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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 91B06CDB474 for ; Mon, 23 Oct 2023 12:49:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230145AbjJWMtx (ORCPT ); Mon, 23 Oct 2023 08:49:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39578 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229613AbjJWMtv (ORCPT ); Mon, 23 Oct 2023 08:49:51 -0400 Received: from mgamail.intel.com (mgamail.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5141CC for ; Mon, 23 Oct 2023 05:49:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1698065389; x=1729601389; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=/06vn1FESH5ehRnRfIJp0ycCvwF0E4N5zV1BYkmcMd4=; b=CJJVLVyjaTpj4HilA1vY97URbnmZ4YaCpmzNmvqBHGPtzwFbJ1DQGa9v jX9bBWiZmUhsM90fNB+SgcutaUeNU59GNtR/0OMDSCTPP1MlY/+8xxB8W 9/1O3tgjK7lnr+peywHmLoAn5Kcw+QyJekhc4qMKwNrusHcwlGCzdB3t7 D6rvcTlqI/TN2aRNtUs8GgVvA5ZWrfMIZuxpv0eEo761LlahrGNVfJyc+ N14GwjeXOzXsWsgiZcPRDhvwz/D+OT6r4SCMb5wIy7QSAGHBX0BJhJQMa byeCrrqFohpVz42TEy/x/xfPwj4bTKuesIkyZBjHa0OyVCU3dEfkqhqrR w==; X-IronPort-AV: E=McAfee;i="6600,9927,10872"; a="385715728" X-IronPort-AV: E=Sophos;i="6.03,244,1694761200"; d="scan'208";a="385715728" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2023 05:49:49 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10872"; a="761731237" X-IronPort-AV: E=Sophos;i="6.03,244,1694761200"; d="scan'208";a="761731237" Received: from evlad-mobl.ger.corp.intel.com (HELO localhost) ([10.252.47.180]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2023 05:49:44 -0700 From: Jani Nikula To: Arnd Bergmann , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , Badal Nilawar , Ashutosh Dixit Cc: Arnd Bergmann , Matt Roper , Vinay Belgaumkar , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drm/i915/mtl: avoid stringop-overflow warning In-Reply-To: <20231016201012.1022812-1-arnd@kernel.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo References: <20231016201012.1022812-1-arnd@kernel.org> Date: Mon, 23 Oct 2023 15:49:41 +0300 Message-ID: <87edhlbj16.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 16 Oct 2023, Arnd Bergmann wrote: > From: Arnd Bergmann > > The newly added memset() causes a warning for some reason I could not figure out: > > In file included from arch/x86/include/asm/string.h:3, > from drivers/gpu/drm/i915/gt/intel_rc6.c:6: > In function 'rc6_res_reg_init', > inlined from 'intel_rc6_init' at drivers/gpu/drm/i915/gt/intel_rc6.c:610:2: > arch/x86/include/asm/string_32.h:195:29: error: '__builtin_memset' writing 16 bytes into a region of size 0 overflows the destination [-Werror=stringop-overflow=] > 195 | #define memset(s, c, count) __builtin_memset(s, c, count) > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/i915/gt/intel_rc6.c:584:9: note: in expansion of macro 'memset' > 584 | memset(rc6->res_reg, INVALID_MMIO_REG.reg, sizeof(rc6->res_reg)); > | ^~~~~~ > In function 'intel_rc6_init': > > Change it to an normal initializer and an added memcpy() that does not have > this problem. > > Fixes: 4bb9ca7ee0745 ("drm/i915/mtl: C6 residency and C state type for MTL SAMedia") > Signed-off-by: Arnd Bergmann > --- > drivers/gpu/drm/i915/gt/intel_rc6.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c > index 8b67abd720be8..7090e4be29cb6 100644 > --- a/drivers/gpu/drm/i915/gt/intel_rc6.c > +++ b/drivers/gpu/drm/i915/gt/intel_rc6.c > @@ -581,19 +581,23 @@ static void __intel_rc6_disable(struct intel_rc6 *rc6) > > static void rc6_res_reg_init(struct intel_rc6 *rc6) > { > - memset(rc6->res_reg, INVALID_MMIO_REG.reg, sizeof(rc6->res_reg)); That's just bollocks. memset() is byte granularity, while INVALID_MMIO_REG.reg is u32. If the value was anything other than 0, this would break. And you're not supposed to look at the guts of i915_reg_t to begin with, that's why it's a typedef. Basically any code that accesses the members of i915_reg_t outside of its implementation are doing it wrong. Reviewed-by: Jani Nikula > + i915_reg_t res_reg[INTEL_RC6_RES_MAX] = { > + [0 ... INTEL_RC6_RES_MAX - 1] = INVALID_MMIO_REG, > + }; > > switch (rc6_to_gt(rc6)->type) { > case GT_MEDIA: > - rc6->res_reg[INTEL_RC6_RES_RC6] = MTL_MEDIA_MC6; > + res_reg[INTEL_RC6_RES_RC6] = MTL_MEDIA_MC6; > break; > default: > - rc6->res_reg[INTEL_RC6_RES_RC6_LOCKED] = GEN6_GT_GFX_RC6_LOCKED; > - rc6->res_reg[INTEL_RC6_RES_RC6] = GEN6_GT_GFX_RC6; > - rc6->res_reg[INTEL_RC6_RES_RC6p] = GEN6_GT_GFX_RC6p; > - rc6->res_reg[INTEL_RC6_RES_RC6pp] = GEN6_GT_GFX_RC6pp; > + res_reg[INTEL_RC6_RES_RC6_LOCKED] = GEN6_GT_GFX_RC6_LOCKED; > + res_reg[INTEL_RC6_RES_RC6] = GEN6_GT_GFX_RC6; > + res_reg[INTEL_RC6_RES_RC6p] = GEN6_GT_GFX_RC6p; > + res_reg[INTEL_RC6_RES_RC6pp] = GEN6_GT_GFX_RC6pp; > break; > } > + > + memcpy(rc6->res_reg, res_reg, sizeof(res_reg)); > } > > void intel_rc6_init(struct intel_rc6 *rc6) -- Jani Nikula, Intel