[PATCH v3 09/18] stack: fix unaligned accesses on 128-bit

[David Marchand]

Caught by UBSan:

../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
	member access within misaligned address 0x7ffd9c67f228 for
	type 'const rte_int128_t', which requires 16 byte alignment
	0x7ffd9c67f228: note: pointer points here
 00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
              ^
 00 00 00 00 00 00 00 00  00 00 00 00
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
	../lib/eal/x86/include/rte_atomic_64.h:206:21 in
	../lib/eal/x86/include/rte_atomic_64.h:206:21: runtime error:
	member access within misaligned address 0x7ffd9c67f228 for type
	'const union rte_int128_t::(anonymous at
	../lib/eal/include/generic/rte_atomic.h:1102:2)', which requires
	16 byte alignment
0x7ffd9c67f228: note: pointer points here
 00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
              ^
 00 00 00 00 00 00 00 00  00 00 00 00
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
	../lib/eal/x86/include/rte_atomic_64.h:206:21 in
	../lib/eal/x86/include/rte_atomic_64.h:206:16: runtime error:
	load of misaligned address 0x7ffd9c67f228 for type
	'const uint64_t' (aka 'const unsigned long'), which requires
	16 byte alignment
0x7ffd9c67f228: note: pointer points here
 00 00 00 00  c0 5d 3e 00 01 00 00 00  01 00 00 00 00 00 00 00
              ^
 00 00 00 00 00 00 00 00  00 00 00 00
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior
	../lib/eal/x86/include/rte_atomic_64.h:206:21 in

Fixes: 3340202f5954 ("stack: add lock-free implementation")
Cc: stable at dpdk.org

Signed-off-by: David Marchand <david.marchand at redhat.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
 lib/stack/rte_stack_lf_c11.h     | 8 ++++----
 lib/stack/rte_stack_lf_generic.h | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/stack/rte_stack_lf_c11.h b/lib/stack/rte_stack_lf_c11.h
index b97e02d6a1..f674731235 100644
--- a/lib/stack/rte_stack_lf_c11.h
+++ b/lib/stack/rte_stack_lf_c11.h
@@ -63,13 +63,13 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
 			  struct rte_stack_lf_elem *last,
 			  unsigned int num)
 {
-	struct rte_stack_lf_head old_head;
+	alignas(16) struct rte_stack_lf_head old_head;
 	int success;
 
 	old_head = list->head;
 
 	do {
-		struct rte_stack_lf_head new_head;
+		alignas(16) struct rte_stack_lf_head new_head;
 
 		/* Swing the top pointer to the first element in the list and
 		 * make the last element point to the old top.
@@ -102,7 +102,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
 			 void **obj_table,
 			 struct rte_stack_lf_elem **last)
 {
-	struct rte_stack_lf_head old_head;
+	alignas(16) struct rte_stack_lf_head old_head;
 	uint64_t len;
 	int success = 0;
 
@@ -129,7 +129,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
 
 	/* Pop num elements */
 	do {
-		struct rte_stack_lf_head new_head;
+		alignas(16) struct rte_stack_lf_head new_head;
 		struct rte_stack_lf_elem *tmp;
 		unsigned int i;
 
diff --git a/lib/stack/rte_stack_lf_generic.h b/lib/stack/rte_stack_lf_generic.h
index cc69e4d168..32f56dffdd 100644
--- a/lib/stack/rte_stack_lf_generic.h
+++ b/lib/stack/rte_stack_lf_generic.h
@@ -36,13 +36,13 @@ __rte_stack_lf_push_elems(struct rte_stack_lf_list *list,
 			  struct rte_stack_lf_elem *last,
 			  unsigned int num)
 {
-	struct rte_stack_lf_head old_head;
+	alignas(16) struct rte_stack_lf_head old_head;
 	int success;
 
 	old_head = list->head;
 
 	do {
-		struct rte_stack_lf_head new_head;
+		alignas(16) struct rte_stack_lf_head new_head;
 
 		/* An acquire fence (or stronger) is needed for weak memory
 		 * models to establish a synchronized-with relationship between
@@ -77,7 +77,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
 			 void **obj_table,
 			 struct rte_stack_lf_elem **last)
 {
-	struct rte_stack_lf_head old_head;
+	alignas(16) struct rte_stack_lf_head old_head;
 	int success = 0;
 
 	/* Reserve num elements, if available */
@@ -99,7 +99,7 @@ __rte_stack_lf_pop_elems(struct rte_stack_lf_list *list,
 
 	/* Pop num elements */
 	do {
-		struct rte_stack_lf_head new_head;
+		alignas(16) struct rte_stack_lf_head new_head;
 		struct rte_stack_lf_elem *tmp;
 		unsigned int i;
 
-- 
2.50.0