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McKenney" Subject: [PATCH v5 bpf-next 3/3] selftests/bpf: Add a test for kmem_cache_iter Date: Thu, 10 Oct 2024 16:25:05 -0700 Message-ID: <20241010232505.1339892-4-namhyung@kernel.org> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog In-Reply-To: <20241010232505.1339892-1-namhyung@kernel.org> References: <20241010232505.1339892-1-namhyung@kernel.org> MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: mhhxmyn8ia7rjp76w9mdfpsw85ti9dz1 X-Rspamd-Queue-Id: D2A0C1A0005 X-Rspamd-Server: rspam11 X-HE-Tag: 1728602708-355061 X-HE-Meta: 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 5/v4nJxH 5S8Z4hxCUOw6m/zCKeiykN1YDKOHE2a269JM2y6/K3DSw702XpDQctJTLa8yyv60jiiWu+cpcjH+X2hUjhhanPHBIvwjZBGXSGZWdygLM1ema/2cwV/1N7OfEALU+90ueLARptxLfxRxc0i/Usq18V3R2reL8fvGKtc8IOHY7utOpkeaHMvWswShb+z5gJpfywid9Sq92QKE/HUVKQ7LULrSbegqGE+58jkhMFOSnUEp/GWWuKrxl3zNsxfG+yD1LqqA8AGsAAmdO0yBOzDwMzBaH/mEhKHfSEpMNuC4ZApfuFnz3KhmmMteGORWt1yD/0ioteKsSuRbfd8PDi0TC4sh74WtuC1wYDzPF X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The test traverses all slab caches using the kmem_cache_iter and save the data into slab_result array map. And check if current task's pointer is from "task_struct" slab cache using bpf_get_kmem_cache(). Also compare the result array with /proc/slabinfo if available (when CONFIG_SLUB_DEBUG is on). Note that many of the fields in the slabinfo are transient, so it only compares the name and objsize fields. Signed-off-by: Namhyung Kim --- .../bpf/prog_tests/kmem_cache_iter.c | 115 ++++++++++++++++++ tools/testing/selftests/bpf/progs/bpf_iter.h | 7 ++ .../selftests/bpf/progs/kmem_cache_iter.c | 95 +++++++++++++++ 3 files changed, 217 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c create mode 100644 tools/testing/selftests/bpf/progs/kmem_cache_iter.c diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c new file mode 100644 index 0000000000000000..848d8fc9171fae45 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c @@ -0,0 +1,115 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Google */ + +#include +#include +#include +#include "kmem_cache_iter.skel.h" + +#define SLAB_NAME_MAX 32 + +struct kmem_cache_result { + char name[SLAB_NAME_MAX]; + long obj_size; +}; + +static void subtest_kmem_cache_iter_check_task_struct(struct kmem_cache_iter *skel) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts, + .flags = 0, /* Run it with the current task */ + ); + int prog_fd = bpf_program__fd(skel->progs.check_task_struct); + + /* Get task_struct and check it if's from a slab cache */ + ASSERT_OK(bpf_prog_test_run_opts(prog_fd, &opts), "prog_test_run"); + + /* The BPF program should set 'found' variable */ + ASSERT_EQ(skel->bss->task_struct_found, 1, "task_struct_found"); +} + +static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) +{ + FILE *fp; + int map_fd; + char name[SLAB_NAME_MAX]; + unsigned long objsize; + char rest_of_line[1000]; + struct kmem_cache_result r; + int seen = 0; + + fp = fopen("/proc/slabinfo", "r"); + if (fp == NULL) { + /* CONFIG_SLUB_DEBUG is not enabled */ + return; + } + + map_fd = bpf_map__fd(skel->maps.slab_result); + + /* Ignore first two lines for header */ + fscanf(fp, "slabinfo - version: %*d.%*d\n"); + fscanf(fp, "# %*s %*s %*s %*s %*s %*s : %[^\n]\n", rest_of_line); + + /* Compare name and objsize only - others can be changes frequently */ + while (fscanf(fp, "%s %*u %*u %lu %*u %*u : %[^\n]\n", + name, &objsize, rest_of_line) == 3) { + int ret = bpf_map_lookup_elem(map_fd, &seen, &r); + + if (!ASSERT_OK(ret, "kmem_cache_lookup")) + break; + + ASSERT_STREQ(r.name, name, "kmem_cache_name"); + ASSERT_EQ(r.obj_size, objsize, "kmem_cache_objsize"); + + seen++; + } + + ASSERT_EQ(skel->bss->kmem_cache_seen, seen, "kmem_cache_seen_eq"); + + fclose(fp); +} + +void test_kmem_cache_iter(void) +{ + DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts); + struct kmem_cache_iter *skel = NULL; + union bpf_iter_link_info linfo = {}; + struct bpf_link *link; + char buf[256]; + int iter_fd; + + skel = kmem_cache_iter__open_and_load(); + if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load")) + return; + + opts.link_info = &linfo; + opts.link_info_len = sizeof(linfo); + + link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts); + if (!ASSERT_OK_PTR(link, "attach_iter")) + goto destroy; + + iter_fd = bpf_iter_create(bpf_link__fd(link)); + if (!ASSERT_GE(iter_fd, 0, "iter_create")) + goto free_link; + + memset(buf, 0, sizeof(buf)); + while (read(iter_fd, buf, sizeof(buf) > 0)) { + /* Read out all contents */ + printf("%s", buf); + } + + /* Next reads should return 0 */ + ASSERT_EQ(read(iter_fd, buf, sizeof(buf)), 0, "read"); + + if (test__start_subtest("check_task_struct")) + subtest_kmem_cache_iter_check_task_struct(skel); + if (test__start_subtest("check_slabinfo")) + subtest_kmem_cache_iter_check_slabinfo(skel); + + close(iter_fd); + +free_link: + bpf_link__destroy(link); +destroy: + kmem_cache_iter__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/bpf_iter.h b/tools/testing/selftests/bpf/progs/bpf_iter.h index c41ee80533ca219a..3305dc3a74b32481 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter.h +++ b/tools/testing/selftests/bpf/progs/bpf_iter.h @@ -24,6 +24,7 @@ #define BTF_F_PTR_RAW BTF_F_PTR_RAW___not_used #define BTF_F_ZERO BTF_F_ZERO___not_used #define bpf_iter__ksym bpf_iter__ksym___not_used +#define bpf_iter__kmem_cache bpf_iter__kmem_cache___not_used #include "vmlinux.h" #undef bpf_iter_meta #undef bpf_iter__bpf_map @@ -48,6 +49,7 @@ #undef BTF_F_PTR_RAW #undef BTF_F_ZERO #undef bpf_iter__ksym +#undef bpf_iter__kmem_cache struct bpf_iter_meta { struct seq_file *seq; @@ -165,3 +167,8 @@ struct bpf_iter__ksym { struct bpf_iter_meta *meta; struct kallsym_iter *ksym; }; + +struct bpf_iter__kmem_cache { + struct bpf_iter_meta *meta; + struct kmem_cache *s; +} __attribute__((preserve_access_index)); diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c new file mode 100644 index 0000000000000000..1cff8c7772683caf --- /dev/null +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2024 Google */ + +#include "bpf_iter.h" +#include +#include + +char _license[] SEC("license") = "GPL"; + +#define SLAB_NAME_MAX 32 + +struct kmem_cache_result { + char name[SLAB_NAME_MAX]; + long obj_size; +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(key_size, sizeof(void *)); + __uint(value_size, SLAB_NAME_MAX); + __uint(max_entries, 1); +} slab_hash SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(key_size, sizeof(int)); + __uint(value_size, sizeof(struct kmem_cache_result)); + __uint(max_entries, 1024); +} slab_result SEC(".maps"); + +extern void bpf_rcu_read_lock(void) __ksym; +extern void bpf_rcu_read_unlock(void) __ksym; +extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; + +/* Result, will be checked by userspace */ +int task_struct_found; +int kmem_cache_seen; + +SEC("iter/kmem_cache") +int slab_info_collector(struct bpf_iter__kmem_cache *ctx) +{ + struct seq_file *seq = ctx->meta->seq; + struct kmem_cache *s = ctx->s; + struct kmem_cache_result *r; + int idx; + + if (s) { + /* To make sure if the slab_iter implements the seq interface + * properly and it's also useful for debugging. + */ + BPF_SEQ_PRINTF(seq, "%s: %u\n", s->name, s->size); + + idx = kmem_cache_seen; + r = bpf_map_lookup_elem(&slab_result, &idx); + if (r == NULL) + return 0; + + kmem_cache_seen++; + + /* Save name and size to match /proc/slabinfo */ + bpf_probe_read_kernel_str(r->name, sizeof(r->name), s->name); + r->obj_size = s->size; + + if (!bpf_strncmp(r->name, 11, "task_struct")) + bpf_map_update_elem(&slab_hash, &s, r->name, BPF_NOEXIST); + } + + return 0; +} + +SEC("raw_tp/bpf_test_finish") +int BPF_PROG(check_task_struct) +{ + u64 curr = bpf_get_current_task(); + struct kmem_cache *s; + char *name; + + bpf_rcu_read_lock(); + + s = bpf_get_kmem_cache(curr); + if (s == NULL) { + task_struct_found = -1; + bpf_rcu_read_unlock(); + return 0; + } + + name = bpf_map_lookup_elem(&slab_hash, &s); + if (name && !bpf_strncmp(name, 11, "task_struct")) + task_struct_found = 1; + else + task_struct_found = -2; + + bpf_rcu_read_unlock(); + return 0; +}