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 7356CC433FE for ; Tue, 11 Oct 2022 14:22:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229484AbiJKOWO (ORCPT ); Tue, 11 Oct 2022 10:22:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229538AbiJKOWJ (ORCPT ); Tue, 11 Oct 2022 10:22:09 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 293E91D67E; Tue, 11 Oct 2022 07:22:08 -0700 (PDT) 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 A59FC6119E; Tue, 11 Oct 2022 14:22:07 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE813C433D6; Tue, 11 Oct 2022 14:22:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1665498127; bh=UnTADQlb1c9sMBi6JfkWaS5g/Z+SghRtz6zwEjj/c/c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MGtgzeVxQqEOw4QNbLspA4olIz6C7JwyqfbtZxRJG0BUivMG16gJ62068dBmONy06 xjPvGfwZzKd7CZSQiTMwGdaxoVjWfnViwMCrzKYDxqIOJ6SdcQtb7dlT2TLcDvKBuw sdk7vi8CEpz6qoQUHjH94ASMTO2htEn4G9bNy84g= Date: Tue, 11 Oct 2022 16:22:50 +0200 From: Greg KH To: Jiaxun Yang Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, tsbogend@alpha.franken.de, linux-api@vger.kernel.org, f.fainelli@gmail.com Subject: Re: [PATCH v6] MIPS: Expose prid and globalnumber to sysfs Message-ID: References: <20221011110951.93404-1-jiaxun.yang@flygoat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221011110951.93404-1-jiaxun.yang@flygoat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 11, 2022 at 12:09:51PM +0100, Jiaxun Yang wrote: > Some application would like to know precise model and rev of processor > to do errata workaround or optimization. > > Expose them in sysfs as: > /sys/devices/system/cpu/cpuX/regs/identification/prid > /sys/devices/system/cpu/cpuX/regs/identification/globalnumber > > Reusing AArch64 CPU registers directory. > > Signed-off-by: Jiaxun Yang > --- > v2: Drop static qualifier for kobj (gregkh) > v3: Use kzalloc to allocate struct cpuregs. > note: When Greg mentioned about static I was thinking about > static qualifier of percpu variable. After reading documents > again it turns out kobjs should be allocated at runtime. Arm64's > cpuinfo kobj is also on a percpu variable... I guess that was a > intentional use? > v4: Properly handle err of kobj creation. (gregkh) > v5: Drop invalid kfree > v6: Correct offline routine, use kobject_put > --- > .../ABI/testing/sysfs-devices-system-cpu | 9 ++ > arch/mips/kernel/topology.c | 97 +++++++++++++++++++ > 2 files changed, 106 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu > index 5bf61881f012..9dea45ad5a22 100644 > --- a/Documentation/ABI/testing/sysfs-devices-system-cpu > +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu > @@ -512,6 +512,15 @@ Description: information about CPUs heterogeneity. > > cpu_capacity: capacity of cpuX. > > +What: /sys/devices/system/cpu/cpuX/regs/identification/prid > + /sys/devices/system/cpu/cpuX/regs/identification/globalnumber > +Date: October 2022 > +Contact: Linux MIPS Kernel Mailing list > +Description: MIPS CPU registers > + > + 'identification' directory exposes the Processor ID and Global Number > + registers for identifying model and revision of the CPU. > + > What: /sys/devices/system/cpu/vulnerabilities > /sys/devices/system/cpu/vulnerabilities/meltdown > /sys/devices/system/cpu/vulnerabilities/spectre_v1 > diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c > index 9429d85a4703..85588ffd6bac 100644 > --- a/arch/mips/kernel/topology.c > +++ b/arch/mips/kernel/topology.c > @@ -5,6 +5,8 @@ > #include > #include > #include > +#include > +#include > > static DEFINE_PER_CPU(struct cpu, cpu_devices); > > @@ -26,3 +28,98 @@ static int __init topology_init(void) > } > > subsys_initcall(topology_init); > + > +static struct kobj_type cpuregs_kobj_type = { > + .sysfs_ops = &kobj_sysfs_ops, > +}; > + > +struct cpureg { > + struct kobject kobj; > + struct cpuinfo_mips *info; > +}; > +static DEFINE_PER_CPU(struct cpureg *, cpuregs); > + > +#define kobj_to_cpureg(kobj) container_of(kobj, struct cpureg, kobj) > +#define CPUREGS_ATTR_RO(_name, _field) \ > + static ssize_t _name##_show(struct kobject *kobj, \ > + struct kobj_attribute *attr, char *buf) \ > + { \ > + struct cpuinfo_mips *info = kobj_to_cpureg(kobj)->info; \ > + \ > + return sysfs_emit(buf, "0x%08x\n", info->_field); \ > + } \ > + static struct kobj_attribute cpuregs_attr_##_name = __ATTR_RO(_name) > + > +CPUREGS_ATTR_RO(prid, processor_id); > +CPUREGS_ATTR_RO(globalnumber, globalnumber); > + > +static struct attribute *cpuregs_id_attrs[] = { > + &cpuregs_attr_prid.attr, > + &cpuregs_attr_globalnumber.attr, > + NULL > +}; > + > +static const struct attribute_group cpuregs_attr_group = { > + .attrs = cpuregs_id_attrs, > + .name = "identification" > +}; > + > +static int cpuregs_cpu_online(unsigned int cpu) > +{ > + int rc; > + struct device *dev; > + struct cpureg *reg; > + > + dev = get_cpu_device(cpu); > + if (!dev) { > + rc = -ENODEV; > + goto out; > + } > + reg = kzalloc(sizeof(struct cpureg), GFP_KERNEL); > + if (!reg) { > + rc = -ENOMEM; > + goto out; > + } > + reg->info = &cpu_data[cpu]; > + > + rc = kobject_init_and_add(®->kobj, &cpuregs_kobj_type, > + &dev->kobj, "regs"); > + if (rc) > + goto out_kobj; > + rc = sysfs_create_group(®->kobj, &cpuregs_attr_group); > + if (rc) > + goto out_kobj; > + > + return 0; > +out_kobj: > + kobject_put(®->kobj); > +out: > + return rc; > +} > + > +static int cpuregs_cpu_offline(unsigned int cpu) > +{ > + struct cpureg *reg = per_cpu(cpuregs, cpu); > + > + if (!reg) > + return -ENODEV; > + sysfs_remove_group(®->kobj, &cpuregs_attr_group); > + kobject_put(®->kobj); You did not test this code :( Please do so, and also exercise the cpu-remove path and fix up all the errors that happen there. thanks, greg k-h