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selftests/bpf: Add link_info test for uprobe_multi link
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Adding fill_link_info test for uprobe_multi link.

Setting up uprobes with bogus ref_ctr_offsets and cookie values
to test all the bpf_link_info::uprobe_multi fields.

Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
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@olsajiri
olsajiri authored and Kernel Patches Daemon committed Nov 20, 2023
1 parent ff19b32 commit ffe3cea
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191 changes: 191 additions & 0 deletions tools/testing/selftests/bpf/prog_tests/fill_link_info.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#include <test_progs.h>
#include "trace_helpers.h"
#include "test_fill_link_info.skel.h"
#include "bpf/libbpf_internal.h"

#define TP_CAT "sched"
#define TP_NAME "sched_switch"
Expand Down Expand Up @@ -300,6 +301,189 @@ static void test_kprobe_multi_fill_link_info(struct test_fill_link_info *skel,
bpf_link__destroy(link);
}

/* Initialize semaphore variables so they don't end up in bss
* section and we could get retrieve their offsets.
*/
static short uprobe_link_info_sema_1 = 1;
static short uprobe_link_info_sema_2 = 1;
static short uprobe_link_info_sema_3 = 1;

noinline void uprobe_link_info_func_1(void)
{
uprobe_link_info_sema_1++;
asm volatile ("");
}

noinline void uprobe_link_info_func_2(void)
{
uprobe_link_info_sema_2++;
asm volatile ("");
}

noinline void uprobe_link_info_func_3(void)
{
uprobe_link_info_sema_3++;
asm volatile ("");
}

static int
verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets,
__u64 *cookies, __u64 *ref_ctr_offsets)
{
char path[PATH_MAX], path_buf[PATH_MAX];
struct bpf_link_info info;
__u32 len = sizeof(info);
__u64 ref_ctr_offsets_buf[3];
__u64 offsets_buf[3];
__u64 cookies_buf[3];
int i, err, bit;
__u32 count = 0;

memset(path, 0, sizeof(path));
err = readlink("/proc/self/exe", path, sizeof(path));
if (!ASSERT_NEQ(err, -1, "readlink"))
return -1;

for (bit = 0; bit < 8; bit++) {
memset(&info, 0, sizeof(info));
info.uprobe_multi.path = ptr_to_u64(path_buf);
info.uprobe_multi.path_size = sizeof(path_buf);
info.uprobe_multi.count = count;

if (bit & 0x1)
info.uprobe_multi.offsets = ptr_to_u64(offsets_buf);
if (bit & 0x2)
info.uprobe_multi.cookies = ptr_to_u64(cookies_buf);
if (bit & 0x4)
info.uprobe_multi.ref_ctr_offsets = ptr_to_u64(ref_ctr_offsets_buf);

err = bpf_link_get_info_by_fd(fd, &info, &len);
if (!ASSERT_OK(err, "bpf_link_get_info_by_fd"))
return -1;

if (!ASSERT_EQ(info.type, BPF_LINK_TYPE_UPROBE_MULTI, "info.type"))
return -1;

ASSERT_EQ(info.uprobe_multi.pid, getpid(), "info.uprobe_multi.pid");
ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count");
ASSERT_EQ(info.uprobe_multi.flags & BPF_F_KPROBE_MULTI_RETURN,
retprobe, "info.uprobe_multi.flags.retprobe");
ASSERT_EQ(info.uprobe_multi.path_size, strlen(path), "info.uprobe_multi.path_size");
ASSERT_STREQ(path_buf, path, "info.uprobe_multi.path");

for (i = 0; i < info.uprobe_multi.count; i++) {
if (info.uprobe_multi.offsets)
ASSERT_EQ(offsets_buf[i], offsets[i], "info.uprobe_multi.offsets");
if (info.uprobe_multi.cookies)
ASSERT_EQ(cookies_buf[i], cookies[i], "info.uprobe_multi.cookies");
if (info.uprobe_multi.ref_ctr_offsets) {
ASSERT_EQ(ref_ctr_offsets_buf[i], ref_ctr_offsets[i],
"info.uprobe_multi.ref_ctr_offsets");
}
}
count = count ?: info.uprobe_multi.count;
}

return 0;
}

static void verify_umulti_invalid_user_buffer(int fd)
{
struct bpf_link_info info;
__u32 len = sizeof(info);
__u64 buf[3];
int err;

/* upath_size defined, not path */
memset(&info, 0, sizeof(info));
info.uprobe_multi.path_size = 3;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "failed_upath_size");

/* path has wrong pointer */
memset(&info, 0, sizeof(info));
info.uprobe_multi.path_size = PATH_MAX;
info.uprobe_multi.path = 123;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EFAULT, "failed_bad_path_ptr");

/* count zero, with offsets */
memset(&info, 0, sizeof(info));
info.uprobe_multi.offsets = ptr_to_u64(buf);
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EINVAL, "failed_count");

/* offsets not big enough */
memset(&info, 0, sizeof(info));
info.uprobe_multi.offsets = ptr_to_u64(buf);
info.uprobe_multi.count = 2;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -ENOSPC, "failed_small_count");

/* offsets has wrong pointer */
memset(&info, 0, sizeof(info));
info.uprobe_multi.offsets = 123;
info.uprobe_multi.count = 3;
err = bpf_link_get_info_by_fd(fd, &info, &len);
ASSERT_EQ(err, -EFAULT, "failed_wrong_offsets");
}

static void test_uprobe_multi_fill_link_info(struct test_fill_link_info *skel,
bool retprobe, bool invalid)
{
LIBBPF_OPTS(bpf_uprobe_multi_opts, opts,
.retprobe = retprobe,
);
const char *syms[3] = {
"uprobe_link_info_func_1",
"uprobe_link_info_func_2",
"uprobe_link_info_func_3",
};
__u64 cookies[3] = {
0xdead,
0xbeef,
0xcafe,
};
const char *sema[3] = {
"uprobe_link_info_sema_1",
"uprobe_link_info_sema_2",
"uprobe_link_info_sema_3",
};
__u64 *offsets, *ref_ctr_offsets;
struct bpf_link *link;
int link_fd, err;

err = elf_resolve_syms_offsets("/proc/self/exe", 3, sema,
(unsigned long **) &ref_ctr_offsets, STT_OBJECT);
if (!ASSERT_OK(err, "elf_resolve_syms_offsets_object"))
return;

err = elf_resolve_syms_offsets("/proc/self/exe", 3, syms,
(unsigned long **) &offsets, STT_FUNC);
if (!ASSERT_OK(err, "elf_resolve_syms_offsets_func"))
return;

opts.syms = syms;
opts.cookies = &cookies[0];
opts.ref_ctr_offsets = (unsigned long *) &ref_ctr_offsets[0];
opts.cnt = ARRAY_SIZE(syms);

link = bpf_program__attach_uprobe_multi(skel->progs.umulti_run, 0,
"/proc/self/exe", NULL, &opts);
if (!ASSERT_OK_PTR(link, "bpf_program__attach_uprobe_multi"))
goto out;

link_fd = bpf_link__fd(link);
if (invalid)
verify_umulti_invalid_user_buffer(link_fd);
else
verify_umulti_link_info(link_fd, retprobe, offsets, cookies, ref_ctr_offsets);

bpf_link__destroy(link);
out:
free(offsets);
}

void test_fill_link_info(void)
{
struct test_fill_link_info *skel;
Expand Down Expand Up @@ -339,6 +523,13 @@ void test_fill_link_info(void)
if (test__start_subtest("kprobe_multi_invalid_ubuff"))
test_kprobe_multi_fill_link_info(skel, true, true);

if (test__start_subtest("uprobe_multi_link_info"))
test_uprobe_multi_fill_link_info(skel, false, false);
if (test__start_subtest("uretprobe_multi_link_info"))
test_uprobe_multi_fill_link_info(skel, true, false);
if (test__start_subtest("uprobe_multi_invalid"))
test_uprobe_multi_fill_link_info(skel, false, true);

cleanup:
test_fill_link_info__destroy(skel);
}
6 changes: 6 additions & 0 deletions tools/testing/selftests/bpf/progs/test_fill_link_info.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,4 +39,10 @@ int BPF_PROG(kmulti_run)
return 0;
}

SEC("uprobe.multi")
int BPF_PROG(umulti_run)
{
return 0;
}

char _license[] SEC("license") = "GPL";

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