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[2620:137:e000::1:20]) by mx.google.com with ESMTP id he44-20020a1709073dac00b0078dee0fce23si241408ejc.123.2022.11.24.04.05.06; Thu, 24 Nov 2022 04:05:30 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=antgroup.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229552AbiKXLwL (ORCPT + 99 others); Thu, 24 Nov 2022 06:52:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229838AbiKXLwK (ORCPT ); Thu, 24 Nov 2022 06:52:10 -0500 Received: from out0-144.mail.aliyun.com (out0-144.mail.aliyun.com [140.205.0.144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C16A9370B for ; Thu, 24 Nov 2022 03:52:08 -0800 (PST) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018047206;MF=houwenlong.hwl@antgroup.com;NM=1;PH=DS;RN=18;SR=0;TI=SMTPD_---.QFud9ec_1669290723; Received: from localhost(mailfrom:houwenlong.hwl@antgroup.com fp:SMTPD_---.QFud9ec_1669290723) by smtp.aliyun-inc.com; Thu, 24 Nov 2022 19:52:03 +0800 From: "Hou Wenlong" To: linux-kernel@vger.kernel.org Cc: "Hou Wenlong" , "Juergen Gross" , " =?utf-8?q?Srivatsa_S=2E_Bhat_=28VMware?= =?utf-8?q?=29?= " , "Alexey Makhalov" , "VMware PV-Drivers Reviewers" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , , "H. Peter Anvin" , "Peter Zijlstra" , "Josh Poimboeuf" , "Kees Cook" , "Song Liu" , "Nadav Amit" , Subject: [PATCH v2] x86/paravirt: Use relative reference for original instruction Date: Thu, 24 Nov 2022 19:51:53 +0800 Message-Id: <73c9ffac157087da78af9fca59cf7d8db7f17226.1669290510.git.houwenlong.hwl@antgroup.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750378919738161262?= X-GMAIL-MSGID: =?utf-8?q?1750379035763018515?= Similar to the alternative patching, use relative reference for original instruction rather than absolute one, which saves 8 bytes for one entry on x86_64. And it could generate R_X86_64_PC32 relocation instead of R_X86_64_64 relocation, which also reduces relocation metadata on relocatable builds. And the alignment could be hard coded to be 4 now. Signed-off-by: Hou Wenlong --- arch/x86/include/asm/paravirt.h | 10 +++++----- arch/x86/include/asm/paravirt_types.h | 8 ++++---- arch/x86/kernel/alternative.c | 8 +++++--- 3 files changed, 14 insertions(+), 12 deletions(-) diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 2851bc2339d5..e56065ea73f2 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -735,16 +735,16 @@ extern void default_banner(void); #else /* __ASSEMBLY__ */ -#define _PVSITE(ptype, ops, word, algn) \ +#define _PVSITE(ptype, ops) \ 771:; \ ops; \ 772:; \ .pushsection .parainstructions,"a"; \ - .align algn; \ - word 771b; \ + .align 4; \ + .long 771b-.; \ .byte ptype; \ .byte 772b-771b; \ - _ASM_ALIGN; \ + .align 4; \ .popsection @@ -752,7 +752,7 @@ extern void default_banner(void); #ifdef CONFIG_PARAVIRT_XXL #define PARA_PATCH(off) ((off) / 8) -#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops, .quad, 8) +#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops) #define PARA_INDIRECT(addr) *addr(%rip) #ifdef CONFIG_DEBUG_ENTRY diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h index 8c1da419260f..68952ae07a3f 100644 --- a/arch/x86/include/asm/paravirt_types.h +++ b/arch/x86/include/asm/paravirt_types.h @@ -5,7 +5,7 @@ #ifndef __ASSEMBLY__ /* These all sit in the .parainstructions section to tell us what to patch. */ struct paravirt_patch_site { - u8 *instr; /* original instructions */ + s32 instr_offset; /* original instructions */ u8 type; /* type of this instruction */ u8 len; /* length of original instruction */ }; @@ -273,11 +273,11 @@ extern struct paravirt_patch_template pv_ops; #define _paravirt_alt(insn_string, type) \ "771:\n\t" insn_string "\n" "772:\n" \ ".pushsection .parainstructions,\"a\"\n" \ - _ASM_ALIGN "\n" \ - _ASM_PTR " 771b\n" \ + " .align 4\n" \ + " .long 771b-.\n" \ " .byte " type "\n" \ " .byte 772b-771b\n" \ - _ASM_ALIGN "\n" \ + " .align 4\n" \ ".popsection\n" /* Generate patchable code, with the default asm parameters. */ diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 111b809f0ac2..6eea563a098d 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -1232,20 +1232,22 @@ void __init_or_module apply_paravirt(struct paravirt_patch_site *start, { struct paravirt_patch_site *p; char insn_buff[MAX_PATCH_LEN]; + u8 *instr; for (p = start; p < end; p++) { unsigned int used; + instr = (u8 *)&p->instr_offset + p->instr_offset; BUG_ON(p->len > MAX_PATCH_LEN); /* prep the buffer with the original instructions */ - memcpy(insn_buff, p->instr, p->len); - used = paravirt_patch(p->type, insn_buff, (unsigned long)p->instr, p->len); + memcpy(insn_buff, instr, p->len); + used = paravirt_patch(p->type, insn_buff, (unsigned long)instr, p->len); BUG_ON(used > p->len); /* Pad the rest with nops */ add_nops(insn_buff + used, p->len - used); - text_poke_early(p->instr, insn_buff, p->len); + text_poke_early(instr, insn_buff, p->len); } } extern struct paravirt_patch_site __start_parainstructions[],