|author||Antonio Nino Diaz <firstname.lastname@example.org>||2019-02-12 11:25:02 +0000|
|committer||Antonio Nino Diaz <email@example.com>||2019-02-14 14:43:43 +0000|
Update macro to check need for CVE-2017-5715 mitigation
Armv8.5 introduces the field CSV2 to register ID_AA64PFR0_EL1. It can have the following 3 values: - 0: Branch targets trained in one hardware described context may affect speculative execution in a different hardware described context. In some CPUs it may be needed to apply mitigations. - 1: Branch targets trained in one hardware described context can only affect speculative execution in a different hardware described context in a hard-to-determine way. No mitigation required. - 2: Same as 1, but the device is also aware of SCXTNUM_ELx register contexts. The TF doesn't use the registers, so there is no difference with 1. The field CSV2 was originally introduced in the TRM of the Cortex-A76 before the release of the Armv8.5 architecture. That TRM only mentions the meaning of values 0 and 1. Because of this, the code only checks if the field has value 1 to know whether to enable or disable the mitigations. This patch makes it aware of value 2 as well. Both values 1 and 2 disable the mitigation, and 0 enables it. Change-Id: I5af33de25a0197c98173f52c6c8c77b51a51429f Signed-off-by: Antonio Nino Diaz <firstname.lastname@example.org>
Diffstat (limited to 'include')
1 files changed, 17 insertions, 5 deletions
diff --git a/include/lib/cpus/aarch64/cpu_macros.S b/include/lib/cpus/aarch64/cpu_macros.S
index b907668b3b..044aacaf41 100644
@@ -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_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
+ cmp \_reg, #3 /* Only values 0 to 2 are expected */
+ cmp \_reg, #0
+ bne \_label