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bpf: correct use/def for may_goto instruction

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may_goto instruction does not use any registers,
but in compute_insn_live_regs() it was treated as a regular
conditional jump of kind BPF_K with r0 as source register.
Thus unnecessarily marking r0 as used.

Fixes: 14c8552db644 ("bpf: simple DFA-based live registers analysis")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250305085436.2731464-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman 2025-03-05 00:54:36 -08:00 committed by Alexei Starovoitov
parent c1d95a0f2d
commit 871ef8d50e
2 changed files with 4 additions and 3 deletions
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1
kernel/bpf/verifier.c
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@ -23567,6 +23567,7 @@ static void compute_insn_live_regs(struct bpf_verifier_env *env,
case BPF_JMP32:
switch (code) {
case BPF_JA:
case BPF_JCOND:
def = 0;
use = 0;
break;

6
tools/testing/selftests/bpf/progs/compute_live_registers.c
View File

@ -294,9 +294,9 @@ __naked void gotol(void)
SEC("socket")
__log_level(2)
__msg("0: 0......... (b7) r1 = 1")
__msg("1: 01........ (e5) may_goto pc+1")
__msg("2: 0......... (05) goto pc-3")
__msg("0: .......... (b7) r1 = 1")
__msg("1: .1........ (e5) may_goto pc+1")
__msg("2: .......... (05) goto pc-3")
__msg("3: .1........ (bf) r0 = r1")
__msg("4: 0......... (95) exit")
__naked void may_goto(void)