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 X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22037C2BB1D for ; Tue, 17 Mar 2020 17:50:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DF4A720714 for ; Tue, 17 Mar 2020 17:50:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584467437; bh=55h+LTkNeZs1axqP9eB5QU4yvfN+pxepOZzoN82h7Nw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=yN3LuWiP6a+rtEwZYTQ4PbdWurdQUaL58UTSQmSLO6yrbd2JIrGlHlS4QFK5yT1ad jNDurMsyFECfawJz3W6Y+80JFyQaOjxWY1PtxxN8M7k+dQcns9tyHz1LuNAsgiz4qP ZDIDJ92SlW2yTLNHSvEV6Hun053vvP9uDhHvvw2c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726647AbgCQRug convert rfc822-to-8bit (ORCPT ); Tue, 17 Mar 2020 13:50:36 -0400 Received: from mail-oi1-f196.google.com ([209.85.167.196]:45762 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726616AbgCQRug (ORCPT ); Tue, 17 Mar 2020 13:50:36 -0400 Received: by mail-oi1-f196.google.com with SMTP id 9so4657121oiq.12; Tue, 17 Mar 2020 10:50:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=YBf9/qey5iqEbmm9p/6OTY8XBEI4m1MbGytjCsa8g54=; b=GWeGTkOkaLk4mPV/FBK80s2mOZSxS7t9w11EdDAk4q3DRPqHmmL4Zkdsbq7XA5DZoq RqE45qMRVV6lDdR2jxl9inZMo3fkRk4lbDlR04zpg0fUfaQ+mZLLgKbAuQpEsnYH4R5r LuqkY4zMhv7kWxMVTUi4vvH71usBy0ghZ9bCGOvWfUR4H0hKlQu4e/7xOL+d8KeGTEHF AVQIORtkECAt+hFnCp3m3yp0ahSfuNdp4XqbbaNBYHrlc3166yQmfasjUBSXVSzSfGVc +s1m08/HQti/tD7XlhbPRx+kDAcep9knfBJBaPkHMhGssyD6KFLEew6c+WGNumNo+BFO ZKbw== X-Gm-Message-State: ANhLgQ3MB6gGNzwww82bBX6LRAIJzyem7Pmr7LOCdcW6rrjMNYqPYoej 2HDxbCIyU699PPCHyjrupUUz8vPsLq9womvsRvk= X-Google-Smtp-Source: ADFU+vs2cxM4lGwiSbL1iii+WsYaWyj8rtiB51rufEEEyznyD7jc5/W/K7D+qefrbuUeEO6XE3EAYugehiJZf02ngNc= X-Received: by 2002:aca:ef08:: with SMTP id n8mr11049oih.115.1584467434960; Tue, 17 Mar 2020 10:50:34 -0700 (PDT) MIME-Version: 1.0 References: <20200317165409.469013-1-colin.king@canonical.com> In-Reply-To: <20200317165409.469013-1-colin.king@canonical.com> From: "Rafael J. Wysocki" Date: Tue, 17 Mar 2020 18:50:23 +0100 Message-ID: Subject: Re: [PATCH][V2] ACPI: sysfs: copy ACPI data using io memory copying To: Colin King Cc: "Rafael J . Wysocki" , Len Brown , Alexander Viro , Andrew Morton , ACPI Devel Maling List , Linux Kernel Mailing List , kernel-janitors@vger.kernel.org, linux-fsdevel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Tue, Mar 17, 2020 at 5:54 PM Colin King wrote: > > From: Colin Ian King > > Reading ACPI data on ARM64 at a non-aligned offset from > /sys/firmware/acpi/tables/data/BERT will cause a splat because > the data is I/O memory mapped and being read with just a memcpy. > Fix this by introducing an I/O variant of memory_read_from_buffer > and using I/O memory mapped copies instead. > > Fixes the following splat: > > [ 439.789355] Unable to handle kernel paging request at virtual address ffff800041ac0007 > [ 439.797275] Mem abort info: > [ 439.800078] ESR = 0x96000021 > [ 439.803131] EC = 0x25: DABT (current EL), IL = 32 bits > [ 439.808437] SET = 0, FnV = 0 > [ 439.811486] EA = 0, S1PTW = 0 > [ 439.814621] Data abort info: > [ 439.817489] ISV = 0, ISS = 0x00000021 > [ 439.821319] CM = 0, WnR = 0 > [ 439.824282] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000817fc000 > [ 439.830979] [ffff800041ac0007] pgd=000000bffcfff003, pud=0000009f27cee003, pmd=000000bf4b993003, pte=0068000080280703 > [ 439.841584] Internal error: Oops: 96000021 [#1] SMP > [ 439.846449] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_ssif input_leds joydev ipmi_devintf ipmi_msghandler thunderx2_pmu sch_fq_codel ip_tables x_tables autofs4 btrfs zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c raid1 raid0 multipath linear i2c_smbus ast i2c_algo_bit crct10dif_ce drm_vram_helper uas ttm ghash_ce drm_kms_helper sha2_ce syscopyarea sha256_arm64 qede sysfillrect mpt3sas sha1_ce sysimgblt fb_sys_fops raid_class qed drm scsi_transport_sas usb_storage ahci crc8 gpio_xlp i2c_xlp9xx hid_generic usbhid hid aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher > [ 439.908474] CPU: 2 PID: 3926 Comm: a.out Not tainted 5.4.0-14-generic #17-Ubuntu > [ 439.915855] Hardware name: To be filled by O.E.M. Saber/Saber, BIOS 0ACKL027 07/01/2019 > [ 439.923844] pstate: 80400009 (Nzcv daif +PAN -UAO) > [ 439.928625] pc : __memcpy+0x90/0x180 > [ 439.932192] lr : memory_read_from_buffer+0x64/0x88 > [ 439.936968] sp : ffff8000350dbc70 > [ 439.940270] x29: ffff8000350dbc70 x28: ffff009e9c444b00 > [ 439.945568] x27: 0000000000000000 x26: 0000000000000000 > [ 439.950866] x25: 0000000056000000 x24: ffff800041ac0000 > [ 439.956164] x23: ffff009ea163f980 x22: 0000000000000007 > [ 439.961462] x21: ffff8000350dbce8 x20: 000000000000000e > [ 439.966760] x19: 0000000000000007 x18: ffff8000112f64a8 > [ 439.972058] x17: 0000000000000000 x16: 0000000000000000 > [ 439.977355] x15: 0000000080280000 x14: ffff800041aed000 > [ 439.982653] x13: ffff009ee9fa2840 x12: ffff800041ad1000 > [ 439.987951] x11: ffff8000115e1360 x10: ffff8000115e1360 > [ 439.993248] x9 : 0000000000010000 x8 : ffff800011ad2658 > [ 439.998546] x7 : ffff800041ac0000 x6 : ffff009ea163f980 > [ 440.003844] x5 : 0140000000000000 x4 : 0000000000010000 > [ 440.009141] x3 : ffff800041ac0000 x2 : 0000000000000007 > [ 440.014439] x1 : ffff800041ac0007 x0 : ffff009ea163f980 > [ 440.019737] Call trace: > [ 440.022173] __memcpy+0x90/0x180 > [ 440.025392] acpi_data_show+0x54/0x80 > [ 440.029044] sysfs_kf_bin_read+0x6c/0xa8 > [ 440.032954] kernfs_file_direct_read+0x90/0x2d0 > [ 440.037470] kernfs_fop_read+0x68/0x78 > [ 440.041210] __vfs_read+0x48/0x90 > [ 440.044511] vfs_read+0xd0/0x1a0 > [ 440.047726] ksys_read+0x78/0x100 > [ 440.051028] __arm64_sys_read+0x24/0x30 > [ 440.054852] el0_svc_common.constprop.0+0xdc/0x1d8 > [ 440.059629] el0_svc_handler+0x34/0xa0 > [ 440.063366] el0_svc+0x10/0x14 > [ 440.066411] Code: 36180062 f8408423 f80084c3 36100062 (b8404423) > [ 440.072492] ---[ end trace 45fb374e8d2d800e ]--- > > A simple reproducer is as follows: > > int main(void) > { > int fd; > char buffer[7]; > ssize_t n; > > fd = open("/sys/firmware/acpi/tables/data/BERT", O_RDONLY); > if (fd < 0) { > perror("open failed"); > return -1; > } > do { > n = read(fd, buffer, sizeof(buffer)); > } while (n > 0); > > return 0; > } > > Signed-off-by: Colin Ian King > --- > V2: Add missing #include without which we get > a build failure when building with allnoconfig > --- > drivers/acpi/sysfs.c | 2 +- > fs/libfs.c | 34 ++++++++++++++++++++++++++++++++++ > include/linux/string.h | 2 ++ > 3 files changed, 37 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c > index c60d2c6..fb9e216 100644 > --- a/drivers/acpi/sysfs.c > +++ b/drivers/acpi/sysfs.c > @@ -446,7 +446,7 @@ static ssize_t acpi_data_show(struct file *filp, struct kobject *kobj, > base = acpi_os_map_memory(data_attr->addr, data_attr->attr.size); > if (!base) > return -ENOMEM; > - rc = memory_read_from_buffer(buf, count, &offset, base, > + rc = memory_read_from_io_buffer(buf, count, &offset, base, > data_attr->attr.size); > acpi_os_unmap_memory(base, data_attr->attr.size); > > diff --git a/fs/libfs.c b/fs/libfs.c > index c686bd9..1a49da1 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > > #include > > @@ -800,6 +801,39 @@ ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, > } > EXPORT_SYMBOL(memory_read_from_buffer); > > +/** > + * memory_read_from_io_buffer - copy data from a io memory mapped buffer > + * @to: the kernel space buffer to read to > + * @count: the maximum number of bytes to read > + * @ppos: the current position in the buffer > + * @from: the buffer to read from > + * @available: the size of the buffer > + * > + * The memory_read_from_buffer() function reads up to @count bytes from the > + * io memory mappy buffer @from at offset @ppos into the kernel space address > + * starting at @to. > + * > + * On success, the number of bytes read is returned and the offset @ppos is > + * advanced by this number, or negative value is returned on error. > + **/ > +ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos, > + const void *from, size_t available) > +{ > + loff_t pos = *ppos; > + > + if (pos < 0) > + return -EINVAL; > + if (pos >= available) > + return 0; > + if (count > available - pos) > + count = available - pos; > + memcpy_fromio(to, from + pos, count); > + *ppos = pos + count; > + > + return count; > +} > +EXPORT_SYMBOL(memory_read_from_io_buffer); > + > /* > * Transaction based IO. > * The file expects a single write which triggers the transaction, and then > diff --git a/include/linux/string.h b/include/linux/string.h > index 6dfbb2e..0c6ec2a 100644 > --- a/include/linux/string.h > +++ b/include/linux/string.h > @@ -216,6 +216,8 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); > > extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, > const void *from, size_t available); > +extern ssize_t memory_read_from_io_buffer(void *to, size_t count, loff_t *ppos, > + const void *from, size_t available); > > int ptr_to_hashval(const void *ptr, unsigned long *hashval_out); > > -- I've replaced the v1 with this one, thanks!