memrange: Add support for stealing required memory from given ranges

This change adds memranges_steal() which allows the user
to steal memory from the list of available ranges by providing a set
of constraints (limit, size, alignment, tag). It tries to find the
first big enough range that can satisfy the constraints, creates a
hole as per the request and returns base of the stolen memory.

BUG=b:149186922

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: Ibe9cfae18fc6101ab2e7e27233e45324c8117708
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39484
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
This commit is contained in:
Furquan Shaikh 2020-03-11 19:06:24 -07:00 committed by Patrick Georgi
parent 1429092d02
commit 9c6274cd8f
2 changed files with 70 additions and 0 deletions

View File

@ -16,6 +16,7 @@
#define MEMRANGE_H_
#include <device/resource.h>
#include <stdbool.h>
/* A memranges structure consists of a list of range_entry(s). The structure
* is exposed so that a memranges can be used on the stack if needed. */
@ -166,4 +167,18 @@ void memranges_update_tag(struct memranges *ranges, unsigned long old_tag,
/* Returns next entry after the provided entry. NULL if r is last. */
struct range_entry *memranges_next_entry(struct memranges *ranges,
const struct range_entry *r);
/* Steals memory from the available list in given ranges as per the constraints:
* limit = Upper bound for the memory range to steal.
* size = Requested size for the stolen memory.
* align = Alignment requirements for the starting address of the stolen memory.
* (Alignment must be a power of 2).
* tag = Use a range that matches the given tag.
*
* If the constraints can be satisfied, this function creates a hole in the memrange,
* writes the base address of that hole to stolen_base and returns true. Otherwise it returns
* false. */
bool memranges_steal(struct memranges *ranges, resource_t limit, resource_t size, size_t align,
unsigned long tag, resource_t *stolen_base);
#endif /* MEMRANGE_H_ */

View File

@ -391,3 +391,58 @@ struct range_entry *memranges_next_entry(struct memranges *ranges,
{
return r->next;
}
/* Find a range entry that satisfies the given constraints to fit a hole that matches the
* required alignment, is big enough, does not exceed the limit and has a matching tag. */
static const struct range_entry *memranges_find_entry(struct memranges *ranges,
resource_t limit, resource_t size,
size_t align, unsigned long tag)
{
const struct range_entry *r;
resource_t base, end;
if (size == 0)
return NULL;
if (!IS_POWER_OF_2(align))
return NULL;
if (!IS_ALIGNED(align, ranges->align))
return NULL;
memranges_each_entry(r, ranges) {
if (r->tag != tag)
continue;
base = ALIGN_UP(r->begin, align);
end = base + size - 1;
if (end > r->end)
continue;
if (end > limit)
continue;
return r;
}
return NULL;
}
bool memranges_steal(struct memranges *ranges, resource_t limit, resource_t size, size_t align,
unsigned long tag, resource_t *stolen_base)
{
resource_t base;
const struct range_entry *r = memranges_find_entry(ranges, limit, size, align, tag);
if (r == NULL)
return false;
base = ALIGN_UP(r->begin, align);
memranges_create_hole(ranges, base, size);
*stolen_base = base;
return true;
}