From f3515b5d0b718cceae9e67802cfa20d5e6f9b567 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 27 Apr 2017 01:39:35 +0200 Subject: [PATCH] bpf: provide a generic macro for percpu values for selftests To overcome bugs as described and fixed in 89087c456fb5 ("bpf: Fix values type used in test_maps"), provide a generic BPF_DECLARE_PERCPU() and bpf_percpu() accessor macro for all percpu map values used in tests. Declaring variables works as follows (also works for structs): BPF_DECLARE_PERCPU(uint32_t, my_value); They can then be accessed normally as uint32_t type through: bpf_percpu(my_value, ) For example: bpf_percpu(my_value, 0)++; Implicitly, we make sure that the passed type is allocated and aligned by gcc at least on a 8-byte boundary, so that it works together with the map lookup/update syscall for percpu maps. We use it as a usage example in test_maps, so that others are free to adapt this into their code when necessary. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- tools/testing/selftests/bpf/bpf_util.h | 7 +++++ tools/testing/selftests/bpf/test_maps.c | 37 +++++++++++++------------ 2 files changed, 27 insertions(+), 17 deletions(-) diff --git a/tools/testing/selftests/bpf/bpf_util.h b/tools/testing/selftests/bpf/bpf_util.h index 7de27966103d..369e7d7bba80 100644 --- a/tools/testing/selftests/bpf/bpf_util.h +++ b/tools/testing/selftests/bpf/bpf_util.h @@ -54,4 +54,11 @@ static inline unsigned int bpf_num_possible_cpus(void) return possible_cpus; } +#define __bpf_percpu_val_align __attribute__((__aligned__(8))) + +#define BPF_DECLARE_PERCPU(type, name) \ + struct { type v; /* padding */ } __bpf_percpu_val_align \ + name[bpf_num_possible_cpus()] +#define bpf_percpu(name, cpu) name[(cpu)].v + #endif /* __BPF_UTIL__ */ diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c index a977c4f7b0ce..93314524de0d 100644 --- a/tools/testing/selftests/bpf/test_maps.c +++ b/tools/testing/selftests/bpf/test_maps.c @@ -137,20 +137,20 @@ static void test_hashmap_sizes(int task, void *data) static void test_hashmap_percpu(int task, void *data) { unsigned int nr_cpus = bpf_num_possible_cpus(); - long long value[nr_cpus]; + BPF_DECLARE_PERCPU(long, value); long long key, next_key, first_key; int expected_key_mask = 0; int fd, i; fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_HASH, sizeof(key), - sizeof(value[0]), 2, map_flags); + sizeof(bpf_percpu(value, 0)), 2, map_flags); if (fd < 0) { printf("Failed to create hashmap '%s'!\n", strerror(errno)); exit(1); } for (i = 0; i < nr_cpus; i++) - value[i] = i + 100; + bpf_percpu(value, i) = i + 100; key = 1; /* Insert key=1 element. */ @@ -170,8 +170,9 @@ static void test_hashmap_percpu(int task, void *data) /* Check that key=1 can be found. Value could be 0 if the lookup * was run from a different CPU. */ - value[0] = 1; - assert(bpf_map_lookup_elem(fd, &key, value) == 0 && value[0] == 100); + bpf_percpu(value, 0) = 1; + assert(bpf_map_lookup_elem(fd, &key, value) == 0 && + bpf_percpu(value, 0) == 100); key = 2; /* Check that key=2 is not found. */ @@ -211,7 +212,7 @@ static void test_hashmap_percpu(int task, void *data) assert(bpf_map_lookup_elem(fd, &next_key, value) == 0); for (i = 0; i < nr_cpus; i++) - assert(value[i] == i + 100); + assert(bpf_percpu(value, i) == i + 100); key = next_key; } @@ -296,34 +297,36 @@ static void test_arraymap(int task, void *data) static void test_arraymap_percpu(int task, void *data) { unsigned int nr_cpus = bpf_num_possible_cpus(); + BPF_DECLARE_PERCPU(long, values); int key, next_key, fd, i; - long long values[nr_cpus]; fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), - sizeof(values[0]), 2, 0); + sizeof(bpf_percpu(values, 0)), 2, 0); if (fd < 0) { printf("Failed to create arraymap '%s'!\n", strerror(errno)); exit(1); } for (i = 0; i < nr_cpus; i++) - values[i] = i + 100; + bpf_percpu(values, i) = i + 100; key = 1; /* Insert key=1 element. */ assert(bpf_map_update_elem(fd, &key, values, BPF_ANY) == 0); - values[0] = 0; + bpf_percpu(values, 0) = 0; assert(bpf_map_update_elem(fd, &key, values, BPF_NOEXIST) == -1 && errno == EEXIST); /* Check that key=1 can be found. */ - assert(bpf_map_lookup_elem(fd, &key, values) == 0 && values[0] == 100); + assert(bpf_map_lookup_elem(fd, &key, values) == 0 && + bpf_percpu(values, 0) == 100); key = 0; /* Check that key=0 is also found and zero initialized. */ assert(bpf_map_lookup_elem(fd, &key, values) == 0 && - values[0] == 0 && values[nr_cpus - 1] == 0); + bpf_percpu(values, 0) == 0 && + bpf_percpu(values, nr_cpus - 1) == 0); /* Check that key=2 cannot be inserted due to max_entries limit. */ key = 2; @@ -353,15 +356,15 @@ static void test_arraymap_percpu(int task, void *data) static void test_arraymap_percpu_many_keys(void) { unsigned int nr_cpus = bpf_num_possible_cpus(); + BPF_DECLARE_PERCPU(long, values); /* nr_keys is not too large otherwise the test stresses percpu * allocator more than anything else */ unsigned int nr_keys = 2000; - long long values[nr_cpus]; int key, fd, i; fd = bpf_create_map(BPF_MAP_TYPE_PERCPU_ARRAY, sizeof(key), - sizeof(values[0]), nr_keys, 0); + sizeof(bpf_percpu(values, 0)), nr_keys, 0); if (fd < 0) { printf("Failed to create per-cpu arraymap '%s'!\n", strerror(errno)); @@ -369,19 +372,19 @@ static void test_arraymap_percpu_many_keys(void) } for (i = 0; i < nr_cpus; i++) - values[i] = i + 10; + bpf_percpu(values, i) = i + 10; for (key = 0; key < nr_keys; key++) assert(bpf_map_update_elem(fd, &key, values, BPF_ANY) == 0); for (key = 0; key < nr_keys; key++) { for (i = 0; i < nr_cpus; i++) - values[i] = 0; + bpf_percpu(values, i) = 0; assert(bpf_map_lookup_elem(fd, &key, values) == 0); for (i = 0; i < nr_cpus; i++) - assert(values[i] == i + 10); + assert(bpf_percpu(values, i) == i + 10); } close(fd); -- GitLab