mm: cma: allocation trigger

Provides a userspace interface to trigger a CMA allocation.

Usage:

        echo [pages] > alloc

This would provide testing/fuzzing access to the CMA allocation paths.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 63 insertions, 1 deletions

diff --git a/mm/cma.c b/mm/cma.c
index 2655b8191656..7f6045420925 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -123,6 +123,12 @@ static int __init cma_activate_area(struct cma *cma)
         } while (--i);
 
         mutex_init(&cma->lock);
+
+#ifdef CONFIG_CMA_DEBUGFS
+        INIT_HLIST_HEAD(&cma->mem_head);
+        spin_lock_init(&cma->mem_head_lock);
+#endif
+
         return 0;
 
 err:
diff --git a/mm/cma.h b/mm/cma.h
index 4141887bbfb0..1132d733556d 100644
--- a/mm/cma.h
+++ b/mm/cma.h
@@ -7,6 +7,10 @@ struct cma {
         unsigned long   *bitmap;
         unsigned int order_per_bit; /* Order of pages represented by one bit */
         struct mutex    lock;
+#ifdef CONFIG_CMA_DEBUGFS
+        struct hlist_head mem_head;
+        spinlock_t mem_head_lock;
+#endif
 };
 
 extern struct cma cma_areas[MAX_CMA_AREAS];
diff --git a/mm/cma_debug.c b/mm/cma_debug.c
index 3af2de6d4e5f..f3baa413ab33 100644
--- a/mm/cma_debug.c
+++ b/mm/cma_debug.c
@@ -7,9 +7,18 @@
 
 #include <linux/debugfs.h>
 #include <linux/cma.h>
+#include <linux/list.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
 
 #include "cma.h"
 
+struct cma_mem {
+        struct hlist_node node;
+        struct page *p;
+        unsigned long n;
+};
+
 static struct dentry *cma_debugfs_root;
 
 static int cma_debugfs_get(void *data, u64 *val)
@@ -23,6 +32,46 @@ static int cma_debugfs_get(void *data, u64 *val)
 
 DEFINE_SIMPLE_ATTRIBUTE(cma_debugfs_fops, cma_debugfs_get, NULL, "%llu\n");
 
+static void cma_add_to_cma_mem_list(struct cma *cma, struct cma_mem *mem)
+{
+        spin_lock(&cma->mem_head_lock);
+        hlist_add_head(&mem->node, &cma->mem_head);
+        spin_unlock(&cma->mem_head_lock);
+}
+
+static int cma_alloc_mem(struct cma *cma, int count)
+{
+        struct cma_mem *mem;
+        struct page *p;
+
+        mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+        if (!mem)
+                return -ENOMEM;
+
+        p = cma_alloc(cma, count, CONFIG_CMA_ALIGNMENT);
+        if (!p) {
+                kfree(mem);
+                return -ENOMEM;
+        }
+
+        mem->p = p;
+        mem->n = count;
+
+        cma_add_to_cma_mem_list(cma, mem);
+
+        return 0;
+}
+
+static int cma_alloc_write(void *data, u64 val)
+{
+        int pages = val;
+        struct cma *cma = data;
+
+        return cma_alloc_mem(cma, pages);
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(cma_alloc_fops, NULL, cma_alloc_write, "%llu\n");
+
 static void cma_debugfs_add_one(struct cma *cma, int idx)
 {
         struct dentry *tmp;
@@ -33,12 +82,15 @@ static void cma_debugfs_add_one(struct cma *cma, int idx)
 
         tmp = debugfs_create_dir(name, cma_debugfs_root);
 
+        debugfs_create_file("alloc", S_IWUSR, cma_debugfs_root, cma,
+                                &cma_alloc_fops);
+
         debugfs_create_file("base_pfn", S_IRUGO, tmp,
                                 &cma->base_pfn, &cma_debugfs_fops);
         debugfs_create_file("count", S_IRUGO, tmp,
                                 &cma->count, &cma_debugfs_fops);
         debugfs_create_file("order_per_bit", S_IRUGO, tmp,
-                        &cma->order_per_bit, &cma_debugfs_fops);
+                                &cma->order_per_bit, &cma_debugfs_fops);
 
         u32s = DIV_ROUND_UP(cma_bitmap_maxno(cma), BITS_PER_BYTE * sizeof(u32));
         debugfs_create_u32_array("bitmap", S_IRUGO, tmp, (u32*)cma->bitmap, u32s);