| Message ID | 20220815165658.11887-1-jiaxun.yang@flygoat.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v3] MIPS: Expose prid and globalnumber to sysfs | expand |
On Mon, Aug 15, 2022 at 04:56:58PM +0000, 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 <jiaxun.yang@flygoat.com> > --- > 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? > --- > .../ABI/testing/sysfs-devices-system-cpu | 11 ++ > arch/mips/kernel/topology.c | 103 ++++++++++++++++++ > 2 files changed, 114 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu > index 5bf61881f012..adf855e7bb9b 100644 > --- a/Documentation/ABI/testing/sysfs-devices-system-cpu > +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu > @@ -512,6 +512,17 @@ Description: information about CPUs heterogeneity. > > cpu_capacity: capacity of cpuX. > > +What: /sys/devices/system/cpu/cpuX/regs/ > + /sys/devices/system/cpu/cpuX/regs/identification/ > + /sys/devices/system/cpu/cpuX/regs/identification/prid > + /sys/devices/system/cpu/cpuX/regs/identification/globalnumber > +Date: Augest 2022 > +Contact: Linux MIPS Kernel Mailing list <linux-mips@vger.kernel.org> > +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..bbb7d4b51ffe 100644 > --- a/arch/mips/kernel/topology.c > +++ b/arch/mips/kernel/topology.c > @@ -5,6 +5,8 @@ > #include <linux/node.h> > #include <linux/nodemask.h> > #include <linux/percpu.h> > +#include <linux/seq_file.h> > +#include <linux/smp.h> > > static DEFINE_PER_CPU(struct cpu, cpu_devices); > > @@ -26,3 +28,104 @@ 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 sprintf(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; > + } > + rc = kobject_init_and_add(®->kobj, &cpuregs_kobj_type, > + &dev->kobj, "regs"); > + if (rc) > + goto out_kfree; No, please read the documentation for kobject_init_and_add() for what to properly do in a failure of this function. thanks, greg k-h
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu index 5bf61881f012..adf855e7bb9b 100644 --- a/Documentation/ABI/testing/sysfs-devices-system-cpu +++ b/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -512,6 +512,17 @@ Description: information about CPUs heterogeneity. cpu_capacity: capacity of cpuX. +What: /sys/devices/system/cpu/cpuX/regs/ + /sys/devices/system/cpu/cpuX/regs/identification/ + /sys/devices/system/cpu/cpuX/regs/identification/prid + /sys/devices/system/cpu/cpuX/regs/identification/globalnumber +Date: Augest 2022 +Contact: Linux MIPS Kernel Mailing list <linux-mips@vger.kernel.org> +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..bbb7d4b51ffe 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -5,6 +5,8 @@ #include <linux/node.h> #include <linux/nodemask.h> #include <linux/percpu.h> +#include <linux/seq_file.h> +#include <linux/smp.h> static DEFINE_PER_CPU(struct cpu, cpu_devices); @@ -26,3 +28,104 @@ 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 sprintf(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; + } + rc = kobject_init_and_add(®->kobj, &cpuregs_kobj_type, + &dev->kobj, "regs"); + if (rc) + goto out_kfree; + rc = sysfs_create_group(®->kobj, &cpuregs_attr_group); + if (rc) + goto out_kobj; + + return 0; +out_kobj: + kobject_del(®->kobj); +out_kfree: + kfree(reg); +out: + return rc; +} + +static int cpuregs_cpu_offline(unsigned int cpu) +{ + struct device *dev; + struct cpureg *reg = per_cpu(cpuregs, cpu); + + dev = get_cpu_device(cpu); + if (!dev || !reg) + return -ENODEV; + if (reg->kobj.parent) { + sysfs_remove_group(®->kobj, &cpuregs_attr_group); + kobject_del(®->kobj); + } + kfree(reg); + + return 0; +} + +static int __init cpuinfo_regs_init(void) +{ + int ret; + + + ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mips/topology:online", + cpuregs_cpu_online, cpuregs_cpu_offline); + if (ret < 0) { + pr_err("cpuinfo: failed to register hotplug callbacks.\n"); + return ret; + } + return 0; +} + +device_initcall(cpuinfo_regs_init);
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 <jiaxun.yang@flygoat.com> --- 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? --- .../ABI/testing/sysfs-devices-system-cpu | 11 ++ arch/mips/kernel/topology.c | 103 ++++++++++++++++++ 2 files changed, 114 insertions(+)