From mboxrd@z Thu Jan 1 00:00:00 1970 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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 44337C432C3 for ; Fri, 15 Nov 2019 09:43:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 23C3F20740 for ; Fri, 15 Nov 2019 09:43:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727547AbfKOJn4 (ORCPT ); Fri, 15 Nov 2019 04:43:56 -0500 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:34080 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727355AbfKOJny (ORCPT ); Fri, 15 Nov 2019 04:43:54 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R911e4;CH=green;DM=||false|;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=shile.zhang@linux.alibaba.com;NM=1;PH=DS;RN=11;SR=0;TI=SMTPD_---0Ti8RdaY_1573811029; Received: from ali-6c96cfdd1403.local(mailfrom:shile.zhang@linux.alibaba.com fp:SMTPD_---0Ti8RdaY_1573811029) by smtp.aliyun-inc.com(127.0.0.1); Fri, 15 Nov 2019 17:43:51 +0800 Subject: Re: [RFC PATCH v3 6/7] scripts/sorttable: Add ORC unwind tables sort concurrently To: Peter Zijlstra Cc: Josh Poimboeuf , Masahiro Yamada , Michal Marek , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org References: <20191115064750.47888-1-shile.zhang@linux.alibaba.com> <20191115064750.47888-7-shile.zhang@linux.alibaba.com> <20191115090723.GS4114@hirez.programming.kicks-ass.net> From: Shile Zhang Message-ID: <9594afbc-52bc-5ae7-4a19-8fc4b36a1abd@linux.alibaba.com> Date: Fri, 15 Nov 2019 17:43:49 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20191115090723.GS4114@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/11/15 17:07, Peter Zijlstra wrote: > On Fri, Nov 15, 2019 at 02:47:49PM +0800, Shile Zhang wrote: > >> +#if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED) >> +/* ORC unwinder only support X86_64 */ >> +#include >> +#include >> +#include >> + >> +#define ORC_REG_UNDEFINED 0 >> +#define ERRSTRING_MAXSZ 256 >> + >> +struct orc_entry { >> + s16 sp_offset; >> + s16 bp_offset; >> + unsigned sp_reg:4; >> + unsigned bp_reg:4; >> + unsigned type:2; >> + unsigned end:1; >> +} __attribute__((packed)); >> + >> +struct orctable_info { >> + size_t orc_size; >> + size_t orc_ip_size; >> +} orctable; > There's ./arch/x86/include/asm/orc_types.h for this. Please don't > duplicate. objtool uses that same header. Good catch! Thanks for your kindly reminder! I'll remove it. >> +/** >> + * sort - sort an array of elements >> + * @base: pointer to data to sort >> + * @num: number of elements >> + * @size: size of each element >> + * @cmp_func: pointer to comparison function >> + * @swap_func: pointer to swap function >> + * >> + * This function does a heapsort on the given array. You may provide a >> + * swap_func function optimized to your element type. >> + * >> + * Sorting time is O(n log n) both on average and worst-case. While >> + * qsort is about 20% faster on average, it suffers from exploitable >> + * O(n*n) worst-case behavior and extra memory requirements that make >> + * it less suitable for kernel use. >> + * >> + * This code token out of /lib/sort.c. >> + */ >> +static void sort(void *base, size_t num, size_t size, >> + int (*cmp_func)(const void *, const void *), >> + void (*swap_func)(void *, void *, int size)) >> +{ >> + /* pre-scale counters for performance */ >> + int i = (num/2 - 1) * size, n = num * size, c, r; >> + >> + /* heapify */ >> + for ( ; i >= 0; i -= size) { >> + for (r = i; r * 2 + size < n; r = c) { >> + c = r * 2 + size; >> + if (c < n - size && >> + cmp_func(base + c, base + c + size) < 0) >> + c += size; >> + if (cmp_func(base + r, base + c) >= 0) >> + break; >> + swap_func(base + r, base + c, size); >> + } >> + } >> + >> + /* sort */ >> + for (i = n - size; i > 0; i -= size) { >> + swap_func(base, base + i, size); >> + for (r = 0; r * 2 + size < i; r = c) { >> + c = r * 2 + size; >> + if (c < i - size && >> + cmp_func(base + c, base + c + size) < 0) >> + c += size; >> + if (cmp_func(base + r, base + c) >= 0) >> + break; >> + swap_func(base + r, base + c, size); >> + } >> + } >> +} > Do we really need to copy the heapsort implementation? That is, why not > use libc's qsort() ? This is userspace after all. Yes, I think qsort is better choice than copy-paste here. But qsort does not support customized swap func, which is needed for ORC unwind swap two tables together. I think it's hard to do with qsort, so I used sort same with original orc unwind table sort.