Merge pull request #1825 from antonio-nino-diaz-arm/an/csv2
Update macro to check need for CVE-2017-5715 mitigation
diff --git a/include/lib/cpus/aarch64/cpu_macros.S b/include/lib/cpus/aarch64/cpu_macros.S
index b907668..044aaca 100644
--- a/include/lib/cpus/aarch64/cpu_macros.S
+++ b/include/lib/cpus/aarch64/cpu_macros.S
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2019, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -7,6 +7,7 @@
#define CPU_MACROS_S
#include <arch.h>
+#include <assert_macros.S>
#include <lib/cpus/errata_report.h>
#define CPU_IMPL_PN_MASK (MIDR_IMPL_MASK << MIDR_IMPL_SHIFT) | \
@@ -263,11 +264,22 @@
mrs \_reg, id_aa64pfr0_el1
ubfx \_reg, \_reg, #ID_AA64PFR0_CSV2_SHIFT, #ID_AA64PFR0_CSV2_LENGTH
/*
- * If the field equals to 1 then branch targets trained in one
- * context cannot affect speculative execution in a different context.
+ * If the field equals 1, branch targets trained in one context cannot
+ * affect speculative execution in a different context.
+ *
+ * If the field equals 2, it means that the system is also aware of
+ * SCXTNUM_ELx register contexts. We aren't using them in the TF, so we
+ * expect users of the registers to do the right thing.
+ *
+ * Only apply mitigations if the value of this field is 0.
*/
- cmp \_reg, #1
- beq \_label
+#if ENABLE_ASSERTIONS
+ cmp \_reg, #3 /* Only values 0 to 2 are expected */
+ ASM_ASSERT(lo)
+#endif
+
+ cmp \_reg, #0
+ bne \_label
.endm
/*