From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (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 4F07A1DFEF for ; Mon, 22 Jul 2024 18:11:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721671918; cv=none; b=F3Yj1jE8FNaYM/dpBhVBDVf2HtXo0//LNQ6W2qujrf5RsvphgoIhcohr9pJTNC4UUMl3P3uCq7+v/HrLNY88qfJWAfEtu5goelQGcFLh0r5k2m/WOC4iRz80NhDsc75nF3WNP3UTCIeftNm0ZF8FZmaeVdu1dInvQggPy/gneK4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721671918; c=relaxed/simple; bh=EEmqBCAGDMciVDpf/RImk7OUYI2tN+ikJBPzjO26udI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=cSklweN1AIa4CrCBuP1ssYS9PyMNeK9Zn+lM3E6l2h3sGQSMi6CvNIAGvZjBV/W06k8d+FXFAjG1fTB9zAGuwPYzPlSVZHyX9c77ULzJA+QHQdVowJfNxz++IJyE2Qov8wLGd1VPcPBQrwgpaqrXLaNTfAPJ/5KoC78hoOYIq3o= 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=peQONMxj; arc=none smtp.client-ip=91.218.175.180 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="peQONMxj" X-Envelope-To: andrii.nakryiko@gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1721671914; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qJSTPuNZhgUWmH5AhwyZz4tUxQp+5Dq8K73nvReJjU8=; b=peQONMxj4dwdxVn0yN7CpaGPJluHzOq8pDEU/R6FVd/b2hAvU6ssBLVS+T1NG2U0fXw7+y ylZBXdS9eDwRl5l66DEO+RgUk0OfuALrIvu+eMhKNKS0tuLm0sTCFoJbIPASxZ3UrZGll0 WE3+I0H0vtAFmYfWby9Yp154gPLG3ew= X-Envelope-To: bpf@vger.kernel.org X-Envelope-To: ast@kernel.org X-Envelope-To: andrii@kernel.org X-Envelope-To: daniel@iogearbox.net X-Envelope-To: kernel-team@fb.com X-Envelope-To: martin.lau@kernel.org Message-ID: <01f36361-2f6c-4035-9b03-0565a81a1ade@linux.dev> Date: Mon, 22 Jul 2024 11:11:49 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v4 2/2] selftests/bpf: Add reg_bounds tests for ldsx and subreg compare Content-Language: en-GB To: Andrii Nakryiko Cc: bpf@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau References: <20240718052821.3753486-1-yonghong.song@linux.dev> <20240718052827.3753696-1-yonghong.song@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 7/19/24 3:58 PM, Andrii Nakryiko wrote: > On Wed, Jul 17, 2024 at 10:28 PM Yonghong Song wrote: >> Add a few reg_bounds selftests to test 32/16/8-bit ldsx and subreg comparison. >> Without the previous patch, all added tests will fail. >> >> Signed-off-by: Yonghong Song >> --- >> .../selftests/bpf/prog_tests/reg_bounds.c | 17 +++++++++++++++++ >> 1 file changed, 17 insertions(+) >> > wow, I already forgot most of the things in here... :( > >> diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c >> index eb74363f9f70..cd9bafe9c057 100644 >> --- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c >> +++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c >> @@ -441,6 +441,20 @@ static struct range range_refine(enum num_t x_t, struct range x, enum num_t y_t, >> if (t_is_32(y_t) && !t_is_32(x_t)) { >> struct range x_swap; >> >> + /* If we know that >> + * - *x* is in the range of signed 32bit value >> + * - *y_cast* range is 32-bit sign non-negative, and > sign -> signed? Ack > >> + * then *x* range can be narrowed to the interaction of > what does it mean "narrowed to the interaction"? Let us change to '*x* range can be improved with *y_cast*. > >> + * *x* and *y_cast*. Otherwise, if the new range for *x* >> + * allows upper 32-bit 0xffffffff then the eventual new >> + * range for *x* will be out of signed 32-bit range >> + * which violates the origin *x* range. >> + */ >> + if (x_t == S64 && y_t == S32 && > tbh, given this is so specific for x_t == S64 and y_T == S32, I'd move > it out from this if into an independent condition, it doesn't benefit > from being inside Okay, I can do this. > >> + !(y_cast.a & 0xffffffff80000000ULL) && !(y_cast.b & 0xffffffff80000000) && > isn't this just a much more convoluted way of checking: > > y_cast.a <= 0x7fffffffULL && y_cast.b <= 0x7fffffffULL Yes, this is indeed simpler. I can use this one. > > ? Is & + negation really easier to follow?... > >> + (long long)x.a >= S32_MIN && (long long)x.b <= S32_MAX) >> + return range_improve(x_t, x, y_cast); >> + >> /* some combinations of upper 32 bits and sign bit can lead to >> * invalid ranges, in such cases it's easier to detect them >> * after cast/swap than try to enumerate all the conditions >> @@ -2108,6 +2122,9 @@ static struct subtest_case crafted_cases[] = { >> {S32, U32, {(u32)S32_MIN, 0}, {0, 0}}, >> {S32, U32, {(u32)S32_MIN, 0}, {(u32)S32_MIN, (u32)S32_MIN}}, >> {S32, U32, {(u32)S32_MIN, S32_MAX}, {S32_MAX, S32_MAX}}, >> + {S64, U32, {0x0, 0x1f}, {0xffffffff80000000ULL, 0x000000007fffffffULL}}, >> + {S64, U32, {0x0, 0x1f}, {0xffffffffffff8000ULL, 0x0000000000007fffULL}}, >> + {S64, U32, {0x0, 0x1f}, {0xffffffffffffff80ULL, 0x000000000000007fULL}}, >> }; >> >> /* Go over crafted hard-coded cases. This is fast, so we do it as part of >> -- >> 2.43.0 >>