1 files changed, 530 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 000000000000..553bc3b62e89
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strobemeta.h
@@ -0,0 +1,530 @@
+// 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_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_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 bpf_map_def SEC("maps") samples = {
+	.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+	.key_size = sizeof(int),
+	.value_size = sizeof(int),
+	.max_entries = 32,
+};
+
+struct bpf_map_def SEC("maps") stacks_0 = {
+	.type = BPF_MAP_TYPE_STACK_TRACE,
+	.key_size = sizeof(uint32_t),
+	.value_size = sizeof(uint64_t) * PERF_MAX_STACK_DEPTH,
+	.max_entries = 16,
+};
+
+struct bpf_map_def SEC("maps") stacks_1 = {
+	.type = BPF_MAP_TYPE_STACK_TRACE,
+	.key_size = sizeof(uint32_t),
+	.value_size = sizeof(uint64_t) * PERF_MAX_STACK_DEPTH,
+	.max_entries = 16,
+};
+
+struct bpf_map_def SEC("maps") sample_heap = {
+	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size = sizeof(uint32_t),
+	.value_size = sizeof(struct strobelight_bpf_sample),
+	.max_entries = 1,
+};
+
+struct bpf_map_def SEC("maps") strobemeta_cfgs = {
+	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
+	.key_size = sizeof(pid_t),
+	.value_size = sizeof(struct strobemeta_cfg),
+	.max_entries = STROBE_MAX_CFGS,
+};
+
+/* 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;
+};
+
+static __always_inline 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(&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(&dtv, sizeof(dtv),
+			       &((struct tcbhead *)tls_base)->dtv);
+		dtv += tls_index.module;
+	} else {
+		dtv = NULL;
+	}
+	bpf_probe_read(&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;
+}
+
+static __always_inline 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(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;
+	uint32_t len;
+
+	data->str_lens[idx] = 0;
+	location = calc_location(&cfg->str_locs[idx], tls_base);
+	if (!location)
+		return 0;
+
+	bpf_probe_read(value, sizeof(struct strobe_value_generic), location);
+	len = bpf_probe_read_str(payload, STROBE_MAX_STR_LEN, value->ptr);
+	/*
+	 * if bpf_probe_read_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_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;
+	uint32_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(value, sizeof(struct strobe_value_generic), location);
+	if (bpf_probe_read(&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_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 < map.cnt; ++i) {
+		descr->key_lens[i] = 0;
+		len = bpf_probe_read_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_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;
+}
+
+/*
+ * read_strobe_meta returns NULL, if no metadata was read; otherwise returns
+ * pointer to *right after* payload ends
+ */
+static __always_inline 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 NO_UNROLL
+#pragma clang loop unroll(disable)
+#else
+#pragma unroll
+#endif
+	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
+	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
+	for (int i = 0; i < STROBE_MAX_MAPS; ++i) {
+		payload = read_map_var(cfg, i, tls_base, &value, data, payload);
+	}
+	/*
+	 * 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";