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Subject[PATCH] NOMMU: Work around the lack of vmap()/vunmap() in firmware_loading_store() [ver #2]
Date
Work around the lack of vmap()/vunmap() in firmware_loading_store() when
operating in NOMMU mode. vmap() cannot be implemented as there's no virtual
mapping available.

Instead, in NOMMU mode, make available a function (vcoalesce()) that can
coalesce the supplied data into one big buffer and store as the address vmap()
would've returned.

This can be #defined to vmap() in NOMMU mode by interested parties.

Signed-off-by: David Howells <dhowells@redhat.com>
---
drivers/base/firmware_class.c | 8 ++++++++
include/linux/vmalloc.h | 1 +
mm/nommu.c | 24 ++++++++++++++++++++++++
3 files changed, 33 insertions(+), 0 deletions(-)

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 985da11..be71e54 100644
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -60,6 +60,14 @@ static struct builtin_fw *__start_builtin_fw;
static struct builtin_fw *__end_builtin_fw;
#endif

+/*
+ * NOMMU mode can't provide vmap() as there's no MMU to do the virtual mapping.
+ * Coalesce the data into a big buffer instead.
+ */
+#ifndef CONFIG_MMU
+#define vmap(pg, c, f, pr) vcoalesce(pg, c, f, pr)
+#endif
+
static void
fw_load_abort(struct firmware_priv *fw_priv)
{
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 227c2a5..f36a4b2 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -48,6 +48,7 @@ extern void __init vmalloc_init(void);
static inline void vmalloc_init(void)
{
}
+extern void *vcoalesce(struct page **, unsigned int, unsigned long, pgprot_t);
#endif

extern void *vmalloc(unsigned long size);
diff --git a/mm/nommu.c b/mm/nommu.c
index 63fa17d..05a5c63 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -405,6 +405,30 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
EXPORT_SYMBOL(vm_insert_page);

/*
+ * NOMMU mode can't provide vmap() as there's no MMU to do the virtual mapping.
+ * Provide a facility to coalesce the data into a big buffer instead.
+ */
+void *vcoalesce(struct page **pages, unsigned int count,
+ unsigned long flags, pgprot_t prot)
+{
+ unsigned int i;
+ void *new_map, *page_data;
+
+ new_map = kmalloc(count << PAGE_SHIFT, GFP_KERNEL);
+ if (!new_map)
+ return NULL;
+
+ for (i = 0; i < count; ++i) {
+ page_data = kmap(pages[i]);
+ memcpy(new_map + (i << PAGE_SHIFT), page_data, PAGE_SIZE);
+ kunmap(page_data);
+ }
+
+ return new_map;
+}
+EXPORT_SYMBOL(vcoalesce);
+
+/*
* sys_brk() for the most part doesn't need the global kernel
* lock, except when an application is doing something nasty
* like trying to un-brk an area that has already been mapped


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