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selftests/bpf: Add tests for BPF_NEG range tracking logic

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BPF_REG now has range tracking logic. Add selftests for BPF_NEG.
Specifically, return value of LSM hook lsm.s/socket_connect is used to
show that the verifer tracks BPF_NEG(1) falls in the [-4095, 0] range;
while BPF_NEG(100000) does not fall in that range.

Signed-off-by: Song Liu <song@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250625164025.3310203-3-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Song Liu 2025-06-25 09:40:25 -07:00 committed by Alexei Starovoitov
parent aced132599
commit 2945434e24
1 changed files with 70 additions and 0 deletions
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70
tools/testing/selftests/bpf/progs/verifier_precision.c
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@ -231,4 +231,74 @@ __naked void bpf_cond_op_not_r10(void)
::: __clobber_all);
}
SEC("lsm.s/socket_connect")
__success __log_level(2)
__msg("0: (b7) r0 = 1 ; R0_w=1")
__msg("1: (84) w0 = -w0 ; R0_w=0xffffffff")
__msg("mark_precise: frame0: last_idx 2 first_idx 0 subseq_idx -1")
__msg("mark_precise: frame0: regs=r0 stack= before 1: (84) w0 = -w0")
__msg("mark_precise: frame0: regs=r0 stack= before 0: (b7) r0 = 1")
__naked int bpf_neg_2(void)
{
/*
* lsm.s/socket_connect requires a return value within [-4095, 0].
* Returning -1 is allowed
*/
asm volatile (
"r0 = 1;"
"w0 = -w0;"
"exit;"
::: __clobber_all);
}
SEC("lsm.s/socket_connect")
__failure __msg("At program exit the register R0 has")
__naked int bpf_neg_3(void)
{
/*
* lsm.s/socket_connect requires a return value within [-4095, 0].
* Returning -10000 is not allowed.
*/
asm volatile (
"r0 = 10000;"
"w0 = -w0;"
"exit;"
::: __clobber_all);
}
SEC("lsm.s/socket_connect")
__success __log_level(2)
__msg("0: (b7) r0 = 1 ; R0_w=1")
__msg("1: (87) r0 = -r0 ; R0_w=-1")
__msg("mark_precise: frame0: last_idx 2 first_idx 0 subseq_idx -1")
__msg("mark_precise: frame0: regs=r0 stack= before 1: (87) r0 = -r0")
__msg("mark_precise: frame0: regs=r0 stack= before 0: (b7) r0 = 1")
__naked int bpf_neg_4(void)
{
/*
* lsm.s/socket_connect requires a return value within [-4095, 0].
* Returning -1 is allowed
*/
asm volatile (
"r0 = 1;"
"r0 = -r0;"
"exit;"
::: __clobber_all);
}
SEC("lsm.s/socket_connect")
__failure __msg("At program exit the register R0 has")
__naked int bpf_neg_5(void)
{
/*
* lsm.s/socket_connect requires a return value within [-4095, 0].
* Returning -10000 is not allowed.
*/
asm volatile (
"r0 = 10000;"
"r0 = -r0;"
"exit;"
::: __clobber_all);
}
char _license[] SEC("license") = "GPL";