From 67bad2fdb754dbef14596c0b5d28b3a12c8dfe84 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 8 Feb 2014 13:34:09 +0100 Subject: cpu: add generic support for CPU feature based module autoloading This patch adds support for advertising optional CPU features over udev using the modalias, and for declaring compatibility with/dependency upon such a feature in a module. The mapping between feature numbers and actual features should be provided by the architecture in a file called which exports the following functions/macros: - cpu_feature(FEAT), a preprocessor macro that maps token FEAT to a numeric index; - bool cpu_have_feature(n), returning whether this CPU has support for feature #n; - MAX_CPU_FEATURES, an upper bound for 'n' in the previous function. The feature can then be enabled by setting CONFIG_GENERIC_CPU_AUTOPROBE for the architecture. For instance, a module that registers its module init function using module_cpu_feature_match(FEAT_X, module_init_function) will be probed automatically when the CPU's support for the 'FEAT_X' feature is advertised over udev, and will only allow the module to be loaded by hand if the 'FEAT_X' feature is supported. Signed-off-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- drivers/base/cpu.c | 50 +++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 45 insertions(+), 5 deletions(-) (limited to 'drivers/base/cpu.c') diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c index f48370dfc908..8a38bf8c792f 100644 --- a/drivers/base/cpu.c +++ b/drivers/base/cpu.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "base.h" @@ -286,6 +287,45 @@ static void cpu_device_release(struct device *dev) */ } +#ifdef CONFIG_HAVE_CPU_AUTOPROBE +#ifdef CONFIG_GENERIC_CPU_AUTOPROBE +static ssize_t print_cpu_modalias(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + ssize_t n; + u32 i; + + n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:", + CPU_FEATURE_TYPEVAL); + + for (i = 0; i < MAX_CPU_FEATURES; i++) + if (cpu_have_feature(i)) { + if (PAGE_SIZE < n + sizeof(",XXXX\n")) { + WARN(1, "CPU features overflow page\n"); + break; + } + n += sprintf(&buf[n], ",%04X", i); + } + buf[n++] = '\n'; + return n; +} +#else +#define print_cpu_modalias arch_print_cpu_modalias +#endif + +static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env) +{ + char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL); + if (buf) { + print_cpu_modalias(NULL, NULL, buf); + add_uevent_var(env, "MODALIAS=%s", buf); + kfree(buf); + } + return 0; +} +#endif + /* * register_cpu - Setup a sysfs device for a CPU. * @cpu - cpu->hotpluggable field set to 1 will generate a control file in @@ -306,8 +346,8 @@ int register_cpu(struct cpu *cpu, int num) cpu->dev.offline_disabled = !cpu->hotpluggable; cpu->dev.offline = !cpu_online(num); cpu->dev.of_node = of_get_cpu_node(num, NULL); -#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE - cpu->dev.bus->uevent = arch_cpu_uevent; +#ifdef CONFIG_HAVE_CPU_AUTOPROBE + cpu->dev.bus->uevent = cpu_uevent; #endif cpu->dev.groups = common_cpu_attr_groups; if (cpu->hotpluggable) @@ -330,8 +370,8 @@ struct device *get_cpu_device(unsigned cpu) } EXPORT_SYMBOL_GPL(get_cpu_device); -#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE -static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL); +#ifdef CONFIG_HAVE_CPU_AUTOPROBE +static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL); #endif static struct attribute *cpu_root_attrs[] = { @@ -344,7 +384,7 @@ static struct attribute *cpu_root_attrs[] = { &cpu_attrs[2].attr.attr, &dev_attr_kernel_max.attr, &dev_attr_offline.attr, -#ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE +#ifdef CONFIG_HAVE_CPU_AUTOPROBE &dev_attr_modalias.attr, #endif NULL -- cgit v1.2.3-59-g8ed1b