// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <stdint.h>
#include <stddef.h>
#include <stdbool.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
#include "bpf_compiler.h"
#define FUNCTION_NAME_LEN 64
#define FILE_NAME_LEN 128
#define TASK_COMM_LEN 16
typedef struct {
int PyThreadState_frame;
int PyThreadState_thread;
int PyFrameObject_back;
int PyFrameObject_code;
int PyFrameObject_lineno;
int PyCodeObject_filename;
int PyCodeObject_name;
int String_data;
int String_size;
} OffsetConfig;
typedef struct {
uintptr_t current_state_addr;
uintptr_t tls_key_addr;
OffsetConfig offsets;
bool use_tls;
} PidData;
typedef struct {
uint32_t success;
} Stats;
typedef struct {
char name[FUNCTION_NAME_LEN];
char file[FILE_NAME_LEN];
} Symbol;
typedef struct {
uint32_t pid;
uint32_t tid;
char comm[TASK_COMM_LEN];
int32_t kernel_stack_id;
int32_t user_stack_id;
bool thread_current;
bool pthread_match;
bool stack_complete;
int16_t stack_len;
int32_t stack[STACK_MAX_LEN];
int has_meta;
int metadata;
char dummy_safeguard;
} Event;
typedef int pid_t;
typedef struct {
void* f_back; // PyFrameObject.f_back, previous frame
void* f_code; // PyFrameObject.f_code, pointer to PyCodeObject
void* co_filename; // PyCodeObject.co_filename
void* co_name; // PyCodeObject.co_name
} FrameData;
#ifdef SUBPROGS
__noinline
#else
__always_inline
#endif
static void *get_thread_state(void *tls_base, PidData *pidData)
{
void* thread_state;
int key;
bpf_probe_read_user(&key, sizeof(key), (void*)(long)pidData->tls_key_addr);
bpf_probe_read_user(&thread_state, sizeof(thread_state),
tls_base + 0x310 + key * 0x10 + 0x08);
return thread_state;
}
static __always_inline bool get_frame_data(void *frame_ptr, PidData *pidData,
FrameData *frame, Symbol *symbol)
{
// read data from PyFrameObject
bpf_probe_read_user(&frame->f_back,
sizeof(frame->f_back),
frame_ptr + pidData->offsets.PyFrameObject_back);
bpf_probe_read_user(&frame->f_code,
sizeof(frame->f_code),
frame_ptr + pidData->offsets.PyFrameObject_code);
// read data from PyCodeObject
if (!frame->f_code)
return false;
bpf_probe_read_user(&frame->co_filename,
sizeof(frame->co_filename),
frame->f_code + pidData->offsets.PyCodeObject_filename);
bpf_probe_read_user(&frame->co_name,
sizeof(frame->co_name),
frame->f_code + pidData->offsets.PyCodeObject_name);
// read actual names into symbol
if (frame->co_filename)
bpf_probe_read_user_str(&symbol->file,
sizeof(symbol->file),
frame->co_filename +
pidData->offsets.String_data);
if (frame->co_name)
bpf_probe_read_user_str(&symbol->name,
sizeof(symbol->name),
frame->co_name +
pidData->offsets.String_data);
return true;
}
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, int);
__type(value, PidData);
} pidmap SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, int);
__type(value, Event);
} eventmap SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1);
__type(key, Symbol);
__type(value, int);
} symbolmap SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, Stats);
} statsmap SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(max_entries, 32);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(int));
} perfmap SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_STACK_TRACE);
__uint(max_entries, 1000);
__uint(key_size, sizeof(int));
__uint(value_size, sizeof(long long) * 127);
} stackmap SEC(".maps");
#ifdef USE_BPF_LOOP
struct process_frame_ctx {
int cur_cpu;
int32_t *symbol_counter;
void *frame_ptr;
FrameData *frame;
PidData *pidData;
Symbol *sym;
Event *event;
bool done;
};
static int process_frame_callback(__u32 i, struct process_frame_ctx *ctx)
{
int zero = 0;
void *frame_ptr = ctx->frame_ptr;
PidData *pidData = ctx->pidData;
FrameData *frame = ctx->frame;
int32_t *symbol_counter = ctx->symbol_counter;
int cur_cpu = ctx->cur_cpu;
Event *event = ctx->event;
Symbol *sym = ctx->sym;
if (frame_ptr && get_frame_data(frame_ptr, pidData, frame, sym)) {
int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu;
int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, sym);
if (!symbol_id) {
bpf_map_update_elem(&symbolmap, sym, &zero, 0);
symbol_id = bpf_map_lookup_elem(&symbolmap, sym);
if (!symbol_id) {
ctx->done = true;
return 1;
}
}
if (*symbol_id == new_symbol_id)
(*symbol_counter)++;
barrier_var(i);
if (i >= STACK_MAX_LEN)
return 1;
event->stack[i] = *symbol_id;
event->stack_len = i + 1;
frame_ptr = frame->f_back;
}
return 0;
}
#endif /* USE_BPF_LOOP */
#ifdef GLOBAL_FUNC
__noinline
#elif defined(SUBPROGS)
static __noinline
#else
static __always_inline
#endif
int __on_event(struct bpf_raw_tracepoint_args *ctx)
{
uint64_t pid_tgid = bpf_get_current_pid_tgid();
pid_t pid = (pid_t)(pid_tgid >> 32);
PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid);
if (!pidData)
return 0;
int zero = 0;
Event* event = bpf_map_lookup_elem(&eventmap, &zero);
if (!event)
return 0;
event->pid = pid;
event->tid = (pid_t)pid_tgid;
bpf_get_current_comm(&event->comm, sizeof(event->comm));
event->user_stack_id = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK);
event->kernel_stack_id = bpf_get_stackid(ctx, &stackmap, 0);
void* thread_state_current = (void*)0;
bpf_probe_read_user(&thread_state_current,
sizeof(thread_state_current),
(void*)(long)pidData->current_state_addr);
struct task_struct* task = (struct task_struct*)bpf_get_current_task();
void* tls_base = (void*)task;
void* thread_state = pidData->use_tls ? get_thread_state(tls_base, pidData)
: thread_state_current;
event->thread_current = thread_state == thread_state_current;
if (pidData->use_tls) {
uint64_t pthread_created;
uint64_t pthread_self;
bpf_probe_read_user(&pthread_self, sizeof(pthread_self),
tls_base + 0x10);
bpf_probe_read_user(&pthread_created,
sizeof(pthread_created),
thread_state +
pidData->offsets.PyThreadState_thread);
event->pthread_match = pthread_created == pthread_self;
} else {
event->pthread_match = 1;
}
if (event->pthread_match || !pidData->use_tls) {
void* frame_ptr;
FrameData frame;
Symbol sym = {};
int cur_cpu = bpf_get_smp_processor_id();
bpf_probe_read_user(&frame_ptr,
sizeof(frame_ptr),
thread_state +
pidData->offsets.PyThreadState_frame);
int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym);
if (symbol_counter == NULL)
return 0;
#ifdef USE_BPF_LOOP
struct process_frame_ctx ctx = {
.cur_cpu = cur_cpu,
.symbol_counter = symbol_counter,
.frame_ptr = frame_ptr,
.frame = &frame,
.pidData = pidData,
.sym = &sym,
.event = event,
};
bpf_loop(STACK_MAX_LEN, process_frame_callback, &ctx, 0);
if (ctx.done)
return 0;
#else
#if defined(USE_ITER)
/* no for loop, no unrolling */
#elif defined(NO_UNROLL)
__pragma_loop_no_unroll
#elif defined(UNROLL_COUNT)
__pragma_loop_unroll_count(UNROLL_COUNT)
#else
__pragma_loop_unroll_full
#endif /* NO_UNROLL */
/* Unwind python stack */
#ifdef USE_ITER
int i;
bpf_for(i, 0, STACK_MAX_LEN) {
#else /* !USE_ITER */
for (int i = 0; i < STACK_MAX_LEN; ++i) {
#endif
if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) {
int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu;
int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
if (!symbol_id) {
bpf_map_update_elem(&symbolmap, &sym, &zero, 0);
symbol_id = bpf_map_lookup_elem(&symbolmap, &sym);
if (!symbol_id)
return 0;
}
if (*symbol_id == new_symbol_id)
(*symbol_counter)++;
event->stack[i] = *symbol_id;
event->stack_len = i + 1;
frame_ptr = frame.f_back;
}
}
#endif /* USE_BPF_LOOP */
event->stack_complete = frame_ptr == NULL;
} else {
event->stack_complete = 1;
}
Stats* stats = bpf_map_lookup_elem(&statsmap, &zero);
if (stats)
stats->success++;
event->has_meta = 0;
bpf_perf_event_output(ctx, &perfmap, 0, event, offsetof(Event, metadata));
return 0;
}
SEC("raw_tracepoint/kfree_skb")
int on_event(struct bpf_raw_tracepoint_args* ctx)
{
int ret = 0;
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
ret |= __on_event(ctx);
return ret;
}
char _license[] SEC("license") = "GPL";
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