1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2019 Facebook 3 #include <linux/sched.h> 4 #include <linux/ptrace.h> 5 #include <stdint.h> 6 #include <stddef.h> 7 #include <stdbool.h> 8 #include <linux/bpf.h> 9 #include "bpf_helpers.h" 10 11 #define FUNCTION_NAME_LEN 64 12 #define FILE_NAME_LEN 128 13 #define TASK_COMM_LEN 16 14 15 typedef struct { 16 int PyThreadState_frame; 17 int PyThreadState_thread; 18 int PyFrameObject_back; 19 int PyFrameObject_code; 20 int PyFrameObject_lineno; 21 int PyCodeObject_filename; 22 int PyCodeObject_name; 23 int String_data; 24 int String_size; 25 } OffsetConfig; 26 27 typedef struct { 28 uintptr_t current_state_addr; 29 uintptr_t tls_key_addr; 30 OffsetConfig offsets; 31 bool use_tls; 32 } PidData; 33 34 typedef struct { 35 uint32_t success; 36 } Stats; 37 38 typedef struct { 39 char name[FUNCTION_NAME_LEN]; 40 char file[FILE_NAME_LEN]; 41 } Symbol; 42 43 typedef struct { 44 uint32_t pid; 45 uint32_t tid; 46 char comm[TASK_COMM_LEN]; 47 int32_t kernel_stack_id; 48 int32_t user_stack_id; 49 bool thread_current; 50 bool pthread_match; 51 bool stack_complete; 52 int16_t stack_len; 53 int32_t stack[STACK_MAX_LEN]; 54 55 int has_meta; 56 int metadata; 57 char dummy_safeguard; 58 } Event; 59 60 61 typedef int pid_t; 62 63 typedef struct { 64 void* f_back; // PyFrameObject.f_back, previous frame 65 void* f_code; // PyFrameObject.f_code, pointer to PyCodeObject 66 void* co_filename; // PyCodeObject.co_filename 67 void* co_name; // PyCodeObject.co_name 68 } FrameData; 69 70 static __always_inline void *get_thread_state(void *tls_base, PidData *pidData) 71 { 72 void* thread_state; 73 int key; 74 75 bpf_probe_read(&key, sizeof(key), (void*)(long)pidData->tls_key_addr); 76 bpf_probe_read(&thread_state, sizeof(thread_state), 77 tls_base + 0x310 + key * 0x10 + 0x08); 78 return thread_state; 79 } 80 81 static __always_inline bool get_frame_data(void *frame_ptr, PidData *pidData, 82 FrameData *frame, Symbol *symbol) 83 { 84 // read data from PyFrameObject 85 bpf_probe_read(&frame->f_back, 86 sizeof(frame->f_back), 87 frame_ptr + pidData->offsets.PyFrameObject_back); 88 bpf_probe_read(&frame->f_code, 89 sizeof(frame->f_code), 90 frame_ptr + pidData->offsets.PyFrameObject_code); 91 92 // read data from PyCodeObject 93 if (!frame->f_code) 94 return false; 95 bpf_probe_read(&frame->co_filename, 96 sizeof(frame->co_filename), 97 frame->f_code + pidData->offsets.PyCodeObject_filename); 98 bpf_probe_read(&frame->co_name, 99 sizeof(frame->co_name), 100 frame->f_code + pidData->offsets.PyCodeObject_name); 101 // read actual names into symbol 102 if (frame->co_filename) 103 bpf_probe_read_str(&symbol->file, 104 sizeof(symbol->file), 105 frame->co_filename + pidData->offsets.String_data); 106 if (frame->co_name) 107 bpf_probe_read_str(&symbol->name, 108 sizeof(symbol->name), 109 frame->co_name + pidData->offsets.String_data); 110 return true; 111 } 112 113 struct { 114 __uint(type, BPF_MAP_TYPE_HASH); 115 __uint(max_entries, 1); 116 __type(key, int); 117 __type(value, PidData); 118 } pidmap SEC(".maps"); 119 120 struct { 121 __uint(type, BPF_MAP_TYPE_HASH); 122 __uint(max_entries, 1); 123 __type(key, int); 124 __type(value, Event); 125 } eventmap SEC(".maps"); 126 127 struct { 128 __uint(type, BPF_MAP_TYPE_HASH); 129 __uint(max_entries, 1); 130 __type(key, Symbol); 131 __type(value, int); 132 } symbolmap SEC(".maps"); 133 134 struct { 135 __uint(type, BPF_MAP_TYPE_ARRAY); 136 __uint(max_entries, 1); 137 __type(key, int); 138 __type(value, Stats); 139 } statsmap SEC(".maps"); 140 141 struct { 142 __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); 143 __uint(max_entries, 32); 144 __uint(key_size, sizeof(int)); 145 __uint(value_size, sizeof(int)); 146 } perfmap SEC(".maps"); 147 148 struct { 149 __uint(type, BPF_MAP_TYPE_STACK_TRACE); 150 __uint(max_entries, 1000); 151 __uint(key_size, sizeof(int)); 152 __uint(value_size, sizeof(long long) * 127); 153 } stackmap SEC(".maps"); 154 155 static __always_inline int __on_event(struct pt_regs *ctx) 156 { 157 uint64_t pid_tgid = bpf_get_current_pid_tgid(); 158 pid_t pid = (pid_t)(pid_tgid >> 32); 159 PidData* pidData = bpf_map_lookup_elem(&pidmap, &pid); 160 if (!pidData) 161 return 0; 162 163 int zero = 0; 164 Event* event = bpf_map_lookup_elem(&eventmap, &zero); 165 if (!event) 166 return 0; 167 168 event->pid = pid; 169 170 event->tid = (pid_t)pid_tgid; 171 bpf_get_current_comm(&event->comm, sizeof(event->comm)); 172 173 event->user_stack_id = bpf_get_stackid(ctx, &stackmap, BPF_F_USER_STACK); 174 event->kernel_stack_id = bpf_get_stackid(ctx, &stackmap, 0); 175 176 void* thread_state_current = (void*)0; 177 bpf_probe_read(&thread_state_current, 178 sizeof(thread_state_current), 179 (void*)(long)pidData->current_state_addr); 180 181 struct task_struct* task = (struct task_struct*)bpf_get_current_task(); 182 void* tls_base = (void*)task; 183 184 void* thread_state = pidData->use_tls ? get_thread_state(tls_base, pidData) 185 : thread_state_current; 186 event->thread_current = thread_state == thread_state_current; 187 188 if (pidData->use_tls) { 189 uint64_t pthread_created; 190 uint64_t pthread_self; 191 bpf_probe_read(&pthread_self, sizeof(pthread_self), tls_base + 0x10); 192 193 bpf_probe_read(&pthread_created, 194 sizeof(pthread_created), 195 thread_state + pidData->offsets.PyThreadState_thread); 196 event->pthread_match = pthread_created == pthread_self; 197 } else { 198 event->pthread_match = 1; 199 } 200 201 if (event->pthread_match || !pidData->use_tls) { 202 void* frame_ptr; 203 FrameData frame; 204 Symbol sym = {}; 205 int cur_cpu = bpf_get_smp_processor_id(); 206 207 bpf_probe_read(&frame_ptr, 208 sizeof(frame_ptr), 209 thread_state + pidData->offsets.PyThreadState_frame); 210 211 int32_t* symbol_counter = bpf_map_lookup_elem(&symbolmap, &sym); 212 if (symbol_counter == NULL) 213 return 0; 214 #ifdef NO_UNROLL 215 #pragma clang loop unroll(disable) 216 #else 217 #pragma clang loop unroll(full) 218 #endif 219 /* Unwind python stack */ 220 for (int i = 0; i < STACK_MAX_LEN; ++i) { 221 if (frame_ptr && get_frame_data(frame_ptr, pidData, &frame, &sym)) { 222 int32_t new_symbol_id = *symbol_counter * 64 + cur_cpu; 223 int32_t *symbol_id = bpf_map_lookup_elem(&symbolmap, &sym); 224 if (!symbol_id) { 225 bpf_map_update_elem(&symbolmap, &sym, &zero, 0); 226 symbol_id = bpf_map_lookup_elem(&symbolmap, &sym); 227 if (!symbol_id) 228 return 0; 229 } 230 if (*symbol_id == new_symbol_id) 231 (*symbol_counter)++; 232 event->stack[i] = *symbol_id; 233 event->stack_len = i + 1; 234 frame_ptr = frame.f_back; 235 } 236 } 237 event->stack_complete = frame_ptr == NULL; 238 } else { 239 event->stack_complete = 1; 240 } 241 242 Stats* stats = bpf_map_lookup_elem(&statsmap, &zero); 243 if (stats) 244 stats->success++; 245 246 event->has_meta = 0; 247 bpf_perf_event_output(ctx, &perfmap, 0, event, offsetof(Event, metadata)); 248 return 0; 249 } 250 251 SEC("raw_tracepoint/kfree_skb") 252 int on_event(struct pt_regs* ctx) 253 { 254 int i, ret = 0; 255 ret |= __on_event(ctx); 256 ret |= __on_event(ctx); 257 ret |= __on_event(ctx); 258 ret |= __on_event(ctx); 259 ret |= __on_event(ctx); 260 return ret; 261 } 262 263 char _license[] SEC("license") = "GPL"; 264