1 files changed, 295 insertions, 0 deletions
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c
new file mode 100644
index 0000000000..b35f651837
--- /dev/null
+++ b/drivers/char/mspec.c
@@ -0,0 +1,295 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights
+ * reserved.
+ */
+
+/*
+ * SN Platform Special Memory (mspec) Support
+ *
+ * This driver exports the SN special memory (mspec) facility to user
+ * processes.
+ * There are two types of memory made available thru this driver:
+ * uncached and cached.
+ *
+ * Uncached are used for memory write combining feature of the ia64
+ * cpu.
+ *
+ * Cached are used for areas of memory that are used as cached addresses
+ * on our partition and used as uncached addresses from other partitions.
+ * Due to a design constraint of the SN2 Shub, you can not have processors
+ * on the same FSB perform both a cached and uncached reference to the
+ * same cache line.  These special memory cached regions prevent the
+ * kernel from ever dropping in a TLB entry and therefore prevent the
+ * processor from ever speculating a cache line from this page.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/vmalloc.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/numa.h>
+#include <linux/refcount.h>
+#include <asm/page.h>
+#include <linux/atomic.h>
+#include <asm/tlbflush.h>
+#include <asm/uncached.h>
+
+
+#define CACHED_ID	"Cached,"
+#define UNCACHED_ID	"Uncached"
+#define REVISION	"4.0"
+#define MSPEC_BASENAME	"mspec"
+
+/*
+ * Page types allocated by the device.
+ */
+enum mspec_page_type {
+	MSPEC_CACHED = 2,
+	MSPEC_UNCACHED
+};
+
+/*
+ * One of these structures is allocated when an mspec region is mmaped. The
+ * structure is pointed to by the vma->vm_private_data field in the vma struct.
+ * This structure is used to record the addresses of the mspec pages.
+ * This structure is shared by all vma's that are split off from the
+ * original vma when split_vma()'s are done.
+ *
+ * The refcnt is incremented atomically because mm->mmap_lock does not
+ * protect in fork case where multiple tasks share the vma_data.
+ */
+struct vma_data {
+	refcount_t refcnt;	/* Number of vmas sharing the data. */
+	spinlock_t lock;	/* Serialize access to this structure. */
+	int count;		/* Number of pages allocated. */
+	enum mspec_page_type type; /* Type of pages allocated. */
+	unsigned long vm_start;	/* Original (unsplit) base. */
+	unsigned long vm_end;	/* Original (unsplit) end. */
+	unsigned long maddr[];	/* Array of MSPEC addresses. */
+};
+
+/*
+ * mspec_open
+ *
+ * Called when a device mapping is created by a means other than mmap
+ * (via fork, munmap, etc.).  Increments the reference count on the
+ * underlying mspec data so it is not freed prematurely.
+ */
+static void
+mspec_open(struct vm_area_struct *vma)
+{
+	struct vma_data *vdata;
+
+	vdata = vma->vm_private_data;
+	refcount_inc(&vdata->refcnt);
+}
+
+/*
+ * mspec_close
+ *
+ * Called when unmapping a device mapping. Frees all mspec pages
+ * belonging to all the vma's sharing this vma_data structure.
+ */
+static void
+mspec_close(struct vm_area_struct *vma)
+{
+	struct vma_data *vdata;
+	int index, last_index;
+	unsigned long my_page;
+
+	vdata = vma->vm_private_data;
+
+	if (!refcount_dec_and_test(&vdata->refcnt))
+		return;
+
+	last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
+	for (index = 0; index < last_index; index++) {
+		if (vdata->maddr[index] == 0)
+			continue;
+		/*
+		 * Clear the page before sticking it back
+		 * into the pool.
+		 */
+		my_page = vdata->maddr[index];
+		vdata->maddr[index] = 0;
+		memset((char *)my_page, 0, PAGE_SIZE);
+		uncached_free_page(my_page, 1);
+	}
+
+	kvfree(vdata);
+}
+
+/*
+ * mspec_fault
+ *
+ * Creates a mspec page and maps it to user space.
+ */
+static vm_fault_t
+mspec_fault(struct vm_fault *vmf)
+{
+	unsigned long paddr, maddr;
+	unsigned long pfn;
+	pgoff_t index = vmf->pgoff;
+	struct vma_data *vdata = vmf->vma->vm_private_data;
+
+	maddr = (volatile unsigned long) vdata->maddr[index];
+	if (maddr == 0) {
+		maddr = uncached_alloc_page(numa_node_id(), 1);
+		if (maddr == 0)
+			return VM_FAULT_OOM;
+
+		spin_lock(&vdata->lock);
+		if (vdata->maddr[index] == 0) {
+			vdata->count++;
+			vdata->maddr[index] = maddr;
+		} else {
+			uncached_free_page(maddr, 1);
+			maddr = vdata->maddr[index];
+		}
+		spin_unlock(&vdata->lock);
+	}
+
+	paddr = maddr & ~__IA64_UNCACHED_OFFSET;
+	pfn = paddr >> PAGE_SHIFT;
+
+	return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
+}
+
+static const struct vm_operations_struct mspec_vm_ops = {
+	.open = mspec_open,
+	.close = mspec_close,
+	.fault = mspec_fault,
+};
+
+/*
+ * mspec_mmap
+ *
+ * Called when mmapping the device.  Initializes the vma with a fault handler
+ * and private data structure necessary to allocate, track, and free the
+ * underlying pages.
+ */
+static int
+mspec_mmap(struct file *file, struct vm_area_struct *vma,
+					enum mspec_page_type type)
+{
+	struct vma_data *vdata;
+	int pages, vdata_size;
+
+	if (vma->vm_pgoff != 0)
+		return -EINVAL;
+
+	if ((vma->vm_flags & VM_SHARED) == 0)
+		return -EINVAL;
+
+	if ((vma->vm_flags & VM_WRITE) == 0)
+		return -EPERM;
+
+	pages = vma_pages(vma);
+	vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
+	vdata = kvzalloc(vdata_size, GFP_KERNEL);
+	if (!vdata)
+		return -ENOMEM;
+
+	vdata->vm_start = vma->vm_start;
+	vdata->vm_end = vma->vm_end;
+	vdata->type = type;
+	spin_lock_init(&vdata->lock);
+	refcount_set(&vdata->refcnt, 1);
+	vma->vm_private_data = vdata;
+
+	vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
+	if (vdata->type == MSPEC_UNCACHED)
+		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	vma->vm_ops = &mspec_vm_ops;
+
+	return 0;
+}
+
+static int
+cached_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return mspec_mmap(file, vma, MSPEC_CACHED);
+}
+
+static int
+uncached_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return mspec_mmap(file, vma, MSPEC_UNCACHED);
+}
+
+static const struct file_operations cached_fops = {
+	.owner = THIS_MODULE,
+	.mmap = cached_mmap,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice cached_miscdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "mspec_cached",
+	.fops = &cached_fops
+};
+
+static const struct file_operations uncached_fops = {
+	.owner = THIS_MODULE,
+	.mmap = uncached_mmap,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice uncached_miscdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "mspec_uncached",
+	.fops = &uncached_fops
+};
+
+/*
+ * mspec_init
+ *
+ * Called at boot time to initialize the mspec facility.
+ */
+static int __init
+mspec_init(void)
+{
+	int ret;
+
+	ret = misc_register(&cached_miscdev);
+	if (ret) {
+		printk(KERN_ERR "%s: failed to register device %i\n",
+		       CACHED_ID, ret);
+		return ret;
+	}
+	ret = misc_register(&uncached_miscdev);
+	if (ret) {
+		printk(KERN_ERR "%s: failed to register device %i\n",
+		       UNCACHED_ID, ret);
+		misc_deregister(&cached_miscdev);
+		return ret;
+	}
+
+	printk(KERN_INFO "%s %s initialized devices: %s %s\n",
+	       MSPEC_BASENAME, REVISION, CACHED_ID, UNCACHED_ID);
+
+	return 0;
+}
+
+static void __exit
+mspec_exit(void)
+{
+	misc_deregister(&uncached_miscdev);
+	misc_deregister(&cached_miscdev);
+}
+
+module_init(mspec_init);
+module_exit(mspec_exit);
+
+MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
+MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
+MODULE_LICENSE("GPL");