1 #include <linux/blkdev.h>
2 #include <uapi/linux/ptrace.h>
3
4 /**
5 * @brief Helper method to filter based on the specified inputString.
6 * @param inputString The operation input string to check against the filter.
7 * @return True if the specified inputString starts with the hard-coded filter string; otherwise, false.
8 */
filter(char const * inputString)9 static inline bool filter(char const* inputString)
10 {
11 static const char* null_ptr = 0x0;
12 static const char null_terminator = '\0';
13
14 static const char filter_string[] = "FILTER_STRING"; ///< The filter string is replaced by python code.
15 if (null_ptr == inputString) {
16 return false;
17 }
18
19 // Compare until (not including) the null-terminator for filter_string
20 for (int i = 0; i < sizeof(filter_string) - 1; ++i) {
21 char c1 = *inputString++;
22 if (null_terminator == c1) {
23 return false; // If the null-terminator for inputString was reached, it can not be equal to filter_string.
24 }
25
26 char c2 = filter_string[i];
27 if (c1 != c2) {
28 return false;
29 }
30 }
31 return true;
32 }
33
34 /**
35 * @brief Contains the operation start data to trace.
36 */
37 struct start_data_t
38 {
39 u64 operation_id; ///< The id of the operation.
40 char input[64]; ///< The input string of the request.
41 u64 start; ///< Timestamp of the start operation (start timestamp).
42 };
43
44 /**
45 * @brief Contains the operation start data.
46 * key: the operation id.
47 * value: The operation start latency data.
48 */
49 BPF_HASH(start_hash, u64, struct start_data_t);
50
51 /**
52 * @brief Reads the operation request arguments and stores the start data in the hash.
53 * @param ctx The BPF context.
54 */
trace_operation_start(struct pt_regs * ctx)55 int trace_operation_start(struct pt_regs* ctx)
56 {
57 struct start_data_t start_data = {};
58 bpf_usdt_readarg_p(2, ctx, &start_data.input, sizeof(start_data.input));
59
60 FILTER_STATEMENT ///< Replaced by python code.
61
62 bpf_usdt_readarg(1, ctx, &start_data.operation_id);
63
64 start_data.start = bpf_ktime_get_ns();
65 start_hash.update(&start_data.operation_id, &start_data);
66 return 0;
67 }
68