epilogue_exit.c

 1// SPDX-License-Identifier: GPL-2.0
 2/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
 3
 4#include <vmlinux.h>
 5#include <bpf/bpf_tracing.h>
 6#include "bpf_misc.h"
 7#include "../test_kmods/bpf_testmod.h"
 8#include "../test_kmods/bpf_testmod_kfunc.h"
 9
10char _license[] SEC("license") = "GPL";
11
12__success
13/* save __u64 *ctx to stack */
14__xlated("0: *(u64 *)(r10 -8) = r1")
15/* main prog */
16__xlated("1: r1 = *(u64 *)(r1 +0)")
17__xlated("2: r2 = *(u64 *)(r1 +0)")
18__xlated("3: r3 = 0")
19__xlated("4: r4 = 1")
20__xlated("5: if r2 == 0x0 goto pc+10")
21__xlated("6: r0 = 0")
22__xlated("7: *(u64 *)(r1 +0) = r3")
23/* epilogue */
24__xlated("8: r1 = *(u64 *)(r10 -8)")
25__xlated("9: r1 = *(u64 *)(r1 +0)")
26__xlated("10: r6 = *(u64 *)(r1 +0)")
27__xlated("11: r6 += 10000")
28__xlated("12: *(u64 *)(r1 +0) = r6")
29__xlated("13: r0 = r6")
30__xlated("14: r0 *= 2")
31__xlated("15: exit")
32/* 2nd part of the main prog after the first exit */
33__xlated("16: *(u64 *)(r1 +0) = r4")
34__xlated("17: r0 = 1")
35/* Clear the r1 to ensure it does not have
36 * off-by-1 error and ensure it jumps back to the
37 * beginning of epilogue which initializes
38 * the r1 with the ctx ptr.
39 */
40__xlated("18: r1 = 0")
41__xlated("19: gotol pc-12")
42SEC("struct_ops/test_epilogue_exit")
43__naked int test_epilogue_exit(void)
44{
45	asm volatile (
46	"r1 = *(u64 *)(r1 +0);"
47	"r2 = *(u64 *)(r1 +0);"
48	"r3 = 0;"
49	"r4 = 1;"
50	"if r2 == 0 goto +3;"
51	"r0 = 0;"
52	"*(u64 *)(r1 + 0) = r3;"
53	"exit;"
54	"*(u64 *)(r1 + 0) = r4;"
55	"r0 = 1;"
56	"r1 = 0;"
57	"exit;"
58	::: __clobber_all);
59}
60
61SEC(".struct_ops.link")
62struct bpf_testmod_st_ops epilogue_exit = {
63	.test_epilogue = (void *)test_epilogue_exit,
64};
65
66SEC("syscall")
67__retval(20000)
68int syscall_epilogue_exit0(void *ctx)
69{
70	struct st_ops_args args = { .a = 1 };
71
72	return bpf_kfunc_st_ops_test_epilogue(&args);
73}
74
75SEC("syscall")
76__retval(20002)
77int syscall_epilogue_exit1(void *ctx)
78{
79	struct st_ops_args args = {};
80
81	return bpf_kfunc_st_ops_test_epilogue(&args);
82}