On Thu, Oct 29, 2020 at 4:19 AM David Verbeiren <david.verbeiren@xxxxxxxxxxxx> wrote: > > Tests that when per-cpu hash map or LRU hash map elements are > re-used as a result of a bpf program inserting elements, the > element values for the other CPUs than the one executing the > BPF code are reset to 0. > > This validates the fix proposed in: > https://lkml.kernel.org/bpf/20201027221324.27894-1-david.verbeiren@xxxxxxxxxxxx/ > > Change-Id: I38bc7b3744ed40704a7b2cc6efa179fb344c4bee > Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Signed-off-by: David Verbeiren <david.verbeiren@xxxxxxxxxxxx> > --- > .../selftests/bpf/prog_tests/map_init.c | 204 ++++++++++++++++++ > 1 file changed, 204 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/map_init.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/map_init.c b/tools/testing/selftests/bpf/prog_tests/map_init.c > new file mode 100644 > index 000000000000..9640cf925908 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/map_init.c > @@ -0,0 +1,204 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +// Copyright (c) 2020 Tessares SA <http://www.tessares.net> > + > +#include <test_progs.h> > + > +#define TEST_VALUE 0x1234 > + > +static int nr_cpus; > +static int duration; > +static char bpf_log_buf[BPF_LOG_BUF_SIZE]; > + > +typedef unsigned long long map_key_t; > +typedef unsigned long long map_value_t; > +typedef struct { > + map_value_t v; /* padding */ > +} __bpf_percpu_val_align pcpu_map_value_t; > + > +/* executes bpf program that updates map with key, value */ > +static int bpf_prog_insert_elem(int fd, map_key_t key, map_value_t value) > +{ > + struct bpf_load_program_attr prog; > + struct bpf_insn insns[] = { > + BPF_LD_IMM64(BPF_REG_8, key), > + BPF_LD_IMM64(BPF_REG_9, value), > + > + /* update: R1=fd, R2=&key, R3=&value, R4=flags */ > + BPF_LD_MAP_FD(BPF_REG_1, fd), > + BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), > + BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), > + BPF_STX_MEM(BPF_DW, BPF_REG_2, BPF_REG_8, 0), > + BPF_MOV64_REG(BPF_REG_3, BPF_REG_2), > + BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -8), > + BPF_STX_MEM(BPF_DW, BPF_REG_3, BPF_REG_9, 0), > + BPF_MOV64_IMM(BPF_REG_4, 0), > + BPF_EMIT_CALL(BPF_FUNC_map_update_elem), > + > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }; Impressive hand written assembly. ;-) I would recommend using skeleton for future work. For example: BPF program: selftests/bpf/progs/bpf_iter_bpf_map.c Use the program in tests: selftests/bpf/prog_tests/bpf_iter.c:#include "bpf_iter_bpf_map.skel.h" > + char buf[64] = {}; > + int pfd, err; > + __u32 retval = 0; > + > + memset(&prog, 0, sizeof(prog)); > + prog.prog_type = BPF_PROG_TYPE_SCHED_CLS; > + prog.insns = insns; > + prog.insns_cnt = ARRAY_SIZE(insns); > + prog.license = "GPL"; > + > + pfd = bpf_load_program_xattr(&prog, bpf_log_buf, BPF_LOG_BUF_SIZE); > + if (CHECK(pfd < 0, "bpf_load_program_xattr", "failed: %s\n%s\n", > + strerror(errno), bpf_log_buf)) > + return -1; > + > + err = bpf_prog_test_run(pfd, 1, buf, sizeof(buf), NULL, NULL, > + &retval, NULL); > + if (CHECK(err || retval, "bpf_prog_test_run", > + "err=%d retval=%d errno=%d\n", err, retval, errno)) > + err = -1; > + > + close(pfd); > + > + return err; > +} > + > +static int check_values_one_cpu(pcpu_map_value_t *value, map_value_t expected) > +{ > + int i, nzCnt = 0; > + map_value_t val; > + > + for (i = 0; i < nr_cpus; i++) { > + val = bpf_percpu(value, i); > + if (val) { > + if (val != expected) { > + PRINT_FAIL("Unexpected value (cpu %d): 0x%llx\n", > + i, val); I guess we can also use CHECK() here? > + return -1; > + } [...] > + > + /* delete key=1 element so it will later be re-used*/ > + key = 1; > + err = bpf_map_delete_elem(map_fd, &key); > + if (CHECK(err, "bpf_map_delete_elem", "failed: %s\n", strerror(errno))) > + goto error_map; > + > + /* run bpf prog that inserts new elem, re-using the slot just freed */ > + err = bpf_prog_insert_elem(map_fd, key, TEST_VALUE); > + if (!ASSERT_OK(err, "bpf_prog_insert_elem")) > + goto error_map; What's the reason to use ASSERT_OK() instead of CHECK()? > + > + /* check that key=1 was re-created by bpf prog */ > + err = bpf_map_lookup_elem(map_fd, &key, value); > + if (CHECK(err, "bpf_map_lookup_elem", "failed: %s\n", strerror(errno))) > + goto error_map; > + > + /* and has expected value for just a single CPU, 0 for all others */ > + check_values_one_cpu(value, TEST_VALUE); > + > +error_map: > + close(map_fd); > +} > + > +/* Add key=1 and key=2 elems with values set for all CPUs > + * Run bpf prog that inserts new key=3 elem > + * (only for current cpu; other cpus should have initial value = 0) > + * Lookup Key=1 and check value is as expected for all CPUs > + */ > +static void test_pcpu_lru_map_init(void) > +{ > + pcpu_map_value_t value[nr_cpus]; > + int map_fd, err; > + map_key_t key; > + > + /* Set up LRU map with 2 elements, values filled for all CPUs. > + * With these 2 elements, the LRU map is full > + */ > + map_fd = map_setup(BPF_MAP_TYPE_LRU_PERCPU_HASH, 2, 2); > + if (CHECK(map_fd < 0, "map_setup", "failed\n")) > + return; > + > + /* run bpf prog that inserts new key=3 element, re-using LRU slot */ > + key = 3; > + err = bpf_prog_insert_elem(map_fd, key, TEST_VALUE); > + if (!ASSERT_OK(err, "bpf_prog_insert_elem")) > + goto error_map; ditto > + > + /* check that key=3 present */ > + err = bpf_map_lookup_elem(map_fd, &key, value); > + if (CHECK(err, "bpf_map_lookup_elem", "failed: %s\n", strerror(errno))) > + goto error_map; > + > + /* and has expected value for just a single CPU, 0 for all others */ > + check_values_one_cpu(value, TEST_VALUE); > + > +error_map: > + close(map_fd); > +} > + > +void test_map_init(void) > +{ > + nr_cpus = bpf_num_possible_cpus(); > + if (CHECK(nr_cpus <= 1, "nr_cpus", "> 1 needed for this test")) > + return; Instead of failing the test, let's skip the tests with something like: printf("%s:SKIP: >1 cpu needed for this test\n", __func__); test__skip(); > + > + if (test__start_subtest("pcpu_map_init")) > + test_pcpu_map_init(); > + if (test__start_subtest("pcpu_lru_map_init")) > + test_pcpu_lru_map_init(); > +} > -- > 2.29.0 >
