From patchwork Fri Mar 4 23:51:14 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Geoff Levand X-Patchwork-Id: 8508341 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 3A1579F314 for ; Fri, 4 Mar 2016 23:54:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 662FA2026C for ; Fri, 4 Mar 2016 23:54:49 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8202520218 for ; Fri, 4 Mar 2016 23:54:48 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1abzWn-0000AZ-Pq; Fri, 04 Mar 2016 23:53:01 +0000 Received: from merlin.infradead.org ([2001:4978:20e::2]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1abzV8-0007HA-PD; Fri, 04 Mar 2016 23:51:18 +0000 Received: from geoff by merlin.infradead.org with local (Exim 4.85 #2 (Red Hat Linux)) id 1abzV4-0004Oi-Av; Fri, 04 Mar 2016 23:51:14 +0000 Message-Id: <12a9fd6a3e684827e9633c129940309bea428fb4.1457135058.git.geoff@infradead.org> In-Reply-To: References: From: Geoff Levand Patch-Date: Fri, 15 Jan 2016 19:18:37 +0000 Subject: [PATCH v14 04/20] arm64: Add new hcall HVC_CALL_FUNC To: Catalin Marinas , Will Deacon Date: Fri, 04 Mar 2016 23:51:14 +0000 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , marc.zyngier@arm.com, kexec@lists.infradead.org, AKASHI Takahiro , James Morse , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add the new hcall HVC_CALL_FUNC that allows execution of a function at EL2. During CPU reset the CPU must be brought to the exception level it had on entry to the kernel. The HVC_CALL_FUNC hcall will provide the mechanism needed for this exception level switch. To allow the HVC_CALL_FUNC exception vector to work without a stack, which is needed to support an hcall at CPU reset, this implementation uses register x18 to store the link register across the caller provided function. This dictates that the caller provided function must preserve the contents of register x18. Signed-off-by: Geoff Levand [Renumbered labels in el1_sync()] Signed-off-by: James Morse --- arch/arm64/include/asm/virt.h | 13 +++++++++++++ arch/arm64/kernel/hyp-stub.S | 19 +++++++++++++++---- 2 files changed, 28 insertions(+), 4 deletions(-) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index eb10368..3070096 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -45,6 +45,19 @@ #define HVC_SET_VECTORS 2 +/* + * HVC_CALL_FUNC - Execute a function at EL2. + * + * @x0: Physical address of the function to be executed. + * @x1: Passed as the first argument to the function. + * @x2: Passed as the second argument to the function. + * @x3: Passed as the third argument to the function. + * + * The called function must preserve the contents of register x18. + */ + +#define HVC_CALL_FUNC 3 + #define BOOT_CPU_MODE_EL1 (0xe11) #define BOOT_CPU_MODE_EL2 (0xe12) diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index 017ab519..cfacfe5 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -59,18 +59,29 @@ el1_sync: and x18, x18, #ESR_ELx_ISS_MASK cmp x17, #ESR_ELx_EC_HVC64 - b.ne 2f // Not an HVC trap + b.ne 9f // Not an HVC trap cmp x18, #HVC_GET_VECTORS b.ne 1f mrs x0, vbar_el2 - b 2f + b 9f 1: cmp x18, #HVC_SET_VECTORS b.ne 2f msr vbar_el2, x0 - -2: eret + b 9f + +2: cmp x18, #HVC_CALL_FUNC + b.ne 9f + mov x18, lr + mov lr, x0 + mov x0, x1 + mov x1, x2 + mov x2, x3 + blr lr + mov lr, x18 + +9: eret ENDPROC(el1_sync) .macro invalid_vector label