From patchwork Mon Aug 14 12:54:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 9898831 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D7040602D9 for ; Mon, 14 Aug 2017 12:58:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CBCE1285FD for ; Mon, 14 Aug 2017 12:58:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C0D642860E; Mon, 14 Aug 2017 12:58:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 6B97D28606 for ; Mon, 14 Aug 2017 12:58:18 +0000 (UTC) Received: (qmail 26507 invoked by uid 550); 14 Aug 2017 12:55:47 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 26175 invoked from network); 14 Aug 2017 12:55:40 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=RlvjCrNlhOGjPHcrdrLCiYJEwgq2Z4Lxt0AS7Ll2Acg=; b=Vqz+1vWdaXaYnh/5YWDFqIzZZWzCOKOU+ziO39eW3vEFA0omuttzfkS2vjONvcvwl0 0o98DBVm6sYJXRG+4lSWirHC2lYhKSYnZOVe6SgupaTZfO7Nd6KtMkCc54sUoFUw1Vp3 eibfxEKI8xK2LolAnhI7UaidGmo8XzrVQwp9o= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=RlvjCrNlhOGjPHcrdrLCiYJEwgq2Z4Lxt0AS7Ll2Acg=; b=uMJViD6aGYcte3mJYuWez7Qc6PyW1GGEHDdxrlSD+NZRNBxUQhF0gyfWW+M0tWBnFp Ki9e/DT1HLzSWJF9lmxzRUH0C+4sWiQ52FNmFGJNwZw1xYI9YH3+G3vRgjUfhSVZfSpV 02HQBBxI+gbmfQELblrH4HDFmImzvkOI12Dk49TmlGdDMN28gPDfB4uH2F3W0TgoVwnw zcA9MJYEDYCV+EPbw7KTNveojD98YPwEt3MunRY5caXq0MOSNq4XOE/oaPCX8rATwzH7 h377OHksLAz7/BfYthtLL3wnIXefymZJy7+sL8PL0WYu/fyCrJWidRKH/0tndPfg9mDy qpOQ== X-Gm-Message-State: AHYfb5iRRLLUKBpKu3jW5ObOvhnrAQ4We+aWBTVrZA457c/TcM/saAw7 Jxz7xDdPpKzvY1pqjtXrWg== X-Received: by 10.28.217.12 with SMTP id q12mr3753718wmg.45.1502715328784; Mon, 14 Aug 2017 05:55:28 -0700 (PDT) From: Ard Biesheuvel To: kernel-hardening@lists.openwall.com Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Arnd Bergmann , Nicolas Pitre , Russell King , Kees Cook , Thomas Garnier , Marc Zyngier , Mark Rutland , Tony Lindgren , Matt Fleming , Dave Martin Date: Mon, 14 Aug 2017 13:54:00 +0100 Message-Id: <20170814125411.22604-20-ard.biesheuvel@linaro.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170814125411.22604-1-ard.biesheuvel@linaro.org> References: <20170814125411.22604-1-ard.biesheuvel@linaro.org> Subject: [kernel-hardening] [PATCH 19/30] ARM: kernel: use PC-relative symbol references in MMU switch code X-Virus-Scanned: ClamAV using ClamSMTP To prepare for adding support for KASLR, which relocates all absolute symbol references at runtime after the caches have been enabled, update the MMU switch code to avoid using absolute symbol references where possible. This ensures these quantities are invariant under runtime relocation. Cc: Russell King Signed-off-by: Ard Biesheuvel --- arch/arm/kernel/head-common.S | 39 ++++++++------------ 1 file changed, 15 insertions(+), 24 deletions(-) diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S index 06035488130c..b74477507a12 100644 --- a/arch/arm/kernel/head-common.S +++ b/arch/arm/kernel/head-common.S @@ -79,9 +79,10 @@ ENDPROC(__vet_atags) */ __INIT __mmap_switched: - adr r3, __mmap_switched_data - - ldmia r3!, {r4, r5, r6, r7} + adr_l r4, __data_loc + adr_l r5, _sdata + adr_l r6, __bss_start + adr_l r7, _end cmp r4, r5 @ Copy data segment if needed 1: cmpne r5, r6 ldrne fp, [r4], #4 @@ -93,9 +94,17 @@ __mmap_switched: strcc fp, [r6],#4 bcc 1b - ARM( ldmia r3, {r4, r5, r6, r7, sp}) - THUMB( ldmia r3, {r4, r5, r6, r7} ) - THUMB( ldr sp, [r3, #16] ) + adr_l r3, init_thread_union + THREAD_START_SP + mov sp, r3 + adr_l r4, processor_id + adr_l r5, __machine_arch_type + adr_l r6, __atags_pointer +#ifdef CONFIG_CPU_CP15 + adr_l r7, cr_alignment +#else + mov r7, #0 +#endif + str r9, [r4] @ Save processor ID str r1, [r5] @ Save machine type str r2, [r6] @ Save atags pointer @@ -104,24 +113,6 @@ __mmap_switched: b start_kernel ENDPROC(__mmap_switched) - .align 2 - .type __mmap_switched_data, %object -__mmap_switched_data: - .long __data_loc @ r4 - .long _sdata @ r5 - .long __bss_start @ r6 - .long _end @ r7 - .long processor_id @ r4 - .long __machine_arch_type @ r5 - .long __atags_pointer @ r6 -#ifdef CONFIG_CPU_CP15 - .long cr_alignment @ r7 -#else - .long 0 @ r7 -#endif - .long init_thread_union + THREAD_START_SP @ sp - .size __mmap_switched_data, . - __mmap_switched_data - /* * This provides a C-API version of __lookup_processor_type */