[POWERPC] pseries: Force 4k update_flash block and list sizes

The enablement of 64k pages on pseries platforms exposed a bug in
the RTAS mechanism for updating firmware.  RTAS assumes 4k for flash
block and list sizes, and use of any other sizes results in a failure,
even though PAPR does not specify any such requirement.

This patch changes the rtas_flash module to force the use of 4k memory
block and list sizes when preparing and sending a firmware image to
RTAS.  The rtas_flash function now uses a slab cache of 4k blocks with
4k alignment, rather than get_zeroed_page(), to allocate the memory for
the flash blocks and lists.  The 4k alignment requirement is specified
in PAPR.

Signed-off-by: John Rose <johnrose@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 37 insertions, 10 deletions

diff --git a/arch/powerpc/kernel/rtas_flash.c b/arch/powerpc/kernel/rtas_flash.c
index 1442b63a75da..6f6fc977cb39 100644
--- a/arch/powerpc/kernel/rtas_flash.c
+++ b/arch/powerpc/kernel/rtas_flash.c
@@ -72,6 +72,10 @@
 #define VALIDATE_BUF_SIZE 4096    
 #define RTAS_MSG_MAXLEN   64
 
+/* Quirk - RTAS requires 4k list length and block size */
+#define RTAS_BLKLIST_LENGTH 4096
+#define RTAS_BLK_SIZE 4096
+
 struct flash_block {
         char *data;
         unsigned long length;
@@ -83,7 +87,7 @@ struct flash_block {
  * into a version/length and translate the pointers
  * to absolute.
  */
-#define FLASH_BLOCKS_PER_NODE ((PAGE_SIZE - 16) / sizeof(struct flash_block))
+#define FLASH_BLOCKS_PER_NODE ((RTAS_BLKLIST_LENGTH - 16) / sizeof(struct flash_block))
 struct flash_block_list {
         unsigned long num_blocks;
         struct flash_block_list *next;
@@ -96,6 +100,9 @@ struct flash_block_list_header { /* just the header of flash_block_list */
 
 static struct flash_block_list_header rtas_firmware_flash_list = {0, NULL};
 
+/* Use slab cache to guarantee 4k alignment */
+static kmem_cache_t *flash_block_cache = NULL;
+
 #define FLASH_BLOCK_LIST_VERSION (1UL)
 
 /* Local copy of the flash block list.
@@ -153,7 +160,7 @@ static int flash_list_valid(struct flash_block_list *flist)
                                 return FLASH_IMG_NULL_DATA;
                         }
                         block_size = f->blocks[i].length;
-                        if (block_size <= 0 || block_size > PAGE_SIZE) {
+                        if (block_size <= 0 || block_size > RTAS_BLK_SIZE) {
                                 return FLASH_IMG_BAD_LEN;
                         }
                         image_size += block_size;
@@ -177,9 +184,9 @@ static void free_flash_list(struct flash_block_list *f)
 
         while (f) {
                 for (i = 0; i < f->num_blocks; i++)
-                        free_page((unsigned long)(f->blocks[i].data));
+                        kmem_cache_free(flash_block_cache, f->blocks[i].data);
                 next = f->next;
-                free_page((unsigned long)f);
+                kmem_cache_free(flash_block_cache, f);
                 f = next;
         }
 }
@@ -278,6 +285,12 @@ static ssize_t rtas_flash_read(struct file *file, char __user *buf,
         return msglen;
 }
 
+/* constructor for flash_block_cache */
+void rtas_block_ctor(void *ptr, kmem_cache_t *cache, unsigned long flags)
+{
+        memset(ptr, 0, RTAS_BLK_SIZE);
+}
+
 /* We could be much more efficient here.  But to keep this function
  * simple we allocate a page to the block list no matter how small the
  * count is.  If the system is low on memory it will be just as well
@@ -302,7 +315,7 @@ static ssize_t rtas_flash_write(struct file *file, const char __user *buffer,
          * proc file
          */
         if (uf->flist == NULL) {
-                uf->flist = (struct flash_block_list *) get_zeroed_page(GFP_KERNEL);
+                uf->flist = kmem_cache_alloc(flash_block_cache, GFP_KERNEL);
                 if (!uf->flist)
                         return -ENOMEM;
         }
@@ -313,21 +326,21 @@ static ssize_t rtas_flash_write(struct file *file, const char __user *buffer,
         next_free = fl->num_blocks;
         if (next_free == FLASH_BLOCKS_PER_NODE) {
                 /* Need to allocate another block_list */
-                fl->next = (struct flash_block_list *)get_zeroed_page(GFP_KERNEL);
+                fl->next = kmem_cache_alloc(flash_block_cache, GFP_KERNEL);
                 if (!fl->next)
                         return -ENOMEM;
                 fl = fl->next;
                 next_free = 0;
         }
 
-        if (count > PAGE_SIZE)
-                count = PAGE_SIZE;
-        p = (char *)get_zeroed_page(GFP_KERNEL);
+        if (count > RTAS_BLK_SIZE)
+                count = RTAS_BLK_SIZE;
+        p = kmem_cache_alloc(flash_block_cache, GFP_KERNEL);
         if (!p)
                 return -ENOMEM;
         
         if(copy_from_user(p, buffer, count)) {
-                free_page((unsigned long)p);
+                kmem_cache_free(flash_block_cache, p);
                 return -EFAULT;
         }
         fl->blocks[next_free].data = p;
@@ -791,6 +804,16 @@ int __init rtas_flash_init(void)
                 goto cleanup;
 
         rtas_flash_term_hook = rtas_flash_firmware;
+
+        flash_block_cache = kmem_cache_create("rtas_flash_cache",
+                                RTAS_BLK_SIZE, RTAS_BLK_SIZE, 0,
+                                rtas_block_ctor, NULL);
+        if (!flash_block_cache) {
+                printk(KERN_ERR "%s: failed to create block cache\n",
+                                __FUNCTION__);
+                rc = -ENOMEM;
+                goto cleanup;
+        }
         return 0;
 
 cleanup:
@@ -805,6 +828,10 @@ cleanup:
 void __exit rtas_flash_cleanup(void)
 {
         rtas_flash_term_hook = NULL;
+
+        if (flash_block_cache)
+                kmem_cache_destroy(flash_block_cache);
+
         remove_flash_pde(firmware_flash_pde);
         remove_flash_pde(firmware_update_pde);
         remove_flash_pde(validate_pde);