From patchwork Mon Aug 12 17:30:13 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 11090301 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4BCB914DB for ; Mon, 12 Aug 2019 17:32:05 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3D8B0283A5 for ; Mon, 12 Aug 2019 17:32:05 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 31DFC284DB; Mon, 12 Aug 2019 17:32:05 +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=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id CEAF5283A5 for ; Mon, 12 Aug 2019 17:32:04 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxE9h-0006vt-8I; Mon, 12 Aug 2019 17:30:49 +0000 Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hxE9f-0006tg-RC for xen-devel@lists.xenproject.org; Mon, 12 Aug 2019 17:30:47 +0000 X-Inumbo-ID: ebaaf76d-bd26-11e9-8980-bc764e045a96 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-rack-dfw2.inumbo.com (Halon) with ESMTP id ebaaf76d-bd26-11e9-8980-bc764e045a96; Mon, 12 Aug 2019 17:30:47 +0000 (UTC) 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 223711715; Mon, 12 Aug 2019 10:30:47 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 70C5A3F706; Mon, 12 Aug 2019 10:30:46 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 12 Aug 2019 18:30:13 +0100 Message-Id: <20190812173019.11956-23-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190812173019.11956-1-julien.grall@arm.com> References: <20190812173019.11956-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v3 22/28] xen/arm32: head: Rework and document launch() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" X-Virus-Scanned: ClamAV using ClamSMTP Boot CPU and secondary CPUs will use different entry point to C code. At the moment, the decision on which entry to use is taken within launch(). In order to avoid using conditional instruction and make the call clearer, launch() is reworked to take in parameters the entry point and its arguments. Lastly, document the behavior and the main registers usage within the function. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- Changes in v3: - Add Stefano's reviewed-by Changes in v2: - Patch added --- xen/arch/arm/arm32/head.S | 34 ++++++++++++++++++++++++---------- 1 file changed, 24 insertions(+), 10 deletions(-) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index ee5c3d2af8..3c18037575 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -174,6 +174,11 @@ primary_switched: /* Use a virtual address to access the UART. */ mov_w r11, EARLY_UART_VIRTUAL_ADDRESS #endif + PRINT("- Ready -\r\n") + /* Setup the arguments for start_xen and jump to C world */ + mov r0, r10 /* r0 := Physical offset */ + mov r1, r8 /* r1 := paddr(FDT) */ + ldr r2, =start_xen b launch ENDPROC(start) @@ -238,6 +243,9 @@ secondary_switched: /* Use a virtual address to access the UART. */ mov_w r11, EARLY_UART_VIRTUAL_ADDRESS #endif + PRINT("- Ready -\r\n") + /* Jump to C world */ + ldr r2, =start_secondary b launch ENDPROC(init_secondary) @@ -583,19 +591,25 @@ setup_fixmap: mov pc, lr ENDPROC(setup_fixmap) +/* + * Setup the initial stack and jump to the C world + * + * Inputs: + * r0 : Argument 0 of the C function to call + * r1 : Argument 1 of the C function to call + * r2 : C entry point + * + * Clobbers r3 + */ launch: - PRINT("- Ready -\r\n") - - ldr r0, =init_data - add r0, #INITINFO_stack /* Find the boot-time stack */ - ldr sp, [r0] + ldr r3, =init_data + add r3, #INITINFO_stack /* Find the boot-time stack */ + ldr sp, [r3] add sp, #STACK_SIZE /* (which grows down from the top). */ sub sp, #CPUINFO_sizeof /* Make room for CPU save record */ - teq r12, #0 - moveq r0, r10 /* Marshal args: - phys_offset */ - moveq r1, r8 /* - DTB address */ - beq start_xen /* and disappear into the land of C */ - b start_secondary /* (to the appropriate entry point) */ + + /* Jump to C world */ + bx r2 ENDPROC(launch) /* Fail-stop */