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selftests/bpf: add kprobe/uprobe selftests
Add tests verifying kprobe/kretprobe/uprobe/uretprobe APIs work as expected. Signed-off-by: Andrii Nakryiko <[email protected]> Reviewed-by: Stanislav Fomichev <[email protected]> Acked-by: Song Liu <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]>
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‎tools/testing/selftests/bpf/prog_tests/attach_probe.c

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// SPDX-License-Identifier: GPL-2.0
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#include <test_progs.h>
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ssize_t get_base_addr() {
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size_t start;
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char buf[256];
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FILE *f;
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f = fopen("/proc/self/maps", "r");
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if (!f)
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return -errno;
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while (fscanf(f, "%zx-%*x %s %*s\n", &start, buf) == 2) {
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if (strcmp(buf, "r-xp") == 0) {
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fclose(f);
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return start;
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}
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}
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fclose(f);
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return -EINVAL;
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}
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#ifdef __x86_64__
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#define SYS_KPROBE_NAME "__x64_sys_nanosleep"
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#else
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#define SYS_KPROBE_NAME "sys_nanosleep"
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#endif
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void test_attach_probe(void)
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{
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const char *kprobe_name = "kprobe/sys_nanosleep";
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const char *kretprobe_name = "kretprobe/sys_nanosleep";
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const char *uprobe_name = "uprobe/trigger_func";
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const char *uretprobe_name = "uretprobe/trigger_func";
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const int kprobe_idx = 0, kretprobe_idx = 1;
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const int uprobe_idx = 2, uretprobe_idx = 3;
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const char *file = "./test_attach_probe.o";
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struct bpf_program *kprobe_prog, *kretprobe_prog;
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struct bpf_program *uprobe_prog, *uretprobe_prog;
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struct bpf_object *obj;
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int err, prog_fd, duration = 0, res;
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struct bpf_link *kprobe_link = NULL;
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struct bpf_link *kretprobe_link = NULL;
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struct bpf_link *uprobe_link = NULL;
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struct bpf_link *uretprobe_link = NULL;
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int results_map_fd;
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size_t uprobe_offset;
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ssize_t base_addr;
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base_addr = get_base_addr();
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if (CHECK(base_addr < 0, "get_base_addr",
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"failed to find base addr: %zd", base_addr))
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return;
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uprobe_offset = (size_t)&get_base_addr - base_addr;
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/* load programs */
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err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
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if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno))
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return;
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kprobe_prog = bpf_object__find_program_by_title(obj, kprobe_name);
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if (CHECK(!kprobe_prog, "find_probe",
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"prog '%s' not found\n", kprobe_name))
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goto cleanup;
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kretprobe_prog = bpf_object__find_program_by_title(obj, kretprobe_name);
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if (CHECK(!kretprobe_prog, "find_probe",
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"prog '%s' not found\n", kretprobe_name))
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goto cleanup;
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uprobe_prog = bpf_object__find_program_by_title(obj, uprobe_name);
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if (CHECK(!uprobe_prog, "find_probe",
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"prog '%s' not found\n", uprobe_name))
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goto cleanup;
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uretprobe_prog = bpf_object__find_program_by_title(obj, uretprobe_name);
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if (CHECK(!uretprobe_prog, "find_probe",
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"prog '%s' not found\n", uretprobe_name))
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goto cleanup;
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/* load maps */
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results_map_fd = bpf_find_map(__func__, obj, "results_map");
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if (CHECK(results_map_fd < 0, "find_results_map",
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"err %d\n", results_map_fd))
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goto cleanup;
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kprobe_link = bpf_program__attach_kprobe(kprobe_prog,
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false /* retprobe */,
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SYS_KPROBE_NAME);
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if (CHECK(IS_ERR(kprobe_link), "attach_kprobe",
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"err %ld\n", PTR_ERR(kprobe_link))) {
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kprobe_link = NULL;
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goto cleanup;
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}
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kretprobe_link = bpf_program__attach_kprobe(kretprobe_prog,
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true /* retprobe */,
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SYS_KPROBE_NAME);
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if (CHECK(IS_ERR(kretprobe_link), "attach_kretprobe",
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"err %ld\n", PTR_ERR(kretprobe_link))) {
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kretprobe_link = NULL;
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goto cleanup;
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}
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uprobe_link = bpf_program__attach_uprobe(uprobe_prog,
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false /* retprobe */,
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0 /* self pid */,
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"/proc/self/exe",
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uprobe_offset);
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if (CHECK(IS_ERR(uprobe_link), "attach_uprobe",
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"err %ld\n", PTR_ERR(uprobe_link))) {
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uprobe_link = NULL;
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goto cleanup;
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}
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uretprobe_link = bpf_program__attach_uprobe(uretprobe_prog,
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true /* retprobe */,
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-1 /* any pid */,
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"/proc/self/exe",
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uprobe_offset);
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if (CHECK(IS_ERR(uretprobe_link), "attach_uretprobe",
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"err %ld\n", PTR_ERR(uretprobe_link))) {
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uretprobe_link = NULL;
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goto cleanup;
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}
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/* trigger & validate kprobe && kretprobe */
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usleep(1);
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err = bpf_map_lookup_elem(results_map_fd, &kprobe_idx, &res);
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if (CHECK(err, "get_kprobe_res",
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"failed to get kprobe res: %d\n", err))
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goto cleanup;
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if (CHECK(res != kprobe_idx + 1, "check_kprobe_res",
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"wrong kprobe res: %d\n", res))
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goto cleanup;
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err = bpf_map_lookup_elem(results_map_fd, &kretprobe_idx, &res);
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if (CHECK(err, "get_kretprobe_res",
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"failed to get kretprobe res: %d\n", err))
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goto cleanup;
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if (CHECK(res != kretprobe_idx + 1, "check_kretprobe_res",
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"wrong kretprobe res: %d\n", res))
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goto cleanup;
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/* trigger & validate uprobe & uretprobe */
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get_base_addr();
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err = bpf_map_lookup_elem(results_map_fd, &uprobe_idx, &res);
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if (CHECK(err, "get_uprobe_res",
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"failed to get uprobe res: %d\n", err))
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goto cleanup;
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if (CHECK(res != uprobe_idx + 1, "check_uprobe_res",
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"wrong uprobe res: %d\n", res))
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goto cleanup;
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err = bpf_map_lookup_elem(results_map_fd, &uretprobe_idx, &res);
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if (CHECK(err, "get_uretprobe_res",
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"failed to get uretprobe res: %d\n", err))
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goto cleanup;
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if (CHECK(res != uretprobe_idx + 1, "check_uretprobe_res",
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"wrong uretprobe res: %d\n", res))
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goto cleanup;
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cleanup:
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bpf_link__destroy(kprobe_link);
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bpf_link__destroy(kretprobe_link);
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bpf_link__destroy(uprobe_link);
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bpf_link__destroy(uretprobe_link);
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bpf_object__close(obj);
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}

‎tools/testing/selftests/bpf/progs/test_attach_probe.c

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// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2017 Facebook
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#include <linux/ptrace.h>
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#include <linux/bpf.h>
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#include "bpf_helpers.h"
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struct {
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int type;
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int max_entries;
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int *key;
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int *value;
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} results_map SEC(".maps") = {
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.type = BPF_MAP_TYPE_ARRAY,
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.max_entries = 4,
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};
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SEC("kprobe/sys_nanosleep")
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int handle_sys_nanosleep_entry(struct pt_regs *ctx)
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{
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const int key = 0, value = 1;
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bpf_map_update_elem(&results_map, &key, &value, 0);
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return 0;
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}
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SEC("kretprobe/sys_nanosleep")
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int handle_sys_getpid_return(struct pt_regs *ctx)
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{
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const int key = 1, value = 2;
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bpf_map_update_elem(&results_map, &key, &value, 0);
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return 0;
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}
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SEC("uprobe/trigger_func")
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int handle_uprobe_entry(struct pt_regs *ctx)
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{
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const int key = 2, value = 3;
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bpf_map_update_elem(&results_map, &key, &value, 0);
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return 0;
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}
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SEC("uretprobe/trigger_func")
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int handle_uprobe_return(struct pt_regs *ctx)
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{
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const int key = 3, value = 4;
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bpf_map_update_elem(&results_map, &key, &value, 0);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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__u32 _version SEC("version") = 1;

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