 ERRATA_A78_1688305     ?=0
@@ -571,6 +575,10 @@ $(eval $(call add_define,ERRATA_A77_1508412))
 $(eval $(call assert_boolean,ERRATA_A77_1800714))
 $(eval $(call add_define,ERRATA_A77_1800714))
 
+# Process ERRATA_A77_1925769 flag
+$(eval $(call assert_boolean,ERRATA_A77_1925769))
+$(eval $(call add_define,ERRATA_A77_1925769))
+
 # Process ERRATA_A78_1688305 flag
 $(eval $(call assert_boolean,ERRATA_A78_1688305))
 $(eval $(call add_define,ERRATA_A78_1688305))