Subject: [PATCH REPOST 3/3] powerpc/vphn: move endianness fixing to vphn_unpack_associativity()

From: Greg Kurz <[email-masked]>
Date: Mon, 17 Nov 2014 18:42:45 +0100

The first argument to vphn_unpack_associativity() is a const long *, but the
parsing code expects __be64 values actually. This is inconsistent. We should
either pass a const __be64 * or change vphn_unpack_associativity() so that
it fixes endianness by itself.

This patch does the latter, since the caller doesn't need to know about
endianness and this allows to fix significant 64-bit values only. Please
note that the previous code was able to cope with 32-bit fields being split
accross two consecutives 64-bit values. Since PAPR+ doesn't say this cannot
happen, the behaviour was kept. It requires extra checking to know when fixing
is needed though.

Signed-off-by: Greg Kurz <[email-masked]>
---
 arch/powerpc/mm/numa.c |   42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index e30c469..903ef27 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1417,30 +1417,49 @@ static int update_cpu_associativity_changes_mask(void)
  */
 static int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
 {
-	int i;
-	const __be16 *field = (const __be16 *) packed;
+	int i, j, k;
+	union {
+		__be64 packed[VPHN_REGISTER_COUNT];
+		__be16 field[VPHN_REGISTER_COUNT * 4];
+	} fixed;
 
 #define VPHN_FIELD_UNUSED	(0xffff)
 #define VPHN_FIELD_MSB		(0x8000)
 #define VPHN_FIELD_MASK		(~VPHN_FIELD_MSB)
 
-	for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
-		if (be16_to_cpup(field) == VPHN_FIELD_UNUSED)
+	for (i = 1, j = 0, k = 0; i < VPHN_ASSOC_BUFSIZE;) {
+		u16 field;
+
+		if (j % 4 == 0) {
+			fixed.packed[k] = cpu_to_be64(packed[k]);
+			k++;
+		}
+
+		field = be16_to_cpu(fixed.field[j]);
+
+		if (field == VPHN_FIELD_UNUSED)
 			/* All significant fields processed.
 			 */
 			break;
 
-		if (be16_to_cpup(field) & VPHN_FIELD_MSB) {
+		if (field & VPHN_FIELD_MSB) {
 			/* Data is in the lower 15 bits of this field */
-			unpacked[i] = cpu_to_be32(
-				be16_to_cpup(field) & VPHN_FIELD_MASK);
-			field++;
+			unpacked[i++] = cpu_to_be32(field & VPHN_FIELD_MASK);
+			j++;
 		} else {
 			/* Data is in the lower 15 bits of this field
 			 * concatenated with the next 16 bit field
 			 */
-			unpacked[i] = *((__be32 *)field);
-			field += 2;
+			if (unlikely(j % 4 == 3)) {
+				/* The next field is to be copied from the next
+				 * 64-bit input value. We must fix it now.
+				 */
+				fixed.packed[k] = cpu_to_be64(packed[k]);
+				k++;
+			}
+
+			unpacked[i++] = *((__be32 *)&fixed.field[j]);
+			j += 2;
 		}
 	}
 
@@ -1460,11 +1479,8 @@ static long hcall_vphn(unsigned long cpu, __be32 *associativity)
 	long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
 	u64 flags = 1;
 	int hwcpu = get_hard_smp_processor_id(cpu);
-	int i;
 
 	rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
-	for (i = 0; i < VPHN_REGISTER_COUNT; i++)
-		retbuf[i] = cpu_to_be64(retbuf[i]);
 	vphn_unpack_associativity(retbuf, associativity);
 
 	return rc;