bpf: Allow bpf sample programs (*_user.c) to change bpf_map_def

The current bpf_map_def is statically defined during compile
time.  This patch allows the *_user.c program to change it during
runtime.  It is done by adding load_bpf_file_fixup_map() which
takes a callback.  The callback will be called before creating
each map so that it has a chance to modify the bpf_map_def.

The current usecase is to change max_entries in map_perf_test.
It is interesting to test with a much bigger map size in
some cases (e.g. the following patch on bpf_lru_map.c).
However,  it is hard to find one size to fit all testing
environment.  Hence, it is handy to take the max_entries
as a cmdline arg and then configure the bpf_map_def during
runtime.

This patch adds two cmdline args.  One is to configure
the map's max_entries.  Another is to configure the max_cnt
which controls how many times a syscall is called.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 201 insertions, 74 deletions

diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index dcdce1270d38..0d449d8032d1 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -21,6 +21,7 @@
 #include <sys/mman.h>
 #include <poll.h>
 #include <ctype.h>
+#include <assert.h>
 #include "libbpf.h"
 #include "bpf_load.h"
 #include "perf-sys.h"
@@ -37,15 +38,6 @@ int event_fd[MAX_PROGS];
 int prog_cnt;
 int prog_array_fd = -1;
 
-struct bpf_map_def {
-        unsigned int type;
-        unsigned int key_size;
-        unsigned int value_size;
-        unsigned int max_entries;
-        unsigned int map_flags;
-        unsigned int inner_map_idx;
-};
-
 static int populate_prog_array(const char *event, int prog_fd)
 {
         int ind = atoi(event), err;
@@ -193,11 +185,14 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
         return 0;
 }
 
-static int load_maps(struct bpf_map_def *maps, int len)
+static int load_maps(struct bpf_map_def *maps, int len,
+                     const char **map_names, fixup_map_cb fixup_map)
 {
         int i;
 
         for (i = 0; i < len / sizeof(struct bpf_map_def); i++) {
+                if (fixup_map)
+                        fixup_map(&maps[i], map_names[i], i);
 
                 if (maps[i].type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
                     maps[i].type == BPF_MAP_TYPE_HASH_OF_MAPS) {
@@ -280,14 +275,64 @@ static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
         return 0;
 }
 
-int load_bpf_file(char *path)
+static int cmp_symbols(const void *l, const void *r)
+{
+        const GElf_Sym *lsym = (const GElf_Sym *)l;
+        const GElf_Sym *rsym = (const GElf_Sym *)r;
+
+        if (lsym->st_value < rsym->st_value)
+                return -1;
+        else if (lsym->st_value > rsym->st_value)
+                return 1;
+        else
+                return 0;
+}
+
+static int get_sorted_map_names(Elf *elf, Elf_Data *symbols, int maps_shndx,
+                                int strtabidx, char **map_names)
+{
+        GElf_Sym map_symbols[MAX_MAPS];
+        int i, nr_maps = 0;
+
+        for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
+                assert(nr_maps < MAX_MAPS);
+                if (!gelf_getsym(symbols, i, &map_symbols[nr_maps]))
+                        continue;
+                if (map_symbols[nr_maps].st_shndx != maps_shndx)
+                        continue;
+                nr_maps++;
+        }
+
+        qsort(map_symbols, nr_maps, sizeof(GElf_Sym), cmp_symbols);
+
+        for (i = 0; i < nr_maps; i++) {
+                char *map_name;
+
+                map_name = elf_strptr(elf, strtabidx, map_symbols[i].st_name);
+                if (!map_name) {
+                        printf("cannot get map symbol\n");
+                        return 1;
+                }
+
+                map_names[i] = strdup(map_name);
+                if (!map_names[i]) {
+                        printf("strdup(%s): %s(%d)\n", map_name,
+                               strerror(errno), errno);
+                        return 1;
+                }
+        }
+
+        return 0;
+}
+
+static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
 {
-        int fd, i;
+        int fd, i, ret, maps_shndx = -1, strtabidx = -1;
         Elf *elf;
         GElf_Ehdr ehdr;
         GElf_Shdr shdr, shdr_prog;
-        Elf_Data *data, *data_prog, *symbols = NULL;
-        char *shname, *shname_prog;
+        Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;
+        char *shname, *shname_prog, *map_names[MAX_MAPS] = { NULL };
 
         /* reset global variables */
         kern_version = 0;
@@ -335,14 +380,33 @@ int load_bpf_file(char *path)
                         }
                         memcpy(&kern_version, data->d_buf, sizeof(int));
                 } else if (strcmp(shname, "maps") == 0) {
-                        processed_sec[i] = true;
-                        if (load_maps(data->d_buf, data->d_size))
-                                return 1;
+                        maps_shndx = i;
+                        data_maps = data;
                 } else if (shdr.sh_type == SHT_SYMTAB) {
+                        strtabidx = shdr.sh_link;
                         symbols = data;
                 }
         }
 
+        ret = 1;
+
+        if (!symbols) {
+                printf("missing SHT_SYMTAB section\n");
+                goto done;
+        }
+
+        if (data_maps) {
+                if (get_sorted_map_names(elf, symbols, maps_shndx, strtabidx,
+                                         map_names))
+                        goto done;
+
+                if (load_maps(data_maps->d_buf, data_maps->d_size,
+                              (const char **)map_names, fixup_map))
+                        goto done;
+
+                processed_sec[maps_shndx] = true;
+        }
+
         /* load programs that need map fixup (relocations) */
         for (i = 1; i < ehdr.e_shnum; i++) {
                 if (processed_sec[i])
@@ -399,8 +463,22 @@ int load_bpf_file(char *path)
                         load_and_attach(shname, data->d_buf, data->d_size);
         }
 
+        ret = 0;
+done:
+        for (i = 0; i < MAX_MAPS; i++)
+                free(map_names[i]);
         close(fd);
-        return 0;
+        return ret;
+}
+
+int load_bpf_file(char *path)
+{
+        return do_load_bpf_file(path, NULL);
+}
+
+int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
+{
+        return do_load_bpf_file(path, fixup_map);
 }
 
 void read_trace_pipe(void)
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index c827827299b3..68f6b2d22507 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -6,6 +6,18 @@
 #define MAX_MAPS 32
 #define MAX_PROGS 32
 
+struct bpf_map_def {
+        unsigned int type;
+        unsigned int key_size;
+        unsigned int value_size;
+        unsigned int max_entries;
+        unsigned int map_flags;
+        unsigned int inner_map_idx;
+};
+
+typedef void (*fixup_map_cb)(struct bpf_map_def *map, const char *map_name,
+                             int idx);
+
 extern int map_fd[MAX_MAPS];
 extern int prog_fd[MAX_PROGS];
 extern int event_fd[MAX_PROGS];
@@ -25,6 +37,7 @@ extern int prog_cnt;
  * returns zero on success
  */
 int load_bpf_file(char *path);
+int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map);
 
 void read_trace_pipe(void);
 struct ksym {
diff --git a/samples/bpf/map_perf_test_user.c b/samples/bpf/map_perf_test_user.c
index 51cb8f238aa2..2a12f48b5c6d 100644
--- a/samples/bpf/map_perf_test_user.c
+++ b/samples/bpf/map_perf_test_user.c
@@ -24,7 +24,7 @@
 #include "libbpf.h"
 #include "bpf_load.h"
 
-#define MAX_CNT 1000000
+#define TEST_BIT(t) (1U << (t))
 
 static __u64 time_get_ns(void)
 {
@@ -34,17 +34,39 @@ static __u64 time_get_ns(void)
         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
 }
 
-#define HASH_PREALLOC           (1 << 0)
-#define PERCPU_HASH_PREALLOC    (1 << 1)
-#define HASH_KMALLOC            (1 << 2)
-#define PERCPU_HASH_KMALLOC     (1 << 3)
-#define LRU_HASH_PREALLOC       (1 << 4)
-#define NOCOMMON_LRU_HASH_PREALLOC      (1 << 5)
-#define LPM_KMALLOC             (1 << 6)
-#define HASH_LOOKUP             (1 << 7)
-#define ARRAY_LOOKUP            (1 << 8)
+enum test_type {
+        HASH_PREALLOC,
+        PERCPU_HASH_PREALLOC,
+        HASH_KMALLOC,
+        PERCPU_HASH_KMALLOC,
+        LRU_HASH_PREALLOC,
+        NOCOMMON_LRU_HASH_PREALLOC,
+        LPM_KMALLOC,
+        HASH_LOOKUP,
+        ARRAY_LOOKUP,
+        NR_TESTS,
+};
+
+const char *test_map_names[NR_TESTS] = {
+        [HASH_PREALLOC] = "hash_map",
+        [PERCPU_HASH_PREALLOC] = "percpu_hash_map",
+        [HASH_KMALLOC] = "hash_map_alloc",
+        [PERCPU_HASH_KMALLOC] = "percpu_hash_map_alloc",
+        [LRU_HASH_PREALLOC] = "lru_hash_map",
+        [NOCOMMON_LRU_HASH_PREALLOC] = "nocommon_lru_hash_map",
+        [LPM_KMALLOC] = "lpm_trie_map_alloc",
+        [HASH_LOOKUP] = "hash_map",
+        [ARRAY_LOOKUP] = "array_map",
+};
 
 static int test_flags = ~0;
+static uint32_t num_map_entries;
+static uint32_t max_cnt = 1000000;
+
+static int check_test_flags(enum test_type t)
+{
+        return test_flags & TEST_BIT(t);
+}
 
 static void test_hash_prealloc(int cpu)
 {
@@ -52,13 +74,13 @@ static void test_hash_prealloc(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_getuid);
         printf("%d:hash_map_perf pre-alloc %lld events per sec\n",
-               cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
-static void do_test_lru(int lru_test_flag, int cpu)
+static void do_test_lru(enum test_type test, int cpu)
 {
         struct sockaddr_in6 in6 = { .sin6_family = AF_INET6 };
         const char *test_name;
@@ -68,10 +90,10 @@ static void do_test_lru(int lru_test_flag, int cpu)
         in6.sin6_addr.s6_addr16[0] = 0xdead;
         in6.sin6_addr.s6_addr16[1] = 0xbeef;
 
-        if (lru_test_flag & LRU_HASH_PREALLOC) {
+        if (test == LRU_HASH_PREALLOC) {
                 test_name = "lru_hash_map_perf";
                 in6.sin6_addr.s6_addr16[7] = 0;
-        } else if (lru_test_flag & NOCOMMON_LRU_HASH_PREALLOC) {
+        } else if (test == NOCOMMON_LRU_HASH_PREALLOC) {
                 test_name = "nocommon_lru_hash_map_perf";
                 in6.sin6_addr.s6_addr16[7] = 1;
         } else {
@@ -79,13 +101,13 @@ static void do_test_lru(int lru_test_flag, int cpu)
         }
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++) {
+        for (i = 0; i < max_cnt; i++) {
                 ret = connect(-1, (const struct sockaddr *)&in6, sizeof(in6));
                 assert(ret == -1 && errno == EBADF);
         }
         printf("%d:%s pre-alloc %lld events per sec\n",
                cpu, test_name,
-               MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
 static void test_lru_hash_prealloc(int cpu)
@@ -104,10 +126,10 @@ static void test_percpu_hash_prealloc(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_geteuid);
         printf("%d:percpu_hash_map_perf pre-alloc %lld events per sec\n",
-               cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
 static void test_hash_kmalloc(int cpu)
@@ -116,10 +138,10 @@ static void test_hash_kmalloc(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_getgid);
         printf("%d:hash_map_perf kmalloc %lld events per sec\n",
-               cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
 static void test_percpu_hash_kmalloc(int cpu)
@@ -128,10 +150,10 @@ static void test_percpu_hash_kmalloc(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_getegid);
         printf("%d:percpu_hash_map_perf kmalloc %lld events per sec\n",
-               cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
 static void test_lpm_kmalloc(int cpu)
@@ -140,10 +162,10 @@ static void test_lpm_kmalloc(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_gettid);
         printf("%d:lpm_perf kmalloc %lld events per sec\n",
-               cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll / (time_get_ns() - start_time));
 }
 
 static void test_hash_lookup(int cpu)
@@ -152,10 +174,10 @@ static void test_hash_lookup(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_getpgid, 0);
         printf("%d:hash_lookup %lld lookups per sec\n",
-               cpu, MAX_CNT * 1000000000ll * 64 / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll * 64 / (time_get_ns() - start_time));
 }
 
 static void test_array_lookup(int cpu)
@@ -164,46 +186,38 @@ static void test_array_lookup(int cpu)
         int i;
 
         start_time = time_get_ns();
-        for (i = 0; i < MAX_CNT; i++)
+        for (i = 0; i < max_cnt; i++)
                 syscall(__NR_getpgrp, 0);
         printf("%d:array_lookup %lld lookups per sec\n",
-               cpu, MAX_CNT * 1000000000ll * 64 / (time_get_ns() - start_time));
+               cpu, max_cnt * 1000000000ll * 64 / (time_get_ns() - start_time));
 }
 
+typedef void (*test_func)(int cpu);
+const test_func test_funcs[] = {
+        [HASH_PREALLOC] = test_hash_prealloc,
+        [PERCPU_HASH_PREALLOC] = test_percpu_hash_prealloc,
+        [HASH_KMALLOC] = test_hash_kmalloc,
+        [PERCPU_HASH_KMALLOC] = test_percpu_hash_kmalloc,
+        [LRU_HASH_PREALLOC] = test_lru_hash_prealloc,
+        [NOCOMMON_LRU_HASH_PREALLOC] = test_nocommon_lru_hash_prealloc,
+        [LPM_KMALLOC] = test_lpm_kmalloc,
+        [HASH_LOOKUP] = test_hash_lookup,
+        [ARRAY_LOOKUP] = test_array_lookup,
+};
+
 static void loop(int cpu)
 {
         cpu_set_t cpuset;
+        int i;
 
         CPU_ZERO(&cpuset);
         CPU_SET(cpu, &cpuset);
         sched_setaffinity(0, sizeof(cpuset), &cpuset);
 
-        if (test_flags & HASH_PREALLOC)
-                test_hash_prealloc(cpu);
-
-        if (test_flags & PERCPU_HASH_PREALLOC)
-                test_percpu_hash_prealloc(cpu);
-
-        if (test_flags & HASH_KMALLOC)
-                test_hash_kmalloc(cpu);
-
-        if (test_flags & PERCPU_HASH_KMALLOC)
-                test_percpu_hash_kmalloc(cpu);
-
-        if (test_flags & LRU_HASH_PREALLOC)
-                test_lru_hash_prealloc(cpu);
-
-        if (test_flags & NOCOMMON_LRU_HASH_PREALLOC)
-                test_nocommon_lru_hash_prealloc(cpu);
-
-        if (test_flags & LPM_KMALLOC)
-                test_lpm_kmalloc(cpu);
-
-        if (test_flags & HASH_LOOKUP)
-                test_hash_lookup(cpu);
-
-        if (test_flags & ARRAY_LOOKUP)
-                test_array_lookup(cpu);
+        for (i = 0; i < NR_TESTS; i++) {
+                if (check_test_flags(i))
+                        test_funcs[i](cpu);
+        }
 }
 
 static void run_perf_test(int tasks)
@@ -260,6 +274,22 @@ static void fill_lpm_trie(void)
         assert(!r);
 }
 
+static void fixup_map(struct bpf_map_def *map, const char *name, int idx)
+{
+        int i;
+
+        if (num_map_entries <= 0)
+                return;
+
+        /* Only change the max_entries for the enabled test(s) */
+        for (i = 0; i < NR_TESTS; i++) {
+                if (!strcmp(test_map_names[i], name) &&
+                    (check_test_flags(i))) {
+                        map->max_entries = num_map_entries;
+                }
+        }
+}
+
 int main(int argc, char **argv)
 {
         struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
@@ -275,7 +305,13 @@ int main(int argc, char **argv)
         if (argc > 2)
                 num_cpu = atoi(argv[2]) ? : num_cpu;
 
-        if (load_bpf_file(filename)) {
+        if (argc > 3)
+                num_map_entries = atoi(argv[3]);
+
+        if (argc > 4)
+                max_cnt = atoi(argv[4]);
+
+        if (load_bpf_file_fixup_map(filename, fixup_map)) {
                 printf("%s", bpf_log_buf);
                 return 1;
         }