[PATCH] arm64: Disable fine grained traps on boot

[Mark Brown]

The arm64 FEAT_FGT extension introduces a set of traps to EL2 for accesses
to small sets of registers and instructions from EL1 and EL0.  Currently
Linux makes no use of this feature, ensure that it is not active at boot by
disabling the traps during EL2 setup.

Signed-off-by: Mark Brown <broonie at kernel.org>
---
 arch/arm64/include/asm/el2_setup.h | 21 +++++++++++++++++++++
 arch/arm64/include/asm/sysreg.h    |  6 ++++++
 2 files changed, 27 insertions(+)

diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index d77d358f9395..f94ef3a76877 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -131,6 +131,26 @@
 .Lskip_sve_\@:
 .endm
 
+/* Disable any fine grained traps */
+.macro __init_el2_fgt
+	mrs	x1, id_aa64mmfr0_el1
+	ubfx	x1, x1, #ID_AA64MMFR0_FGT_SHIFT, #4
+	cbz	x1, .Lskip_fgt_\@
+
+	msr_s	SYS_HDFGRTR_EL2, xzr
+	msr_s	SYS_HDFGWTR_EL2, xzr
+	msr_s	SYS_HFGRTR_EL2, xzr
+	msr_s	SYS_HFGITR_EL2, xzr
+	msr_s	SYS_HFGWTR_EL2, xzr
+
+	mrs	x1, id_aa64pfr0_el1		// AMU traps UNDEF without AMU
+	ubfx	x1, x1, #ID_AA64PFR0_AMU_SHIFT, #4
+	cbz	x1, .Lskip_fgt_\@
+
+	msr_s	SYS_HAFGRTR_EL2, xzr
+.Lskip_fgt_\@:
+.endm
+
 .macro __init_el2_nvhe_prepare_eret
 	mov	x0, #INIT_PSTATE_EL1
 	msr	spsr_el2, x0
@@ -155,6 +175,7 @@
 	__init_el2_nvhe_idregs
 	__init_el2_nvhe_cptr
 	__init_el2_nvhe_sve
+	__init_el2_fgt
 	__init_el2_nvhe_prepare_eret
 .endm
 
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index d4a5fca984c3..b35468927363 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -475,9 +475,15 @@
 #define SYS_PMCCFILTR_EL0		sys_reg(3, 3, 14, 15, 7)
 
 #define SYS_SCTLR_EL2			sys_reg(3, 4, 1, 0, 0)
+#define SYS_HFGRTR_EL2			sys_reg(3, 4, 1, 1, 4)
+#define SYS_HFGWTR_EL2			sys_reg(3, 4, 1, 1, 5)
+#define SYS_HFGITR_EL2			sys_reg(3, 4, 1, 1, 6)
 #define SYS_ZCR_EL2			sys_reg(3, 4, 1, 2, 0)
 #define SYS_TRFCR_EL2			sys_reg(3, 4, 1, 2, 1)
 #define SYS_DACR32_EL2			sys_reg(3, 4, 3, 0, 0)
+#define SYS_HDFGRTR_EL2			sys_reg(3, 4, 3, 1, 4)
+#define SYS_HDFGWTR_EL2			sys_reg(3, 4, 3, 1, 5)
+#define SYS_HAFGRTR_EL2			sys_reg(3, 4, 3, 1, 6)
 #define SYS_SPSR_EL2			sys_reg(3, 4, 4, 0, 0)
 #define SYS_ELR_EL2			sys_reg(3, 4, 4, 0, 1)
 #define SYS_IFSR32_EL2			sys_reg(3, 4, 5, 0, 1)
-- 
2.20.1