[PATCH v3 12/18] malloc: fix mp message alignment

[David Marchand]

Content (param[]) of received multiprocess messages are aligned with
a 4 bytes constraint.

Before patch:
struct mp_msg_internal {
 int type;                                                     /*   0     4 */
 struct rte_mp_msg {
  char name[64];                                               /*   4    64 */
  /* --- cacheline 1 boundary (64 bytes) was 4 bytes ago --- */
  int len_param;                                               /*  68     4 */
  int num_fds;                                                 /*  72     4 */
  /* typedef uint8_t -> __uint8_t */ unsigned char param[256]; /*  76   256 */
  /* --- cacheline 5 boundary (320 bytes) was 12 bytes ago --- */
  int fds[253];                                                /* 332  1012 */
 } msg;                                                        /*   4  1340 */

 /* size: 1344, cachelines: 21, members: 2 */
};

This results in many unaligned accesses for multiprocess malloc requests.

Examples:
../lib/eal/common/malloc_mp.c:308:32: runtime error:
	member access within misaligned address 0x7f7b35df4684 for type
	'const struct malloc_mp_req', which requires 8 byte alignment

../lib/eal/common/malloc_mp.c:158:9: runtime error:
	member access within misaligned address 0x7f36a535bb5c for type
	'const struct malloc_mp_req', which requires 8 byte alignment

../lib/eal/common/malloc_mp.c:171:8: runtime error:
	member access within misaligned address 0x7f4ba65f296c for type
	'struct malloc_mp_req', which requires 8 byte alignment

Signed-off-by: David Marchand <david.marchand at redhat.com>
---
 lib/eal/common/eal_common_proc.c |  2 +-
 lib/eal/common/malloc_mp.c       | 18 +++++++++---------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/eal/common/eal_common_proc.c b/lib/eal/common/eal_common_proc.c
index 0dea787e38..3846c7178d 100644
--- a/lib/eal/common/eal_common_proc.c
+++ b/lib/eal/common/eal_common_proc.c
@@ -62,7 +62,7 @@ enum mp_type {
 
 struct mp_msg_internal {
 	int type;
-	struct rte_mp_msg msg;
+	alignas(8) struct rte_mp_msg msg;
 };
 
 struct async_request_param {
diff --git a/lib/eal/common/malloc_mp.c b/lib/eal/common/malloc_mp.c
index 9765277f5d..000c7f6b47 100644
--- a/lib/eal/common/malloc_mp.c
+++ b/lib/eal/common/malloc_mp.c
@@ -148,7 +148,7 @@ get_unique_id(void)
 static int
 handle_sync(const struct rte_mp_msg *msg, const void *peer)
 {
-	struct rte_mp_msg reply;
+	alignas(8) struct rte_mp_msg reply;
 	const struct malloc_mp_req *req =
 			(const struct malloc_mp_req *)msg->param;
 	struct malloc_mp_req *resp =
@@ -330,7 +330,7 @@ handle_request(const struct rte_mp_msg *msg, const void *peer __rte_unused)
 	}
 
 	if (ret != 0) {
-		struct rte_mp_msg resp_msg;
+		alignas(8) struct rte_mp_msg resp_msg;
 		struct malloc_mp_req *resp =
 				(struct malloc_mp_req *)resp_msg.param;
 
@@ -351,7 +351,7 @@ handle_request(const struct rte_mp_msg *msg, const void *peer __rte_unused)
 		/* we did not modify the request */
 		free(entry);
 	} else {
-		struct rte_mp_msg sr_msg;
+		alignas(8) struct rte_mp_msg sr_msg;
 		struct malloc_mp_req *sr =
 				(struct malloc_mp_req *)sr_msg.param;
 		struct timespec ts;
@@ -444,7 +444,7 @@ handle_sync_response(const struct rte_mp_msg *request,
 	}
 
 	if (entry->user_req.t == REQ_TYPE_FREE) {
-		struct rte_mp_msg msg;
+		alignas(8) struct rte_mp_msg msg;
 		struct malloc_mp_req *resp = (struct malloc_mp_req *)msg.param;
 
 		memset(&msg, 0, sizeof(msg));
@@ -465,7 +465,7 @@ handle_sync_response(const struct rte_mp_msg *request,
 	} else if (entry->user_req.t == REQ_TYPE_ALLOC &&
 			result == REQ_RESULT_SUCCESS) {
 		struct malloc_heap *heap = entry->alloc_state.heap;
-		struct rte_mp_msg msg;
+		alignas(8) struct rte_mp_msg msg;
 		struct malloc_mp_req *resp =
 				(struct malloc_mp_req *)msg.param;
 
@@ -489,7 +489,7 @@ handle_sync_response(const struct rte_mp_msg *request,
 		free(entry);
 	} else if (entry->user_req.t == REQ_TYPE_ALLOC &&
 			result == REQ_RESULT_FAIL) {
-		struct rte_mp_msg rb_msg;
+		alignas(8) struct rte_mp_msg rb_msg;
 		struct malloc_mp_req *rb =
 				(struct malloc_mp_req *)rb_msg.param;
 		struct timespec ts;
@@ -551,7 +551,7 @@ static int
 handle_rollback_response(const struct rte_mp_msg *request,
 		const struct rte_mp_reply *reply __rte_unused)
 {
-	struct rte_mp_msg msg;
+	alignas(8) struct rte_mp_msg msg;
 	struct malloc_mp_req *resp = (struct malloc_mp_req *)msg.param;
 	const struct malloc_mp_req *mpreq =
 			(const struct malloc_mp_req *)request->param;
@@ -628,7 +628,7 @@ handle_response(const struct rte_mp_msg *msg, const void *peer  __rte_unused)
 int
 request_sync(void)
 {
-	struct rte_mp_msg msg;
+	alignas(8) struct rte_mp_msg msg;
 	struct rte_mp_reply reply;
 	struct malloc_mp_req *req = (struct malloc_mp_req *)msg.param;
 	struct timespec ts;
@@ -697,7 +697,7 @@ request_sync(void)
 int
 request_to_primary(struct malloc_mp_req *user_req)
 {
-	struct rte_mp_msg msg;
+	alignas(8) struct rte_mp_msg msg;
 	struct malloc_mp_req *msg_req = (struct malloc_mp_req *)msg.param;
 	struct mp_request *entry;
 	struct timespec ts;
-- 
2.50.0