From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout03.his.huawei.com (canpmsgout03.his.huawei.com [113.46.200.218]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E1A56341AAF; Wed, 17 Dec 2025 09:47:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.218 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765964863; cv=none; b=tFmFC80CbxBnuwNBqsBqbl8HICeGQXr8b5j94lveOLtaHg+xWuVyd1ipreG1hg8J3fjostOyDLiCu074DInLSCkf0dLaTYPFA3wL1DPlN2YkCmxrlNgJZTqpZZIWoTAV3Po4biuzRu/2RoNVhvOKbJ/jXmBAF53svYrovBMfg+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765964863; c=relaxed/simple; bh=xdj2dOafBgFbUnGcj+EiAB/dKWHz+XPBCerKpx/HE6U=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=n8eNEhghtYwsy73xTCeP5YjYMLkjDopAgGQnqdJOKQmpWQKuc2D7yzGoyDWwfBevgA41d5kc3ayOgQItDM0FSYsMAdiZHhj80pYeTe00k/bokXqR5oE2G8gHVycMSu3rRFm1p8QegcasL/JpRc24i8eEP9apdRnCX91UdfoEkXs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=XMQIrcYP; arc=none smtp.client-ip=113.46.200.218 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="XMQIrcYP" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=ZQ9EAf6urRQxQaV20GCoVkxo1RVP74p1WDO98ViQaBw=; b=XMQIrcYPjH1uPWtTWrUwg7QGl7Sf8lgCE2r/nrbPEUlWB6YN811its5DaYSrkAZ7sq3zCT7mv ZW5eaHXhVabj8SScKzn+/qGFb7V1xC5bHvC+QMiROry7JxiwCR8hhlsZsYMcJMSrkEbqFkPgudm dRfrOaWJfPKlObw5706rBJA= Received: from mail.maildlp.com (unknown [172.19.162.254]) by canpmsgout03.his.huawei.com (SkyGuard) with ESMTPS id 4dWTRK3Q8hzpStQ; Wed, 17 Dec 2025 17:44:45 +0800 (CST) Received: from kwepemr500012.china.huawei.com (unknown [7.202.195.23]) by mail.maildlp.com (Postfix) with ESMTPS id 3D2261804F2; Wed, 17 Dec 2025 17:47:29 +0800 (CST) Received: from [100.103.109.72] (100.103.109.72) by kwepemr500012.china.huawei.com (7.202.195.23) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 17 Dec 2025 17:47:28 +0800 Message-ID: Date: Wed, 17 Dec 2025 17:47:27 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] PCI/sysfs: Prohibit unaligned access to I/O port on non-x86 To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= CC: , , LKML , , , , References: <20251216083912.758219-1-duziming2@huawei.com> <20251216083912.758219-3-duziming2@huawei.com> <43e40c50-e23b-0ebc-9f82-986b2ea55943@linux.intel.com> From: duziming In-Reply-To: <43e40c50-e23b-0ebc-9f82-986b2ea55943@linux.intel.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200001.china.huawei.com (7.221.188.67) To kwepemr500012.china.huawei.com (7.202.195.23) 在 2025/12/16 18:43, Ilpo Järvinen 写道: > On Tue, 16 Dec 2025, Ziming Du wrote: > >> From: Yongqiang Liu >> >> Unaligned access is harmful for non-x86 archs such as arm64. When we >> use pwrite or pread to access the I/O port resources with unaligned >> offset, system will crash as follows: >> >> Unable to handle kernel paging request at virtual address fffffbfffe8010c1 >> Internal error: Oops: 0000000096000061 [#1] SMP >> Modules linked in: >> CPU: 1 PID: 44230 Comm: syz.1.10955 Not tainted 6.6.0+ #1 >> Hardware name: linux,dummy-virt (DT) >> pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> pc : __raw_writew arch/arm64/include/asm/io.h:33 [inline] >> pc : _outw include/asm-generic/io.h:594 [inline] >> pc : logic_outw+0x54/0x218 lib/logic_pio.c:305 >> lr : _outw include/asm-generic/io.h:593 [inline] >> lr : logic_outw+0x40/0x218 lib/logic_pio.c:305 >> sp : ffff800083097a30 >> x29: ffff800083097a30 x28: ffffba71ba86e130 x27: 1ffff00010612f93 >> x26: ffff3bae63b3a420 x25: ffffba71bbf585d0 x24: 0000000000005ac1 >> x23: 00000000000010c1 x22: ffff3baf0deb6488 x21: 0000000000000002 >> x20: 00000000000010c1 x19: 0000000000ffbffe x18: 0000000000000000 >> x17: 0000000000000000 x16: ffffba71b9f44b48 x15: 00000000200002c0 >> x14: 0000000000000000 x13: 0000000000000000 x12: ffff6775ca80451f >> x11: 1fffe775ca80451e x10: ffff6775ca80451e x9 : ffffba71bb78cf2c >> x8 : 0000988a357fbae2 x7 : ffff3bae540228f7 x6 : 0000000000000001 >> x5 : 1fffe775e2b43c78 x4 : dfff800000000000 x3 : ffffba71b9a00000 >> x2 : ffff80008d22a000 x1 : ffffc58ec6600000 x0 : fffffbfffe8010c1 >> Call trace: >> _outw include/asm-generic/io.h:594 [inline] >> logic_outw+0x54/0x218 lib/logic_pio.c:305 >> pci_resource_io drivers/pci/pci-sysfs.c:1157 [inline] >> pci_write_resource_io drivers/pci/pci-sysfs.c:1191 [inline] >> pci_write_resource_io+0x208/0x260 drivers/pci/pci-sysfs.c:1181 >> sysfs_kf_bin_write+0x188/0x210 fs/sysfs/file.c:158 >> kernfs_fop_write_iter+0x2e8/0x4b0 fs/kernfs/file.c:338 >> call_write_iter include/linux/fs.h:2085 [inline] >> new_sync_write fs/read_write.c:493 [inline] >> vfs_write+0x7bc/0xac8 fs/read_write.c:586 >> ksys_write+0x12c/0x270 fs/read_write.c:639 >> __do_sys_write fs/read_write.c:651 [inline] >> __se_sys_write fs/read_write.c:648 [inline] >> __arm64_sys_write+0x78/0xb8 fs/read_write.c:648 >> __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline] >> invoke_syscall+0x8c/0x2e0 arch/arm64/kernel/syscall.c:51 >> el0_svc_common.constprop.0+0x200/0x2a8 arch/arm64/kernel/syscall.c:134 >> do_el0_svc+0x4c/0x70 arch/arm64/kernel/syscall.c:176 >> el0_svc+0x44/0x1d8 arch/arm64/kernel/entry-common.c:806 >> el0t_64_sync_handler+0x100/0x130 arch/arm64/kernel/entry-common.c:844 >> el0t_64_sync+0x3c8/0x3d0 arch/arm64/kernel/entry.S:757 >> >> Powerpc seems affected as well, so prohibit the unaligned access >> on non-x86 archs. >> >> Fixes: 8633328be242 ("PCI: Allow read/write access to sysfs I/O port resources") >> Signed-off-by: Yongqiang Liu >> Signed-off-by: Ziming Du >> --- >> drivers/pci/pci-sysfs.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c >> index 7e697b82c5e1..6fa3c9d0e97e 100644 >> --- a/drivers/pci/pci-sysfs.c >> +++ b/drivers/pci/pci-sysfs.c >> @@ -1141,6 +1141,13 @@ static int pci_mmap_resource_wc(struct file *filp, struct kobject *kobj, >> return pci_mmap_resource(kobj, attr, vma, 1); >> } >> >> +#if !defined(CONFIG_X86) >> +static bool is_unaligned(unsigned long port, size_t size) >> +{ >> + return port & (size - 1); >> +} >> +#endif >> + >> static ssize_t pci_resource_io(struct file *filp, struct kobject *kobj, >> const struct bin_attribute *attr, char *buf, >> loff_t off, size_t count, bool write) >> @@ -1158,6 +1165,11 @@ static ssize_t pci_resource_io(struct file *filp, struct kobject *kobj, >> if (port + count - 1 > pci_resource_end(pdev, bar)) >> return -EINVAL; >> >> +#if !defined(CONFIG_X86) >> + if (is_unaligned(port, count)) >> + return -EFAULT; >> +#endif >> + > This changes return value from -EINVAL -> -EFAULT for some values of count > which seems not justified. > > To me it's not clear why even x86 should allow unaligned access. This > interface is very much geared towards natural alignment and sizing of the > reads (e.g. count = 3 leads to -EINVAL), so it feels somewhat artificial > to make x86 behave different here from the others. Thanks for your review! We verify that when count = 3, the return value will not be -EFAULT; It will only return -EFAULT in cases of unaligned access. We conduct a POC on QEMU with the ARM architecture as follows: #include #include #include int main() {         int fd = open("/sys/bus/pci/devices/0000:00:01.0/resource0", O_RDWR);         char buf[] = "1233333";         if (fd < 0) {                 printf("open failed\n");                 return 1;         }         pwrite(fd, buf, 2, 1);         return 0; } On x86, this does not trigger a kernel panic. >> switch (count) { >> case 1: >> if (write) >>