[PATCH kexec-tools 12/32] kexec: add helper to exlude a region from a set of memory ranges
Pratyush Anand
panand at redhat.com
Fri May 27 08:07:41 PDT 2016
On Thu, May 26, 2016 at 2:26 PM, Russell King - ARM Linux
<linux at armlinux.org.uk> wrote:
> On Wed, May 25, 2016 at 01:30:44PM +0530, Pratyush Anand wrote:
>> On Tue, May 3, 2016 at 3:52 PM, Russell King <rmk at arm.linux.org.uk> wrote:
>> > +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)?
>
> I suppose that could happen, so what about this patch on top (untested).
I think, it should be fine, except.....
> This isn't something I'd be able to test on real hardware, it needs a
> separate test-suite to be written to do modular testing...
>
> kexec/mem_regions.c | 94 +++++++++++++++++++++++++++++++----------------------
> 1 file changed, 55 insertions(+), 39 deletions(-)
>
> diff --git a/kexec/mem_regions.c b/kexec/mem_regions.c
> index c6ba942..4e7061b 100644
> --- a/kexec/mem_regions.c
> +++ b/kexec/mem_regions.c
> @@ -29,6 +29,50 @@ void mem_regions_sort(struct memory_ranges *ranges)
> }
>
> /**
> + * 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
> + * @base: base address of memory region
> + * @length: length of memory region in bytes
> + * @type: type of memory region
> + *
> + * Add the memory region to the set of ranges, and return %0 if successful,
> + * or %-1 if we ran out of space.
> + */
> +int mem_regions_add(struct memory_ranges *ranges, unsigned long long base,
> + unsigned long long length, int type)
> +{
> + struct memory_range *range;
> +
> + if (ranges->size >= ranges->max_size)
> + return -1;
> +
> + range = ranges->ranges + ranges->size++;
> + range->start = base;
> + range->end = base + length - 1;
> + range->type = type;
> +
> + return 0;
> +}
> +
> +static void mem_regions_remove(struct memory_ranges *ranges, int index)
> +{
> + int tail_entries;
> +
> + /* we are assured to have at least one entry */
> + ranges->size -= 1;
> +
> + /* if we have following entries, shuffle them down one place */
> + tail_entries = ranges->size - index;
> + if (tail_entries)
> + memmove(ranges->ranges + index, ranges->ranges + index + 1,
> + tail_entries * sizeof(*ranges->ranges));
> +
> + /* zero the new tail entry */
> + memset(ranges->ranges + ranges->size, 0, sizeof(*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
> @@ -40,7 +84,7 @@ void mem_regions_sort(struct memory_ranges *ranges)
> int mem_regions_exclude(struct memory_ranges *ranges,
> const struct memory_range *range)
> {
> - int i;
> + int i, ret;
>
> for (i = 0; i < ranges->size; i++) {
> struct memory_range *r = ranges->ranges + i;
> @@ -51,25 +95,25 @@ int mem_regions_exclude(struct memory_ranges *ranges,
> */
> 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;
> + if (r->end == range->end)
> + /* Remove this entry */
> + mem_regions_remove(ranges, i);
> + else
> + /* 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;
> } 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;
> + ret = mem_regions_add(ranges, range->end + 1,
> + r->end, 0);
3rd argument should be (r->end - range->end)
> + if (ret < 0)
> + return ret;
>
> /*
> * Update this area to end before excluded
> @@ -82,31 +126,3 @@ int mem_regions_exclude(struct memory_ranges *ranges,
> }
> 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
> - * @base: base address of memory region
> - * @length: length of memory region in bytes
> - * @type: type of memory region
> - *
> - * Add the memory region to the set of ranges, and return %0 if successful,
> - * or %-1 if we ran out of space.
> - */
> -int mem_regions_add(struct memory_ranges *ranges, unsigned long long base,
> - unsigned long long length, int type)
> -{
> - struct memory_range *range;
> -
> - if (ranges->size >= ranges->max_size)
> - return -1;
> -
> - range = ranges->ranges + ranges->size++;
> - range->start = base;
> - range->end = base + length - 1;
> - range->type = type;
> -
> - return 0;
> -}
> -
>
>
> --
> RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
> according to speedtest.net.
~Pratyush
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