From patchwork Thu May 18 15:07:06 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Gerlach X-Patchwork-Id: 9734639 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 D7216600CC for ; Thu, 18 May 2017 15:09:19 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C69BA2871E for ; Thu, 18 May 2017 15:09:19 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BB22F2884E; Thu, 18 May 2017 15:09:19 +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=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5C1DD28833 for ; Thu, 18 May 2017 15:09:18 +0000 (UTC) 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:MIME-Version:Message-ID:Date:Subject:To :From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=/Qoq7kFHl9aPU6uYybwdFS7zzuE24/Bw39ADTo6GZx0=; b=CgeXNYCPTR4ZgQ Zy58K5owZu/8dBqpUOTcW78gzm6Il8MXPXPnEMMiOPBGrSXfHqpcZEXrmwPfupoclF82K7H44xfy6 qfIQkZt4FP1kUP2R+Ehl9ghPiYLwFVgBWPCwa78QSab0yjKdCuW1lgMrpptbBXrtBL4m+csoP7AAX nff4BKJ1XTpMQy5rayggcg2GbeAcqH+om5mHXEkD7mfYlIzk5nBnAARUj7NkwYt182JQte5ytqFY/ ybdEzTWEtVGxhombrk2lyiCUjjfgQdhMeF9GBSZ+HUQjonHIeI4uihfPqxSBXk0ZyZHB3kQAc9fPF TJlv78HPwg/lQ/9FYotQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dBN3E-0005MX-PX; Thu, 18 May 2017 15:09:16 +0000 Received: from fllnx209.ext.ti.com ([198.47.19.16]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dBN37-000591-7t for linux-arm-kernel@lists.infradead.org; Thu, 18 May 2017 15:09:13 +0000 Received: from dlelxv90.itg.ti.com ([172.17.2.17]) by fllnx209.ext.ti.com (8.15.1/8.15.1) with ESMTP id v4IF7ECT010761; Thu, 18 May 2017 10:07:14 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ti.com; s=ti-com-17Q1; t=1495120034; bh=F2+dleGvFlawmnBfm3q1xslY6nJT9lkco78oNfNC27s=; h=From:To:CC:Subject:Date; b=c/94uvf5tthpboyvWQ6akbdq79Fss3cVWE7lr8mNeYvRB1bNXo9Aq0ijiN2XSvb0d TlxQCpTzJ6AbM7eMAHlNYvYip/2Im1NpMFJuHqoz2zZRwItYuqQPNMzINYkWxWzW0U w1wCobsV2R6RHyfgoaxVORU7AtUoci/+0gCSskLU= Received: from DFLE73.ent.ti.com (dfle73.ent.ti.com [128.247.5.110]) by dlelxv90.itg.ti.com (8.14.3/8.13.8) with ESMTP id v4IF79WY016725; Thu, 18 May 2017 10:07:09 -0500 Received: from dflp33.itg.ti.com (10.64.6.16) by DFLE73.ent.ti.com (128.247.5.110) with Microsoft SMTP Server id 14.3.294.0; Thu, 18 May 2017 10:07:08 -0500 Received: from legion.dal.design.ti.com (legion.dal.design.ti.com [128.247.22.53]) by dflp33.itg.ti.com (8.14.3/8.13.8) with ESMTP id v4IF78x3015276; Thu, 18 May 2017 10:07:08 -0500 Received: from localhost (uda0274052.dhcp.ti.com [128.247.59.203]) by legion.dal.design.ti.com (8.11.7p1+Sun/8.11.7) with ESMTP id v4IF78319828; Thu, 18 May 2017 10:07:08 -0500 (CDT) From: Dave Gerlach To: Greg Kroah-Hartman , Tony Lindgren , Russell King Subject: [PATCH v3] misc: sram-exec: Use aligned fncpy instead of memcpy Date: Thu, 18 May 2017 10:07:06 -0500 Message-ID: <20170518150706.9235-1-d-gerlach@ti.com> X-Mailer: git-send-email 2.13.0 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170518_080909_649929_55A8A54F X-CRM114-Status: GOOD ( 14.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , Dave Gerlach , linux-kernel@vger.kernel.org, Alexandre Belloni , linux-omap@vger.kernel.org, Shawn Guo , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Currently the sram-exec functionality, which allows allocation of executable memory and provides an API to move code to it, is only selected in configs for the ARM architecture. Based on commit 5756e9dd0de6 ("ARM: 6640/1: Thumb-2: Symbol manipulation macros for function body copying") simply copying a C function pointer address using memcpy without consideration of alignment and Thumb is unsafe on ARM platforms. The aforementioned patch introduces the fncpy macro which is a safe way to copy executable code on ARM platforms, so let's make use of that here rather than the unsafe plain memcpy that was previously used by sram_exec_copy. Now sram_exec_copy will move the code to "dst" and return an address that is guaranteed to be safely callable. In the future, architectures hoping to make use of the sram-exec functionality must define an fncpy macro just as ARM has done to guarantee or check for safe copying to executable memory before allowing the arch to select CONFIG_SRAM_EXEC. Acked-by: Tony Lindgren Acked-by: Russell King Reviewed-by: Alexandre Belloni Signed-off-by: Dave Gerlach --- v3 changes: Rebase on v4.12-rc1 and added Acks from v2. v2: https://www.spinics.net/lists/kernel/msg2485366.html v1: http://www.spinics.net/lists/linux-omap/msg136517.html drivers/misc/sram-exec.c | 27 ++++++++++++++++++++------- include/linux/sram.h | 8 ++++---- 2 files changed, 24 insertions(+), 11 deletions(-) diff --git a/drivers/misc/sram-exec.c b/drivers/misc/sram-exec.c index 3d528a13b8fc..426ad912b441 100644 --- a/drivers/misc/sram-exec.c +++ b/drivers/misc/sram-exec.c @@ -19,6 +19,7 @@ #include #include +#include #include #include "sram.h" @@ -58,20 +59,32 @@ int sram_add_protect_exec(struct sram_partition *part) * @src: Source address for the data to copy * @size: Size of copy to perform, which starting from dst, must reside in pool * + * Return: Address for copied data that can safely be called through function + * pointer, or NULL if problem. + * * This helper function allows sram driver to act as central control location * of 'protect-exec' pools which are normal sram pools but are always set * read-only and executable except when copying data to them, at which point * they are set to read-write non-executable, to make sure no memory is * writeable and executable at the same time. This region must be page-aligned * and is checked during probe, otherwise page attribute manipulation would - * not be possible. + * not be possible. Care must be taken to only call the returned address as + * dst address is not guaranteed to be safely callable. + * + * NOTE: This function uses the fncpy macro to move code to the executable + * region. Some architectures have strict requirements for relocating + * executable code, so fncpy is a macro that must be defined by any arch + * making use of this functionality that guarantees a safe copy of exec + * data and returns a safe address that can be called as a C function + * pointer. */ -int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, - size_t size) +void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, + size_t size) { struct sram_partition *part = NULL, *p; unsigned long base; int pages; + void *dst_cpy; mutex_lock(&exec_pool_list_mutex); list_for_each_entry(p, &exec_pool_list, list) { @@ -81,10 +94,10 @@ int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, mutex_unlock(&exec_pool_list_mutex); if (!part) - return -EINVAL; + return NULL; if (!addr_in_gen_pool(pool, (unsigned long)dst, size)) - return -EINVAL; + return NULL; base = (unsigned long)part->base; pages = PAGE_ALIGN(size) / PAGE_SIZE; @@ -94,13 +107,13 @@ int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, set_memory_nx((unsigned long)base, pages); set_memory_rw((unsigned long)base, pages); - memcpy(dst, src, size); + dst_cpy = fncpy(dst, src, size); set_memory_ro((unsigned long)base, pages); set_memory_x((unsigned long)base, pages); mutex_unlock(&part->lock); - return 0; + return dst_cpy; } EXPORT_SYMBOL_GPL(sram_exec_copy); diff --git a/include/linux/sram.h b/include/linux/sram.h index c97dcbe8ce25..4fb405fb0480 100644 --- a/include/linux/sram.h +++ b/include/linux/sram.h @@ -16,12 +16,12 @@ struct gen_pool; #ifdef CONFIG_SRAM_EXEC -int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, size_t size); +void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, size_t size); #else -static inline int sram_exec_copy(struct gen_pool *pool, void *dst, void *src, - size_t size) +static inline void *sram_exec_copy(struct gen_pool *pool, void *dst, void *src, + size_t size) { - return -ENODEV; + return NULL; } #endif /* CONFIG_SRAM_EXEC */ #endif /* __LINUX_SRAM_H__ */