Commit 254b2fd0 authored by Heiko Carstens's avatar Heiko Carstens Committed by Alexander Gordeev
Browse files

s390/mm: provide minimal setup_per_cpu_areas() implementation 



s390 allows to enable CONFIG_NUMA, mainly to enable a couple of system
calls which are only present if NUMA is enabled. The NUMA specific system
calls are required by a couple of applications, which wouldn't work if the
system calls wouldn't be present.

The NUMA implementation itself maps all CPUs and memory to node 0. A
special case is the generic percpu setup code, which doesn't expect an s390
like implementation and therefore emits a message/warning:
"percpu: cpu 0 has no node -1 or node-local memory".

In order to get rid of this message, and also to provide sane CPU to node
and CPU distance mappings implement a minimal setup_per_cpu_areas()
function, which is very close to the generic variant.

Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent 2e71df94

arch/s390/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -197,6 +197,7 @@ config S390 
	select HAVE_RSEQ

	select HAVE_SAMPLE_FTRACE_DIRECT

	select HAVE_SAMPLE_FTRACE_DIRECT_MULTI

	select HAVE_SETUP_PER_CPU_AREA

	select HAVE_SOFTIRQ_ON_OWN_STACK

	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_VIRT_CPU_ACCOUNTING
@@ -208,6 +209,7 @@ config S390 
	select MMU_GATHER_MERGE_VMAS

	select MODULES_USE_ELF_RELA

	select NEED_DMA_MAP_STATE	if PCI

	select NEED_PER_CPU_EMBED_FIRST_CHUNK

	select NEED_SG_DMA_LENGTH	if PCI

	select OLD_SIGACTION

	select OLD_SIGSUSPEND3

arch/s390/mm/init.c

+36 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#include <linux/cma.h>

#include <linux/gfp.h>

#include <linux/dma-direct.h>

#include <linux/percpu.h>

#include <asm/processor.h>

#include <linux/uaccess.h>

#include <asm/pgalloc.h>
@@ -222,6 +223,41 @@ unsigned long memory_block_size_bytes(void) 
	return max_t(unsigned long, MIN_MEMORY_BLOCK_SIZE, sclp.rzm);

}



unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;

EXPORT_SYMBOL(__per_cpu_offset);



static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)

{

	return LOCAL_DISTANCE;

}



static int __init pcpu_cpu_to_node(int cpu)

{

	return 0;

}



void __init setup_per_cpu_areas(void)

{

	unsigned long delta;

	unsigned int cpu;

	int rc;



	/*

	 * Always reserve area for module percpu variables.  That's

	 * what the legacy allocator did.

	 */

	rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,

				    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE,

				    pcpu_cpu_distance,

				    pcpu_cpu_to_node);

	if (rc < 0)

		panic("Failed to initialize percpu areas.");



	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;

	for_each_possible_cpu(cpu)

		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];

}



#ifdef CONFIG_MEMORY_HOTPLUG



#ifdef CONFIG_CMA