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 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 37C20C00140 for ; Mon, 15 Aug 2022 15:52:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=R8L4CQmLLSWestwPe726rDsseJ1GGKjqR5WkSpxjHLE=; b=DuDc0g/XNXz3UV 9jEiVIWxiEIe1dvrlrKktj5W3ywryIp898/ZjB8VBvfM19mJbPoHFLlugrO0K7emwFavg0eWLxP4b t1Yd1dA1L5zP8Fto4JKlRC/VbmBwrrkJ0EHQgQZx8vFlOZRH9zhRRZRocK2KLDA0XQMrmVeCiRwRv GbJDv3dnv/PiuC8Z5EGWVMX+iUU56BOu/cLX7jmVtjSquIrw30l+jDk31KcgK3IfSeFe76yTKXtaA lfvbYUVkI78RSreFjcIoajQZBGyJOA8iL1lKK4LwOlHTcGIM3tU3v/K7Q+04bLGA/KhLuB9edADEb FaVKNEErWnF8T+MFWcUg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oNcO8-0017GJ-51; Mon, 15 Aug 2022 15:52:24 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oNcCp-000zUS-JQ for linux-riscv@lists.infradead.org; Mon, 15 Aug 2022 15:40:45 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C0DBD61119; Mon, 15 Aug 2022 15:40:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E07BBC433D6; Mon, 15 Aug 2022 15:40:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1660578041; bh=kPtbQ65lpd7sMhX39eVsqVHxLDidqIVwHkotLDx1XPM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=U5HQKBFm0fsdUMTfIxpYuqF2OYeHy4WJcZyQxa3u+ZbfdEJFbsTUBWnB/a2ybNGx6 ZoSFWJamfiQape+4kAJSHqL+J0mkYF1S75EDtKPPnmwxJuNCZLu5DVIbo5UfoOKJTi WDGz676NhzHeRxpAnbsnnemisYJ4rTC0hAalNGlpgiwSMU52S2gdR8go999TNZxyc/ zKeOrNNoQCDAE+cxzN50yGSGUHYZFH3Mng7x3JL8H9+XNlzUq/SbqGGqfD8Eq9GjSU o1pkhFBSNUQPmrZVgrtMz9yEyod3oYMubjuPSW+FyvceNF0yKE8aGYT0fkPxGtPV7+ C1ujBBaQ3o9/g== Date: Mon, 15 Aug 2022 08:40:39 -0700 From: Nathan Chancellor To: Palmer Dabbelt Cc: linux-riscv@lists.infradead.org, anup@brainfault.org, kernel test robot Subject: Re: [PATCH v2] RISC-V: Clean up the Zicbom block size probing Message-ID: References: <20220812154010.18280-1-palmer@rivosinc.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220812154010.18280-1-palmer@rivosinc.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220815_084043_773603_14340FD8 X-CRM114-Status: GOOD ( 30.24 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Hi Palmer, On Fri, Aug 12, 2022 at 08:40:10AM -0700, Palmer Dabbelt wrote: > This fixes two issues: I truncated the warning's hart ID when porting to > the 64-bit hart ID code, and the original code's warning handling could > fire on an uninitialized hart ID. > > The biggest change here is that riscv_cbom_block_size is no longer > initialized, as IMO the default isn't sane: there's nothing in the ISA > that mandates any specific cache block size, so falling back to one will > just silently produce the wrong answer on some systems. This also > changes the probing order so the cache block size is known before > enabling Zicbom support. > > Fixes: 3aefb2ee5bdd ("riscv: implement Zicbom-based CMO instructions + the t-head variant") > Fixes: 1631ba1259d6 ("riscv: Add support for non-coherent devices using zicbom extension") > Reported-by: kernel test robot > Signed-off-by: Palmer Dabbelt > > --- > > Changes since v1 : > > * Everything but the unsigned long cbom_hartid. > --- > arch/riscv/kernel/setup.c | 2 +- > arch/riscv/mm/dma-noncoherent.c | 22 ++++++++++++---------- > 2 files changed, 13 insertions(+), 11 deletions(-) > > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index 95ef6e2bf45c..2dfc463b86bb 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -296,8 +296,8 @@ void __init setup_arch(char **cmdline_p) > setup_smp(); > #endif > > - riscv_fill_hwcap(); > riscv_init_cbom_blocksize(); > + riscv_fill_hwcap(); > apply_boot_alternatives(); > } > > diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c > index cd2225304c82..3aa3572715d6 100644 > --- a/arch/riscv/mm/dma-noncoherent.c > +++ b/arch/riscv/mm/dma-noncoherent.c > @@ -12,7 +12,7 @@ > #include > #include > > -static unsigned int riscv_cbom_block_size = L1_CACHE_BYTES; > +static unsigned int riscv_cbom_block_size; > static bool noncoherent_supported; > > void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, > @@ -80,37 +80,39 @@ void riscv_init_cbom_blocksize(void) > { > struct device_node *node; > int ret; > - u32 val; > + u32 val, probed_block_size; > > + probed_block_size = 0; > for_each_of_cpu_node(node) { > - unsigned long hartid; > - int cbom_hartid; > + unsigned long hartid, cbom_hartid; > > ret = riscv_of_processor_hartid(node, &hartid); > if (ret) > continue; > > - if (hartid < 0) > - continue; > - > /* set block-size for cbom extension if available */ > ret = of_property_read_u32(node, "riscv,cbom-block-size", &val); > if (ret) > continue; > > - if (!riscv_cbom_block_size) { > - riscv_cbom_block_size = val; > + if (!probed_block_size) { > + probed_block_size = val; > cbom_hartid = hartid; > } else { > - if (riscv_cbom_block_size != val) > + if (probed_block_size != val) > pr_warn("cbom-block-size mismatched between harts %d and %lu\n", ^ %lu? > cbom_hartid, hartid); > } > } > + > + if (probed_block_size) > + riscv_cbom_block_size = probed_block_size; > } > #endif > > void riscv_noncoherent_supported(void) > { > + WARN_ON(!riscv_cbom_block_size, > + "Non-coherent DMA support enabled without a block size\n"); > noncoherent_supported = true; > } > -- > 2.34.1 For what it's worth, while this should address the uninitialized cbom_hartid at runtime (from the quick glance I gave it), it doesn't address the compile time warning. I am not sure how to make it clear to clang that the if statement will be executed during the first loop iteration because probed_block_size is initialized to zero... Additionally, it appears that WARN() is the right macro, not WARN_ON() and an '#include ' is needed. arch/riscv/mm/dma-noncoherent.c:104:6: error: variable 'cbom_hartid' is uninitialized when used here [-Werror,-Wuninitialized] cbom_hartid, hartid); ^~~~~~~~~~~ include/linux/printk.h:517:37: note: expanded from macro 'pr_warn' printk(KERN_WARNING pr_fmt(fmt), ##__VA_ARGS__) ^~~~~~~~~~~ include/linux/printk.h:464:60: note: expanded from macro 'printk' #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__) ^~~~~~~~~~~ include/linux/printk.h:436:19: note: expanded from macro 'printk_index_wrap' _p_func(_fmt, ##__VA_ARGS__); \ ^~~~~~~~~~~ arch/riscv/mm/dma-noncoherent.c:87:36: note: initialize the variable 'cbom_hartid' to silence this warning unsigned long hartid, cbom_hartid; ^ = 0 arch/riscv/mm/dma-noncoherent.c:116:10: error: too many arguments provided to function-like macro invocation "Non-coherent DMA support enabled without a block size\n"); ^ include/asm-generic/bug.h:121:9: note: macro 'WARN_ON' defined here #define WARN_ON(condition) ({ \ ^ arch/riscv/mm/dma-noncoherent.c:115:2: error: use of undeclared identifier 'WARN_ON' WARN_ON(!riscv_cbom_block_size, ^ 3 errors generated. Cheers, Nathan _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv