1// SPDX-License-Identifier: MIT
  2/*
  3 * Copyright © 2020 Intel Corporation
  4 */
  5
  6#include <linux/mm.h>
  7#include <linux/pagemap.h>
  8#include <linux/shmem_fs.h>
  9
 10#include "gem/i915_gem_object.h"
 11#include "shmem_utils.h"
 12
 13struct file *shmem_create_from_data(const char *name, void *data, size_t len)
 14{
 15	struct file *file;
 16	int err;
 17
 18	file = shmem_file_setup(name, PAGE_ALIGN(len), VM_NORESERVE);
 19	if (IS_ERR(file))
 20		return file;
 21
 22	err = shmem_write(file, 0, data, len);
 23	if (err) {
 24		fput(file);
 25		return ERR_PTR(err);
 26	}
 27
 28	return file;
 29}
 30
 31struct file *shmem_create_from_object(struct drm_i915_gem_object *obj)
 32{
 33	struct file *file;
 34	void *ptr;
 35
 36	if (obj->ops == &i915_gem_shmem_ops) {
 37		file = obj->base.filp;
 38		atomic_long_inc(&file->f_count);
 39		return file;
 40	}
 41
 42	ptr = i915_gem_object_pin_map(obj, I915_MAP_WB);
 43	if (IS_ERR(ptr))
 44		return ERR_CAST(ptr);
 45
 46	file = shmem_create_from_data("", ptr, obj->base.size);
 47	i915_gem_object_unpin_map(obj);
 48
 49	return file;
 50}
 51
 52static size_t shmem_npte(struct file *file)
 53{
 54	return file->f_mapping->host->i_size >> PAGE_SHIFT;
 55}
 56
 57static void __shmem_unpin_map(struct file *file, void *ptr, size_t n_pte)
 58{
 59	unsigned long pfn;
 60
 61	vunmap(ptr);
 62
 63	for (pfn = 0; pfn < n_pte; pfn++) {
 64		struct page *page;
 65
 66		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
 67						   GFP_KERNEL);
 68		if (!WARN_ON(IS_ERR(page))) {
 69			put_page(page);
 70			put_page(page);
 71		}
 72	}
 73}
 74
 75void *shmem_pin_map(struct file *file)
 76{
 77	const size_t n_pte = shmem_npte(file);
 78	pte_t *stack[32], **ptes, **mem;
 79	struct vm_struct *area;
 80	unsigned long pfn;
 81
 82	mem = stack;
 83	if (n_pte > ARRAY_SIZE(stack)) {
 84		mem = kvmalloc_array(n_pte, sizeof(*mem), GFP_KERNEL);
 85		if (!mem)
 86			return NULL;
 87	}
 88
 89	area = alloc_vm_area(n_pte << PAGE_SHIFT, mem);
 90	if (!area) {
 91		if (mem != stack)
 92			kvfree(mem);
 93		return NULL;
 94	}
 95
 96	ptes = mem;
 97	for (pfn = 0; pfn < n_pte; pfn++) {
 98		struct page *page;
 99
100		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
101						   GFP_KERNEL);
102		if (IS_ERR(page))
103			goto err_page;
104
105		**ptes++ = mk_pte(page,  PAGE_KERNEL);
106	}
107
108	if (mem != stack)
109		kvfree(mem);
110
111	mapping_set_unevictable(file->f_mapping);
112	return area->addr;
113
114err_page:
115	if (mem != stack)
116		kvfree(mem);
117
118	__shmem_unpin_map(file, area->addr, pfn);
119	return NULL;
120}
121
122void shmem_unpin_map(struct file *file, void *ptr)
123{
124	mapping_clear_unevictable(file->f_mapping);
125	__shmem_unpin_map(file, ptr, shmem_npte(file));
126}
127
128static int __shmem_rw(struct file *file, loff_t off,
129		      void *ptr, size_t len,
130		      bool write)
131{
132	unsigned long pfn;
133
134	for (pfn = off >> PAGE_SHIFT; len; pfn++) {
135		unsigned int this =
136			min_t(size_t, PAGE_SIZE - offset_in_page(off), len);
137		struct page *page;
138		void *vaddr;
139
140		page = shmem_read_mapping_page_gfp(file->f_mapping, pfn,
141						   GFP_KERNEL);
142		if (IS_ERR(page))
143			return PTR_ERR(page);
144
145		vaddr = kmap(page);
146		if (write)
147			memcpy(vaddr + offset_in_page(off), ptr, this);
148		else
149			memcpy(ptr, vaddr + offset_in_page(off), this);
150		kunmap(page);
151		put_page(page);
152
153		len -= this;
154		ptr += this;
155		off = 0;
156	}
157
158	return 0;
159}
160
161int shmem_read(struct file *file, loff_t off, void *dst, size_t len)
162{
163	return __shmem_rw(file, off, dst, len, false);
164}
165
166int shmem_write(struct file *file, loff_t off, void *src, size_t len)
167{
168	return __shmem_rw(file, off, src, len, true);
169}
170
171#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
172#include "st_shmem_utils.c"
173#endif