projects/linux·blob master · refs

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1// SPDX-License-Identifier: GPL-2.0
2/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
3
4#include <vmlinux.h>
5#include <bpf/bpf_helpers.h>
6#include "../test_kmods/bpf_testmod_kfunc.h"
7#include "bpf_misc.h"
8
9#if (defined(__TARGET_ARCH_x86) || defined(__TARGET_ARCH_arm64)) && \
10 defined(__BPF_FEATURE_STACK_ARGUMENT)
11
12/* Force kfunc extern BTF generation for inline asm call below.
13 * Uses its own SEC so it's not included as a .text subprog.
14 * The '?' prefix sets autoload=false so libbpf won't load it.
15 */
16SEC("?tc")
17int __btf_kfunc_gen(struct __sk_buff *ctx)
18{
19 char buf[8] = {};
20
21 return bpf_kfunc_call_stack_arg_mem(0, 0, 0, 0, 0, buf, sizeof(buf));
22}
23
24/*
25 * Test precision backtracking across bpf-to-bpf call for kfunc stack arg.
26 * subprog_call_mem_kfunc receives a size as incoming stack arg (arg6)
27 * and forwards it as mem__sz (arg7) to bpf_kfunc_call_stack_arg_mem.
28 */
29__naked __noinline __used
30static long subprog_call_mem_kfunc(long a, long b, long c, long d, long e, long size)
31{
32 asm volatile (
33 "r1 = *(u64 *)(r11 + 8);" /* r1 = incoming arg6 (size) */
34 "r2 = 0x0807060504030201 ll;" /* r2 = buf contents */
35 "*(u64 *)(r10 - 8) = r2;" /* store buf to stack */
36 "r2 = r10;"
37 "r2 += -8;" /* r2 = &buf */
38 "*(u64 *)(r11 - 8) = r2;" /* outgoing arg6 = buf */
39 "*(u64 *)(r11 - 16) = r1;" /* outgoing arg7 = size */
40 "r1 = 1;"
41 "r2 = 2;"
42 "r3 = 3;"
43 "r4 = 4;"
44 "r5 = 5;"
45 "call %[bpf_kfunc_call_stack_arg_mem];"
46 "exit;"
47 :
48 : __imm(bpf_kfunc_call_stack_arg_mem)
49 : __clobber_all
50 );
51}
52
53SEC("tc")
54__description("stack_arg: precision backtracking across bpf2bpf call for kfunc")
55__success
56__log_level(2)
57__flag(BPF_F_TEST_STATE_FREQ)
58__btf_func_path("btf__stack_arg_precision.bpf.o")
59__msg("mark_precise: frame1: last_idx 26 first_idx 13 subseq_idx -1")
60__msg("mark_precise: frame1: regs= stack= before 25: (b7) r5 = 5")
61__msg("mark_precise: frame1: regs= stack= before 24: (b7) r4 = 4")
62__msg("mark_precise: frame1: regs= stack= before 23: (b7) r3 = 3")
63__msg("mark_precise: frame1: regs= stack= before 22: (b7) r2 = 2")
64__msg("mark_precise: frame1: regs= stack= before 21: (b7) r1 = 1")
65__msg("mark_precise: frame1: regs= stack= before 20: (7b) *(u64 *)(r11 -16) = r1")
66__msg("mark_precise: frame1: regs=r1 stack= before 19: (7b) *(u64 *)(r11 -8) = r2")
67__msg("mark_precise: frame1: regs=r1 stack= before 18: (07) r2 += -8")
68__msg("mark_precise: frame1: regs=r1 stack= before 17: (bf) r2 = r10")
69__msg("mark_precise: frame1: regs=r1 stack= before 16: (7b) *(u64 *)(r10 -8) = r2")
70__msg("mark_precise: frame1: regs=r1 stack= before 14: (18) r2 = 0x807060504030201")
71__msg("mark_precise: frame1: regs=r1 stack= before 13: (79) r1 = *(u64 *)(r11 +8)")
72__msg("mark_precise: frame1: parent state regs= stack=: frame1: R10=fp0")
73__msg("mark_precise: frame0: parent state regs= stack=: R10=fp0")
74__msg("mark_precise: frame1: last_idx 11 first_idx 11 subseq_idx 13")
75__msg("mark_precise: frame1: regs= stack= before 11: (85) call pc+1")
76__msg("mark_precise: frame0: parent state regs= stack=: R1=1 R2=2 R3=3 R4=4 R5=5 R10=fp0")
77__msg("mark_precise: frame0: last_idx 9 first_idx 7 subseq_idx 11")
78__msg("mark_precise: frame0: regs= stack= before 9: (05) goto pc+1")
79__msg("mark_precise: frame0: regs= stack= before 8: (7a) *(u64 *)(r11 -8) = 4")
80__msg("mark_precise: frame1: last_idx 26 first_idx 13 subseq_idx -1 ")
81__msg("mark_precise: frame1: regs= stack= before 25: (b7) r5 = 5")
82__msg("mark_precise: frame1: regs= stack= before 24: (b7) r4 = 4")
83__msg("mark_precise: frame1: regs= stack= before 23: (b7) r3 = 3")
84__msg("mark_precise: frame1: regs= stack= before 22: (b7) r2 = 2")
85__msg("mark_precise: frame1: regs= stack= before 21: (b7) r1 = 1")
86__msg("mark_precise: frame1: regs= stack= before 20: (7b) *(u64 *)(r11 -16) = r1")
87__msg("mark_precise: frame1: regs=r1 stack= before 19: (7b) *(u64 *)(r11 -8) = r2")
88__msg("mark_precise: frame1: regs=r1 stack= before 18: (07) r2 += -8")
89__msg("mark_precise: frame1: regs=r1 stack= before 17: (bf) r2 = r10")
90__msg("mark_precise: frame1: regs=r1 stack= before 16: (7b) *(u64 *)(r10 -8) = r2")
91__msg("mark_precise: frame1: regs=r1 stack= before 14: (18) r2 = 0x807060504030201")
92__msg("mark_precise: frame1: regs=r1 stack= before 13: (79) r1 = *(u64 *)(r11 +8)")
93__msg("mark_precise: frame1: parent state regs= stack=: frame1: R10=fp0")
94__msg("mark_precise: frame0: parent state regs= stack=: R10=fp0")
95__msg("mark_precise: frame1: last_idx 11 first_idx 11 subseq_idx 13 ")
96__msg("mark_precise: frame1: regs= stack= before 11: (85) call pc+1")
97__msg("mark_precise: frame0: parent state regs= stack=: R1=1 R2=2 R3=3 R4=4 R5=5 R10=fp0")
98__msg("mark_precise: frame0: last_idx 10 first_idx 10 subseq_idx 11 ")
99__msg("mark_precise: frame0: regs= stack= before 10: (7a) *(u64 *)(r11 -8) = 6")
100__naked void stack_arg_precision_bpf2bpf(void)
101{
102 asm volatile (
103 "call %[bpf_get_prandom_u32];"
104 "r6 = r0;"
105 "r1 = 1;"
106 "r2 = 2;"
107 "r3 = 3;"
108 "r4 = 4;"
109 "r5 = 5;"
110 "if r6 < 2 goto l0_%=;"
111 "*(u64 *)(r11 - 8) = 4;"
112 "goto l1_%=;"
113 "l0_%=:"
114 "*(u64 *)(r11 - 8) = 6;"
115 "l1_%=:"
116 "call subprog_call_mem_kfunc;"
117 "exit;"
118 :: __imm(bpf_get_prandom_u32)
119 : __clobber_all
120 );
121}
122
123#else
124
125SEC("socket")
126__description("stack_arg_precision: not supported, dummy test")
127__success
128int dummy_test(void)
129{
130 return 0;
131}
132
133#endif
134
135char _license[] SEC("license") = "GPL";