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@@ -40,6 +40,23 @@ EXPORT_SYMBOL(iomem_resource);
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static DEFINE_RWLOCK(resource_lock);
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+/*
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+ * By default, we allocate free space bottom-up. The architecture can request
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+ * top-down by clearing this flag. The user can override the architecture's
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+ * choice with the "resource_alloc_from_bottom" kernel boot option, but that
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+ * should only be a debugging tool.
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+ */
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+int resource_alloc_from_bottom = 1;
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+
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+static __init int setup_alloc_from_bottom(char *s)
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+{
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+ printk(KERN_INFO
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+ "resource: allocating from bottom-up; please report a bug\n");
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+ resource_alloc_from_bottom = 1;
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+ return 0;
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+}
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+early_param("resource_alloc_from_bottom", setup_alloc_from_bottom);
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+
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static void *r_next(struct seq_file *m, void *v, loff_t *pos)
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{
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struct resource *p = v;
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@@ -357,8 +374,97 @@ int __weak page_is_ram(unsigned long pfn)
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return walk_system_ram_range(pfn, 1, NULL, __is_ram) == 1;
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}
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+static resource_size_t simple_align_resource(void *data,
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+ const struct resource *avail,
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+ resource_size_t size,
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+ resource_size_t align)
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+{
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+ return avail->start;
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+}
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+
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+static void resource_clip(struct resource *res, resource_size_t min,
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+ resource_size_t max)
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+{
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+ if (res->start < min)
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+ res->start = min;
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+ if (res->end > max)
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+ res->end = max;
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+}
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+
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+static bool resource_contains(struct resource *res1, struct resource *res2)
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+{
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+ return res1->start <= res2->start && res1->end >= res2->end;
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+}
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+
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+/*
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+ * Find the resource before "child" in the sibling list of "root" children.
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+ */
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+static struct resource *find_sibling_prev(struct resource *root, struct resource *child)
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+{
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+ struct resource *this;
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+
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+ for (this = root->child; this; this = this->sibling)
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+ if (this->sibling == child)
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+ return this;
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+
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+ return NULL;
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+}
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+
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/*
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* Find empty slot in the resource tree given range and alignment.
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+ * This version allocates from the end of the root resource first.
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+ */
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+static int find_resource_from_top(struct resource *root, struct resource *new,
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+ resource_size_t size, resource_size_t min,
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+ resource_size_t max, resource_size_t align,
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+ resource_size_t (*alignf)(void *,
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+ const struct resource *,
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+ resource_size_t,
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+ resource_size_t),
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+ void *alignf_data)
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+{
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+ struct resource *this;
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+ struct resource tmp, avail, alloc;
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+
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+ tmp.start = root->end;
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+ tmp.end = root->end;
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+
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+ this = find_sibling_prev(root, NULL);
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+ for (;;) {
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+ if (this) {
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+ if (this->end < root->end)
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+ tmp.start = this->end + 1;
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+ } else
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+ tmp.start = root->start;
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+
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+ resource_clip(&tmp, min, max);
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+
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+ /* Check for overflow after ALIGN() */
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+ avail = *new;
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+ avail.start = ALIGN(tmp.start, align);
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+ avail.end = tmp.end;
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+ if (avail.start >= tmp.start) {
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+ alloc.start = alignf(alignf_data, &avail, size, align);
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+ alloc.end = alloc.start + size - 1;
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+ if (resource_contains(&avail, &alloc)) {
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+ new->start = alloc.start;
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+ new->end = alloc.end;
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+ return 0;
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+ }
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+ }
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+
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+ if (!this || this->start == root->start)
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+ break;
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+
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+ tmp.end = this->start - 1;
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+ this = find_sibling_prev(root, this);
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+ }
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+ return -EBUSY;
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+}
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+
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+/*
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+ * Find empty slot in the resource tree given range and alignment.
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+ * This version allocates from the beginning of the root resource first.
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*/
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static int find_resource(struct resource *root, struct resource *new,
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resource_size_t size, resource_size_t min,
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@@ -370,36 +476,43 @@ static int find_resource(struct resource *root, struct resource *new,
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void *alignf_data)
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{
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struct resource *this = root->child;
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- struct resource tmp = *new;
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+ struct resource tmp = *new, avail, alloc;
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tmp.start = root->start;
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/*
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- * Skip past an allocated resource that starts at 0, since the assignment
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- * of this->start - 1 to tmp->end below would cause an underflow.
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+ * Skip past an allocated resource that starts at 0, since the
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+ * assignment of this->start - 1 to tmp->end below would cause an
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+ * underflow.
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*/
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if (this && this->start == 0) {
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tmp.start = this->end + 1;
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this = this->sibling;
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}
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- for(;;) {
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+ for (;;) {
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if (this)
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tmp.end = this->start - 1;
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else
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tmp.end = root->end;
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- if (tmp.start < min)
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- tmp.start = min;
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- if (tmp.end > max)
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- tmp.end = max;
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- tmp.start = ALIGN(tmp.start, align);
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- if (alignf)
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- tmp.start = alignf(alignf_data, &tmp, size, align);
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- if (tmp.start < tmp.end && tmp.end - tmp.start >= size - 1) {
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- new->start = tmp.start;
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- new->end = tmp.start + size - 1;
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- return 0;
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+
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+ resource_clip(&tmp, min, max);
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+
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+ /* Check for overflow after ALIGN() */
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+ avail = *new;
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+ avail.start = ALIGN(tmp.start, align);
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+ avail.end = tmp.end;
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+ if (avail.start >= tmp.start) {
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+ alloc.start = alignf(alignf_data, &avail, size, align);
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+ alloc.end = alloc.start + size - 1;
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+ if (resource_contains(&avail, &alloc)) {
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+ new->start = alloc.start;
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+ new->end = alloc.end;
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+ return 0;
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+ }
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}
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+
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if (!this)
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break;
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+
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tmp.start = this->end + 1;
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this = this->sibling;
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}
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@@ -428,8 +541,14 @@ int allocate_resource(struct resource *root, struct resource *new,
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{
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int err;
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+ if (!alignf)
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+ alignf = simple_align_resource;
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+
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write_lock(&resource_lock);
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- err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
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+ if (resource_alloc_from_bottom)
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+ err = find_resource(root, new, size, min, max, align, alignf, alignf_data);
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+ else
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+ err = find_resource_from_top(root, new, size, min, max, align, alignf, alignf_data);
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if (err >= 0 && __request_resource(root, new))
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err = -EBUSY;
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write_unlock(&resource_lock);
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