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selftests/bpf: Add uprobe fail tests for uprobe multi

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Adding tests for checking on recovery after failing to
attach uprobe.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240722202758.3889061-2-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2024-07-22 22:27:57 +02:00 committed by Andrii Nakryiko
parent d17f9b370d
commit 30c2980c10
1 changed files with 118 additions and 0 deletions
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118
tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
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@ -516,6 +516,122 @@ cleanup:
uprobe_multi__destroy(skel);
}
#ifdef __x86_64__
noinline void uprobe_multi_error_func(void)
{
/*
* If --fcf-protection=branch is enabled the gcc generates endbr as
* first instruction, so marking the exact address of int3 with the
* symbol to be used in the attach_uprobe_fail_trap test below.
*/
asm volatile (
".globl uprobe_multi_error_func_int3; \n"
"uprobe_multi_error_func_int3: \n"
"int3 \n"
);
}
/*
* Attaching uprobe on uprobe_multi_error_func results in error
* because it already starts with int3 instruction.
*/
static void attach_uprobe_fail_trap(struct uprobe_multi *skel)
{
LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
const char *syms[4] = {
"uprobe_multi_func_1",
"uprobe_multi_func_2",
"uprobe_multi_func_3",
"uprobe_multi_error_func_int3",
};
opts.syms = syms;
opts.cnt = ARRAY_SIZE(syms);
skel->links.uprobe = bpf_program__attach_uprobe_multi(skel->progs.uprobe, -1,
"/proc/self/exe", NULL, &opts);
if (!ASSERT_ERR_PTR(skel->links.uprobe, "bpf_program__attach_uprobe_multi")) {
bpf_link__destroy(skel->links.uprobe);
skel->links.uprobe = NULL;
}
}
#else
static void attach_uprobe_fail_trap(struct uprobe_multi *skel) { }
#endif
short sema_1 __used, sema_2 __used;
static void attach_uprobe_fail_refctr(struct uprobe_multi *skel)
{
unsigned long *tmp_offsets = NULL, *tmp_ref_ctr_offsets = NULL;
unsigned long offsets[3], ref_ctr_offsets[3];
LIBBPF_OPTS(bpf_link_create_opts, opts);
const char *path = "/proc/self/exe";
const char *syms[3] = {
"uprobe_multi_func_1",
"uprobe_multi_func_2",
};
const char *sema[3] = {
"sema_1",
"sema_2",
};
int prog_fd, link_fd, err;
prog_fd = bpf_program__fd(skel->progs.uprobe_extra);
err = elf_resolve_syms_offsets("/proc/self/exe", 2, (const char **) &syms,
&tmp_offsets, STT_FUNC);
if (!ASSERT_OK(err, "elf_resolve_syms_offsets_func"))
return;
err = elf_resolve_syms_offsets("/proc/self/exe", 2, (const char **) &sema,
&tmp_ref_ctr_offsets, STT_OBJECT);
if (!ASSERT_OK(err, "elf_resolve_syms_offsets_sema"))
goto cleanup;
/*
* We attach to 3 uprobes on 2 functions, so 2 uprobes share single function,
* but with different ref_ctr_offset which is not allowed and results in fail.
*/
offsets[0] = tmp_offsets[0]; /* uprobe_multi_func_1 */
offsets[1] = tmp_offsets[1]; /* uprobe_multi_func_2 */
offsets[2] = tmp_offsets[1]; /* uprobe_multi_func_2 */
ref_ctr_offsets[0] = tmp_ref_ctr_offsets[0]; /* sema_1 */
ref_ctr_offsets[1] = tmp_ref_ctr_offsets[1]; /* sema_2 */
ref_ctr_offsets[2] = tmp_ref_ctr_offsets[0]; /* sema_1, error */
opts.uprobe_multi.path = path;
opts.uprobe_multi.offsets = (const unsigned long *) &offsets;
opts.uprobe_multi.ref_ctr_offsets = (const unsigned long *) &ref_ctr_offsets;
opts.uprobe_multi.cnt = 3;
link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_UPROBE_MULTI, &opts);
if (!ASSERT_ERR(link_fd, "link_fd"))
close(link_fd);
cleanup:
free(tmp_ref_ctr_offsets);
free(tmp_offsets);
}
static void test_attach_uprobe_fails(void)
{
struct uprobe_multi *skel = NULL;
skel = uprobe_multi__open_and_load();
if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load"))
return;
/* attach fails due to adding uprobe on trap instruction, x86_64 only */
attach_uprobe_fail_trap(skel);
/* attach fail due to wrong ref_ctr_offs on one of the uprobes */
attach_uprobe_fail_refctr(skel);
uprobe_multi__destroy(skel);
}
static void __test_link_api(struct child *child)
{
int prog_fd, link1_fd = -1, link2_fd = -1, link3_fd = -1, link4_fd = -1;
@ -703,4 +819,6 @@ void test_uprobe_multi_test(void)
test_bench_attach_usdt();
if (test__start_subtest("attach_api_fails"))
test_attach_api_fails();
if (test__start_subtest("attach_uprobe_fails"))
test_attach_uprobe_fails();
}