From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-84.mta1.migadu.com [95.215.58.84]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A55D236DA1A for ; Tue, 18 Aug 2026 19:35:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.84 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787081761; cv=none; b=i7lfLf1FFc9XwXR9qF1t9Cs4ySKhh034qxmCfzIVe3kkN7hqO7FXFFHYu957vU00HRPRHKqV3SYvpWKiBTt8iUVsbPEWEkD0kKVWMo62+dHVyJHw10zJ5wvMWgaKvqvtP4//8FKN2Hab/PHZvcJMoyeX0WwyLLUC+L8x3v8TmEE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787081761; c=relaxed/simple; bh=kIKvNM7BPSkBXUN2eWH5O/FffUslGwSPxg0v8WZ5jtQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aEc74a68TTeiMIw6v4xg6A+d9VpLQTe6VZ42jXHtA1LcqrSpqZmHfHKKEc/v2kZwh1kv3HM/NB/e/O7Ve1qtOjK/zrrSAAuZFi6Bviw2K4sMKsNwzNwLgtMGYcTnk1z0C6mpBnhSR/J5OqaQO0mSF5U9j4yJ/Vl2GPRLQ22z/Q8= 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=IX2t5N2Q; arc=none smtp.client-ip=95.215.58.84 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="IX2t5N2Q" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=kIKvNM7BPSkBXUN2eWH5O/FffUslGwSPxg0v8WZ5jtQ=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1787081756; v=1; x=1787686556; b=IX2t5N2Qtlehe0MBhmGgZgIgs/YqedxJnHd/Iy/roV2XpuxnQx5gPAuA+KeZAn+hCinsJpL0 g6YbavXXBBDWZ0ngZDaSCqe+zDvZpfNj4YZbvbF87EvHImXew9Gq3SNfo9Gc8HsYnklJTHSxOY8 ybno+20HsgPqXisfVfdYAehM= X-Envelope-To: linux-kernel@vger.kernel.org Received: from [IPV6:2a03:83e0:1251:27:17dc:c6a5:7074:ce30] (2620:10d:c090:500::7:86e7) by smtp.migadu.com with ESMTPS id b107c2617882a1d3; Tue, 18 Aug 2026 19:35:54 +0000 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Tue, 18 Aug 2026 12:35:46 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next v2 2/2] selftests/bpf: Cover mixed arena and stack atomics To: Eduard Zingerman , Yiyang Chen , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20260816-bpf-next-038-mixed-atomic-v1-v2-0-4644c1886dbc@mails.tsinghua.edu.cn> <20260816-bpf-next-038-mixed-atomic-v1-v2-2-4644c1886dbc@mails.tsinghua.edu.cn> <123a014b2b4ecd7d19cbdfe62c62d994e612b6f0.camel@gmail.com> From: Vineet Gupta Content-Language: en-US In-Reply-To: <123a014b2b4ecd7d19cbdfe62c62d994e612b6f0.camel@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 8/16/26 4:36 PM, Eduard Zingerman wrote: > On Sun, 2026-08-16 at 16:17 -0700, Eduard Zingerman wrote: >> On Sun, 2026-08-16 at 10:56 +0000, Yiyang Chen wrote: >>> Add a verifier test with one atomic RMW instruction reached through >>> PTR_TO_ARENA and PTR_TO_STACK paths. The verifier must reject the >>> shared instruction with the existing incompatible-pointer diagnostic. >>> >>> Signed-off-by: Yiyang Chen >>> --- >>>  tools/testing/selftests/bpf/progs/verifier_arena.c | 39 ++++++++++++++++++++++ >>>  1 file changed, 39 insertions(+) >>> >>> diff --git a/tools/testing/selftests/bpf/progs/verifier_arena.c b/tools/testing/selftests/bpf/progs/verifier_arena.c >>> index b241bbcf54a8a..b22bab33301ab 100644 >>> --- a/tools/testing/selftests/bpf/progs/verifier_arena.c >>> +++ b/tools/testing/selftests/bpf/progs/verifier_arena.c >>> @@ -637,6 +637,45 @@ int non_arena_ptr_add_to_arena_ptr(void *ctx) >>> >>>  #endif >>> >>> +static const struct bpf_insn addr_space_cast_insn = { >>> + .code = 0xbf, >>> + .dst_reg = BPF_REG_7, >>> + .src_reg = BPF_REG_7, >>> + .off = 1, >>> + .imm = 1, >>> +}; >>> + >>> +SEC("socket") >>> +__description("arena and stack atomic at the same instruction") >>> +__failure __msg("same insn cannot be used with different pointers") >>> +__arch_x86_64 >>> +__load_if_JITed() >>> +__naked void mixed_arena_stack_atomic(void) >>> +{ >>> + asm volatile (" \ >>> + r1 = %[arena] ll; \ >>> + r6 = r10; \ >>> + r6 += -8; \ >>> + r9 = 0; \ >>> + *(u64 *)(r6 + 0) = r9; \ >>> + r7 = 8192; \ >>> + .8byte %[addr_space_cast]; \ >> I'm going to fix this to: >> >> r7 = addr_space_cast(r7, 0, 1); \ >> >> as in the test case above. >> Waiting for CI [1]. >> >> [1] https://github.com/kernel-patches/bpf/pull/13325 > > A...and it requires another exception for GCC-BPF: > https://github.com/kernel-patches/bpf/blob/bpf-next_base/ci/vmtest/configs/DENYLIST.test_progs-bpf_gcc > > Ihor, it's a third time GCC-BPF strikes this weekend. > What do people think about downgrading it to may-fail until the > DENYLIST decreases to something reasonable? While bpf-gcc is improving, slowly, we can in parallel do alittle better on test hygiene as well. In this case by correctly bracketing the tests with _BPF_FEATURE_XXX. Co-incidently I have a series in works from an accidental discovery of llvm-only testing coverage (rely solely on __clang_version macro) which I'll follow up on the list shortly. Thx, -Vineet > > Anyway, I'll wrap-up with this patch-set in the evening. > >>> + call %[bpf_get_prandom_u32]; \ >>> + if w0 != 0 goto 1f; \ >>> + r8 = r6; \ >>> + goto 2f; \ >>> +1: r8 = r7; \ >>> +2: r9 = 1; \ >>> + lock *(u64 *)(r8 + 0) += r9; \ >>> + r0 = 0; \ >>> + exit; \ >>> +" : >>> + : __imm_addr(arena), >>> +   __imm_insn(addr_space_cast, addr_space_cast_insn), >>> +   __imm(bpf_get_prandom_u32) >>> + : __clobber_all); >>> +} >>> + >>>  static __noinline >>>  u32 __arena *check_arena_arg_nonglobal(u32 __arena *arg) >>>  {