arm64: add comments about EC exception levels

To make it clear which exceptions can't be taken to EL1 or EL2, add
comments next to the ESR_ELx_EC_* macro definitions.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/esr.h

@@ -29,23 +29,23 @@
 #define ESR_ELx_EC_CP14_MR	(0x05)
 #define ESR_ELx_EC_CP14_LS	(0x06)
 #define ESR_ELx_EC_FP_ASIMD	(0x07)
-#define ESR_ELx_EC_CP10_ID	(0x08)
+#define ESR_ELx_EC_CP10_ID	(0x08)	/* EL2 only */
 /* Unallocated EC: 0x09 - 0x0B */
 #define ESR_ELx_EC_CP14_64	(0x0C)
 /* Unallocated EC: 0x0d */
 #define ESR_ELx_EC_ILL		(0x0E)
 /* Unallocated EC: 0x0F - 0x10 */
 #define ESR_ELx_EC_SVC32	(0x11)
-#define ESR_ELx_EC_HVC32	(0x12)
-#define ESR_ELx_EC_SMC32	(0x13)
+#define ESR_ELx_EC_HVC32	(0x12)	/* EL2 only */
+#define ESR_ELx_EC_SMC32	(0x13)	/* EL2 and above */
 /* Unallocated EC: 0x14 */
 #define ESR_ELx_EC_SVC64	(0x15)
-#define ESR_ELx_EC_HVC64	(0x16)
-#define ESR_ELx_EC_SMC64	(0x17)
+#define ESR_ELx_EC_HVC64	(0x16)	/* EL2 and above */
+#define ESR_ELx_EC_SMC64	(0x17)	/* EL2 and above */
 #define ESR_ELx_EC_SYS64	(0x18)
 #define ESR_ELx_EC_SVE		(0x19)
 /* Unallocated EC: 0x1A - 0x1E */
-#define ESR_ELx_EC_IMP_DEF	(0x1f)
+#define ESR_ELx_EC_IMP_DEF	(0x1f)	/* EL3 only */
 #define ESR_ELx_EC_IABT_LOW	(0x20)
 #define ESR_ELx_EC_IABT_CUR	(0x21)
 #define ESR_ELx_EC_PC_ALIGN	(0x22)
@@ -68,7 +68,7 @@
 /* Unallocated EC: 0x36 - 0x37 */
 #define ESR_ELx_EC_BKPT32	(0x38)
 /* Unallocated EC: 0x39 */
-#define ESR_ELx_EC_VECTOR32	(0x3A)
+#define ESR_ELx_EC_VECTOR32	(0x3A)	/* EL2 only */
 /* Unallocted EC: 0x3B */
 #define ESR_ELx_EC_BRK64	(0x3C)
 /* Unallocated EC: 0x3D - 0x3F */