s390/crypto: cpacf function detection

The CPACF code makes some assumptions about the availablity of hardware
support. E.g. if the machine supports KM(AES-256) without chaining it is
assumed that KMC(AES-256) with chaining is available as well. For the
existing CPUs this is true but the architecturally correct way is to
check each CPACF functions on its own. This is what the query function
of each instructions is all about.

Reviewed-by: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 34 insertions, 21 deletions

diff --git a/arch/s390/include/asm/cpacf.h b/arch/s390/include/asm/cpacf.h
index c226c9ba24ac..2c680db7e5c1 100644
--- a/arch/s390/include/asm/cpacf.h
+++ b/arch/s390/include/asm/cpacf.h
@@ -106,6 +106,8 @@
 #define CPACF_PPNO_SHA512_DRNG_GEN	0x03
 #define CPACF_PPNO_SHA512_DRNG_SEED	0x83
 
+typedef struct { unsigned char bytes[16]; } cpacf_mask_t;
+
 /**
  * cpacf_query() - check if a specific CPACF function is available
  * @opcode: the opcode of the crypto instruction
@@ -116,55 +118,66 @@
  *
  * Returns 1 if @func is available for @opcode, 0 otherwise
  */
-static inline void __cpacf_query(unsigned int opcode, unsigned char *status)
+static inline void __cpacf_query(unsigned int opcode, cpacf_mask_t *mask)
 {
-	typedef struct { unsigned char _[16]; } status_type;
 	register unsigned long r0 asm("0") = 0;	/* query function */
-	register unsigned long r1 asm("1") = (unsigned long) status;
+	register unsigned long r1 asm("1") = (unsigned long) mask;
 
 	asm volatile(
 		"	spm 0\n" /* pckmo doesn't change the cc */
 		/* Parameter registers are ignored, but may not be 0 */
 		"0:	.insn	rrf,%[opc] << 16,2,2,2,0\n"
 		"	brc	1,0b\n"	/* handle partial completion */
-		: "=m" (*(status_type *) status)
+		: "=m" (*mask)
 		: [fc] "d" (r0), [pba] "a" (r1), [opc] "i" (opcode)
 		: "cc");
 }
 
-static inline int cpacf_query(unsigned int opcode, unsigned int func)
+static inline int __cpacf_check_opcode(unsigned int opcode)
 {
-	unsigned char status[16];
-
 	switch (opcode) {
 	case CPACF_KMAC:
 	case CPACF_KM:
 	case CPACF_KMC:
 	case CPACF_KIMD:
 	case CPACF_KLMD:
-		if (!test_facility(17))	/* check for MSA */
-			return 0;
-		break;
+		return test_facility(17);	/* check for MSA */
 	case CPACF_PCKMO:
-		if (!test_facility(76))	/* check for MSA3 */
-			return 0;
-		break;
+		return test_facility(76);	/* check for MSA3 */
 	case CPACF_KMF:
 	case CPACF_KMO:
 	case CPACF_PCC:
 	case CPACF_KMCTR:
-		if (!test_facility(77))	/* check for MSA4 */
-			return 0;
-		break;
+		return test_facility(77);	/* check for MSA4 */
 	case CPACF_PPNO:
-		if (!test_facility(57))	/* check for MSA5 */
-			return 0;
-		break;
+		return test_facility(57);	/* check for MSA5 */
 	default:
 		BUG();
 	}
-	__cpacf_query(opcode, status);
-	return (status[func >> 3] & (0x80 >> (func & 7))) != 0;
+}
+
+static inline int cpacf_query(unsigned int opcode, cpacf_mask_t *mask)
+{
+	if (__cpacf_check_opcode(opcode)) {
+		__cpacf_query(opcode, mask);
+		return 1;
+	}
+	memset(mask, 0, sizeof(*mask));
+	return 0;
+}
+
+static inline int cpacf_test_func(cpacf_mask_t *mask, unsigned int func)
+{
+	return (mask->bytes[func >> 3] & (0x80 >> (func & 7))) != 0;
+}
+
+static inline int cpacf_query_func(unsigned int opcode, unsigned int func)
+{
+	cpacf_mask_t mask;
+
+	if (cpacf_query(opcode, &mask))
+		return cpacf_test_func(&mask, func);
+	return 0;
 }
 
 /**