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[2620:137:e000::1:20]) by mx.google.com with ESMTP id lp17-20020a17090b4a9100b0024df9561b5asi4117960pjb.143.2023.05.01.15.29.42; Mon, 01 May 2023 15:30:02 -0700 (PDT) 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; dkim=pass header.i=@google.com header.s=20221208 header.b=U3MTB4tz; 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=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232749AbjEAWZ5 (ORCPT + 99 others); Mon, 1 May 2023 18:25:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56584 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229863AbjEAWZz (ORCPT ); Mon, 1 May 2023 18:25:55 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EAE82123 for ; Mon, 1 May 2023 15:25:54 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-b9a8075bd7cso5423749276.1 for ; Mon, 01 May 2023 15:25:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1682979954; x=1685571954; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=1BxhGqqIjMamiGADI4rmVFfxoo9kAM2Y8zr5TqlELr0=; b=U3MTB4tzWaoAeuLf7zTSo4Amq9ScioPloA+jQir4eqboGDJVyEgqL6DdVasMfZHsZg vBrehczzN1QTDBrGeQtOjR2w5eHKvycMGoOQXD/HWtb/lBc4NbvnS5An/1CbpglUq5qW SeAvFePY6ORF0a+vI3w3jbAKcvG5ZU5Zr2VElZ27XoWwdAvOUCBMnebjx9wV12CbMCCE ZE2aNA6Yye5kE6xtjIZ/PAWB3laZQjF1We1N2y0aGiJyGWJDDFeV9w3eRY8Z9/5nsH1u fJ+xc92EqXKQ9t/nvrZ6KoEflzOlDUJE2xukjZk/QYj71b51EMACkelg/5rJaWRwVJth 0q+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682979954; x=1685571954; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=1BxhGqqIjMamiGADI4rmVFfxoo9kAM2Y8zr5TqlELr0=; b=GQS4B5nO+tel6/hlz3GwV7GWfTEFFLMCUzTdItxUUvU5bubWPgCPg+Snl9NDAI71Gc uRqmaQIZ9KumyojOPvtHYP5QOiNPkDYa2GYt2gl+0XurEPa8/fBhsnyoTp8fyFYfLLXv pJxZGnSzpbFFBKFwu7U0aG4IupvKcEaGHGORK7FgR0vL3tzket+kvYLCkPUT7Va9LA3n RP10Qhh9127dcK2Bw25Vgg2XVL+azKLG6G/v9VwUiIV/ShYXdrZvC8eA8jeWTiae+t/h MCX1KIe8XDBtCspjUE6NVf4UBaQj3DNO6uF0YpaXknpbZlBSsp/mJcdycaPqThBbbz94 qPpQ== X-Gm-Message-State: AC+VfDxST5oHDY/LSkL2ZxYeNzuW3zZ9JQn8VnxYRkPmPiMVqrfN9aAE T/XEGknwdJ2qb2NGBAMe0wfIKhUR4Veh X-Received: from meowing-l.c.googlers.com ([fda3:e722:ac3:cc00:24:72f4:c0a8:3eba]) (user=maskray job=sendgmr) by 2002:a05:6902:100e:b0:b8b:f584:6b73 with SMTP id w14-20020a056902100e00b00b8bf5846b73mr5947503ybt.10.1682979953813; Mon, 01 May 2023 15:25:53 -0700 (PDT) Date: Mon, 1 May 2023 22:25:51 +0000 Mime-Version: 1.0 Message-ID: <20230501222551.1254686-1-maskray@google.com> Subject: [PATCH v2] arm64: lds: move .got section out of .text From: Fangrui Song To: Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel Cc: linux-kernel@vger.kernel.org, Bill Wendling , Nick Desaulniers , Fangrui Song X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL 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?1764732649075652879?= X-GMAIL-MSGID: =?utf-8?q?1764732649075652879?= Currently, the .got section is placed within the output section .text. However, when .got is non-empty, the SHF_WRITE flag is set for .text when linked by lld. GNU ld recognizes .text as a special section and ignores the SHF_WRITE flag. By renaming .text, we can also get the SHF_WRITE flag. The kernel has performed R_AARCH64_RELATIVE resolving very early, and can then assume that .got is read-only. Let's move .got to the vmlinux_rodata pseudo-segment. The change avoids a section with both executable and writable permissions. Signed-off-by: Fangrui Song Reviewed-by: Ard Biesheuvel --- Changes from v1 (https://lore.kernel.org/lkml/20230428050442.180913-1-maskray@google.com/) * move .got to the vmlinux_rodata pseudo-segment as suggested by Ard Biesheuvel --- arch/arm64/kernel/vmlinux.lds.S | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index b9202c2ee18e..3cd7e76cc562 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -181,10 +181,17 @@ SECTIONS KPROBES_TEXT HYPERVISOR_TEXT *(.gnu.warning) - . = ALIGN(16); - *(.got) /* Global offset table */ } + . = ALIGN(SEGMENT_ALIGN); + _etext = .; /* End of text section */ + + /* everything from this point to __init_begin will be marked RO NX */ + RO_DATA(PAGE_SIZE) + + HYPERVISOR_DATA_SECTIONS + + .got : { *(.got) } /* * Make sure that the .got.plt is either completely empty or it * contains only the lazy dispatch entries. @@ -193,14 +200,6 @@ SECTIONS ASSERT(SIZEOF(.got.plt) == 0 || SIZEOF(.got.plt) == 0x18, "Unexpected GOT/PLT entries detected!") - . = ALIGN(SEGMENT_ALIGN); - _etext = .; /* End of text section */ - - /* everything from this point to __init_begin will be marked RO NX */ - RO_DATA(PAGE_SIZE) - - HYPERVISOR_DATA_SECTIONS - /* code sections that are never executed via the kernel mapping */ .rodata.text : { TRAMP_TEXT