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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham 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 2C7F4C3404C for ; Wed, 19 Feb 2020 00:08:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01B9024656 for ; Wed, 19 Feb 2020 00:08:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qufzpGjE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728031AbgBSAIy (ORCPT ); Tue, 18 Feb 2020 19:08:54 -0500 Received: from mail-pg1-f202.google.com ([209.85.215.202]:44434 "EHLO mail-pg1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728008AbgBSAIw (ORCPT ); Tue, 18 Feb 2020 19:08:52 -0500 Received: by mail-pg1-f202.google.com with SMTP id o2so14859358pgj.11 for ; Tue, 18 Feb 2020 16:08:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=qufzpGjEppDMWPImhTuGEdGT5fSrkUOCFRhcyjZobkamDvVW8lKE7S9n8IfeI9kMjN GjSsbQERqiJCrQWg5+yur9ZmpwI3842rBfYePp5EboZsGV0A9NX4KJSaHBYX9WS8TV/B YxOPfKJb3HR14olUqNzIghumWLSF9JfupKrwhtKGLhHcH+iy/cZLakuxTBBKr3BSQC+Q l/d2gtUBVVI2+sDEnrXi83zlWZ5bO/OYVixaPN92nFcUWQ3ZPH+WoaCJq/ch+3VstHjI DDMR+HT+E10IhOJZsyS+YJ4gi2CPv7gIBX5icVylNk3GYCOKGpIchxJrvY+jCKqp3YLe pYjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=gD1EbNdmSN3xdDALYMYu0SkdBUjchQH+FAHRIofJxFzLYHGNI0fus/t1RtKDi1uiRV QVbAuTkPf7tRtjzmnT1TybQWcHesuYeeXxs3mbl6c2XHX/n0De8TPGGTgG9ua7XzGrwR Gollb8GZ2Fhv/h9mfwZmqBF9hd5Pcoi2oEZvb7AuY9/mbu+JbqjHELCAh3azwIs4a3P1 3zRdfm2VBVti2SCSzwiASHIrjeQFCZaXrP907ZmKnZZNnax1Ct/g1+e/NCOszAlLM6is uxmLCloIn+/rgWMUv+rjLB5NYevAal/Y/QH8pHXoCRbboKdcHd6RDRHiM8KGkTg/jNEW humw== X-Gm-Message-State: APjAAAWGELITEMPyrLwKzbTMPwtZWRWtBomQZQhWVbCvENa05j1A4DH+ froERjo6Rg7oUsI9cdpy/c9Yan5sZMIc9BGnBUM= X-Google-Smtp-Source: APXvYqwciBBhLealMEWoo9KoEMacGgV/WZH2VTZ4SCan5a+9yYr+272BEeKH1BEVWPC4FCthWzaq/J27w407jXSF4NM= X-Received: by 2002:a63:bc02:: with SMTP id q2mr24517139pge.174.1582070930907; Tue, 18 Feb 2020 16:08:50 -0800 (PST) Date: Tue, 18 Feb 2020 16:08:12 -0800 In-Reply-To: <20200219000817.195049-1-samitolvanen@google.com> Message-Id: <20200219000817.195049-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200219000817.195049-1-samitolvanen@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v8 07/12] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , james.morse@arm.com Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If we detect a corrupted x18, restore the register before jumping back to potentially SCS instrumented code. This is safe, because the wrapper is called with preemption disabled and a separate shadow stack is used for interrupt handling. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Will Deacon --- arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S index 3fc71106cb2b..6ca6c0dc11a1 100644 --- a/arch/arm64/kernel/efi-rt-wrapper.S +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -34,5 +34,14 @@ ENTRY(__efi_rt_asm_wrapper) ldp x29, x30, [sp], #32 b.ne 0f ret -0: b efi_handle_corrupted_x18 // tail call +0: + /* + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a + * shadow stack pointer, which we need to restore before returning to + * potentially instrumented code. This is safe because the wrapper is + * called with preemption disabled and a separate shadow stack is used + * for interrupts. + */ + mov x18, x2 + b efi_handle_corrupted_x18 // tail call ENDPROC(__efi_rt_asm_wrapper) -- 2.25.0.265.gbab2e86ba0-goog 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=-9.7 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 2F580C34031 for ; Wed, 19 Feb 2020 00:10:33 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 024AA22B48 for ; Wed, 19 Feb 2020 00:10:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="q0zLkAqC"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="qufzpGjE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 024AA22B48 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:To:From:Subject:References:Mime-Version :Message-Id:In-Reply-To:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Mta+urjKXaKaOHv9z8GNkMB6pw1+rO5EkXIdJGgl3Pk=; b=q0zLkAqCKtBto1 0VOF9REtuSIuV0h4uQISofE9w8Yg/yOLVBGbu2Ad4TXWbG+ek1dZSVmBZKvb3QPMFSOwj7tZ+rSy2 sRDvMTBK5xI3lkpFIbXMrJX67MN8omzD1I8epas1jVdk7cjvR4rCqMf7p2wWWpUjd7AGDQAkhMNf6 qOMg2d1/euja17nwfKOUcuvQ0qSXJoameg4zLWj9m2h44x8KlgJoWk8eSialM04ENyft8X2aiGyhc x/qYgCESG6UhlcJzSZIO0EKUxdAbOVxcM8KmLzrdefW2PhQvgYyUf19dQzjJKAEsF7lAPVoxJ0g2c xyeSczyu1p5oWA2/Exgw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4Cwe-0002Sp-1s; Wed, 19 Feb 2020 00:10:28 +0000 Received: from mail-pg1-x54a.google.com ([2607:f8b0:4864:20::54a]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4Cv6-0008Dt-Gl for linux-arm-kernel@lists.infradead.org; Wed, 19 Feb 2020 00:08:54 +0000 Received: by mail-pg1-x54a.google.com with SMTP id j29so14897972pgj.2 for ; Tue, 18 Feb 2020 16:08:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=qufzpGjEppDMWPImhTuGEdGT5fSrkUOCFRhcyjZobkamDvVW8lKE7S9n8IfeI9kMjN GjSsbQERqiJCrQWg5+yur9ZmpwI3842rBfYePp5EboZsGV0A9NX4KJSaHBYX9WS8TV/B YxOPfKJb3HR14olUqNzIghumWLSF9JfupKrwhtKGLhHcH+iy/cZLakuxTBBKr3BSQC+Q l/d2gtUBVVI2+sDEnrXi83zlWZ5bO/OYVixaPN92nFcUWQ3ZPH+WoaCJq/ch+3VstHjI DDMR+HT+E10IhOJZsyS+YJ4gi2CPv7gIBX5icVylNk3GYCOKGpIchxJrvY+jCKqp3YLe pYjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=Np6pBwhtLuvucwEiF287eQrxkwZd1Op2VN8YBDCUeGoFP3WyJP3wAlLyk74qzQP/Rh wLX87T3xq6rMdyK4yI8HPwwQIII3K3BGRtb/QyhMG8sXjnwEioh3v0SACpaCZ9MdXsUT lEciJMvx+7hXuwBlxUb0RfrgfkRQYK59tusSNsR/VJs9P29kBalRhflvBa29uHuRBlGp F049OeLKXXLVY/lvJx0wo7ExCWRtXA+mAEky1DxTlJ58LTvWrSlCBB1V5hebFHqCCYIv REd0H0rs1YxnOrc4pxUArF586qhy0mfVgNEQtzxiipmdBC27MOyS2flzCyOKZbVMqOhH Atyg== X-Gm-Message-State: APjAAAXNyvkehBR7m5N6HkDGsP5p7smdg38rr0jDVkNUAowNy+zTxvTD 0Ibm8AGBHp2qQY66XSv0fBWF/lrFDTq/iaF7GTc= X-Google-Smtp-Source: APXvYqwciBBhLealMEWoo9KoEMacGgV/WZH2VTZ4SCan5a+9yYr+272BEeKH1BEVWPC4FCthWzaq/J27w407jXSF4NM= X-Received: by 2002:a63:bc02:: with SMTP id q2mr24517139pge.174.1582070930907; Tue, 18 Feb 2020 16:08:50 -0800 (PST) Date: Tue, 18 Feb 2020 16:08:12 -0800 In-Reply-To: <20200219000817.195049-1-samitolvanen@google.com> Message-Id: <20200219000817.195049-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200219000817.195049-1-samitolvanen@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v8 07/12] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , james.morse@arm.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200218_160852_673370_3290F698 X-CRM114-Status: GOOD ( 11.33 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , Jann Horn , Masahiro Yamada , Marc Zyngier , kernel-hardening@lists.openwall.com, Nick Desaulniers , linux-kernel@vger.kernel.org, Miguel Ojeda , clang-built-linux@googlegroups.com, Sami Tolvanen , Laura Abbott , Dave Martin , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org If we detect a corrupted x18, restore the register before jumping back to potentially SCS instrumented code. This is safe, because the wrapper is called with preemption disabled and a separate shadow stack is used for interrupt handling. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Will Deacon --- arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S index 3fc71106cb2b..6ca6c0dc11a1 100644 --- a/arch/arm64/kernel/efi-rt-wrapper.S +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -34,5 +34,14 @@ ENTRY(__efi_rt_asm_wrapper) ldp x29, x30, [sp], #32 b.ne 0f ret -0: b efi_handle_corrupted_x18 // tail call +0: + /* + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a + * shadow stack pointer, which we need to restore before returning to + * potentially instrumented code. This is safe because the wrapper is + * called with preemption disabled and a separate shadow stack is used + * for interrupts. + */ + mov x18, x2 + b efi_handle_corrupted_x18 // tail call ENDPROC(__efi_rt_asm_wrapper) -- 2.25.0.265.gbab2e86ba0-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel 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=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 C24CDC34031 for ; Wed, 19 Feb 2020 00:09:38 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 1CDA622B48 for ; Wed, 19 Feb 2020 00:09:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="qufzpGjE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1CDA622B48 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17833-kernel-hardening=archiver.kernel.org@lists.openwall.com Received: (qmail 32409 invoked by uid 550); 19 Feb 2020 00:09:03 -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: Received: (qmail 32316 invoked from network); 19 Feb 2020 00:09:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=qufzpGjEppDMWPImhTuGEdGT5fSrkUOCFRhcyjZobkamDvVW8lKE7S9n8IfeI9kMjN GjSsbQERqiJCrQWg5+yur9ZmpwI3842rBfYePp5EboZsGV0A9NX4KJSaHBYX9WS8TV/B YxOPfKJb3HR14olUqNzIghumWLSF9JfupKrwhtKGLhHcH+iy/cZLakuxTBBKr3BSQC+Q l/d2gtUBVVI2+sDEnrXi83zlWZ5bO/OYVixaPN92nFcUWQ3ZPH+WoaCJq/ch+3VstHjI DDMR+HT+E10IhOJZsyS+YJ4gi2CPv7gIBX5icVylNk3GYCOKGpIchxJrvY+jCKqp3YLe pYjg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=QniVckAJWtqLmmFgAWqtQvDUqGmhiEDDkK5Atd0uI+w=; b=c93dUL279+s4dhZOOvQvqXyIaTz19/LdehOOPs3pqj3KMEVu5xT46dNOUZquX6d5Xv eomYoiWdpZSsS5yiPbiFc1RFWDP3bec9yzviXHWobuk5n2yhsa41CSVEVkwzS83bMBW2 c89GOPqRNDZsdAw9de9xbbirjexYWohmX0rxQNMrxVLLKdcFRTCI5MpoOncMO/fj55xk 0NUtcjJ7bp/QCd5SCCuTvanBhnIgrWmVmqDl2wYRhANXLze9/2SxbSSrL+Q3zHSAzmm3 9F8K42aw8iyK/k9rjD9HSroNj2x+Hqbdz4RIton3dGh71UVXe5VvQWcUDOpamWGhD9SJ pYBQ== X-Gm-Message-State: APjAAAU4zO8N6Lrn0WPvvhl5IJGnn7tKTcHfMP+8DTWeK+pJHjSYiqlw nrF/vIzuk0N/aOs1WvzPRfjoqxAWi8/RTk0jF4I= X-Google-Smtp-Source: APXvYqwciBBhLealMEWoo9KoEMacGgV/WZH2VTZ4SCan5a+9yYr+272BEeKH1BEVWPC4FCthWzaq/J27w407jXSF4NM= X-Received: by 2002:a63:bc02:: with SMTP id q2mr24517139pge.174.1582070930907; Tue, 18 Feb 2020 16:08:50 -0800 (PST) Date: Tue, 18 Feb 2020 16:08:12 -0800 In-Reply-To: <20200219000817.195049-1-samitolvanen@google.com> Message-Id: <20200219000817.195049-8-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20200219000817.195049-1-samitolvanen@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v8 07/12] arm64: efi: restore x18 if it was corrupted From: Sami Tolvanen To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel , Mark Rutland , james.morse@arm.com Cc: Dave Martin , Kees Cook , Laura Abbott , Marc Zyngier , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" If we detect a corrupted x18, restore the register before jumping back to potentially SCS instrumented code. This is safe, because the wrapper is called with preemption disabled and a separate shadow stack is used for interrupt handling. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Acked-by: Will Deacon --- arch/arm64/kernel/efi-rt-wrapper.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/efi-rt-wrapper.S b/arch/arm64/kernel/efi-rt-wrapper.S index 3fc71106cb2b..6ca6c0dc11a1 100644 --- a/arch/arm64/kernel/efi-rt-wrapper.S +++ b/arch/arm64/kernel/efi-rt-wrapper.S @@ -34,5 +34,14 @@ ENTRY(__efi_rt_asm_wrapper) ldp x29, x30, [sp], #32 b.ne 0f ret -0: b efi_handle_corrupted_x18 // tail call +0: + /* + * With CONFIG_SHADOW_CALL_STACK, the kernel uses x18 to store a + * shadow stack pointer, which we need to restore before returning to + * potentially instrumented code. This is safe because the wrapper is + * called with preemption disabled and a separate shadow stack is used + * for interrupts. + */ + mov x18, x2 + b efi_handle_corrupted_x18 // tail call ENDPROC(__efi_rt_asm_wrapper) -- 2.25.0.265.gbab2e86ba0-goog