1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/bpf.h>
4 #include <bpf/bpf_helpers.h>
5 #include "bpf_misc.h"
6 
7 SEC("socket")
8 __description("check w reg equal if r reg upper32 bits 0")
9 __success
subreg_equality_1(void)10 __naked void subreg_equality_1(void)
11 {
12 	asm volatile ("					\
13 	call %[bpf_ktime_get_ns];			\
14 	*(u64 *)(r10 - 8) = r0;				\
15 	r2 = *(u32 *)(r10 - 8);				\
16 	/* At this point upper 4-bytes of r2 are 0,	\
17 	 * thus insn w3 = w2 should propagate reg id,	\
18 	 * and w2 < 9 comparison would also propagate	\
19 	 * the range for r3.				\
20 	 */						\
21 	w3 = w2;					\
22 	if w2 < 9 goto l0_%=;				\
23 	exit;						\
24 l0_%=:	if r3 < 9 goto l1_%=;				\
25 	/* r1 read is illegal at this point */		\
26 	r0 -= r1;					\
27 l1_%=:	exit;						\
28 "	:
29 	: __imm(bpf_ktime_get_ns)
30 	: __clobber_all);
31 }
32 
33 SEC("socket")
34 __description("check w reg not equal if r reg upper32 bits not 0")
35 __failure __msg("R1 !read_ok")
subreg_equality_2(void)36 __naked void subreg_equality_2(void)
37 {
38 	asm volatile ("					\
39 	call %[bpf_ktime_get_ns];			\
40 	r2 = r0;					\
41 	/* Upper 4-bytes of r2 may not be 0, thus insn	\
42 	 * w3 = w2 should not propagate reg id,	and	\
43 	 * w2 < 9 comparison should not propagate	\
44 	 * the range for r3 either.			\
45 	 */						\
46 	w3 = w2;					\
47 	if w2 < 9 goto l0_%=;				\
48 	exit;						\
49 l0_%=:	if r3 < 9 goto l1_%=;				\
50 	/* r1 read is illegal at this point */		\
51 	r0 -= r1;					\
52 l1_%=:	exit;						\
53 "	:
54 	: __imm(bpf_ktime_get_ns)
55 	: __clobber_all);
56 }
57 
58 char _license[] SEC("license") = "GPL";
59