Commit 440a0857 authored by Nathan Lynch's avatar Nathan Lynch Committed by Benjamin Herrenschmidt
Browse files

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: default avatarNathan Lynch <ntl@pobox.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 0764bf63

arch/powerpc/kernel/smp.c

+64 −0
Original line number Diff line number Diff line
@@ -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;

}

include/asm-powerpc/smp.h

+1 −0
Original line number Diff line number Diff line
@@ -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.

 *

include/asm-powerpc/topology.h

+1 −0
Original line number Diff line number Diff line
@@ -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

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