diff options
| author | Alexei Fedorov <Alexei.Fedorov@arm.com> | 2019-05-24 12:17:09 +0100 |
|---|---|---|
| committer | Alexei Fedorov <Alexei.Fedorov@arm.com> | 2019-05-24 14:44:45 +0100 |
| commit | 9fc59639e649f614318f78ae2ca103fe102405ec (patch) | |
| tree | dc3edbb0a38dcc6b033c088dbaa156cfec653baa /make_helpers | |
| parent | ced1711297347f24fee45e75e73c7767507a0982 (diff) | |
Add support for Branch Target Identification
This patch adds the functionality needed for platforms to provide
Branch Target Identification (BTI) extension, introduced to AArch64
in Armv8.5-A by adding BTI instruction used to mark valid targets
for indirect branches. The patch sets new GP bit [50] to the stage 1
Translation Table Block and Page entries to denote guarded EL3 code
pages which will cause processor to trap instructions in protected
pages trying to perform an indirect branch to any instruction other
than BTI.
BTI feature is selected by BRANCH_PROTECTION option which supersedes
the previous ENABLE_PAUTH used for Armv8.3-A Pointer Authentication
and is disabled by default. Enabling BTI requires compiler support
and was tested with GCC versions 9.0.0, 9.0.1 and 10.0.0.
The assembly macros and helpers are modified to accommodate the BTI
instruction.
This is an experimental feature.
Note. The previous ENABLE_PAUTH build option to enable PAuth in EL3
is now made as an internal flag and BRANCH_PROTECTION flag should be
used instead to enable Pointer Authentication.
Note. USE_LIBROM=1 option is currently not supported.
Change-Id: Ifaf4438609b16647dc79468b70cd1f47a623362e
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Diffstat (limited to 'make_helpers')
| -rw-r--r-- | make_helpers/defaults.mk | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk index dc797ed1..6becf808 100644 --- a/make_helpers/defaults.mk +++ b/make_helpers/defaults.mk @@ -33,6 +33,9 @@ BL2_AT_EL3 := 0 # when BL2_AT_EL3 is 1. BL2_IN_XIP_MEM := 0 +# Select the branch protection features to use. +BRANCH_PROTECTION := 0 + # By default, consider that the platform may release several CPUs out of reset. # The platform Makefile is free to override this value. COLD_BOOT_SINGLE_CPU := 0 @@ -90,7 +93,14 @@ ENABLE_STACK_PROTECTOR := 0 # Flag to enable exception handling in EL3 EL3_EXCEPTION_HANDLING := 0 -# Flag to enable Pointer Authentication +# Flag to enable Branch Target Identification. +# Internal flag not meant for direct setting. +# Use BRANCH_PROTECTION to enable BTI. +ENABLE_BTI := 0 + +# Flag to enable Pointer Authentication. +# Internal flag not meant for direct setting. +# Use BRANCH_PROTECTION to enable PAUTH. ENABLE_PAUTH := 0 # Build flag to treat usage of deprecated platform and framework APIs as error. |