arm64: Refactor sysinstr exception handling

Right now we trap some of the user space data cache operations
based on a few Errata (ARM 819472, 826319, 827319 and 824069).
We need to trap userspace access to CTR_EL0, if we detect mismatched
cache line size. Since both these traps share the EC, refactor
the handler a little bit to make it a bit more reader friendly.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/esr.h

@@ -78,6 +78,23 @@
 
 #define ESR_ELx_IL		(UL(1) << 25)
 #define ESR_ELx_ISS_MASK	(ESR_ELx_IL - 1)
+
+/* ISS field definitions shared by different classes */
+#define ESR_ELx_WNR		(UL(1) << 6)
+
+/* Shared ISS field definitions for Data/Instruction aborts */
+#define ESR_ELx_EA		(UL(1) << 9)
+#define ESR_ELx_S1PTW		(UL(1) << 7)
+
+/* Shared ISS fault status code(IFSC/DFSC) for Data/Instruction aborts */
+#define ESR_ELx_FSC		(0x3F)
+#define ESR_ELx_FSC_TYPE	(0x3C)
+#define ESR_ELx_FSC_EXTABT	(0x10)
+#define ESR_ELx_FSC_ACCESS	(0x08)
+#define ESR_ELx_FSC_FAULT	(0x04)
+#define ESR_ELx_FSC_PERM	(0x0C)
+
+/* ISS field definitions for Data Aborts */
 #define ESR_ELx_ISV		(UL(1) << 24)
 #define ESR_ELx_SAS_SHIFT	(22)
 #define ESR_ELx_SAS		(UL(3) << ESR_ELx_SAS_SHIFT)
@@ -86,16 +103,9 @@
 #define ESR_ELx_SRT_MASK	(UL(0x1F) << ESR_ELx_SRT_SHIFT)
 #define ESR_ELx_SF 		(UL(1) << 15)
 #define ESR_ELx_AR 		(UL(1) << 14)
-#define ESR_ELx_EA 		(UL(1) << 9)
 #define ESR_ELx_CM 		(UL(1) << 8)
-#define ESR_ELx_S1PTW 		(UL(1) << 7)
-#define ESR_ELx_WNR		(UL(1) << 6)
-#define ESR_ELx_FSC		(0x3F)
-#define ESR_ELx_FSC_TYPE	(0x3C)
-#define ESR_ELx_FSC_EXTABT	(0x10)
-#define ESR_ELx_FSC_ACCESS	(0x08)
-#define ESR_ELx_FSC_FAULT	(0x04)
-#define ESR_ELx_FSC_PERM	(0x0C)
+
+/* ISS field definitions for exceptions taken in to Hyp */
 #define ESR_ELx_CV		(UL(1) << 24)
 #define ESR_ELx_COND_SHIFT	(20)
 #define ESR_ELx_COND_MASK	(UL(0xF) << ESR_ELx_COND_SHIFT)
@@ -109,6 +119,54 @@
 	((ESR_ELx_EC_BRK64 << ESR_ELx_EC_SHIFT) | ESR_ELx_IL |	\
 	 ((imm) & 0xffff))
 
+/* ISS field definitions for System instruction traps */
+#define ESR_ELx_SYS64_ISS_RES0_SHIFT	22
+#define ESR_ELx_SYS64_ISS_RES0_MASK	(UL(0x7) << ESR_ELx_SYS64_ISS_RES0_SHIFT)
+#define ESR_ELx_SYS64_ISS_DIR_MASK	0x1
+#define ESR_ELx_SYS64_ISS_DIR_READ	0x1
+#define ESR_ELx_SYS64_ISS_DIR_WRITE	0x0
+
+#define ESR_ELx_SYS64_ISS_RT_SHIFT	5
+#define ESR_ELx_SYS64_ISS_RT_MASK	(UL(0x1f) << ESR_ELx_SYS64_ISS_RT_SHIFT)
+#define ESR_ELx_SYS64_ISS_CRM_SHIFT	1
+#define ESR_ELx_SYS64_ISS_CRM_MASK	(UL(0xf) << ESR_ELx_SYS64_ISS_CRM_SHIFT)
+#define ESR_ELx_SYS64_ISS_CRN_SHIFT	10
+#define ESR_ELx_SYS64_ISS_CRN_MASK	(UL(0xf) << ESR_ELx_SYS64_ISS_CRN_SHIFT)
+#define ESR_ELx_SYS64_ISS_OP1_SHIFT	14
+#define ESR_ELx_SYS64_ISS_OP1_MASK	(UL(0x7) << ESR_ELx_SYS64_ISS_OP1_SHIFT)
+#define ESR_ELx_SYS64_ISS_OP2_SHIFT	17
+#define ESR_ELx_SYS64_ISS_OP2_MASK	(UL(0x7) << ESR_ELx_SYS64_ISS_OP2_SHIFT)
+#define ESR_ELx_SYS64_ISS_OP0_SHIFT	20
+#define ESR_ELx_SYS64_ISS_OP0_MASK	(UL(0x3) << ESR_ELx_SYS64_ISS_OP0_SHIFT)
+#define ESR_ELx_SYS64_ISS_SYS_MASK	(ESR_ELx_SYS64_ISS_OP0_MASK | \
+					 ESR_ELx_SYS64_ISS_OP1_MASK | \
+					 ESR_ELx_SYS64_ISS_OP2_MASK | \
+					 ESR_ELx_SYS64_ISS_CRN_MASK | \
+					 ESR_ELx_SYS64_ISS_CRM_MASK)
+#define ESR_ELx_SYS64_ISS_SYS_VAL(op0, op1, op2, crn, crm) \
+					(((op0) << ESR_ELx_SYS64_ISS_OP0_SHIFT) | \
+					 ((op1) << ESR_ELx_SYS64_ISS_OP1_SHIFT) | \
+					 ((op2) << ESR_ELx_SYS64_ISS_OP2_SHIFT) | \
+					 ((crn) << ESR_ELx_SYS64_ISS_CRN_SHIFT) | \
+					 ((crm) << ESR_ELx_SYS64_ISS_CRM_SHIFT))
+/*
+ * User space cache operations have the following sysreg encoding
+ * in System instructions.
+ * op0=1, op1=3, op2=1, crn=7, crm={ 5, 10, 11, 14 }, WRITE (L=0)
+ */
+#define ESR_ELx_SYS64_ISS_CRM_DC_CIVAC	14
+#define ESR_ELx_SYS64_ISS_CRM_DC_CVAU	11
+#define ESR_ELx_SYS64_ISS_CRM_DC_CVAC	10
+#define ESR_ELx_SYS64_ISS_CRM_IC_IVAU	5
+
+#define ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK	(ESR_ELx_SYS64_ISS_OP0_MASK | \
+						 ESR_ELx_SYS64_ISS_OP1_MASK | \
+						 ESR_ELx_SYS64_ISS_OP2_MASK | \
+						 ESR_ELx_SYS64_ISS_CRN_MASK | \
+						 ESR_ELx_SYS64_ISS_DIR_MASK)
+#define ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL \
+				(ESR_ELx_SYS64_ISS_SYS_VAL(1, 3, 1, 7, 0) | \
+				 ESR_ELx_SYS64_ISS_DIR_WRITE)
 #ifndef __ASSEMBLY__
 #include <asm/types.h>
 

arch/arm64/kernel/traps.c

@@ -447,39 +447,32 @@ void cpu_enable_cache_maint_trap(void *__unused)
 		: "=r" (res)					\
 		: "r" (address), "i" (-EFAULT) )
 
-asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
+static void user_cache_maint_handler(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;
+	int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;
+	int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT;
+	int ret = 0;
 
 	address = (rt == 31) ? 0 : regs->regs[rt];
 
 	switch (crm) {
-		case 11:		/* DC CVAU, gets promoted */
+	case ESR_ELx_SYS64_ISS_CRM_DC_CVAU:	/* DC CVAU, gets promoted */
 		__user_cache_maint("dc civac", address, ret);
 		break;
-		case 10:		/* DC CVAC, gets promoted */
+	case ESR_ELx_SYS64_ISS_CRM_DC_CVAC:	/* DC CVAC, gets promoted */
 		__user_cache_maint("dc civac", address, ret);
 		break;
-		case 14:		/* DC CIVAC */
+	case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC:	/* DC CIVAC */
 		__user_cache_maint("dc civac", address, ret);
 		break;
-		case 5:			/* IC IVAU */
+	case ESR_ELx_SYS64_ISS_CRM_IC_IVAU:	/* 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);
@@ -487,6 +480,34 @@ asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
 		regs->pc += 4;
 }
 
+struct sys64_hook {
+	unsigned int esr_mask;
+	unsigned int esr_val;
+	void (*handler)(unsigned int esr, struct pt_regs *regs);
+};
+
+static struct sys64_hook sys64_hooks[] = {
+	{
+		.esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK,
+		.esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL,
+		.handler = user_cache_maint_handler,
+	},
+	{},
+};
+
+asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
+{
+	struct sys64_hook *hook;
+
+	for (hook = sys64_hooks; hook->handler; hook++)
+		if ((hook->esr_mask & esr) == hook->esr_val) {
+			hook->handler(esr, regs);
+			return;
+		}
+
+	force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
+}
+
 long compat_arm_syscall(struct pt_regs *regs);
 
 asmlinkage long do_ni_syscall(struct pt_regs *regs)