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Commit eb18f1b5 authored by Tejun Heo's avatar Tejun Heo
Browse files

memblock: Make memblock functions handle overflowing range @size 



Allow memblock users to specify range where @base + @size overflows
and automatically cap it at maximum.  This makes the interface more
robust and specifying till-the-end-of-memory easier.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Yinghai Lu <yinghai@kernel.org>
parent 71936180

mm/memblock.c

+12 −3
Original line number Diff line number Diff line
@@ -49,6 +49,12 @@ static inline const char *memblock_type_name(struct memblock_type *type) 
		return "unknown";

}



/* adjust *@size so that (@base + *@size) doesn't overflow, return new size */

static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)

{

	return *size = min(*size, (phys_addr_t)ULLONG_MAX - base);

}



/*

 * Address comparison utilities

 */
@@ -328,7 +334,8 @@ static int __init_memblock memblock_add_region(struct memblock_type *type, 
					       phys_addr_t base, phys_addr_t size)

{

	bool insert = false;

	phys_addr_t obase = base, end = base + size;

	phys_addr_t obase = base;

	phys_addr_t end = base + memblock_cap_size(base, &size);

	int i, nr_new;



	/* special case for empty array */
@@ -420,7 +427,7 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type, 
					phys_addr_t base, phys_addr_t size,

					int *start_rgn, int *end_rgn)

{

	phys_addr_t end = base + size;

	phys_addr_t end = base + memblock_cap_size(base, &size);

	int i;



	*start_rgn = *end_rgn = 0;
@@ -868,16 +875,18 @@ int __init_memblock memblock_is_memory(phys_addr_t addr) 
int __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t size)

{

	int idx = memblock_search(&memblock.memory, base);

	phys_addr_t end = base + memblock_cap_size(base, &size);



	if (idx == -1)

		return 0;

	return memblock.memory.regions[idx].base <= base &&

		(memblock.memory.regions[idx].base +

		 memblock.memory.regions[idx].size) >= (base + size);

		 memblock.memory.regions[idx].size) >= end;

}



int __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t size)

{

	memblock_cap_size(base, &size);

	return memblock_overlaps_region(&memblock.reserved, base, size) >= 0;

}