From patchwork Tue Apr 20 02:50:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Maciej W. Rozycki" X-Patchwork-Id: 12213215 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 997C1C433ED for ; Tue, 20 Apr 2021 02:50:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7279B60FE6 for ; Tue, 20 Apr 2021 02:50:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233661AbhDTCvA (ORCPT ); Mon, 19 Apr 2021 22:51:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39290 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhDTCu7 (ORCPT ); Mon, 19 Apr 2021 22:50:59 -0400 Received: from angie.orcam.me.uk (angie.orcam.me.uk [IPv6:2001:4190:8020::4]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3D736C06174A; Mon, 19 Apr 2021 19:50:29 -0700 (PDT) Received: by angie.orcam.me.uk (Postfix, from userid 500) id 8182592009E; Tue, 20 Apr 2021 04:50:28 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by angie.orcam.me.uk (Postfix) with ESMTP id 7DA0C92009B; Tue, 20 Apr 2021 04:50:28 +0200 (CEST) Date: Tue, 20 Apr 2021 04:50:28 +0200 (CEST) From: "Maciej W. Rozycki" To: Arnd Bergmann , Thomas Bogendoerfer cc: Huacai Chen , Huacai Chen , Jiaxun Yang , linux-arch@vger.kernel.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/4] lib/math: Add a `do_div' test module In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Implement a module for correctness and performance evaluation for the `do_div' function, often handled in an optimised manner by platform code. Use a somewhat randomly generated set of inputs that is supposed to be representative, using the same set of divisors twice, expressed as a constant and as a variable each, so as to verify the implementation for both cases should they be handled by different code execution paths. Reference results were produced with GNU bc. At the conclusion output the total execution time elapsed. Signed-off-by: Maciej W. Rozycki --- NB there's a `checkpatch.pl' warning for a split line, but I can see no gain from joining it. --- lib/Kconfig.debug | 10 ++ lib/math/Makefile | 2 lib/math/test_div64.c | 249 ++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 261 insertions(+) linux-div64-test.diff Index: linux-3maxp-div64/lib/Kconfig.debug =================================================================== --- linux-3maxp-div64.orig/lib/Kconfig.debug +++ linux-3maxp-div64/lib/Kconfig.debug @@ -2027,6 +2027,16 @@ config TEST_SORT If unsure, say N. +config TEST_DIV64 + tristate "64bit/32bit division and modulo test" + depends on DEBUG_KERNEL || m + help + Enable this to turn on 'do_div()' function test. This test is + executed only once during system boot (so affects only boot time), + or at module load time. + + If unsure, say N. + config KPROBES_SANITY_TEST bool "Kprobes sanity tests" depends on DEBUG_KERNEL Index: linux-3maxp-div64/lib/math/Makefile =================================================================== --- linux-3maxp-div64.orig/lib/math/Makefile +++ linux-3maxp-div64/lib/math/Makefile @@ -4,3 +4,5 @@ obj-y += div64.o gcd.o lcm.o int_pow.o i obj-$(CONFIG_CORDIC) += cordic.o obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o obj-$(CONFIG_RATIONAL) += rational.o + +obj-$(CONFIG_TEST_DIV64) += test_div64.o Index: linux-3maxp-div64/lib/math/test_div64.c =================================================================== --- /dev/null +++ linux-3maxp-div64/lib/math/test_div64.c @@ -0,0 +1,249 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2021 Maciej W. Rozycki + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include + +#include + +#define TEST_DIV64_N_ITER 1024 + +static const u64 test_div64_dividents[] = { + 0x00000000ab275080, + 0x0000000fe73c1959, + 0x000000e54c0a74b1, + 0x00000d4398ff1ef9, + 0x0000a18c2ee1c097, + 0x00079fb80b072e4a, + 0x0072db27380dd689, + 0x0842f488162e2284, + 0xf66745411d8ab063, +}; +#define SIZE_DIV64_DIVIDENTS ARRAY_SIZE(test_div64_dividents) + +#define TEST_DIV64_DIVISOR_0 0x00000009 +#define TEST_DIV64_DIVISOR_1 0x0000007c +#define TEST_DIV64_DIVISOR_2 0x00000204 +#define TEST_DIV64_DIVISOR_3 0x0000cb5b +#define TEST_DIV64_DIVISOR_4 0x00010000 +#define TEST_DIV64_DIVISOR_5 0x0008a880 +#define TEST_DIV64_DIVISOR_6 0x003fd3ae +#define TEST_DIV64_DIVISOR_7 0x0b658fac +#define TEST_DIV64_DIVISOR_8 0xdc08b349 + +static const u32 test_div64_divisors[] = { + TEST_DIV64_DIVISOR_0, + TEST_DIV64_DIVISOR_1, + TEST_DIV64_DIVISOR_2, + TEST_DIV64_DIVISOR_3, + TEST_DIV64_DIVISOR_4, + TEST_DIV64_DIVISOR_5, + TEST_DIV64_DIVISOR_6, + TEST_DIV64_DIVISOR_7, + TEST_DIV64_DIVISOR_8, +}; +#define SIZE_DIV64_DIVISORS ARRAY_SIZE(test_div64_divisors) + +static const struct { + u64 quotient; + u32 remainder; +} test_div64_results[SIZE_DIV64_DIVISORS][SIZE_DIV64_DIVIDENTS] = { + { + { 0x0000000013045e47, 0x00000001 }, + { 0x000000000161596c, 0x00000030 }, + { 0x000000000054e9d4, 0x00000130 }, + { 0x000000000000d776, 0x0000278e }, + { 0x000000000000ab27, 0x00005080 }, + { 0x00000000000013c4, 0x0004ce80 }, + { 0x00000000000002ae, 0x001e143c }, + { 0x000000000000000f, 0x0033e56c }, + { 0x0000000000000000, 0xab275080 }, + }, { + { 0x00000001c45c02d1, 0x00000000 }, + { 0x0000000020d5213c, 0x00000049 }, + { 0x0000000007e3d65f, 0x000001dd }, + { 0x0000000000140531, 0x000065ee }, + { 0x00000000000fe73c, 0x00001959 }, + { 0x000000000001d637, 0x0004e5d9 }, + { 0x0000000000003fc9, 0x000713bb }, + { 0x0000000000000165, 0x029abe7d }, + { 0x0000000000000012, 0x6e9f7e37 }, + }, { + { 0x000000197a3a0cf7, 0x00000002 }, + { 0x00000001d9632e5c, 0x00000021 }, + { 0x0000000071c28039, 0x000001cd }, + { 0x000000000120a844, 0x0000b885 }, + { 0x0000000000e54c0a, 0x000074b1 }, + { 0x00000000001a7bb3, 0x00072331 }, + { 0x00000000000397ad, 0x0002c61b }, + { 0x000000000000141e, 0x06ea2e89 }, + { 0x000000000000010a, 0xab002ad7 }, + }, { + { 0x0000017949e37538, 0x00000001 }, + { 0x0000001b62441f37, 0x00000055 }, + { 0x0000000694a3391d, 0x00000085 }, + { 0x0000000010b2a5d2, 0x0000a753 }, + { 0x000000000d4398ff, 0x00001ef9 }, + { 0x0000000001882ec6, 0x0005cbf9 }, + { 0x000000000035333b, 0x0017abdf }, + { 0x00000000000129f1, 0x0ab4520d }, + { 0x0000000000000f6e, 0x8ac0ce9b }, + }, { + { 0x000011f321a74e49, 0x00000006 }, + { 0x0000014d8481d211, 0x0000005b }, + { 0x0000005025cbd92d, 0x000001e3 }, + { 0x00000000cb5e71e3, 0x000043e6 }, + { 0x00000000a18c2ee1, 0x0000c097 }, + { 0x0000000012a88828, 0x00036c97 }, + { 0x000000000287f16f, 0x002c2a25 }, + { 0x00000000000e2cc7, 0x02d581e3 }, + { 0x000000000000bbf4, 0x1ba08c03 }, + }, { + { 0x0000d8db8f72935d, 0x00000005 }, + { 0x00000fbd5aed7a2e, 0x00000002 }, + { 0x000003c84b6ea64a, 0x00000122 }, + { 0x0000000998fa8829, 0x000044b7 }, + { 0x000000079fb80b07, 0x00002e4a }, + { 0x00000000e16b20fa, 0x0002a14a }, + { 0x000000001e940d22, 0x00353b2e }, + { 0x0000000000ab40ac, 0x06fba6ba }, + { 0x000000000008debd, 0x72d98365 }, + }, { + { 0x000cc3045b8fc281, 0x00000000 }, + { 0x0000ed1f48b5c9fc, 0x00000079 }, + { 0x000038fb9c63406a, 0x000000e1 }, + { 0x000000909705b825, 0x00000a62 }, + { 0x00000072db27380d, 0x0000d689 }, + { 0x0000000d43fce827, 0x00082b09 }, + { 0x00000001ccaba11a, 0x0037e8dd }, + { 0x000000000a13f729, 0x0566dffd }, + { 0x000000000085a14b, 0x23d36726 }, + }, { + { 0x00eafeb9c993592b, 0x00000001 }, + { 0x00110e5befa9a991, 0x00000048 }, + { 0x00041947b4a1d36a, 0x000000dc }, + { 0x00000a6679327311, 0x0000c079 }, + { 0x00000842f488162e, 0x00002284 }, + { 0x000000f4459740fc, 0x00084484 }, + { 0x0000002122c47bf9, 0x002ca446 }, + { 0x00000000b9936290, 0x004979c4 }, + { 0x00000000099ca89d, 0x9db446bf }, + }, { + { 0x1b60cece589da1d2, 0x00000001 }, + { 0x01fcb42be1453f5b, 0x0000004f }, + { 0x007a3f2457df0749, 0x0000013f }, + { 0x0001363130e3ec7b, 0x000017aa }, + { 0x0000f66745411d8a, 0x0000b063 }, + { 0x00001c757dfab350, 0x00048863 }, + { 0x000003dc4979c652, 0x00224ea7 }, + { 0x000000159edc3144, 0x06409ab3 }, + { 0x000000011eadfee3, 0xa99c48a8 }, + }, +}; + +static inline bool test_div64_verify(u64 quotient, u32 remainder, int i, int j) +{ + return (quotient == test_div64_results[i][j].quotient && + remainder == test_div64_results[i][j].remainder); +} + +/* + * This needs to be a macro, because we don't want to rely on the compiler + * to do constant propagation, and `do_div' may take a different path for + * constants, so we do want to verify that as well. + */ +#define test_div64_one(divident, divisor, i, j) ({ \ + bool result = true; \ + u64 quotient; \ + u32 remainder; \ + \ + quotient = divident; \ + remainder = do_div(quotient, divisor); \ + if (!test_div64_verify(quotient, remainder, i, j)) { \ + pr_err("ERROR: %016llx / %08x => %016llx,%08x\n", \ + divident, divisor, quotient, remainder); \ + pr_err("ERROR: expected value=> %016llx,%08x\n", \ + test_div64_results[i][j].quotient, \ + test_div64_results[i][j].remainder); \ + result = false; \ + } \ + result; \ +}) + +/* + * Run calculation for the same divisor value expressed as a constant + * and as a variable, so as to verify the implementation for both cases + * should they be handled by different code execution paths. + */ +static bool __init test_div64(void) +{ + u64 divident; + int i, j; + + for (i = 0; i < SIZE_DIV64_DIVIDENTS; i++) { + divident = test_div64_dividents[i]; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_0, i, 0)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_1, i, 1)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_2, i, 2)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_3, i, 3)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_4, i, 4)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_5, i, 5)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_6, i, 6)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_7, i, 7)) + return false; + if (!test_div64_one(divident, TEST_DIV64_DIVISOR_8, i, 8)) + return false; + for (j = 0; j < SIZE_DIV64_DIVISORS; j++) { + if (!test_div64_one(divident, test_div64_divisors[j], + i, j)) + return false; + } + } + return true; +} + +static int __init test_div64_init(void) +{ + struct timespec64 ts, ts0, ts1; + int i; + + pr_info("Starting 64bit/32bit division and modulo test\n"); + ktime_get_ts64(&ts0); + + for (i = 0; i < TEST_DIV64_N_ITER; i++) + if (!test_div64()) + break; + + ktime_get_ts64(&ts1); + ts = timespec64_sub(ts1, ts0); + pr_info("Completed 64bit/32bit division and modulo test, " + "%llu.%09lus elapsed\n", ts.tv_sec, ts.tv_nsec); + + return 0; +} + +static void __exit test_div64_exit(void) +{ +} + +module_init(test_div64_init); +module_exit(test_div64_exit); + +MODULE_AUTHOR("Maciej W. Rozycki "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("64bit/32bit division and modulo test module");