[PATCH 1/2] memblock: Differentiate regions overlap from both regions being the same

Lucas Tanure
2023-04-06T15:15:08Z

Add support for memblock_addrs_overlap to return a different value when
both regions are exactly the same region, where base and size are equal
between the regions.

Signed-off-by: Lucas Tanure <tanure@linux.com>
---
include/linux/memblock.h | 18 +++++++++++++++---
mm/memblock.c | 37 ++++++++++++++++++++++++-------------
2 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 50ad19662a32..c7ba8b01a637 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -49,6 +49,18 @@ enum memblock_flags {
MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver */
};

+/**
+ * enum memblock_overlap_type - result of comparison between two memory regions
+ * @MEMBLOCK_NO_OVERLAPS: there is no overlap between the two regions
+ * @MEMBLOCK_OVERLAPS: the two regions overlap each other, but are not the same
+ * @MEMBLOCK_EQUAL: both bases and sizes are equal, so the two regions are exactly the same
+ */
+enum memblock_overlap_type {
+ MEMBLOCK_NO_OVERLAPS,
+ MEMBLOCK_OVERLAPS,
+ MEMBLOCK_EQUAL,
+};
+
/**
* struct memblock_region - represents a memory region
* @base: base address of the region
@@ -118,8 +130,8 @@ int memblock_reserve(phys_addr_t base, phys_addr_t size);
int memblock_physmem_add(phys_addr_t base, phys_addr_t size);
#endif
void memblock_trim_memory(phys_addr_t align);
-bool memblock_overlaps_region(struct memblock_type *type,
- phys_addr_t base, phys_addr_t size);
+unsigned int memblock_overlaps_region(struct memblock_type *type,
+ phys_addr_t base, phys_addr_t size);
int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
@@ -486,7 +498,7 @@ bool memblock_is_memory(phys_addr_t addr);
bool memblock_is_map_memory(phys_addr_t addr);
bool memblock_is_region_memory(phys_addr_t base, phys_addr_t size);
bool memblock_is_reserved(phys_addr_t addr);
-bool memblock_is_region_reserved(phys_addr_t base, phys_addr_t size);
+unsigned int memblock_is_region_reserved(phys_addr_t base, phys_addr_t size);

void memblock_dump_all(void);

diff --git a/mm/memblock.c b/mm/memblock.c
index 25fd0626a9e7..948cc1bc3edf 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -175,24 +175,33 @@ static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
/*
* Address comparison utilities
*/
-static unsigned long __init_memblock memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1,
- phys_addr_t base2, phys_addr_t size2)
+static unsigned int __init_memblock memblock_addrs_overlap(phys_addr_t base1, phys_addr_t size1,
+ phys_addr_t base2, phys_addr_t size2)
{
- return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
+ if (base1 == base2 && size1 == size2)
+ return MEMBLOCK_EQUAL;
+
+ if ((base1 < (base2 + size2)) && (base2 < (base1 + size1)))
+ return MEMBLOCK_OVERLAPS;
+
+ return MEMBLOCK_NO_OVERLAPS;
}

-bool __init_memblock memblock_overlaps_region(struct memblock_type *type,
- phys_addr_t base, phys_addr_t size)
+unsigned int __init_memblock memblock_overlaps_region(struct memblock_type *type,
+ phys_addr_t base, phys_addr_t size)
{
- unsigned long i;
+ unsigned long i, ret;

memblock_cap_size(base, &size);

- for (i = 0; i < type->cnt; i++)
- if (memblock_addrs_overlap(base, size, type->regions[i].base,
- type->regions[i].size))
- break;
- return i < type->cnt;
+ for (i = 0; i < type->cnt; i++) {
+ ret = memblock_addrs_overlap(base, size, type->regions[i].base,
+ type->regions[i].size);
+ if (ret)
+ return ret;
+ }
+
+ return MEMBLOCK_NO_OVERLAPS;
}

/**
@@ -1857,9 +1866,11 @@ bool __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t siz
* memory block.
*
* Return:
- * True if they intersect, false if not.
+ * MEMBLOCK_NO_OVERLAPS if there is no intersection,
+ * MEMBLOCK_OVERLAPS if they only intersect,
+ * MEMBLOCK_EQUAL if the region matches base and size to an reserved memory.
*/
-bool __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t size)
+unsigned int __init_memblock memblock_is_region_reserved(phys_addr_t base, phys_addr_t size)
{
return memblock_overlaps_region(&memblock.reserved, base, size);
}
--
2.40.0