Introducing Queue/Stack helpers and clang frontend

This commit aims to introduce helpers to declare Queue/Stack maps. I have supported also
the creation of shared/public/pinned ones, as for the "traditional" tables.
In clang frontend I have added both declaration of maps type/queue, type/stack and all the operations
supported so far by these new maps (push/pop/peek).

Possible declarations introduced:

* BPF_QUEUESTACK(<"queue"/"stack">, <name>, <leaf_type>, <max_entries>, <flags>)
* BPF_QUEUESTACK_SHARED(...)
* BPF_QUEUESTACK_PINNED(...)
* BPF_QUEUESTACK_PUBLIC(...)
* BPF_QUEUE(<name>, <leaf_type>, <max_entries>)
* BPF_QUEUE(<name>, <leaf_type>, <max_entries>, <flags>)
* BPF_STACK(<name>, <leaf_type>, <max_entries>)
* BPF_STACK(<name>, <leaf_type>, <max_entries>, <flags>)

Signed-off-by: Simone Magnani <[email protected]>
Co-authored-by: Sebastiano Miano <[email protected]>

src/cc/export/helpers.h

@@ -79,6 +79,15 @@ R"********(
  __attribute__ ((section(".maps." #name), used)) \
  ____btf_map_##name = { }
 
+// Associate map with its key/value types for QUEUE/STACK map types
+#define BPF_ANNOTATE_KV_PAIR_QUEUESTACK(name, type_val) \
+ struct ____btf_map_##name { \
+ type_val value; \
+ }; \
+ struct ____btf_map_##name \
+ __attribute__ ((section(".maps." #name), used)) \
+ ____btf_map_##name = { }
+
 // Changes to the macro require changes in BFrontendAction classes
 #define BPF_F_TABLE(_table_type, _key_type, _leaf_type, _name, _max_entries, _flags) \
 struct _name##_table_t { \
@@ -100,6 +109,51 @@ __attribute__((section("maps/" _table_type))) \
 struct _name##_table_t _name = { .flags = (_flags), .max_entries = (_max_entries) }; \
 BPF_ANNOTATE_KV_PAIR(_name, _key_type, _leaf_type)
 
+
+// Changes to the macro require changes in BFrontendAction classes
+#define BPF_QUEUESTACK(_table_type, _name, _leaf_type, _max_entries, _flags) \
+struct _name##_table_t { \
+ _leaf_type leaf; \
+ int * (*peek) (_leaf_type *); \
+ int * (*pop) (_leaf_type *); \
+ int * (*push) (_leaf_type *, u64); \
+ u32 max_entries; \
+ int flags; \
+}; \
+__attribute__((section("maps/" _table_type))) \
+struct _name##_table_t _name = { .flags = (_flags), .max_entries = (_max_entries) }; \
+BPF_ANNOTATE_KV_PAIR_QUEUESTACK(_name, _leaf_type)
+
+// define queue with 3 parameters (_type=queue/stack automatically) and default flags to 0
+#define BPF_QUEUE_STACK3(_type, _name, _leaf_type, _max_entries) \
+ BPF_QUEUESTACK(_type, _name, _leaf_type, _max_entries, 0)
+
+// define queue with 4 parameters (_type=queue/stack automatically)
+#define BPF_QUEUE_STACK4(_type, _name, _leaf_type, _max_entries, _flags) \
+ BPF_QUEUESTACK(_type, _name, _leaf_type, _max_entries, _flags)
+
+// helper for default-variable macro function
+#define BPF_QUEUE_STACKX(_1, _2, _3, _4, NAME, ...) NAME
+
+#define BPF_QUEUE(...) \
+ BPF_QUEUE_STACKX(__VA_ARGS__, BPF_QUEUE_STACK4, BPF_QUEUE_STACK3)("queue", __VA_ARGS__)
+
+#define BPF_STACK(...) \
+ BPF_QUEUE_STACKX(__VA_ARGS__, BPF_QUEUE_STACK4, BPF_QUEUE_STACK3)("stack", __VA_ARGS__)
+
+#define BPF_QUEUESTACK_PINNED(_table_type, _name, _leaf_type, _max_entries, _flags, _pinned) \
+BPF_QUEUESTACK(_table_type ":" _pinned, _name, _leaf_type, _max_entries, _flags)
+
+#define BPF_QUEUESTACK_PUBLIC(_table_type, _name, _leaf_type, _max_entries, _flags) \
+BPF_QUEUESTACK(_table_type, _name, _leaf_type, _max_entries, _flags); \
+__attribute__((section("maps/export"))) \
+struct _name##_table_t __##_name
+
+#define BPF_QUEUESTACK_SHARED(_table_type, _name, _leaf_type, _max_entries, _flags) \
+BPF_QUEUESTACK(_table_type, _name, _leaf_type, _max_entries, _flags); \
+__attribute__((section("maps/shared"))) \
+struct _name##_table_t __##_name
+
 #define BPF_TABLE(_table_type, _key_type, _leaf_type, _name, _max_entries) \
 BPF_F_TABLE(_table_type, _key_type, _leaf_type, _name, _max_entries, 0)
 

src/cc/frontends/clang/b_frontend_action.cc

@@ -1036,7 +1036,16 @@ bool BTypeVisitor::VisitCallExpr(CallExpr *Call) {
  } else if (memb_name == "get_local_storage") {
  prefix = "bpf_get_local_storage";
  suffix = ")";
- } else {
+ } else if (memb_name == "push") {
+ prefix = "bpf_map_push_elem";
+ suffix = ")";
+ } else if (memb_name == "pop") {
+ prefix = "bpf_map_pop_elem";
+ suffix = ")";
+ } else if (memb_name == "peek") {
+ prefix = "bpf_map_peek_elem";
+ suffix = ")";
+ } else {
  error(GET_BEGINLOC(Call), "invalid bpf_table operation %0") << memb_name;
  return false;
  }
@@ -1419,6 +1428,12 @@ bool BTypeVisitor::VisitVarDecl(VarDecl *Decl) {
  table.leaf_size = 0;
  } else if (section_attr == "maps/perf_array") {
  map_type = BPF_MAP_TYPE_PERF_EVENT_ARRAY;
+ } else if (section_attr == "maps/queue") {
+ table.key_size = 0;
+ map_type = BPF_MAP_TYPE_QUEUE;
+ } else if (section_attr == "maps/stack") {
+ table.key_size = 0;
+ map_type = BPF_MAP_TYPE_STACK;
  } else if (section_attr == "maps/cgroup_array") {
  map_type = BPF_MAP_TYPE_CGROUP_ARRAY;
  } else if (section_attr == "maps/stacktrace") {