arm64: compat: Add separate CP15 trapping hook

Instead of directly generating an UNDEF when trapping a CP15 access,
let's add a new entry point to that effect (which only generates an
UNDEF for now).

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 8556876..f0a0464 100644 (file)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -697,9 +697,9 @@ el0_sync_compat:
        cmp     x24, #ESR_ELx_EC_UNKNOWN        // unknown exception in EL0
        b.eq    el0_undef
        cmp     x24, #ESR_ELx_EC_CP15_32        // CP15 MRC/MCR trap
-       b.eq    el0_undef
+       b.eq    el0_cp15
        cmp     x24, #ESR_ELx_EC_CP15_64        // CP15 MRRC/MCRR trap
-       b.eq    el0_undef
+       b.eq    el0_cp15
        cmp     x24, #ESR_ELx_EC_CP14_MR        // CP14 MRC/MCR trap
        b.eq    el0_undef
        cmp     x24, #ESR_ELx_EC_CP14_LS        // CP14 LDC/STC trap
@@ -722,6 +722,17 @@ el0_irq_compat:
 el0_error_compat:
        kernel_entry 0, 32
        b       el0_error_naked
+
+el0_cp15:
+       /*
+        * Trapped CP15 (MRC, MCR, MRRC, MCRR) instructions
+        */
+       enable_daif
+       ct_user_exit
+       mov     x0, x25
+       mov     x1, sp
+       bl      do_cp15instr
+       b       ret_to_user
 #endif
 
 el0_da:

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 21689c6..0e26659 100644 (file)
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -547,6 +547,19 @@ static struct sys64_hook sys64_hooks[] = {
        {},
 };
 
+
+#ifdef CONFIG_COMPAT
+asmlinkage void __exception do_cp15instr(unsigned int esr, struct pt_regs *regs)
+{
+       /*
+        * New cp15 instructions may previously have been undefined at
+        * EL0. Fall back to our usual undefined instruction handler
+        * so that we handle these consistently.
+        */
+       do_undefinstr(regs);
+}
+#endif
+
 asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
 {
        struct sys64_hook *hook;