Commit f05f62d0 authored by David Hildenbrand's avatar David Hildenbrand Committed by Heiko Carstens
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s390/vmem: get rid of memory segment list 



I can't come up with a satisfying reason why we still need the memory
segment list. We used to represent in the list:
- boot memory
- standby memory added via add_memory()
- loaded dcss segments

When loading/unloading dcss segments, we already track them in a
separate list and check for overlaps
(arch/s390/mm/extmem.c:segment_overlaps_others()) when loading segments.

The overlap check was introduced for some segments in
commit b2300b9e ("[S390] dcssblk: add >2G DCSSs support and stacked
contiguous DCSSs support.")
and was extended to cover all dcss segments in
commit ca571146 ("s390/extmem: remove code for 31 bit addressing
mode").

Although I doubt that overlaps with boot memory and standby memory
are relevant, let's reshuffle the checks in load_segment() to request
the resource first. This will bail out in case we have overlaps with
other resources (esp. boot memory and standby memory). The order
is now different compared to segment_unload() and segment_unload(), but
that should not matter.

This smells like a leftover from ancient times, let's get rid of it. We
can now convert vmem_remove_mapping() into a void function - everybody
ignored the return value already.

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20200625150029.45019-1-david@redhat.com>
Reviewed-by: default avatarGerald Schaefer <gerald.schaefer@de.ibm.com>
Tested-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [DCSS]
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 66a049b7

arch/s390/include/asm/pgtable.h

+1 −1
Original line number Diff line number Diff line
@@ -1669,7 +1669,7 @@ static inline swp_entry_t __swp_entry(unsigned long type, unsigned long offset) 
#define kern_addr_valid(addr)   (1)



extern int vmem_add_mapping(unsigned long start, unsigned long size);

extern int vmem_remove_mapping(unsigned long start, unsigned long size);

extern void vmem_remove_mapping(unsigned long start, unsigned long size);

extern int s390_enable_sie(void);

extern int s390_enable_skey(void);

extern void s390_reset_cmma(struct mm_struct *mm);

arch/s390/mm/extmem.c

+13 −12
Original line number Diff line number Diff line
@@ -313,15 +313,10 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long 
		goto out_free;

	}



	rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);



	if (rc)

		goto out_free;



	seg->res = kzalloc(sizeof(struct resource), GFP_KERNEL);

	if (seg->res == NULL) {

		rc = -ENOMEM;

		goto out_shared;

		goto out_free;

	}

	seg->res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;

	seg->res->start = seg->start_addr;
@@ -335,12 +330,17 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long 
	if (rc == SEG_TYPE_SC ||

	    ((rc == SEG_TYPE_SR || rc == SEG_TYPE_ER) && !do_nonshared))

		seg->res->flags |= IORESOURCE_READONLY;



	/* Check for overlapping resources before adding the mapping. */

	if (request_resource(&iomem_resource, seg->res)) {

		rc = -EBUSY;

		kfree(seg->res);

		goto out_shared;

		goto out_free_resource;

	}



	rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);

	if (rc)

		goto out_resource;



	if (do_nonshared)

		diag_cc = dcss_diag(&loadnsr_scode, seg->dcss_name,

				&start_addr, &end_addr);
@@ -351,14 +351,14 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long 
		dcss_diag(&purgeseg_scode, seg->dcss_name,

				&dummy, &dummy);

		rc = diag_cc;

		goto out_resource;

		goto out_mapping;

	}

	if (diag_cc > 1) {

		pr_warn("Loading DCSS %s failed with rc=%ld\n", name, end_addr);

		rc = dcss_diag_translate_rc(end_addr);

		dcss_diag(&purgeseg_scode, seg->dcss_name,

				&dummy, &dummy);

		goto out_resource;

		goto out_mapping;

	}

	seg->start_addr = start_addr;

	seg->end = end_addr;
@@ -377,11 +377,12 @@ __segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long 
			(void*) seg->end, segtype_string[seg->vm_segtype]);

	}

	goto out;

 out_mapping:

	vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);

 out_resource:

	release_resource(seg->res);

 out_free_resource:

	kfree(seg->res);

 out_shared:

	vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);

 out_free:

	kfree(seg);

 out:

arch/s390/mm/vmem.c

+7 −108
Original line number Diff line number Diff line
@@ -20,14 +20,6 @@ 


static DEFINE_MUTEX(vmem_mutex);



struct memory_segment {

	struct list_head list;

	unsigned long start;

	unsigned long size;

};



static LIST_HEAD(mem_segs);



static void __ref *vmem_alloc_pages(unsigned int order)

{

	unsigned long size = PAGE_SIZE << order;
@@ -300,94 +292,25 @@ void vmemmap_free(unsigned long start, unsigned long end, 
{

}



/*

 * Add memory segment to the segment list if it doesn't overlap with

 * an already present segment.

 */

static int insert_memory_segment(struct memory_segment *seg)

{

	struct memory_segment *tmp;



	if (seg->start + seg->size > VMEM_MAX_PHYS ||

	    seg->start + seg->size < seg->start)

		return -ERANGE;



	list_for_each_entry(tmp, &mem_segs, list) {

		if (seg->start >= tmp->start + tmp->size)

			continue;

		if (seg->start + seg->size <= tmp->start)

			continue;

		return -ENOSPC;

	}

	list_add(&seg->list, &mem_segs);

	return 0;

}



/*

 * Remove memory segment from the segment list.

 */

static void remove_memory_segment(struct memory_segment *seg)

{

	list_del(&seg->list);

}



static void __remove_shared_memory(struct memory_segment *seg)

void vmem_remove_mapping(unsigned long start, unsigned long size)

{

	remove_memory_segment(seg);

	vmem_remove_range(seg->start, seg->size);

}



int vmem_remove_mapping(unsigned long start, unsigned long size)

{

	struct memory_segment *seg;

	int ret;



	mutex_lock(&vmem_mutex);



	ret = -ENOENT;

	list_for_each_entry(seg, &mem_segs, list) {

		if (seg->start == start && seg->size == size)

			break;

	}



	if (seg->start != start || seg->size != size)

		goto out;



	ret = 0;

	__remove_shared_memory(seg);

	kfree(seg);

out:

	vmem_remove_range(start, size);

	mutex_unlock(&vmem_mutex);

	return ret;

}



int vmem_add_mapping(unsigned long start, unsigned long size)

{

	struct memory_segment *seg;

	int ret;



	mutex_lock(&vmem_mutex);

	ret = -ENOMEM;

	seg = kzalloc(sizeof(*seg), GFP_KERNEL);

	if (!seg)

		goto out;

	seg->start = start;

	seg->size = size;



	ret = insert_memory_segment(seg);

	if (ret)

		goto out_free;

	if (start + size > VMEM_MAX_PHYS ||

	    start + size < start)

		return -ERANGE;



	mutex_lock(&vmem_mutex);

	ret = vmem_add_mem(start, size);

	if (ret)

		goto out_remove;

	goto out;



out_remove:

	__remove_shared_memory(seg);

out_free:

	kfree(seg);

out:

		vmem_remove_range(start, size);

	mutex_unlock(&vmem_mutex);

	return ret;

}
@@ -421,27 +344,3 @@ void __init vmem_map_init(void) 
	pr_info("Write protected kernel read-only data: %luk\n",

		(unsigned long)(__end_rodata - _stext) >> 10);

}
 


/*

 * Convert memblock.memory  to a memory segment list so there is a single

 * list that contains all memory segments.

 */

static int __init vmem_convert_memory_chunk(void)

{

	struct memblock_region *reg;

	struct memory_segment *seg;



	mutex_lock(&vmem_mutex);

	for_each_memblock(memory, reg) {

		seg = kzalloc(sizeof(*seg), GFP_KERNEL);

		if (!seg)

			panic("Out of memory...\n");

		seg->start = reg->base;

		seg->size = reg->size;

		insert_memory_segment(seg);

	}

	mutex_unlock(&vmem_mutex);

	return 0;

}



core_initcall(vmem_convert_memory_chunk);

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