@@ -27,6 +27,14 @@
ubfx x0, x0, #ID_AA64MMFR1_EL1_HCX_SHIFT, #4
cbz x0, .Lskip_hcrx_\@
mov_q x0, HCRX_HOST_FLAGS
+
+ /* Enable GCS if supported */
+ mrs_s x1, SYS_ID_AA64PFR1_EL1
+ ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
+ cbz x1, .Lset_hcrx_\@
+ orr x0, x0, #HCRX_EL2_GCSEn
+
+.Lset_hcrx_\@:
msr_s SYS_HCRX_EL2, x0
.Lskip_hcrx_\@:
.endm
@@ -191,6 +199,15 @@
orr x0, x0, #HFGxTR_EL2_nPIR_EL1
orr x0, x0, #HFGxTR_EL2_nPIRE0_EL1
+ /* GCS depends on PIE so we don't check it if PIE is absent */
+ mrs_s x1, SYS_ID_AA64PFR1_EL1
+ ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
+ cbz x1, .Lset_fgt_\@
+
+ /* Disable traps of access to GCS registers at EL0 and EL1 */
+ orr x0, x0, #HFGxTR_EL2_nGCS_EL1_MASK
+ orr x0, x0, #HFGxTR_EL2_nGCS_EL0_MASK
+
.Lset_fgt_\@:
msr_s SYS_HFGRTR_EL2, x0
msr_s SYS_HFGWTR_EL2, x0
@@ -204,6 +221,17 @@
.Lskip_fgt_\@:
.endm
+.macro __init_el2_gcs
+ mrs_s x1, SYS_ID_AA64PFR1_EL1
+ ubfx x1, x1, #ID_AA64PFR1_EL1_GCS_SHIFT, #4
+ cbz x1, .Lskip_gcs_\@
+
+ /* Ensure GCS is not enabled when we start trying to do BLs */
+ msr_s SYS_GCSCR_EL1, xzr
+ msr_s SYS_GCSCRE0_EL1, xzr
+.Lskip_gcs_\@:
+.endm
+
.macro __init_el2_nvhe_prepare_eret
mov x0, #INIT_PSTATE_EL1
msr spsr_el2, x0
@@ -229,6 +257,7 @@
__init_el2_nvhe_idregs
__init_el2_cptr
__init_el2_fgt
+ __init_el2_gcs
.endm
#ifndef __KVM_NVHE_HYPERVISOR__
There is a control HCRX_EL2.GCSEn which must be set to allow GCS features to take effect at lower ELs and also fine grained traps for GCS usage at EL0 and EL1. Configure all these to allow GCS usage by EL0 and EL1. We also initialise GCSCR_EL1 and GCSCRE0_EL1 to ensure that we can execute function call instructions without faulting regardless of the state when the kernel is started. Signed-off-by: Mark Brown <broonie@kernel.org> --- arch/arm64/include/asm/el2_setup.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+)