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[14/35] arm64: Disable traps for GCS usage at EL0 and EL1

Message ID 20230716-arm64-gcs-v1-14-bf567f93bba6@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64/gcs: Provide support for GCS at EL0 | expand

Commit Message

Mark Brown July 16, 2023, 9:51 p.m. UTC 
There are fine grained traps for GCS usage at EL0 and EL1, disable them
for the host kernel if we detect GCS.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/include/asm/el2_setup.h | 9 +++++++++
 1 file changed, 9 insertions(+)
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Patch

diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index 8e5ffb58f83e..c941b0dc0418 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -186,6 +186,15 @@ 
 	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