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-rw-r--r--tools/testing/selftests/bpf/progs/strobemeta.h616
1 files changed, 616 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/strobemeta.h b/tools/testing/selftests/bpf/progs/strobemeta.h
new file mode 100644
index 000000000..753718595
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strobemeta.h
@@ -0,0 +1,616 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include <linux/ptrace.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <bpf/bpf_helpers.h>
+
+typedef uint32_t pid_t;
+struct task_struct {};
+
+#define TASK_COMM_LEN 16
+#define PERF_MAX_STACK_DEPTH 127
+
+#define STROBE_TYPE_INVALID 0
+#define STROBE_TYPE_INT 1
+#define STROBE_TYPE_STR 2
+#define STROBE_TYPE_MAP 3
+
+#define STACK_TABLE_EPOCH_SHIFT 20
+#define STROBE_MAX_STR_LEN 1
+#define STROBE_MAX_CFGS 32
+#define STROBE_MAX_PAYLOAD \
+ (STROBE_MAX_STRS * STROBE_MAX_STR_LEN + \
+ STROBE_MAX_MAPS * (1 + STROBE_MAX_MAP_ENTRIES * 2) * STROBE_MAX_STR_LEN)
+
+struct strobe_value_header {
+ /*
+ * meaning depends on type:
+ * 1. int: 0, if value not set, 1 otherwise
+ * 2. str: 1 always, whether value is set or not is determined by ptr
+ * 3. map: 1 always, pointer points to additional struct with number
+ * of entries (up to STROBE_MAX_MAP_ENTRIES)
+ */
+ uint16_t len;
+ /*
+ * _reserved might be used for some future fields/flags, but we always
+ * want to keep strobe_value_header to be 8 bytes, so BPF can read 16
+ * bytes in one go and get both header and value
+ */
+ uint8_t _reserved[6];
+};
+
+/*
+ * strobe_value_generic is used from BPF probe only, but needs to be a union
+ * of strobe_value_int/strobe_value_str/strobe_value_map
+ */
+struct strobe_value_generic {
+ struct strobe_value_header header;
+ union {
+ int64_t val;
+ void *ptr;
+ };
+};
+
+struct strobe_value_int {
+ struct strobe_value_header header;
+ int64_t value;
+};
+
+struct strobe_value_str {
+ struct strobe_value_header header;
+ const char* value;
+};
+
+struct strobe_value_map {
+ struct strobe_value_header header;
+ const struct strobe_map_raw* value;
+};
+
+struct strobe_map_entry {
+ const char* key;
+ const char* val;
+};
+
+/*
+ * Map of C-string key/value pairs with fixed maximum capacity. Each map has
+ * corresponding int64 ID, which application can use (or ignore) in whatever
+ * way appropriate. Map is "write-only", there is no way to get data out of
+ * map. Map is intended to be used to provide metadata for profilers and is
+ * not to be used for internal in-app communication. All methods are
+ * thread-safe.
+ */
+struct strobe_map_raw {
+ /*
+ * general purpose unique ID that's up to application to decide
+ * whether and how to use; for request metadata use case id is unique
+ * request ID that's used to match metadata with stack traces on
+ * Strobelight backend side
+ */
+ int64_t id;
+ /* number of used entries in map */
+ int64_t cnt;
+ /*
+ * having volatile doesn't change anything on BPF side, but clang
+ * emits warnings for passing `volatile const char *` into
+ * bpf_probe_read_user_str that expects just `const char *`
+ */
+ const char* tag;
+ /*
+ * key/value entries, each consisting of 2 pointers to key and value
+ * C strings
+ */
+ struct strobe_map_entry entries[STROBE_MAX_MAP_ENTRIES];
+};
+
+/* Following values define supported values of TLS mode */
+#define TLS_NOT_SET -1
+#define TLS_LOCAL_EXEC 0
+#define TLS_IMM_EXEC 1
+#define TLS_GENERAL_DYN 2
+
+/*
+ * structure that universally represents TLS location (both for static
+ * executables and shared libraries)
+ */
+struct strobe_value_loc {
+ /*
+ * tls_mode defines what TLS mode was used for particular metavariable:
+ * - -1 (TLS_NOT_SET) - no metavariable;
+ * - 0 (TLS_LOCAL_EXEC) - Local Executable mode;
+ * - 1 (TLS_IMM_EXEC) - Immediate Executable mode;
+ * - 2 (TLS_GENERAL_DYN) - General Dynamic mode;
+ * Local Dynamic mode is not yet supported, because never seen in
+ * practice. Mode defines how offset field is interpreted. See
+ * calc_location() in below for details.
+ */
+ int64_t tls_mode;
+ /*
+ * TLS_LOCAL_EXEC: offset from thread pointer (fs:0 for x86-64,
+ * tpidr_el0 for aarch64).
+ * TLS_IMM_EXEC: absolute address of GOT entry containing offset
+ * from thread pointer;
+ * TLS_GENERAL_DYN: absolute addres of double GOT entry
+ * containing tls_index_t struct;
+ */
+ int64_t offset;
+};
+
+struct strobemeta_cfg {
+ int64_t req_meta_idx;
+ struct strobe_value_loc int_locs[STROBE_MAX_INTS];
+ struct strobe_value_loc str_locs[STROBE_MAX_STRS];
+ struct strobe_value_loc map_locs[STROBE_MAX_MAPS];
+};
+
+struct strobe_map_descr {
+ uint64_t id;
+ int16_t tag_len;
+ /*
+ * cnt <0 - map value isn't set;
+ * 0 - map has id set, but no key/value entries
+ */
+ int16_t cnt;
+ /*
+ * both key_lens[i] and val_lens[i] should be >0 for present key/value
+ * entry
+ */
+ uint16_t key_lens[STROBE_MAX_MAP_ENTRIES];
+ uint16_t val_lens[STROBE_MAX_MAP_ENTRIES];
+};
+
+struct strobemeta_payload {
+ /* req_id has valid request ID, if req_meta_valid == 1 */
+ int64_t req_id;
+ uint8_t req_meta_valid;
+ /*
+ * mask has Nth bit set to 1, if Nth metavar was present and
+ * successfully read
+ */
+ uint64_t int_vals_set_mask;
+ int64_t int_vals[STROBE_MAX_INTS];
+ /* len is >0 for present values */
+ uint16_t str_lens[STROBE_MAX_STRS];
+ /* if map_descrs[i].cnt == -1, metavar is not present/set */
+ struct strobe_map_descr map_descrs[STROBE_MAX_MAPS];
+ /*
+ * payload has compactly packed values of str and map variables in the
+ * form: strval1\0strval2\0map1key1\0map1val1\0map2key1\0map2val1\0
+ * (and so on); str_lens[i], key_lens[i] and val_lens[i] determines
+ * value length
+ */
+ char payload[STROBE_MAX_PAYLOAD];
+};
+
+struct strobelight_bpf_sample {
+ uint64_t ktime;
+ char comm[TASK_COMM_LEN];
+ pid_t pid;
+ int user_stack_id;
+ int kernel_stack_id;
+ int has_meta;
+ struct strobemeta_payload metadata;
+ /*
+ * makes it possible to pass (<real payload size> + 1) as data size to
+ * perf_submit() to avoid perf_submit's paranoia about passing zero as
+ * size, as it deduces that <real payload size> might be
+ * **theoretically** zero
+ */
+ char dummy_safeguard;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(max_entries, 32);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(int));
+} samples SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_STACK_TRACE);
+ __uint(max_entries, 16);
+ __uint(key_size, sizeof(uint32_t));
+ __uint(value_size, sizeof(uint64_t) * PERF_MAX_STACK_DEPTH);
+} stacks_0 SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_STACK_TRACE);
+ __uint(max_entries, 16);
+ __uint(key_size, sizeof(uint32_t));
+ __uint(value_size, sizeof(uint64_t) * PERF_MAX_STACK_DEPTH);
+} stacks_1 SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(max_entries, 1);
+ __type(key, uint32_t);
+ __type(value, struct strobelight_bpf_sample);
+} sample_heap SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(max_entries, STROBE_MAX_CFGS);
+ __type(key, pid_t);
+ __type(value, struct strobemeta_cfg);
+} strobemeta_cfgs SEC(".maps");
+
+/* Type for the dtv. */
+/* https://github.com/lattera/glibc/blob/master/nptl/sysdeps/x86_64/tls.h#L34 */
+typedef union dtv {
+ size_t counter;
+ struct {
+ void* val;
+ bool is_static;
+ } pointer;
+} dtv_t;
+
+/* Partial definition for tcbhead_t */
+/* https://github.com/bminor/glibc/blob/master/sysdeps/x86_64/nptl/tls.h#L42 */
+struct tcbhead {
+ void* tcb;
+ dtv_t* dtv;
+};
+
+/*
+ * TLS module/offset information for shared library case.
+ * For x86-64, this is mapped onto two entries in GOT.
+ * For aarch64, this is pointed to by second GOT entry.
+ */
+struct tls_index {
+ uint64_t module;
+ uint64_t offset;
+};
+
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void *calc_location(struct strobe_value_loc *loc, void *tls_base)
+{
+ /*
+ * tls_mode value is:
+ * - -1 (TLS_NOT_SET), if no metavar is present;
+ * - 0 (TLS_LOCAL_EXEC), if metavar uses Local Executable mode of TLS
+ * (offset from fs:0 for x86-64 or tpidr_el0 for aarch64);
+ * - 1 (TLS_IMM_EXEC), if metavar uses Immediate Executable mode of TLS;
+ * - 2 (TLS_GENERAL_DYN), if metavar uses General Dynamic mode of TLS;
+ * This schema allows to use something like:
+ * (tls_mode + 1) * (tls_base + offset)
+ * to get NULL for "no metavar" location, or correct pointer for local
+ * executable mode without doing extra ifs.
+ */
+ if (loc->tls_mode <= TLS_LOCAL_EXEC) {
+ /* static executable is simple, we just have offset from
+ * tls_base */
+ void *addr = tls_base + loc->offset;
+ /* multiply by (tls_mode + 1) to get NULL, if we have no
+ * metavar in this slot */
+ return (void *)((loc->tls_mode + 1) * (int64_t)addr);
+ }
+ /*
+ * Other modes are more complicated, we need to jump through few hoops.
+ *
+ * For immediate executable mode (currently supported only for aarch64):
+ * - loc->offset is pointing to a GOT entry containing fixed offset
+ * relative to tls_base;
+ *
+ * For general dynamic mode:
+ * - loc->offset is pointing to a beginning of double GOT entries;
+ * - (for aarch64 only) second entry points to tls_index_t struct;
+ * - (for x86-64 only) two GOT entries are already tls_index_t;
+ * - tls_index_t->module is used to find start of TLS section in
+ * which variable resides;
+ * - tls_index_t->offset provides offset within that TLS section,
+ * pointing to value of variable.
+ */
+ struct tls_index tls_index;
+ dtv_t *dtv;
+ void *tls_ptr;
+
+ bpf_probe_read_user(&tls_index, sizeof(struct tls_index),
+ (void *)loc->offset);
+ /* valid module index is always positive */
+ if (tls_index.module > 0) {
+ /* dtv = ((struct tcbhead *)tls_base)->dtv[tls_index.module] */
+ bpf_probe_read_user(&dtv, sizeof(dtv),
+ &((struct tcbhead *)tls_base)->dtv);
+ dtv += tls_index.module;
+ } else {
+ dtv = NULL;
+ }
+ bpf_probe_read_user(&tls_ptr, sizeof(void *), dtv);
+ /* if pointer has (void *)-1 value, then TLS wasn't initialized yet */
+ return tls_ptr && tls_ptr != (void *)-1
+ ? tls_ptr + tls_index.offset
+ : NULL;
+}
+
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void read_int_var(struct strobemeta_cfg *cfg,
+ size_t idx, void *tls_base,
+ struct strobe_value_generic *value,
+ struct strobemeta_payload *data)
+{
+ void *location = calc_location(&cfg->int_locs[idx], tls_base);
+ if (!location)
+ return;
+
+ bpf_probe_read_user(value, sizeof(struct strobe_value_generic), location);
+ data->int_vals[idx] = value->val;
+ if (value->header.len)
+ data->int_vals_set_mask |= (1 << idx);
+}
+
+static __always_inline uint64_t read_str_var(struct strobemeta_cfg *cfg,
+ size_t idx, void *tls_base,
+ struct strobe_value_generic *value,
+ struct strobemeta_payload *data,
+ void *payload)
+{
+ void *location;
+ uint64_t len;
+
+ data->str_lens[idx] = 0;
+ location = calc_location(&cfg->str_locs[idx], tls_base);
+ if (!location)
+ return 0;
+
+ bpf_probe_read_user(value, sizeof(struct strobe_value_generic), location);
+ len = bpf_probe_read_user_str(payload, STROBE_MAX_STR_LEN, value->ptr);
+ /*
+ * if bpf_probe_read_user_str returns error (<0), due to casting to
+ * unsinged int, it will become big number, so next check is
+ * sufficient to check for errors AND prove to BPF verifier, that
+ * bpf_probe_read_user_str won't return anything bigger than
+ * STROBE_MAX_STR_LEN
+ */
+ if (len > STROBE_MAX_STR_LEN)
+ return 0;
+
+ data->str_lens[idx] = len;
+ return len;
+}
+
+static __always_inline void *read_map_var(struct strobemeta_cfg *cfg,
+ size_t idx, void *tls_base,
+ struct strobe_value_generic *value,
+ struct strobemeta_payload *data,
+ void *payload)
+{
+ struct strobe_map_descr* descr = &data->map_descrs[idx];
+ struct strobe_map_raw map;
+ void *location;
+ uint64_t len;
+ int i;
+
+ descr->tag_len = 0; /* presume no tag is set */
+ descr->cnt = -1; /* presume no value is set */
+
+ location = calc_location(&cfg->map_locs[idx], tls_base);
+ if (!location)
+ return payload;
+
+ bpf_probe_read_user(value, sizeof(struct strobe_value_generic), location);
+ if (bpf_probe_read_user(&map, sizeof(struct strobe_map_raw), value->ptr))
+ return payload;
+
+ descr->id = map.id;
+ descr->cnt = map.cnt;
+ if (cfg->req_meta_idx == idx) {
+ data->req_id = map.id;
+ data->req_meta_valid = 1;
+ }
+
+ len = bpf_probe_read_user_str(payload, STROBE_MAX_STR_LEN, map.tag);
+ if (len <= STROBE_MAX_STR_LEN) {
+ descr->tag_len = len;
+ payload += len;
+ }
+
+#ifdef NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma unroll
+#endif
+ for (int i = 0; i < STROBE_MAX_MAP_ENTRIES; ++i) {
+ if (i >= map.cnt)
+ break;
+
+ descr->key_lens[i] = 0;
+ len = bpf_probe_read_user_str(payload, STROBE_MAX_STR_LEN,
+ map.entries[i].key);
+ if (len <= STROBE_MAX_STR_LEN) {
+ descr->key_lens[i] = len;
+ payload += len;
+ }
+ descr->val_lens[i] = 0;
+ len = bpf_probe_read_user_str(payload, STROBE_MAX_STR_LEN,
+ map.entries[i].val);
+ if (len <= STROBE_MAX_STR_LEN) {
+ descr->val_lens[i] = len;
+ payload += len;
+ }
+ }
+
+ return payload;
+}
+
+#ifdef USE_BPF_LOOP
+enum read_type {
+ READ_INT_VAR,
+ READ_MAP_VAR,
+ READ_STR_VAR,
+};
+
+struct read_var_ctx {
+ struct strobemeta_payload *data;
+ void *tls_base;
+ struct strobemeta_cfg *cfg;
+ void *payload;
+ /* value gets mutated */
+ struct strobe_value_generic *value;
+ enum read_type type;
+};
+
+static int read_var_callback(__u32 index, struct read_var_ctx *ctx)
+{
+ switch (ctx->type) {
+ case READ_INT_VAR:
+ if (index >= STROBE_MAX_INTS)
+ return 1;
+ read_int_var(ctx->cfg, index, ctx->tls_base, ctx->value, ctx->data);
+ break;
+ case READ_MAP_VAR:
+ if (index >= STROBE_MAX_MAPS)
+ return 1;
+ ctx->payload = read_map_var(ctx->cfg, index, ctx->tls_base,
+ ctx->value, ctx->data, ctx->payload);
+ break;
+ case READ_STR_VAR:
+ if (index >= STROBE_MAX_STRS)
+ return 1;
+ ctx->payload += read_str_var(ctx->cfg, index, ctx->tls_base,
+ ctx->value, ctx->data, ctx->payload);
+ break;
+ }
+ return 0;
+}
+#endif /* USE_BPF_LOOP */
+
+/*
+ * read_strobe_meta returns NULL, if no metadata was read; otherwise returns
+ * pointer to *right after* payload ends
+ */
+#ifdef SUBPROGS
+__noinline
+#else
+__always_inline
+#endif
+static void *read_strobe_meta(struct task_struct *task,
+ struct strobemeta_payload *data)
+{
+ pid_t pid = bpf_get_current_pid_tgid() >> 32;
+ struct strobe_value_generic value = {0};
+ struct strobemeta_cfg *cfg;
+ void *tls_base, *payload;
+
+ cfg = bpf_map_lookup_elem(&strobemeta_cfgs, &pid);
+ if (!cfg)
+ return NULL;
+
+ data->int_vals_set_mask = 0;
+ data->req_meta_valid = 0;
+ payload = data->payload;
+ /*
+ * we don't have struct task_struct definition, it should be:
+ * tls_base = (void *)task->thread.fsbase;
+ */
+ tls_base = (void *)task;
+
+#ifdef USE_BPF_LOOP
+ struct read_var_ctx ctx = {
+ .cfg = cfg,
+ .tls_base = tls_base,
+ .value = &value,
+ .data = data,
+ .payload = payload,
+ };
+ int err;
+
+ ctx.type = READ_INT_VAR;
+ err = bpf_loop(STROBE_MAX_INTS, read_var_callback, &ctx, 0);
+ if (err != STROBE_MAX_INTS)
+ return NULL;
+
+ ctx.type = READ_STR_VAR;
+ err = bpf_loop(STROBE_MAX_STRS, read_var_callback, &ctx, 0);
+ if (err != STROBE_MAX_STRS)
+ return NULL;
+
+ ctx.type = READ_MAP_VAR;
+ err = bpf_loop(STROBE_MAX_MAPS, read_var_callback, &ctx, 0);
+ if (err != STROBE_MAX_MAPS)
+ return NULL;
+#else
+#ifdef NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma unroll
+#endif /* NO_UNROLL */
+ for (int i = 0; i < STROBE_MAX_INTS; ++i) {
+ read_int_var(cfg, i, tls_base, &value, data);
+ }
+#ifdef NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma unroll
+#endif /* NO_UNROLL */
+ for (int i = 0; i < STROBE_MAX_STRS; ++i) {
+ payload += read_str_var(cfg, i, tls_base, &value, data, payload);
+ }
+#ifdef NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma unroll
+#endif /* NO_UNROLL */
+ for (int i = 0; i < STROBE_MAX_MAPS; ++i) {
+ payload = read_map_var(cfg, i, tls_base, &value, data, payload);
+ }
+#endif /* USE_BPF_LOOP */
+
+ /*
+ * return pointer right after end of payload, so it's possible to
+ * calculate exact amount of useful data that needs to be sent
+ */
+ return payload;
+}
+
+SEC("raw_tracepoint/kfree_skb")
+int on_event(struct pt_regs *ctx) {
+ pid_t pid = bpf_get_current_pid_tgid() >> 32;
+ struct strobelight_bpf_sample* sample;
+ struct task_struct *task;
+ uint32_t zero = 0;
+ uint64_t ktime_ns;
+ void *sample_end;
+
+ sample = bpf_map_lookup_elem(&sample_heap, &zero);
+ if (!sample)
+ return 0; /* this will never happen */
+
+ sample->pid = pid;
+ bpf_get_current_comm(&sample->comm, TASK_COMM_LEN);
+ ktime_ns = bpf_ktime_get_ns();
+ sample->ktime = ktime_ns;
+
+ task = (struct task_struct *)bpf_get_current_task();
+ sample_end = read_strobe_meta(task, &sample->metadata);
+ sample->has_meta = sample_end != NULL;
+ sample_end = sample_end ? : &sample->metadata;
+
+ if ((ktime_ns >> STACK_TABLE_EPOCH_SHIFT) & 1) {
+ sample->kernel_stack_id = bpf_get_stackid(ctx, &stacks_1, 0);
+ sample->user_stack_id = bpf_get_stackid(ctx, &stacks_1, BPF_F_USER_STACK);
+ } else {
+ sample->kernel_stack_id = bpf_get_stackid(ctx, &stacks_0, 0);
+ sample->user_stack_id = bpf_get_stackid(ctx, &stacks_0, BPF_F_USER_STACK);
+ }
+
+ uint64_t sample_size = sample_end - (void *)sample;
+ /* should always be true */
+ if (sample_size < sizeof(struct strobelight_bpf_sample))
+ bpf_perf_event_output(ctx, &samples, 0, sample, 1 + sample_size);
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-13 09:13:38 +0000