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>

1 files changed, 47 insertions, 26 deletions

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index e04f83873af7..224f64eddd93 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -447,36 +447,29 @@ 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;
+        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;
 
-        /* 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];
 
-                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 {
+        switch (crm) {
+        case ESR_ELx_SYS64_ISS_CRM_DC_CVAU:     /* DC CVAU, gets promoted */
+                __user_cache_maint("dc civac", address, ret);
+                break;
+        case ESR_ELx_SYS64_ISS_CRM_DC_CVAC:     /* DC CVAC, gets promoted */
+                __user_cache_maint("dc civac", address, ret);
+                break;
+        case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC:    /* DC CIVAC */
+                __user_cache_maint("dc civac", address, ret);
+                break;
+        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;
         }
@@ -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)