ashmem: remove cache maintenance support

The cache maintenance routines in ashmem were causing
several security issues. Since they are not being used
anymore by any drivers, its well to remove them entirely.

Bug: 34126808
Bug: 34173755
Bug: 34203176
CRs-Fixed: 1107034, 2001129, 2007786
Change-Id: I955e33d90b888d58db5cf6bb490905283374425b
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>

drivers/staging/android/ashmem.c

@@ -32,7 +32,6 @@
 #include <linux/mutex.h>
 #include <linux/shmem_fs.h>
 #include <linux/ashmem.h>
-#include <asm/cacheflush.h>
 
 #define ASHMEM_NAME_PREFIX "dev/ashmem/"
 #define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
@@ -704,51 +703,6 @@ done:
 }
 #endif
 
-static int ashmem_cache_op(struct ashmem_area *asma,
-	void (*cache_func)(unsigned long vstart, unsigned long length,
-				unsigned long pstart))
-{
-	int ret = 0;
-	struct vm_area_struct *vma;
-#ifdef CONFIG_OUTER_CACHE
-	unsigned long vaddr;
-#endif
-	if (!asma->vm_start)
-		return -EINVAL;
-
-	down_read(&current->mm->mmap_sem);
-	vma = find_vma(current->mm, asma->vm_start);
-	if (!vma) {
-		ret = -EINVAL;
-		goto done;
-	}
-	if (vma->vm_file != asma->file) {
-		ret = -EINVAL;
-		goto done;
-	}
-	if ((asma->vm_start + asma->size) > vma->vm_end) {
-		ret = -EINVAL;
-		goto done;
-	}
-#ifndef CONFIG_OUTER_CACHE
-	cache_func(asma->vm_start, asma->size, 0);
-#else
-	for (vaddr = asma->vm_start; vaddr < asma->vm_start + asma->size;
-		vaddr += PAGE_SIZE) {
-		unsigned long physaddr;
-		physaddr = virtaddr_to_physaddr(vaddr);
-		if (!physaddr)
-			return -EINVAL;
-		cache_func(vaddr, PAGE_SIZE, physaddr);
-	}
-#endif
-done:
-	up_read(&current->mm->mmap_sem);
-	if (ret)
-		asma->vm_start = 0;
-	return ret;
-}
-
 static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct ashmem_area *asma = file->private_data;
@@ -794,15 +748,6 @@ static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			ashmem_shrink(&ashmem_shrinker, &sc);
 		}
 		break;
-	case ASHMEM_CACHE_FLUSH_RANGE:
-		ret = ashmem_cache_op(asma, &clean_and_invalidate_caches);
-		break;
-	case ASHMEM_CACHE_CLEAN_RANGE:
-		ret = ashmem_cache_op(asma, &clean_caches);
-		break;
-	case ASHMEM_CACHE_INV_RANGE:
-		ret = ashmem_cache_op(asma, &invalidate_caches);
-		break;
 	}
 
 	return ret;

include/uapi/linux/ashmem.h

@@ -34,9 +34,6 @@ struct ashmem_pin {
 #define ASHMEM_UNPIN		_IOW(__ASHMEMIOC, 8, struct ashmem_pin)
 #define ASHMEM_GET_PIN_STATUS	_IO(__ASHMEMIOC, 9)
 #define ASHMEM_PURGE_ALL_CACHES	_IO(__ASHMEMIOC, 10)
-#define ASHMEM_CACHE_FLUSH_RANGE	_IO(__ASHMEMIOC, 11)
-#define ASHMEM_CACHE_CLEAN_RANGE	_IO(__ASHMEMIOC, 12)
-#define ASHMEM_CACHE_INV_RANGE		_IO(__ASHMEMIOC, 13)
 
 /* support of 32bit userspace on 64bit platforms */
 #ifdef CONFIG_COMPAT