From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-179.mta0.migadu.com (out-179.mta0.migadu.com [91.218.175.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 057DE286D56 for ; Mon, 3 Nov 2025 06:32:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.179 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762151557; cv=none; b=vFmBKX7usbYXrMXNZwsJqyanBU0KCSkltt7wSE5VN/oIDFpNxvWb/irxwFOoBb8T++zUz2BaLoOfAOANHoDWmhfY4qErexG36vPS1d7fGfARHr89SLaBk4nDZdicQ8+72aF/XeUASiDr+2aW49T0oxySVGugWkcwwSVaLJOarFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762151557; c=relaxed/simple; bh=kbe8hMT2OvfiqAmCP4GWUa8XfLFY+MoXA/QxrTvkDww=; h=From:To:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ljxSVUXFa2R3G41HO0r5WUI9OVFuLlrTrDD/QGUpGe3FUJKShBxdQmUVEm6XfPZ4lvjW9u1VH7KISOgJ7xvtLDNRy2kDV7iR37RWxR6uf0OwufdhSio2BWRSxkNTOXmRkIEwDx8QKHyJPMvzIs7oNJWB+dNZEYsLhsD4UtN68Uc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=BFOkXztw; arc=none smtp.client-ip=91.218.175.179 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="BFOkXztw" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1762151553; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=9Co4HTS5uOZjTPA1XBfD/RtU0DY8DXK6Y5uls97p0Vw=; b=BFOkXztwNIL5K8mOH+vAFRaD0ZZkLd1UA9FuPUUuW5dS0hRu5IsyrUUg3PqdK/0YoXhElP cLXB95uuCrazQ9v7FRnqwBUjKZn9g75ncFFabEM/tm/9czjc/T0aXhGdEuf5FFS8OLw7we QpsPF7CfUSYZPdMFHwEmLkUDuKJF8Ec= From: KaFai Wan To: ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, shuah@kernel.org, paul.chaignon@gmail.com, m.shachnai@gmail.com, kafai.wan@linux.dev, harishankar.vishwanathan@gmail.com, colin.i.king@gmail.com, luis.gerhorst@fau.de, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next v4 2/2] selftests/bpf: Add test for conditional jumps on same scalar register Date: Mon, 3 Nov 2025 14:31:08 +0800 Message-ID: <20251103063108.1111764-3-kafai.wan@linux.dev> In-Reply-To: <20251103063108.1111764-1-kafai.wan@linux.dev> References: <20251103063108.1111764-1-kafai.wan@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT Add test cases to verify the correctness of the BPF verifier's branch analysis when conditional jumps are performed on the same scalar register. And make sure that JGT does not trigger verifier BUG. Signed-off-by: KaFai Wan --- .../selftests/bpf/progs/verifier_bounds.c | 154 ++++++++++++++++++ 1 file changed, 154 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_bounds.c b/tools/testing/selftests/bpf/progs/verifier_bounds.c index 0a72e0228ea9..e975dc285db6 100644 --- a/tools/testing/selftests/bpf/progs/verifier_bounds.c +++ b/tools/testing/selftests/bpf/progs/verifier_bounds.c @@ -1709,4 +1709,158 @@ __naked void jeq_disagreeing_tnums(void *ctx) : __clobber_all); } +SEC("socket") +__description("conditional jump on same register, branch taken") +__not_msg("20: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void condition_jump_on_same_register(void *ctx) +{ + asm volatile(" \ + call %[bpf_get_prandom_u32]; \ + w8 = 0x80000000; \ + r0 &= r8; \ + if r0 == r0 goto +1; \ + goto l1_%=; \ + if r0 >= r0 goto +1; \ + goto l1_%=; \ + if r0 s>= r0 goto +1; \ + goto l1_%=; \ + if r0 <= r0 goto +1; \ + goto l1_%=; \ + if r0 s<= r0 goto +1; \ + goto l1_%=; \ + if r0 != r0 goto l1_%=; \ + if r0 > r0 goto l1_%=; \ + if r0 s> r0 goto l1_%=; \ + if r0 < r0 goto l1_%=; \ + if r0 s< r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, constant value branch taken") +__not_msg("7: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_1(void *ctx) +{ + asm volatile(" \ + r0 = 0; \ + if r0 & r0 goto l1_%=; \ + r0 = 1; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value branch taken") +__not_msg("12: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__retval(0) __flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_2(void *ctx) +{ + asm volatile(" \ + /* range [1;2] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 += 1; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ + /* range [-2;-1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 -= 2; \ + if r0 & r0 goto +1; \ + goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 1") +__msg("3: (b7) r0 = 0 {{.*}} R0=0") +__msg("5: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_3(void *ctx) +{ + asm volatile(" \ + /* range [0;1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 2") +__msg("4: (b7) r0 = 0 {{.*}} R0=0") +__msg("6: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_4(void *ctx) +{ + asm volatile(" \ + /* range [-1;0] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x1; \ + r0 -= 1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + +SEC("socket") +__description("jset on same register, scalar value unknown branch 3") +__msg("4: (b7) r0 = 0 {{.*}} R0=0") +__msg("6: (b7) r0 = 1 {{.*}} R0=1") +__success __log_level(2) +__flag(BPF_F_TEST_REG_INVARIANTS) +__naked void jset_on_same_register_5(void *ctx) +{ + asm volatile(" \ + /* range [-1;-1] */ \ + call %[bpf_get_prandom_u32]; \ + r0 &= 0x2; \ + r0 -= 1; \ + if r0 & r0 goto l1_%=; \ +l0_%=: r0 = 0; \ + exit; \ +l1_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_get_prandom_u32) + : __clobber_all); +} + char _license[] SEC("license") = "GPL"; -- 2.43.0