bpf: correct use/def for may_goto instruction

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>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 4edb2db0f889c5b236416ce0016d74fda2e09a18..3303a3605ee808d9d5e77526668f9090e10b8c42 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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;

diff --git a/tools/testing/selftests/bpf/progs/compute_live_registers.c b/tools/testing/selftests/bpf/progs/compute_live_registers.c
index 14df92949e81ae44e39f1a62276776c1ab82fa52..f3d79aecbf9356b4b9a147ead194d1d80b8f9927 100644 (file)
--- a/tools/testing/selftests/bpf/progs/compute_live_registers.c
+++ b/tools/testing/selftests/bpf/progs/compute_live_registers.c
@@ -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)