From patchwork Mon Aug 12 10:15:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13760389 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 70345C52D7C for ; Mon, 12 Aug 2024 10:20:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tpk8l83fE6femNoSqLoRqeI92qaT/Hm8Uhy7IFNg0j0=; b=DtgNniIkpKIJIzy48ZN7ihOnTx swuP8n9ClhEvUUxKcsVY70LwbnhCjWrABBnreLda4p9xG2UdhJHlC7gjmkI18t0qm9yampOJ7V418 nFuFFqWRpIfC8TbxJaYOTfkTBnXCjhWpPzxmtnHumufysbT6Q9iYOU/IrDEkJkZJDXDc4S/YtNE7M Y6R+j6EjRvM8mqO8qfOOfejnSMbrEzXfQTPkWEus2uFsonLlkA22kwBU39NpAKmXZMy26lm/y+SkE JxfXEtSCIBLIgrNuBR6xobS3omOekgQvGiOyLjw0JOkdyivkxLtPAUKXPDQmtVjtMp6VO0ly1UdkM MSWHct4A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdSAI-0000000HaTz-3c7g; Mon, 12 Aug 2024 10:20:38 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sdS5y-0000000HZhv-1xYV for linux-arm-kernel@lists.infradead.org; Mon, 12 Aug 2024 10:16:11 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 598D2106F; Mon, 12 Aug 2024 03:16:35 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9D5053F6A8; Mon, 12 Aug 2024 03:16:08 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: akos.denke@arm.com, andre.przywara@arm.com, luca.fancellu@arm.com, mark.rutland@arm.com, maz@kernel.org Subject: [BOOT-WRAPPER v2 06/10] aarch32: Always enter kernel via exception return Date: Mon, 12 Aug 2024 11:15:51 +0100 Message-Id: <20240812101555.3558589-7-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240812101555.3558589-1-mark.rutland@arm.com> References: <20240812101555.3558589-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240812_031610_578116_BFD77CA1 X-CRM114-Status: GOOD ( 12.28 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org When the boot-wrapper is entered at Seculre PL1 it will enter the kernel via an exception return, ERET, and when entered at Hyp it will branch to the kernel directly. This is an artifact of the way the boot-wrapper was originally written in assembly, and it would be preferable to always enter the kernel via an exception return so that PSTATE is always initialized to a known-good value. Rework jump_kernel() to always enter the kernel via ERET, matching the stype of the AArch64 version of jump_kernel() Signed-off-by: Mark Rutland Acked-by: Marc Zyngier Cc: Akos Denke Cc: Andre Przywara Cc: Luca Fancellu --- arch/aarch32/boot.S | 48 +++++++++++++++++++++++---------------------- 1 file changed, 25 insertions(+), 23 deletions(-) diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S index f21f89a..78d19a0 100644 --- a/arch/aarch32/boot.S +++ b/arch/aarch32/boot.S @@ -76,10 +76,6 @@ reset_at_hyp: bl setup_stack - mov r0, #1 - ldr r1, =flag_no_el3 - str r0, [r1] - bl cpu_init_bootwrapper bl cpu_init_arch @@ -96,9 +92,10 @@ err_invalid_id: * r1-r3, sp[0]: kernel arguments */ ASM_FUNC(jump_kernel) - sub sp, #4 @ Ignore fourth argument - push {r0 - r3} - mov r5, sp + mov r4, r0 + mov r5, r1 + mov r6, r2 + mov r7, r3 ldr r0, =HSCTLR_KERNEL mcr p15, 4, r0, c1, c0, 0 @ HSCTLR @@ -111,23 +108,28 @@ ASM_FUNC(jump_kernel) bl find_logical_id bl setup_stack - ldr lr, [r5], #4 - ldm r5, {r0 - r2} - - ldr r4, =flag_no_el3 - ldr r4, [r4] - cmp r4, #1 - bxeq lr @ no EL3 + mov r0, r5 + mov r1, r6 + mov r2, r7 + ldr r3, =SPSR_KERNEL - ldr r4, =SPSR_KERNEL /* Return in thumb2 mode when bit 0 of address is 1 */ - tst lr, #1 - orrne r4, #PSR_T + tst r4, #1 + orrne r3, #PSR_T + + mrs r5, cpsr + and r5, #PSR_MODE_MASK + cmp r5, #PSR_MON + beq eret_at_mon + cmp r5, #PSR_HYP + beq eret_at_hyp + b . - msr spsr_cxf, r4 +eret_at_mon: + mov lr, r4 + msr spsr_cxf, r3 movs pc, lr - - .section .data - .align 2 -flag_no_el3: - .long 0 +eret_at_hyp: + msr elr_hyp, r4 + msr spsr_cxf, r3 + eret