Workaround for CVE-2017-5715 on Cortex A57 and A72
Invalidate the Branch Target Buffer (BTB) on entry to EL3 by disabling
and enabling the MMU. To achieve this without performing any branch
instruction, a per-cpu vbar is installed which executes the workaround
and then branches off to the corresponding vector entry in the main
vector table. A side effect of this change is that the main vbar is
configured before any reset handling. This is to allow the per-cpu
reset function to override the vbar setting.
This workaround is enabled by default on the affected CPUs.
Change-Id: I97788d38463a5840a410e3cea85ed297a1678265
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
diff --git a/lib/cpus/cpu-ops.mk b/lib/cpus/cpu-ops.mk
index 31adfb4..3ba8c1f 100644
--- a/lib/cpus/cpu-ops.mk
+++ b/lib/cpus/cpu-ops.mk
@@ -16,6 +16,8 @@
# It is enabled by default.
A57_DISABLE_NON_TEMPORAL_HINT ?=1
+WORKAROUND_CVE_2017_5715 ?=1
+
# Process SKIP_A57_L1_FLUSH_PWR_DWN flag
$(eval $(call assert_boolean,SKIP_A57_L1_FLUSH_PWR_DWN))
$(eval $(call add_define,SKIP_A57_L1_FLUSH_PWR_DWN))
@@ -28,6 +30,9 @@
$(eval $(call assert_boolean,A57_DISABLE_NON_TEMPORAL_HINT))
$(eval $(call add_define,A57_DISABLE_NON_TEMPORAL_HINT))
+# Process WORKAROUND_CVE_2017_5715 flag
+$(eval $(call assert_boolean,WORKAROUND_CVE_2017_5715))
+$(eval $(call add_define,WORKAROUND_CVE_2017_5715))
# CPU Errata Build flags.
# These should be enabled by the platform if the erratum workaround needs to be
