fs/pstore/ram_core.c - linux - Git at Google

 /*
  * Copyright (C) 2012 Google, Inc.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
  * may be copied, distributed, and modified under those terms.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  */

 #define pr_fmt(fmt) "persistent_ram: " fmt

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/list.h>
 #include <linux/memblock.h>
 #include <linux/rslib.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
 #include <linux/pstore_ram.h>
 #include <asm/page.h>

 struct persistent_ram_buffer {
 	uint32_t    sig;
 	atomic_t    start;
 	atomic_t    size;
 	uint8_t     data[0];
 };

 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */

 static inline size_t buffer_size(struct persistent_ram_zone *prz)
 {
 	return atomic_read(&prz->buffer->size);
 }

 static inline size_t buffer_start(struct persistent_ram_zone *prz)
 {
 	return atomic_read(&prz->buffer->start);
 }

 /* increase and wrap the start pointer, returning the old value */
 static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
 {
 	int old;
 	int new;

 	do {
 		old = atomic_read(&prz->buffer->start);
 		new = old + a;
 		while (unlikely(new >= prz->buffer_size))
 			new -= prz->buffer_size;
 	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);

 	return old;
 }

 /* increase the size counter until it hits the max size */
 static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
 {
 	size_t old;
 	size_t new;

 	if (atomic_read(&prz->buffer->size) == prz->buffer_size)
 		return;

 	do {
 		old = atomic_read(&prz->buffer->size);
 		new = old + a;
 		if (new > prz->buffer_size)
 			new = prz->buffer_size;
 	} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
 }

 static DEFINE_RAW_SPINLOCK(buffer_lock);

 /* increase and wrap the start pointer, returning the old value */
 static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
 {
 	int old;
 	int new;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&buffer_lock, flags);

 	old = atomic_read(&prz->buffer->start);
 	new = old + a;
 	while (unlikely(new >= prz->buffer_size))
 		new -= prz->buffer_size;
 	atomic_set(&prz->buffer->start, new);

 	raw_spin_unlock_irqrestore(&buffer_lock, flags);

 	return old;
 }

 /* increase the size counter until it hits the max size */
 static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
 {
 	size_t old;
 	size_t new;
 	unsigned long flags;

 	raw_spin_lock_irqsave(&buffer_lock, flags);

 	old = atomic_read(&prz->buffer->size);
 	if (old == prz->buffer_size)
 		goto exit;

 	new = old + a;
 	if (new > prz->buffer_size)
 		new = prz->buffer_size;
 	atomic_set(&prz->buffer->size, new);

 exit:
 	raw_spin_unlock_irqrestore(&buffer_lock, flags);
 }

 static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
 static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;

 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
 	uint8_t *data, size_t len, uint8_t *ecc)
 {
 	int i;
 	uint16_t par[prz->ecc_info.ecc_size];

 	/* Initialize the parity buffer */
 	memset(par, 0, sizeof(par));
 	encode_rs8(prz->rs_decoder, data, len, par, 0);
 	for (i = 0; i < prz->ecc_info.ecc_size; i++)
 		ecc[i] = par[i];
 }

 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 	void *data, size_t len, uint8_t *ecc)
 {
 	int i;
 	uint16_t par[prz->ecc_info.ecc_size];

 	for (i = 0; i < prz->ecc_info.ecc_size; i++)
 		par[i] = ecc[i];
 	return decode_rs8(prz->rs_decoder, data, par, len,
 				NULL, 0, NULL, 0, NULL);
 }

 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 	unsigned int start, unsigned int count)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	uint8_t *buffer_end = buffer->data + prz->buffer_size;
 	uint8_t *block;
 	uint8_t *par;
 	int ecc_block_size = prz->ecc_info.block_size;
 	int ecc_size = prz->ecc_info.ecc_size;
 	int size = ecc_block_size;

 	if (!ecc_size)
 		return;

 	block = buffer->data + (start & ~(ecc_block_size - 1));
 	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;

 	do {
 		if (block + ecc_block_size > buffer_end)
 			size = buffer_end - block;
 		persistent_ram_encode_rs8(prz, block, size, par);
 		block += ecc_block_size;
 		par += ecc_size;
 	} while (block < buffer->data + start + count);
 }

 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;

 	if (!prz->ecc_info.ecc_size)
 		return;

 	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 				  prz->par_header);
 }

 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	uint8_t *block;
 	uint8_t *par;

 	if (!prz->ecc_info.ecc_size)
 		return;

 	block = buffer->data;
 	par = prz->par_buffer;
 	while (block < buffer->data + buffer_size(prz)) {
 		int numerr;
 		int size = prz->ecc_info.block_size;
 		if (block + size > buffer->data + prz->buffer_size)
 			size = buffer->data + prz->buffer_size - block;
 		numerr = persistent_ram_decode_rs8(prz, block, size, par);
 		if (numerr > 0) {
 			pr_devel("error in block %p, %d\n", block, numerr);
 			prz->corrected_bytes += numerr;
 		} else if (numerr < 0) {
 			pr_devel("uncorrectable error in block %p\n", block);
 			prz->bad_blocks++;
 		}
 		block += prz->ecc_info.block_size;
 		par += prz->ecc_info.ecc_size;
 	}
 }

 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 				   struct persistent_ram_ecc_info *ecc_info)
 {
 	int numerr;
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	int ecc_blocks;
 	size_t ecc_total;

 	if (!ecc_info || !ecc_info->ecc_size)
 		return 0;

 	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
 	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
 	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
 	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;

 	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
 				  prz->ecc_info.block_size +
 				  prz->ecc_info.ecc_size);
 	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
 	if (ecc_total >= prz->buffer_size) {
 		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 		       __func__, prz->ecc_info.ecc_size,
 		       ecc_total, prz->buffer_size);
 		return -EINVAL;
 	}

 	prz->buffer_size -= ecc_total;
 	prz->par_buffer = buffer->data + prz->buffer_size;
 	prz->par_header = prz->par_buffer +
 			  ecc_blocks * prz->ecc_info.ecc_size;

 	/*
 	 * first consecutive root is 0
 	 * primitive element to generate roots = 1
 	 */
 	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 				  0, 1, prz->ecc_info.ecc_size);
 	if (prz->rs_decoder == NULL) {
 		pr_info("init_rs failed\n");
 		return -EINVAL;
 	}

 	prz->corrected_bytes = 0;
 	prz->bad_blocks = 0;

 	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 					   prz->par_header);
 	if (numerr > 0) {
 		pr_info("error in header, %d\n", numerr);
 		prz->corrected_bytes += numerr;
 	} else if (numerr < 0) {
 		pr_info("uncorrectable error in header\n");
 		prz->bad_blocks++;
 	}

 	return 0;
 }

 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 	char *str, size_t len)
 {
 	ssize_t ret;

 	if (!prz->ecc_info.ecc_size)
 		return 0;

 	if (prz->corrected_bytes || prz->bad_blocks)
 		ret = snprintf(str, len, ""
 			"\n%d Corrected bytes, %d unrecoverable blocks\n",
 			prz->corrected_bytes, prz->bad_blocks);
 	else
 		ret = snprintf(str, len, "\nNo errors detected\n");

 	return ret;
 }

 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 	const void *s, unsigned int start, unsigned int count)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	memcpy(buffer->data + start, s, count);
 	persistent_ram_update_ecc(prz, start, count);
 }

 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 {
 	struct persistent_ram_buffer *buffer = prz->buffer;
 	size_t size = buffer_size(prz);
 	size_t start = buffer_start(prz);

 	if (!size)
 		return;

 	if (!prz->old_log) {
 		persistent_ram_ecc_old(prz);
 		prz->old_log = kmalloc(size, GFP_KERNEL);
 	}
 	if (!prz->old_log) {
 		pr_err("failed to allocate buffer\n");
 		return;
 	}

 	prz->old_log_size = size;
 	memcpy(prz->old_log, &buffer->data[start], size - start);
 	memcpy(prz->old_log + size - start, &buffer->data[0], start);
 }

 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 	const void *s, unsigned int count)
 {
 	int rem;
 	int c = count;
 	size_t start;

 	if (unlikely(c > prz->buffer_size)) {
 		s += c - prz->buffer_size;
 		c = prz->buffer_size;
 	}

 	buffer_size_add(prz, c);

 	start = buffer_start_add(prz, c);

 	rem = prz->buffer_size - start;
 	if (unlikely(rem < c)) {
 		persistent_ram_update(prz, s, start, rem);
 		s += rem;
 		c -= rem;
 		start = 0;
 	}
 	persistent_ram_update(prz, s, start, c);

 	persistent_ram_update_header_ecc(prz);

 	return count;
 }

 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 {
 	return prz->old_log_size;
 }

 void *persistent_ram_old(struct persistent_ram_zone *prz)
 {
 	return prz->old_log;
 }

 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 {
 	kfree(prz->old_log);
 	prz->old_log = NULL;
 	prz->old_log_size = 0;
 }

 void persistent_ram_zap(struct persistent_ram_zone *prz)
 {
 	atomic_set(&prz->buffer->start, 0);
 	atomic_set(&prz->buffer->size, 0);
 	persistent_ram_update_header_ecc(prz);
 }

 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 {
 	struct page **pages;
 	phys_addr_t page_start;
 	unsigned int page_count;
 	pgprot_t prot;
 	unsigned int i;
 	void *vaddr;

 	page_start = start - offset_in_page(start);
 	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);

 	prot = pgprot_noncached(PAGE_KERNEL);

 	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 	if (!pages) {
 		pr_err("%s: Failed to allocate array for %u pages\n",
 		       __func__, page_count);
 		return NULL;
 	}

 	for (i = 0; i < page_count; i++) {
 		phys_addr_t addr = page_start + i * PAGE_SIZE;
 		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 	}
 	vaddr = vmap(pages, page_count, VM_MAP, prot);
 	kfree(pages);

 	return vaddr;
 }

 static void *persistent_ram_iomap(phys_addr_t start, size_t size)
 {
 	if (!request_mem_region(start, size, "persistent_ram")) {
 		pr_err("request mem region (0x%llx@0x%llx) failed\n",
 			(unsigned long long)size, (unsigned long long)start);
 		return NULL;
 	}

 	buffer_start_add = buffer_start_add_locked;
 	buffer_size_add = buffer_size_add_locked;

 	return ioremap(start, size);
 }

 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 		struct persistent_ram_zone *prz)
 {
 	prz->paddr = start;
 	prz->size = size;

 	if (pfn_valid(start >> PAGE_SHIFT))
 		prz->vaddr = persistent_ram_vmap(start, size);
 	else
 		prz->vaddr = persistent_ram_iomap(start, size);

 	if (!prz->vaddr) {
 		pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 			(unsigned long long)size, (unsigned long long)start);
 		return -ENOMEM;
 	}

 	prz->buffer = prz->vaddr + offset_in_page(start);
 	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);

 	return 0;
 }

 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 				    struct persistent_ram_ecc_info *ecc_info)
 {
 	int ret;

 	ret = persistent_ram_init_ecc(prz, ecc_info);
 	if (ret)
 		return ret;

 	sig ^= PERSISTENT_RAM_SIG;

 	if (prz->buffer->sig == sig) {
 		if (buffer_size(prz) > prz->buffer_size ||
 		    buffer_start(prz) > buffer_size(prz))
 			pr_info("found existing invalid buffer, size %zu, start %zu\n",
 				buffer_size(prz), buffer_start(prz));
 		else {
 			pr_debug("found existing buffer, size %zu, start %zu\n",
 				 buffer_size(prz), buffer_start(prz));
 			persistent_ram_save_old(prz);
 			return 0;
 		}
 	} else {
 		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 			 prz->buffer->sig);
 	}

 	prz->buffer->sig = sig;
 	persistent_ram_zap(prz);

 	return 0;
 }

 void persistent_ram_free(struct persistent_ram_zone *prz)
 {
 	if (!prz)
 		return;

 	if (prz->vaddr) {
 		if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 			vunmap(prz->vaddr);
 		} else {
 			iounmap(prz->vaddr);
 			release_mem_region(prz->paddr, prz->size);
 		}
 		prz->vaddr = NULL;
 	}
 	persistent_ram_free_old(prz);
 	kfree(prz);
 }

 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 			u32 sig, struct persistent_ram_ecc_info *ecc_info)
 {
 	struct persistent_ram_zone *prz;
 	int ret = -ENOMEM;

 	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 	if (!prz) {
 		pr_err("failed to allocate persistent ram zone\n");
 		goto err;
 	}

 	ret = persistent_ram_buffer_map(start, size, prz);
 	if (ret)
 		goto err;

 	ret = persistent_ram_post_init(prz, sig, ecc_info);
 	if (ret)
 		goto err;

 	return prz;
 err:
 	persistent_ram_free(prz);
 	return ERR_PTR(ret);
 }
	/*
	* Copyright (C) 2012 Google, Inc.
	*
	* This software is licensed under the terms of the GNU General Public
	* License version 2, as published by the Free Software Foundation, and
	* may be copied, distributed, and modified under those terms.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	*/

	#define pr_fmt(fmt) "persistent_ram: " fmt

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/list.h>
	#include <linux/memblock.h>
	#include <linux/rslib.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>
	#include <linux/pstore_ram.h>
	#include <asm/page.h>

	struct persistent_ram_buffer {
	uint32_t sig;
	atomic_t start;
	atomic_t size;
	uint8_t data[0];
	};

	#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */

	static inline size_t buffer_size(struct persistent_ram_zone *prz)
	{
	return atomic_read(&prz->buffer->size);
	}

	static inline size_t buffer_start(struct persistent_ram_zone *prz)
	{
	return atomic_read(&prz->buffer->start);
	}

	/* increase and wrap the start pointer, returning the old value */
	static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
	{
	int old;
	int new;

	do {
	old = atomic_read(&prz->buffer->start);
	new = old + a;
	while (unlikely(new >= prz->buffer_size))
	new -= prz->buffer_size;
	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);

	return old;
	}

	/* increase the size counter until it hits the max size */
	static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
	{
	size_t old;
	size_t new;

	if (atomic_read(&prz->buffer->size) == prz->buffer_size)
	return;

	do {
	old = atomic_read(&prz->buffer->size);
	new = old + a;
	if (new > prz->buffer_size)
	new = prz->buffer_size;
	} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
	}

	static DEFINE_RAW_SPINLOCK(buffer_lock);

	/* increase and wrap the start pointer, returning the old value */
	static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
	{
	int old;
	int new;
	unsigned long flags;

	raw_spin_lock_irqsave(&buffer_lock, flags);

	old = atomic_read(&prz->buffer->start);
	new = old + a;
	while (unlikely(new >= prz->buffer_size))
	new -= prz->buffer_size;
	atomic_set(&prz->buffer->start, new);

	raw_spin_unlock_irqrestore(&buffer_lock, flags);

	return old;
	}

	/* increase the size counter until it hits the max size */
	static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
	{
	size_t old;
	size_t new;
	unsigned long flags;

	raw_spin_lock_irqsave(&buffer_lock, flags);

	old = atomic_read(&prz->buffer->size);
	if (old == prz->buffer_size)
	goto exit;

	new = old + a;
	if (new > prz->buffer_size)
	new = prz->buffer_size;
	atomic_set(&prz->buffer->size, new);

	exit:
	raw_spin_unlock_irqrestore(&buffer_lock, flags);
	}

	static size_t (buffer_start_add)(struct persistent_ram_zone , size_t) = buffer_start_add_atomic;
	static void (buffer_size_add)(struct persistent_ram_zone , size_t) = buffer_size_add_atomic;

	static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
	uint8_t data, size_t len, uint8_t ecc)
	{
	int i;
	uint16_t par[prz->ecc_info.ecc_size];

	/* Initialize the parity buffer */
	memset(par, 0, sizeof(par));
	encode_rs8(prz->rs_decoder, data, len, par, 0);
	for (i = 0; i < prz->ecc_info.ecc_size; i++)
	ecc[i] = par[i];
	}

	static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
	void data, size_t len, uint8_t ecc)
	{
	int i;
	uint16_t par[prz->ecc_info.ecc_size];

	for (i = 0; i < prz->ecc_info.ecc_size; i++)
	par[i] = ecc[i];
	return decode_rs8(prz->rs_decoder, data, par, len,
	NULL, 0, NULL, 0, NULL);
	}

	static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
	unsigned int start, unsigned int count)
	{
	struct persistent_ram_buffer *buffer = prz->buffer;
	uint8_t *buffer_end = buffer->data + prz->buffer_size;
	uint8_t *block;
	uint8_t *par;
	int ecc_block_size = prz->ecc_info.block_size;
	int ecc_size = prz->ecc_info.ecc_size;
	int size = ecc_block_size;

	if (!ecc_size)
	return;

	block = buffer->data + (start & ~(ecc_block_size - 1));
	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;

	do {
	if (block + ecc_block_size > buffer_end)
	size = buffer_end - block;
	persistent_ram_encode_rs8(prz, block, size, par);
	block += ecc_block_size;
	par += ecc_size;
	} while (block < buffer->data + start + count);
	}

	static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
	{
	struct persistent_ram_buffer *buffer = prz->buffer;

	if (!prz->ecc_info.ecc_size)
	return;

	persistent_ram_encode_rs8(prz, (uint8_t )buffer, sizeof(buffer),
	prz->par_header);
	}

	static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
	{
	struct persistent_ram_buffer *buffer = prz->buffer;
	uint8_t *block;
	uint8_t *par;

	if (!prz->ecc_info.ecc_size)
	return;

	block = buffer->data;
	par = prz->par_buffer;
	while (block < buffer->data + buffer_size(prz)) {
	int numerr;
	int size = prz->ecc_info.block_size;
	if (block + size > buffer->data + prz->buffer_size)
	size = buffer->data + prz->buffer_size - block;
	numerr = persistent_ram_decode_rs8(prz, block, size, par);
	if (numerr > 0) {
	pr_devel("error in block %p, %d\n", block, numerr);
	prz->corrected_bytes += numerr;
	} else if (numerr < 0) {
	pr_devel("uncorrectable error in block %p\n", block);
	prz->bad_blocks++;
	}
	block += prz->ecc_info.block_size;
	par += prz->ecc_info.ecc_size;
	}
	}

	static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
	struct persistent_ram_ecc_info *ecc_info)
	{
	int numerr;
	struct persistent_ram_buffer *buffer = prz->buffer;
	int ecc_blocks;
	size_t ecc_total;

	if (!ecc_info \|\| !ecc_info->ecc_size)
	return 0;

	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;

	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
	prz->ecc_info.block_size +
	prz->ecc_info.ecc_size);
	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
	if (ecc_total >= prz->buffer_size) {
	pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
	__func__, prz->ecc_info.ecc_size,
	ecc_total, prz->buffer_size);
	return -EINVAL;
	}

	prz->buffer_size -= ecc_total;
	prz->par_buffer = buffer->data + prz->buffer_size;
	prz->par_header = prz->par_buffer +
	ecc_blocks * prz->ecc_info.ecc_size;

	/*
	* first consecutive root is 0
	* primitive element to generate roots = 1
	*/
	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
	0, 1, prz->ecc_info.ecc_size);
	if (prz->rs_decoder == NULL) {
	pr_info("init_rs failed\n");
	return -EINVAL;
	}

	prz->corrected_bytes = 0;
	prz->bad_blocks = 0;

	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
	prz->par_header);
	if (numerr > 0) {
	pr_info("error in header, %d\n", numerr);
	prz->corrected_bytes += numerr;
	} else if (numerr < 0) {
	pr_info("uncorrectable error in header\n");
	prz->bad_blocks++;
	}

	return 0;
	}

	ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
	char *str, size_t len)
	{
	ssize_t ret;

	if (!prz->ecc_info.ecc_size)
	return 0;

	if (prz->corrected_bytes \|\| prz->bad_blocks)
	ret = snprintf(str, len, ""
	"\n%d Corrected bytes, %d unrecoverable blocks\n",
	prz->corrected_bytes, prz->bad_blocks);
	else
	ret = snprintf(str, len, "\nNo errors detected\n");

	return ret;
	}

	static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
	const void *s, unsigned int start, unsigned int count)
	{
	struct persistent_ram_buffer *buffer = prz->buffer;
	memcpy(buffer->data + start, s, count);
	persistent_ram_update_ecc(prz, start, count);
	}

	void persistent_ram_save_old(struct persistent_ram_zone *prz)
	{
	struct persistent_ram_buffer *buffer = prz->buffer;
	size_t size = buffer_size(prz);
	size_t start = buffer_start(prz);

	if (!size)
	return;

	if (!prz->old_log) {
	persistent_ram_ecc_old(prz);
	prz->old_log = kmalloc(size, GFP_KERNEL);
	}
	if (!prz->old_log) {
	pr_err("failed to allocate buffer\n");
	return;
	}

	prz->old_log_size = size;
	memcpy(prz->old_log, &buffer->data[start], size - start);
	memcpy(prz->old_log + size - start, &buffer->data[0], start);
	}

	int notrace persistent_ram_write(struct persistent_ram_zone *prz,
	const void *s, unsigned int count)
	{
	int rem;
	int c = count;
	size_t start;

	if (unlikely(c > prz->buffer_size)) {
	s += c - prz->buffer_size;
	c = prz->buffer_size;
	}

	buffer_size_add(prz, c);

	start = buffer_start_add(prz, c);

	rem = prz->buffer_size - start;
	if (unlikely(rem < c)) {
	persistent_ram_update(prz, s, start, rem);
	s += rem;
	c -= rem;
	start = 0;
	}
	persistent_ram_update(prz, s, start, c);

	persistent_ram_update_header_ecc(prz);

	return count;
	}

	size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
	{
	return prz->old_log_size;
	}

	void persistent_ram_old(struct persistent_ram_zone prz)
	{
	return prz->old_log;
	}

	void persistent_ram_free_old(struct persistent_ram_zone *prz)
	{
	kfree(prz->old_log);
	prz->old_log = NULL;
	prz->old_log_size = 0;
	}

	void persistent_ram_zap(struct persistent_ram_zone *prz)
	{
	atomic_set(&prz->buffer->start, 0);
	atomic_set(&prz->buffer->size, 0);
	persistent_ram_update_header_ecc(prz);
	}

	static void *persistent_ram_vmap(phys_addr_t start, size_t size)
	{
	struct page **pages;
	phys_addr_t page_start;
	unsigned int page_count;
	pgprot_t prot;
	unsigned int i;
	void *vaddr;

	page_start = start - offset_in_page(start);
	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);

	prot = pgprot_noncached(PAGE_KERNEL);

	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
	if (!pages) {
	pr_err("%s: Failed to allocate array for %u pages\n",
	__func__, page_count);
	return NULL;
	}

	for (i = 0; i < page_count; i++) {
	phys_addr_t addr = page_start + i * PAGE_SIZE;
	pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
	}
	vaddr = vmap(pages, page_count, VM_MAP, prot);
	kfree(pages);

	return vaddr;
	}

	static void *persistent_ram_iomap(phys_addr_t start, size_t size)
	{
	if (!request_mem_region(start, size, "persistent_ram")) {
	pr_err("request mem region (0x%llx@0x%llx) failed\n",
	(unsigned long long)size, (unsigned long long)start);
	return NULL;
	}

	buffer_start_add = buffer_start_add_locked;
	buffer_size_add = buffer_size_add_locked;

	return ioremap(start, size);
	}

	static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
	struct persistent_ram_zone *prz)
	{
	prz->paddr = start;
	prz->size = size;

	if (pfn_valid(start >> PAGE_SHIFT))
	prz->vaddr = persistent_ram_vmap(start, size);
	else
	prz->vaddr = persistent_ram_iomap(start, size);

	if (!prz->vaddr) {
	pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
	(unsigned long long)size, (unsigned long long)start);
	return -ENOMEM;
	}

	prz->buffer = prz->vaddr + offset_in_page(start);
	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);

	return 0;
	}

	static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
	struct persistent_ram_ecc_info *ecc_info)
	{
	int ret;

	ret = persistent_ram_init_ecc(prz, ecc_info);
	if (ret)
	return ret;

	sig ^= PERSISTENT_RAM_SIG;

	if (prz->buffer->sig == sig) {
	if (buffer_size(prz) > prz->buffer_size \|\|
	buffer_start(prz) > buffer_size(prz))
	pr_info("found existing invalid buffer, size %zu, start %zu\n",
	buffer_size(prz), buffer_start(prz));
	else {
	pr_debug("found existing buffer, size %zu, start %zu\n",
	buffer_size(prz), buffer_start(prz));
	persistent_ram_save_old(prz);
	return 0;
	}
	} else {
	pr_debug("no valid data in buffer (sig = 0x%08x)\n",
	prz->buffer->sig);
	}

	prz->buffer->sig = sig;
	persistent_ram_zap(prz);

	return 0;
	}

	void persistent_ram_free(struct persistent_ram_zone *prz)
	{
	if (!prz)
	return;

	if (prz->vaddr) {
	if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
	vunmap(prz->vaddr);
	} else {
	iounmap(prz->vaddr);
	release_mem_region(prz->paddr, prz->size);
	}
	prz->vaddr = NULL;
	}
	persistent_ram_free_old(prz);
	kfree(prz);
	}

	struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
	u32 sig, struct persistent_ram_ecc_info *ecc_info)
	{
	struct persistent_ram_zone *prz;
	int ret = -ENOMEM;

	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
	if (!prz) {
	pr_err("failed to allocate persistent ram zone\n");
	goto err;
	}

	ret = persistent_ram_buffer_map(start, size, prz);
	if (ret)
	goto err;

	ret = persistent_ram_post_init(prz, sig, ecc_info);
	if (ret)
	goto err;

	return prz;
	err:
	persistent_ram_free(prz);
	return ERR_PTR(ret);
	}