Merge branch 'bpf-btf-for-htab-lru'

Yonghong Song says:

====================
Commit a26ca7c ("bpf: btf: Add pretty print support to
the basic arraymap") added pretty print support to array map.
This patch adds pretty print for hash and lru_hash maps.

The following example shows the pretty-print result of a pinned
hashmap. Without this patch set, user will get an error instead.

    struct map_value {
            int count_a;
            int count_b;
    };

    cat /sys/fs/bpf/pinned_hash_map:

    87907: {87907,87908}
    57354: {37354,57355}
    76625: {76625,76626}
    ...

Patch #1 fixed a bug in bpffs map_seq_next() function so that
all elements in the hash table will be traversed.
Patch #2 implemented map_seq_show_elem() and map_check_btf()
callback functions for hash and lru hash maps.
Patch #3 enhanced tools/testing/selftests/bpf/test_btf.c to
test bpffs hash and lru hash map pretty print.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

kernel/bpf/hashtab.c

@@ -11,9 +11,11 @@
  * General Public License for more details.
  */
 #include <linux/bpf.h>
+#include <linux/btf.h>
 #include <linux/jhash.h>
 #include <linux/filter.h>
 #include <linux/rculist_nulls.h>
+#include <uapi/linux/btf.h>
 #include "percpu_freelist.h"
 #include "bpf_lru_list.h"
 #include "map_in_map.h"
@@ -1162,6 +1164,44 @@ static void htab_map_free(struct bpf_map *map)
 	kfree(htab);
 }
 
+static void htab_map_seq_show_elem(struct bpf_map *map, void *key,
+				   struct seq_file *m)
+{
+	void *value;
+
+	rcu_read_lock();
+
+	value = htab_map_lookup_elem(map, key);
+	if (!value) {
+		rcu_read_unlock();
+		return;
+	}
+
+	btf_type_seq_show(map->btf, map->btf_key_type_id, key, m);
+	seq_puts(m, ": ");
+	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
+	seq_puts(m, "\n");
+
+	rcu_read_unlock();
+}
+
+static int htab_map_check_btf(const struct bpf_map *map, const struct btf *btf,
+			      u32 btf_key_id, u32 btf_value_id)
+{
+	const struct btf_type *key_type, *value_type;
+	u32 key_size, value_size;
+
+	key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
+	if (!key_type || key_size != map->key_size)
+		return -EINVAL;
+
+	value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
+	if (!value_type || value_size != map->value_size)
+		return -EINVAL;
+
+	return 0;
+}
+
 const struct bpf_map_ops htab_map_ops = {
 	.map_alloc_check = htab_map_alloc_check,
 	.map_alloc = htab_map_alloc,
@@ -1171,6 +1211,8 @@ const struct bpf_map_ops htab_map_ops = {
 	.map_update_elem = htab_map_update_elem,
 	.map_delete_elem = htab_map_delete_elem,
 	.map_gen_lookup = htab_map_gen_lookup,
+	.map_seq_show_elem = htab_map_seq_show_elem,
+	.map_check_btf = htab_map_check_btf,
 };
 
 const struct bpf_map_ops htab_lru_map_ops = {
@@ -1182,6 +1224,8 @@ const struct bpf_map_ops htab_lru_map_ops = {
 	.map_update_elem = htab_lru_map_update_elem,
 	.map_delete_elem = htab_lru_map_delete_elem,
 	.map_gen_lookup = htab_lru_map_gen_lookup,
+	.map_seq_show_elem = htab_map_seq_show_elem,
+	.map_check_btf = htab_map_check_btf,
 };
 
 /* Called from eBPF program */

kernel/bpf/inode.c

@@ -196,19 +196,21 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 {
 	struct bpf_map *map = seq_file_to_map(m);
 	void *key = map_iter(m)->key;
+	void *prev_key;
 
 	if (map_iter(m)->done)
 		return NULL;
 
 	if (unlikely(v == SEQ_START_TOKEN))
-		goto done;
+		prev_key = NULL;
+	else
+		prev_key = key;
 
-	if (map->ops->map_get_next_key(map, key, key)) {
+	if (map->ops->map_get_next_key(map, prev_key, key)) {
 		map_iter(m)->done = true;
 		return NULL;
 	}
 
-done:
 	++(*pos);
 	return key;
 }

tools/testing/selftests/bpf/test_btf.c

@@ -131,6 +131,8 @@ struct btf_raw_test {
 	__u32 max_entries;
 	bool btf_load_err;
 	bool map_create_err;
+	bool ordered_map;
+	bool lossless_map;
 	int hdr_len_delta;
 	int type_off_delta;
 	int str_off_delta;
@@ -2093,8 +2095,7 @@ struct pprint_mapv {
 	} aenum;
 };
 
-static struct btf_raw_test pprint_test = {
-	.descr = "BTF pretty print test #1",
+static struct btf_raw_test pprint_test_template = {
 	.raw_types = {
 		/* unsighed char */			/* [1] */
 		BTF_TYPE_INT_ENC(NAME_TBD, 0, 0, 8, 1),
@@ -2146,15 +2147,47 @@ static struct btf_raw_test pprint_test = {
 	},
 	.str_sec = "\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum",
 	.str_sec_size = sizeof("\0unsigned char\0unsigned short\0unsigned int\0int\0unsigned long long\0uint8_t\0uint16_t\0uint32_t\0int32_t\0uint64_t\0ui64\0ui8a\0ENUM_ZERO\0ENUM_ONE\0ENUM_TWO\0ENUM_THREE\0pprint_mapv\0ui32\0ui16\0si32\0unused_bits2a\0bits28\0unused_bits2b\0aenum"),
-	.map_type = BPF_MAP_TYPE_ARRAY,
-	.map_name = "pprint_test",
 	.key_size = sizeof(unsigned int),
 	.value_size = sizeof(struct pprint_mapv),
 	.key_type_id = 3,	/* unsigned int */
 	.value_type_id = 16,	/* struct pprint_mapv */
 	.max_entries = 128 * 1024,
 };
 
+static struct btf_pprint_test_meta {
+	const char *descr;
+	enum bpf_map_type map_type;
+	const char *map_name;
+	bool ordered_map;
+	bool lossless_map;
+} pprint_tests_meta[] = {
+{
+	.descr = "BTF pretty print array",
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "pprint_test_array",
+	.ordered_map = true,
+	.lossless_map = true,
+},
+
+{
+	.descr = "BTF pretty print hash",
+	.map_type = BPF_MAP_TYPE_HASH,
+	.map_name = "pprint_test_hash",
+	.ordered_map = false,
+	.lossless_map = true,
+},
+
+{
+	.descr = "BTF pretty print lru hash",
+	.map_type = BPF_MAP_TYPE_LRU_HASH,
+	.map_name = "pprint_test_lru_hash",
+	.ordered_map = false,
+	.lossless_map = false,
+},
+
+};
+
+
 static void set_pprint_mapv(struct pprint_mapv *v, uint32_t i)
 {
 	v->ui32 = i;
@@ -2166,10 +2199,12 @@ static void set_pprint_mapv(struct pprint_mapv *v, uint32_t i)
 	v->aenum = i & 0x03;
 }
 
-static int test_pprint(void)
+static int do_test_pprint(void)
 {
-	const struct btf_raw_test *test = &pprint_test;
+	const struct btf_raw_test *test = &pprint_test_template;
 	struct bpf_create_map_attr create_attr = {};
+	unsigned int key, nr_read_elems;
+	bool ordered_map, lossless_map;
 	int map_fd = -1, btf_fd = -1;
 	struct pprint_mapv mapv = {};
 	unsigned int raw_btf_size;
@@ -2178,7 +2213,6 @@ static int test_pprint(void)
 	char pin_path[255];
 	size_t line_len = 0;
 	char *line = NULL;
-	unsigned int key;
 	uint8_t *raw_btf;
 	ssize_t nread;
 	int err, ret;
@@ -2251,14 +2285,18 @@ static int test_pprint(void)
 		goto done;
 	}
 
-	key = 0;
+	nr_read_elems = 0;
+	ordered_map = test->ordered_map;
+	lossless_map = test->lossless_map;
 	do {
 		ssize_t nexpected_line;
+		unsigned int next_key;
 
-		set_pprint_mapv(&mapv, key);
+		next_key = ordered_map ? nr_read_elems : atoi(line);
+		set_pprint_mapv(&mapv, next_key);
 		nexpected_line = snprintf(expected_line, sizeof(expected_line),
 					  "%u: {%u,0,%d,0x%x,0x%x,0x%x,{%lu|[%u,%u,%u,%u,%u,%u,%u,%u]},%s}\n",
-					  key,
+					  next_key,
 					  mapv.ui32, mapv.si32,
 					  mapv.unused_bits2a, mapv.bits28, mapv.unused_bits2b,
 					  mapv.ui64,
@@ -2281,11 +2319,12 @@ static int test_pprint(void)
 		}
 
 		nread = getline(&line, &line_len, pin_file);
-	} while (++key < test->max_entries && nread > 0);
+	} while (++nr_read_elems < test->max_entries && nread > 0);
 
-	if (CHECK(key < test->max_entries,
-		  "Unexpected EOF. key:%u test->max_entries:%u",
-		  key, test->max_entries)) {
+	if (lossless_map &&
+	    CHECK(nr_read_elems < test->max_entries,
+		  "Unexpected EOF. nr_read_elems:%u test->max_entries:%u",
+		  nr_read_elems, test->max_entries)) {
 		err = -1;
 		goto done;
 	}
@@ -2314,6 +2353,24 @@ static int test_pprint(void)
 	return err;
 }
 
+static int test_pprint(void)
+{
+	unsigned int i;
+	int err = 0;
+
+	for (i = 0; i < ARRAY_SIZE(pprint_tests_meta); i++) {
+		pprint_test_template.descr = pprint_tests_meta[i].descr;
+		pprint_test_template.map_type = pprint_tests_meta[i].map_type;
+		pprint_test_template.map_name = pprint_tests_meta[i].map_name;
+		pprint_test_template.ordered_map = pprint_tests_meta[i].ordered_map;
+		pprint_test_template.lossless_map = pprint_tests_meta[i].lossless_map;
+
+		err |= count_result(do_test_pprint());
+	}
+
+	return err;
+}
+
 static void usage(const char *cmd)
 {
 	fprintf(stderr, "Usage: %s [-l] [[-r test_num (1 - %zu)] | [-g test_num (1 - %zu)] | [-f test_num (1 - %zu)] | [-p]]\n",
@@ -2409,7 +2466,7 @@ int main(int argc, char **argv)
 		err |= test_file();
 
 	if (args.pprint_test)
-		err |= count_result(test_pprint());
+		err |= test_pprint();
 
 	if (args.raw_test || args.get_info_test || args.file_test ||
 	    args.pprint_test)