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>
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@ -16,6 +16,7 @@
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#define MEMRANGE_H_
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#include <device/resource.h>
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#include <stdbool.h>
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/* A memranges structure consists of a list of range_entry(s). The structure
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* is exposed so that a memranges can be used on the stack if needed. */
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@ -166,4 +167,18 @@ void memranges_update_tag(struct memranges *ranges, unsigned long old_tag,
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/* Returns next entry after the provided entry. NULL if r is last. */
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struct range_entry *memranges_next_entry(struct memranges *ranges,
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const struct range_entry *r);
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/* Steals memory from the available list in given ranges as per the constraints:
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* limit = Upper bound for the memory range to steal.
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* size = Requested size for the stolen memory.
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* align = Alignment requirements for the starting address of the stolen memory.
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* (Alignment must be a power of 2).
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* tag = Use a range that matches the given tag.
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*
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* If the constraints can be satisfied, this function creates a hole in the memrange,
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* writes the base address of that hole to stolen_base and returns true. Otherwise it returns
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* false. */
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bool memranges_steal(struct memranges *ranges, resource_t limit, resource_t size, size_t align,
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unsigned long tag, resource_t *stolen_base);
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#endif /* MEMRANGE_H_ */
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@ -391,3 +391,58 @@ struct range_entry *memranges_next_entry(struct memranges *ranges,
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{
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return r->next;
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}
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/* Find a range entry that satisfies the given constraints to fit a hole that matches the
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* required alignment, is big enough, does not exceed the limit and has a matching tag. */
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static const struct range_entry *memranges_find_entry(struct memranges *ranges,
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resource_t limit, resource_t size,
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size_t align, unsigned long tag)
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{
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const struct range_entry *r;
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resource_t base, end;
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if (size == 0)
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return NULL;
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if (!IS_POWER_OF_2(align))
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return NULL;
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if (!IS_ALIGNED(align, ranges->align))
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return NULL;
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memranges_each_entry(r, ranges) {
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if (r->tag != tag)
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continue;
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base = ALIGN_UP(r->begin, align);
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end = base + size - 1;
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if (end > r->end)
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continue;
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if (end > limit)
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continue;
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return r;
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}
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return NULL;
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}
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bool memranges_steal(struct memranges *ranges, resource_t limit, resource_t size, size_t align,
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unsigned long tag, resource_t *stolen_base)
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{
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resource_t base;
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const struct range_entry *r = memranges_find_entry(ranges, limit, size, align, tag);
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if (r == NULL)
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return false;
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base = ALIGN_UP(r->begin, align);
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memranges_create_hole(ranges, base, size);
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*stolen_base = base;
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return true;
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}
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