diff options
| -rw-r--r-- | include/linux/mm.h | 1 | ||||
| -rw-r--r-- | kernel/resource.c | 36 |
2 files changed, 37 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index fa0d74e06428..4cd45cb95e6d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -347,6 +347,7 @@ static inline int put_page_unless_one(struct page *page) } extern int page_is_ram(unsigned long pfn); +extern int region_is_ram(resource_size_t phys_addr, unsigned long size); /* Support for virtually mapped pages */ struct page *vmalloc_to_page(const void *addr); diff --git a/kernel/resource.c b/kernel/resource.c index 46322019ab7d..0bcebffc4e77 100644 --- a/kernel/resource.c +++ b/kernel/resource.c @@ -491,6 +491,42 @@ int __weak page_is_ram(unsigned long pfn) } EXPORT_SYMBOL_GPL(page_is_ram); +/* + * Search for a resouce entry that fully contains the specified region. + * If found, return 1 if it is RAM, 0 if not. + * If not found, or region is not fully contained, return -1 + * + * Used by the ioremap functions to ensure the user is not remapping RAM and is + * a vast speed up over walking through the resource table page by page. + */ +int region_is_ram(resource_size_t start, unsigned long size) +{ + struct resource *p; + resource_size_t end = start + size - 1; + int flags = IORESOURCE_MEM | IORESOURCE_BUSY; + const char *name = "System RAM"; + int ret = -1; + + read_lock(&resource_lock); + for (p = iomem_resource.child; p ; p = p->sibling) { + if (end < p->start) + continue; + + if (p->start <= start && end <= p->end) { + /* resource fully contains region */ + if ((p->flags != flags) || strcmp(p->name, name)) + ret = 0; + else + ret = 1; + break; + } + if (p->end < start) + break; /* not found */ + } + read_unlock(&resource_lock); + return ret; +} + void __weak arch_remove_reservations(struct resource *avail) { } |