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