5 files changed, 75 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index cef1cf398356..ace0a96e7d6e 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -192,5 +192,6 @@ static inline void spin_lock_prefetch(const void *ptr)
 
 void cpu_enable_pan(void *__unused);
 void cpu_enable_uao(void *__unused);
+void cpu_enable_cache_maint_trap(void *__unused);
 
 #endif /* __ASM_PROCESSOR_H */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index 751e901c8d37..cc06794b7346 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -98,11 +98,11 @@
 			 SCTLR_ELx_SA | SCTLR_ELx_I)
 
 /* SCTLR_EL1 specific flags. */
+#define SCTLR_EL1_UCI		(1 << 26)
 #define SCTLR_EL1_SPAN		(1 << 23)
 #define SCTLR_EL1_SED		(1 << 8)
 #define SCTLR_EL1_CP15BEN	(1 << 5)
 
-
 /* id_aa64isar0 */
 #define ID_AA64ISAR0_RDM_SHIFT		28
 #define ID_AA64ISAR0_ATOMICS_SHIFT	20
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index c2261a7a316e..af647d2cee22 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -46,6 +46,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.desc = "ARM errata 826319, 827319, 824069",
 		.capability = ARM64_WORKAROUND_CLEAN_CACHE,
 		MIDR_RANGE(MIDR_CORTEX_A53, 0x00, 0x02),
+		.enable = cpu_enable_cache_maint_trap,
 	},
 #endif
 #ifdef CONFIG_ARM64_ERRATUM_819472
@@ -54,6 +55,7 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 		.desc = "ARM errata 819472",
 		.capability = ARM64_WORKAROUND_CLEAN_CACHE,
 		MIDR_RANGE(MIDR_CORTEX_A53, 0x00, 0x01),
+		.enable = cpu_enable_cache_maint_trap,
 	},
 #endif
 #ifdef CONFIG_ARM64_ERRATUM_832075
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index eefffa81c6df..3eca5d34f7a6 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -451,7 +451,7 @@ el0_sync:
 	cmp	x24, #ESR_ELx_EC_FP_EXC64	// FP/ASIMD exception
 	b.eq	el0_fpsimd_exc
 	cmp	x24, #ESR_ELx_EC_SYS64		// configurable trap
-	b.eq	el0_undef
+	b.eq	el0_sys
 	cmp	x24, #ESR_ELx_EC_SP_ALIGN	// stack alignment exception
 	b.eq	el0_sp_pc
 	cmp	x24, #ESR_ELx_EC_PC_ALIGN	// pc alignment exception
@@ -579,6 +579,16 @@ el0_undef:
 	mov	x0, sp
 	bl	do_undefinstr
 	b	ret_to_user
+el0_sys:
+	/*
+	 * System instructions, for trapped cache maintenance instructions
+	 */
+	enable_dbg_and_irq
+	ct_user_exit
+	mov	x0, x25
+	mov	x1, sp
+	bl	do_sysinstr
+	b	ret_to_user
 el0_dbg:
 	/*
 	 * Debug exception handling
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index d8a5366dcc24..e04f83873af7 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -41,6 +41,7 @@
 #include <asm/stacktrace.h>
 #include <asm/exception.h>
 #include <asm/system_misc.h>
+#include <asm/sysreg.h>
 
 static const char *handler[]= {
 	"Synchronous Abort",
@@ -427,6 +428,65 @@ asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 	force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
 }
 
+void cpu_enable_cache_maint_trap(void *__unused)
+{
+	config_sctlr_el1(SCTLR_EL1_UCI, 0);
+}
+
+#define __user_cache_maint(insn, address, res)			\
+	asm volatile (						\
+		"1:	" insn ", %1\n"				\
+		"	mov	%w0, #0\n"			\
+		"2:\n"						\
+		"	.pushsection .fixup,\"ax\"\n"		\
+		"	.align	2\n"				\
+		"3:	mov	%w0, %w2\n"			\
+		"	b	2b\n"				\
+		"	.popsection\n"				\
+		_ASM_EXTABLE(1b, 3b)				\
+		: "=r" (res)					\
+		: "r" (address), "i" (-EFAULT) )
+
+asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
+{
+	unsigned long address;
+	int ret;
+
+	/* if this is a write with: Op0=1, Op2=1, Op1=3, CRn=7 */
+	if ((esr & 0x01fffc01) == 0x0012dc00) {
+		int rt = (esr >> 5) & 0x1f;
+		int crm = (esr >> 1) & 0x0f;
+
+		address = (rt == 31) ? 0 : regs->regs[rt];
+
+		switch (crm) {
+		case 11:		/* DC CVAU, gets promoted */
+			__user_cache_maint("dc civac", address, ret);
+			break;
+		case 10:		/* DC CVAC, gets promoted */
+			__user_cache_maint("dc civac", address, ret);
+			break;
+		case 14:		/* DC CIVAC */
+			__user_cache_maint("dc civac", address, ret);
+			break;
+		case 5:			/* IC IVAU */
+			__user_cache_maint("ic ivau", address, ret);
+			break;
+		default:
+			force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
+			return;
+		}
+	} else {
+		force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
+		return;
+	}
+
+	if (ret)
+		arm64_notify_segfault(regs, address);
+	else
+		regs->pc += 4;
+}
+
 long compat_arm_syscall(struct pt_regs *regs);
 
 asmlinkage long do_ni_syscall(struct pt_regs *regs)