On Tue, May 3, 2016 at 3:52 PM, Russell King <rmk at arm.linux.org.uk> wrote:
> Add a helper to exclude a region from a set of memory ranges.
>
> Signed-off-by: Russell King <rmk at arm.linux.org.uk>
> ---
> kexec/mem_regions.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> kexec/mem_regions.h | 4 ++++
> 2 files changed, 59 insertions(+)
>
> diff --git a/kexec/mem_regions.c b/kexec/mem_regions.c
> index 804984a..c6ba942 100644
> --- a/kexec/mem_regions.c
> +++ b/kexec/mem_regions.c
> @@ -29,6 +29,61 @@ void mem_regions_sort(struct memory_ranges *ranges)
> }
>
> /**
> + * mem_regions_exclude() - excludes a memory region from a set of memory ranges
> + * @ranges: memory ranges to exclude the region from
> + * @range: memory range to exclude
> + *
> + * Exclude a memory region from a set of memory ranges. We assume that
> + * the region to be excluded is either wholely located within one of the
> + * memory ranges, or not at all.
> + */
> +int mem_regions_exclude(struct memory_ranges *ranges,
> + const struct memory_range *range)
> +{
> + int i;
> +
> + for (i = 0; i < ranges->size; i++) {
> + struct memory_range *r = ranges->ranges + i;
> +
> + /*
> + * We assume that crash area is fully contained in
> + * some larger memory area.
> + */
> + if (r->start <= range->start && r->end >= range->end) {
> + if (r->start == range->start) {
> + /* Shrink the start of this memory range */
> + r->start = range->end + 1;
> + } else if (r->end == range->end) {
> + /* Shrink the end of this memory range */
> + r->end = range->start - 1;
What if r->start == range->start) && (r->end == range->end)?
> + } else {
> + struct memory_range *new;
> +
> + /*
> + * Split this area into 2 smaller ones and
> + * remove excluded range from between. First
> + * create new entry for the remaining area.
> + */
> + if (ranges->size >= ranges->max_size)
> + return -1;
> +
> + new = ranges->ranges + ranges->size++;
> + new->start = range->end + 1;
> + new->end = r->end;
> +
> + /*
> + * Update this area to end before excluded
> + * range.
> + */
> + r->end = range->start - 1;
> + break;
> + }
> + }
> + }
> + return 0;
> +}
> +
> +/**
> * mem_regions_add() - add a memory region to a set of ranges
> * @ranges: ranges to add the memory region to
> * @max: maximum number of entries in memory region
> diff --git a/kexec/mem_regions.h b/kexec/mem_regions.h
> index da7b5e8..ae9e972 100644
> --- a/kexec/mem_regions.h
> +++ b/kexec/mem_regions.h
> @@ -2,9 +2,13 @@
> #define MEM_REGIONS_H
>
> struct memory_ranges;
> +struct memory_range;
>
> void mem_regions_sort(struct memory_ranges *ranges);
>
> +int mem_regions_exclude(struct memory_ranges *ranges,
> + const struct memory_range *range);
> +
> int mem_regions_add(struct memory_ranges *ranges, unsigned long long base,
> unsigned long long length, int type);
>
> --
> 1.9.1
>
