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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Red Hat */
#include <test_progs.h>
#include <bpf/btf.h>
#include "bpf/libbpf_internal.h"
#include "cgroup_helpers.h"
#include "bpf_util.h"
static const char *module_name = "bpf_testmod";
static const char *symbol_name = "bpf_fentry_shadow_test";
static int get_bpf_testmod_btf_fd(void)
{
struct bpf_btf_info info;
char name[64];
__u32 id = 0, len;
int err, fd;
while (true) {
err = bpf_btf_get_next_id(id, &id);
if (err) {
log_err("failed to iterate BTF objects");
return err;
}
fd = bpf_btf_get_fd_by_id(id);
if (fd < 0) {
if (errno == ENOENT)
continue; /* expected race: BTF was unloaded */
err = -errno;
log_err("failed to get FD for BTF object #%d", id);
return err;
}
len = sizeof(info);
memset(&info, 0, sizeof(info));
info.name = ptr_to_u64(name);
info.name_len = sizeof(name);
err = bpf_obj_get_info_by_fd(fd, &info, &len);
if (err) {
err = -errno;
log_err("failed to get info for BTF object #%d", id);
close(fd);
return err;
}
if (strcmp(name, module_name) == 0)
return fd;
close(fd);
}
return -ENOENT;
}
void test_module_fentry_shadow(void)
{
struct btf *vmlinux_btf = NULL, *mod_btf = NULL;
int err, i;
int btf_fd[2] = {};
int prog_fd[2] = {};
int link_fd[2] = {};
__s32 btf_id[2] = {};
if (!env.has_testmod) {
test__skip();
return;
}
LIBBPF_OPTS(bpf_prog_load_opts, load_opts,
.expected_attach_type = BPF_TRACE_FENTRY,
);
const struct bpf_insn trace_program[] = {
BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(),
};
vmlinux_btf = btf__load_vmlinux_btf();
if (!ASSERT_OK_PTR(vmlinux_btf, "load_vmlinux_btf"))
return;
btf_fd[1] = get_bpf_testmod_btf_fd();
if (!ASSERT_GE(btf_fd[1], 0, "get_bpf_testmod_btf_fd"))
goto out;
mod_btf = btf_get_from_fd(btf_fd[1], vmlinux_btf);
if (!ASSERT_OK_PTR(mod_btf, "btf_get_from_fd"))
goto out;
btf_id[0] = btf__find_by_name_kind(vmlinux_btf, symbol_name, BTF_KIND_FUNC);
if (!ASSERT_GT(btf_id[0], 0, "btf_find_by_name"))
goto out;
btf_id[1] = btf__find_by_name_kind(mod_btf, symbol_name, BTF_KIND_FUNC);
if (!ASSERT_GT(btf_id[1], 0, "btf_find_by_name"))
goto out;
for (i = 0; i < 2; i++) {
load_opts.attach_btf_id = btf_id[i];
load_opts.attach_btf_obj_fd = btf_fd[i];
prog_fd[i] = bpf_prog_load(BPF_PROG_TYPE_TRACING, NULL, "GPL",
trace_program,
ARRAY_SIZE(trace_program),
&load_opts);
if (!ASSERT_GE(prog_fd[i], 0, "bpf_prog_load"))
goto out;
/* If the verifier incorrectly resolves addresses of the
* shadowed functions and uses the same address for both the
* vmlinux and the bpf_testmod functions, this will fail on
* attempting to create two trampolines for the same address,
* which is forbidden.
*/
link_fd[i] = bpf_link_create(prog_fd[i], 0, BPF_TRACE_FENTRY, NULL);
if (!ASSERT_GE(link_fd[i], 0, "bpf_link_create"))
goto out;
}
err = bpf_prog_test_run_opts(prog_fd[0], NULL);
ASSERT_OK(err, "running test");
out:
btf__free(vmlinux_btf);
btf__free(mod_btf);
for (i = 0; i < 2; i++) {
if (btf_fd[i])
close(btf_fd[i]);
if (prog_fd[i] > 0)
close(prog_fd[i]);
if (link_fd[i] > 0)
close(link_fd[i]);
}
}
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