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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: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2022-10-31 14:11:57 +01:00 committed by Alexander Gordeev
parent 2e71df9469
commit 254b2fd02e
2 changed files with 38 additions and 0 deletions
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2
arch/s390/Kconfig
View File

@ -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

36
arch/s390/mm/init.c
View File

@ -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