powerpc: Make core sibling information available to userspace

Implement the notion of "core siblings" for powerpc.  This makes
/sys/devices/system/cpu/cpu*/topology/core_siblings present sensible
values, indicating online CPUs which share an L2 cache.

BenH: Made cpu_to_l2cache() use of_find_node_by_phandle() instead
of IBM-specific open coded search

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 3c4d07e..f7a2f81 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -63,10 +63,12 @@ struct thread_info *secondary_ti;
 cpumask_t cpu_possible_map = CPU_MASK_NONE;
 cpumask_t cpu_online_map = CPU_MASK_NONE;
 DEFINE_PER_CPU(cpumask_t, cpu_sibling_map) = CPU_MASK_NONE;
+DEFINE_PER_CPU(cpumask_t, cpu_core_map) = CPU_MASK_NONE;
 
 EXPORT_SYMBOL(cpu_online_map);
 EXPORT_SYMBOL(cpu_possible_map);
 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
+EXPORT_PER_CPU_SYMBOL(cpu_core_map);
 
 /* SMP operations for this machine */
 struct smp_ops_t *smp_ops;
@@ -230,6 +232,7 @@ void __devinit smp_prepare_boot_cpu(void)
 
        cpu_set(boot_cpuid, cpu_online_map);
        cpu_set(boot_cpuid, per_cpu(cpu_sibling_map, boot_cpuid));
+       cpu_set(boot_cpuid, per_cpu(cpu_core_map, boot_cpuid));
 #ifdef CONFIG_PPC64
        paca[boot_cpuid].__current = current;
 #endif
@@ -377,11 +380,36 @@ int __cpuinit __cpu_up(unsigned int cpu)
        return 0;
 }
 
+/* Must be called when no change can occur to cpu_present_map,
+ * i.e. during cpu online or offline.
+ */
+static struct device_node *cpu_to_l2cache(int cpu)
+{
+       struct device_node *np;
+       const phandle *php;
+       phandle ph;
+
+       if (!cpu_present(cpu))
+               return NULL;
+
+       np = of_get_cpu_node(cpu, NULL);
+       if (np == NULL)
+               return NULL;
+
+       php = of_get_property(np, "l2-cache", NULL);
+       if (php == NULL)
+               return NULL;
+       ph = *php;
+       of_node_put(np);
+
+       return of_find_node_by_phandle(ph);
+}
 
 /* Activate a secondary processor. */
 int __devinit start_secondary(void *unused)
 {
        unsigned int cpu = smp_processor_id();
+       struct device_node *l2_cache;
        int i, base;
 
        atomic_inc(&init_mm.mm_count);
@@ -410,7 +438,26 @@ int __devinit start_secondary(void *unused)
                        continue;
                cpu_set(cpu, per_cpu(cpu_sibling_map, base + i));
                cpu_set(base + i, per_cpu(cpu_sibling_map, cpu));
+
+               /* cpu_core_map should be a superset of
+                * cpu_sibling_map even if we don't have cache
+                * information, so update the former here, too.
+                */
+               cpu_set(cpu, per_cpu(cpu_core_map, base +i));
+               cpu_set(base + i, per_cpu(cpu_core_map, cpu));
        }
+       l2_cache = cpu_to_l2cache(cpu);
+       for_each_online_cpu(i) {
+               struct device_node *np = cpu_to_l2cache(i);
+               if (!np)
+                       continue;
+               if (np == l2_cache) {
+                       cpu_set(cpu, per_cpu(cpu_core_map, i));
+                       cpu_set(i, per_cpu(cpu_core_map, cpu));
+               }
+               of_node_put(np);
+       }
+       of_node_put(l2_cache);
        ipi_call_unlock();
 
        local_irq_enable();
@@ -448,6 +495,7 @@ void __init smp_cpus_done(unsigned int max_cpus)
 #ifdef CONFIG_HOTPLUG_CPU
 int __cpu_disable(void)
 {
+       struct device_node *l2_cache;
        int cpu = smp_processor_id();
        int base, i;
        int err;
@@ -464,7 +512,23 @@ int __cpu_disable(void)
        for (i = 0; i < threads_per_core; i++) {
                cpu_clear(cpu, per_cpu(cpu_sibling_map, base + i));
                cpu_clear(base + i, per_cpu(cpu_sibling_map, cpu));
+               cpu_clear(cpu, per_cpu(cpu_core_map, base +i));
+               cpu_clear(base + i, per_cpu(cpu_core_map, cpu));
+       }
+
+       l2_cache = cpu_to_l2cache(cpu);
+       for_each_present_cpu(i) {
+               struct device_node *np = cpu_to_l2cache(i);
+               if (!np)
+                       continue;
+               if (np == l2_cache) {
+                       cpu_clear(cpu, per_cpu(cpu_core_map, i));
+                       cpu_clear(i, per_cpu(cpu_core_map, cpu));
+               }
+               of_node_put(np);
        }
+       of_node_put(l2_cache);
+
 
        return 0;
 }

diff --git a/include/asm-powerpc/smp.h b/include/asm-powerpc/smp.h
index 416d4c2..32e9100 100644 (file)
--- a/include/asm-powerpc/smp.h
+++ b/include/asm-powerpc/smp.h
@@ -62,6 +62,7 @@ extern int smp_hw_index[];
 #endif
 
 DECLARE_PER_CPU(cpumask_t, cpu_sibling_map);
+DECLARE_PER_CPU(cpumask_t, cpu_core_map);
 
 /* Since OpenPIC has only 4 IPIs, we use slightly different message numbers.
  *

diff --git a/include/asm-powerpc/topology.h b/include/asm-powerpc/topology.h
index 100c6fb..f00e8e5 100644 (file)
--- a/include/asm-powerpc/topology.h
+++ b/include/asm-powerpc/topology.h
@@ -108,6 +108,7 @@ static inline void sysfs_remove_device_from_node(struct sys_device *dev,
 #include <asm/smp.h>
 
 #define topology_thread_siblings(cpu)  (per_cpu(cpu_sibling_map, cpu))
+#define topology_core_siblings(cpu)    (per_cpu(cpu_core_map, cpu))
 #endif
 #endif