From patchwork Mon Jul 3 03:32:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amma Lee X-Patchwork-Id: 13299578 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 03A2DEB64DA for ; Mon, 3 Jul 2023 03:33:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:Message-Id:Date:Subject:Cc:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=ujvFF8jQ4q/7b88cRjoKJup0uqbl9uluqZ0YfvN0oe0=; b=bwQdm6O0oDY1kP Nv+XtSLCIe8SQoqISvaqFNC6UNNOHi3wlc05EcJ96kiTbN8KbPz/0UOdCayg2GvWiI3DnF1ImiC6O 7FhnWfyBQth8AC7AfAQfXERxTfNbvIq4JVmvxHB8PQGtOdfxnV9El3iGjYR1HJpHh6U0e+r8vHeuZ b2OBoAj1X6bEaakdcq43ZpNZPTAaHY/G9rMOcs3t3vmaB9TO6Mj6yhOsg0zooT1hea1GKFT+C4ppl txWeondFsjzzDGJyDzufCg70twGny5F/5rWjnsgIlC7y0qoMIC2XeSlaFzFHlHHYWZsUbiAHgVFeo XuN0ViWswveAy2LEC8ng==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qGAJP-009Apo-00; Mon, 03 Jul 2023 03:33:15 +0000 Received: from out28-125.mail.aliyun.com ([115.124.28.125]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1qGAJL-009AnU-39 for linux-riscv@lists.infradead.org; Mon, 03 Jul 2023 03:33:14 +0000 X-Alimail-AntiSpam: AC=CONTINUE;BC=0.07437741|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_system_inform|0.0371712-0.0010859-0.961743;FP=0|0|0|0|0|-1|-1|-1;HT=ay29a033018047192;MF=lixiaoyun@binary-semi.com;NM=1;PH=DS;RN=7;RT=7;SR=0;TI=SMTPD_---.TjpOQK9_1688355167; Received: from localhost.localdomain(mailfrom:lixiaoyun@binary-semi.com fp:SMTPD_---.TjpOQK9_1688355167) by smtp.aliyun-inc.com; Mon, 03 Jul 2023 11:32:58 +0800 From: Amma Lee To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu Cc: lixiaoyun@binary-semi.com, xiezx@binary-semi.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] riscv: optimize ELF relocation function in riscv Date: Mon, 3 Jul 2023 11:32:12 +0800 Message-Id: <1688355132-62933-1-git-send-email-lixiaoyun@binary-semi.com> X-Mailer: git-send-email 1.9.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230702_203312_219289_A9D9D7E9 X-CRM114-Status: GOOD ( 16.57 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org The patch can optimize the running times of insmod command by modify ELF relocation function. In the 5.10 and latest kernel, when install the riscv ELF drivers which contains multiple symbol table items to be relocated, kernel takes a lot of time to execute the relocation. For example, we install a 3+MB driver need 180+s. We focus on the riscv architecture handle R_RISCV_HI20 and R_RISCV_LO20 type items relocation function in the arch\riscv\kernel\module.c and find that there are two-loops in the function. If we modify the begin number in the second for-loops iteration, we could save significant time for installation. We install the same 3+MB driver could just need 2s. Signed-off-by: Amma Lee --- arch/riscv/kernel/module.c | 67 +++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 64 insertions(+), 3 deletions(-) diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c index 7c651d5..b8df144 100755 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -345,13 +345,13 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, int (*handler)(struct module *me, u32 *location, Elf_Addr v); Elf_Sym *sym; u32 *location; - unsigned int i, type; + unsigned int i, type, j_idx; Elf_Addr v; int res; pr_debug("Applying relocate section %u to %u\n", relsec, sechdrs[relsec].sh_info); - + j_idx = 0; for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { /* This is where to make the change */ location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr @@ -386,7 +386,15 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) { unsigned int j; - for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) { + /*In the second for-loops, each traversal for j is + * starts from 0 to the symbol table item index which + * is detected. By the tool "readelf", we find that all + * the symbol table items about R_RISCV_PCREL_HI20 type + * are incrementally added in order. It means that we + * could interate the j with the previous loop end + * value(j_idx) as the begin number in the next loop; + */ + for (j = j_idx; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) { unsigned long hi20_loc = sechdrs[sechdrs[relsec].sh_info].sh_addr + rel[j].r_offset; @@ -420,11 +428,64 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, } } if (j == sechdrs[relsec].sh_size / sizeof(*rel)) { + if (j_idx == 0) { pr_err( "%s: Can not find HI20 relocation information\n", me->name); return -EINVAL; +} + + /*If the last j-loop have been traversed to the + * maximum value but never match the + * corresponding symbol relocation item, the + * j-loop will execute the second loop which + * is begin from 0 to the prerious index (j_idx) + * unless the previous j_idx == 0; + * */ + for (j = 0; j < j_idx; j++) { + unsigned long hi20_loc = + sechdrs[sechdrs[relsec].sh_info].sh_addr + + rel[j].r_offset; + u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info); + + /* Find the corresponding HI20 relocation entry */ + if (hi20_loc == sym->st_value + && (hi20_type == R_RISCV_PCREL_HI20 + || hi20_type == R_RISCV_GOT_HI20)) { + s32 hi20, lo12; + Elf_Sym *hi20_sym = + (Elf_Sym *)sechdrs[symindex].sh_addr + + ELF_RISCV_R_SYM(rel[j].r_info); + unsigned long hi20_sym_val = + hi20_sym->st_value + + rel[j].r_addend; + + /* Calculate lo12 */ + size_t offset = hi20_sym_val - hi20_loc; + if (IS_ENABLED(CONFIG_MODULE_SECTIONS) + && hi20_type == R_RISCV_GOT_HI20) { + offset = module_emit_got_entry( + me, hi20_sym_val); + offset = offset - hi20_loc; + } + hi20 = (offset + 0x800) & 0xfffff000; + lo12 = offset - hi20; + v = lo12; + + break; + } } + + if (j == j_idx) { + pr_err( + "%s: Can not find HI20 relocation information\n", + me->name); + return -EINVAL; + } + } + + /* Record the previous j-loop end index */ + j_idx = j; } res = handler(me, location, v);