[linux.git] / fs / pstore / ram_core.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Google, Inc.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

/**
 * struct persistent_ram_buffer - persistent circular RAM buffer
 *
 * @sig:
 *	signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
 * @start:
 *	offset into @data where the beginning of the stored bytes begin
 * @size:
 *	number of valid bytes stored in @data
 */
struct persistent_ram_buffer {
	uint32_t    sig;
	atomic_t    start;
	atomic_t    size;
	uint8_t     data[];
};

#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(struct persistent_ram_zone *prz, size_t a)
{
	int old;
	int new;
	unsigned long flags = 0;

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_lock_irqsave(&prz->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);

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);

	return old;
}

/* increase the size counter until it hits the max size */
static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
{
	size_t old;
	size_t new;
	unsigned long flags = 0;

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_lock_irqsave(&prz->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:
	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
}

static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
	uint8_t *data, size_t len, uint8_t *ecc)
{
	int i;

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

static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
	void *data, size_t len, uint8_t *ecc)
{
	int i;

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

	/* allocate workspace instead of using stack VLA */
	prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
					  sizeof(*prz->ecc_info.par),
					  GFP_KERNEL);
	if (!prz->ecc_info.par) {
		pr_err("cannot allocate ECC parity workspace\n");
		return -ENOMEM;
	}

	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_toio(buffer->data + start, s, count);
	persistent_ram_update_ecc(prz, start, count);
}

static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
	const void __user *s, unsigned int start, unsigned int count)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
		-EFAULT : 0;
	persistent_ram_update_ecc(prz, start, count);
	return ret;
}

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_fromio(prz->old_log, &buffer->data[start], size - start);
	memcpy_fromio(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;
}

int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
	const void __user *s, unsigned int count)
{
	int rem, ret = 0, 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)) {
		ret = persistent_ram_update_user(prz, s, start, rem);
		s += rem;
		c -= rem;
		start = 0;
	}
	if (likely(!ret))
		ret = persistent_ram_update_user(prz, s, start, c);

	persistent_ram_update_header_ecc(prz);

	return unlikely(ret) ? ret : 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,
		unsigned int memtype)
{
	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);

	if (memtype)
		prot = pgprot_noncached(PAGE_KERNEL);
	else
		prot = pgprot_writecombine(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);

	/*
	 * Since vmap() uses page granularity, we must add the offset
	 * into the page here, to get the byte granularity address
	 * into the mapping to represent the actual "start" location.
	 */
	return vaddr + offset_in_page(start);
}

static void *persistent_ram_iomap(phys_addr_t start, size_t size,
		unsigned int memtype, char *label)
{
	void *va;

	if (!request_mem_region(start, size, label ?: "ramoops")) {
		pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
			label ?: "ramoops",
			(unsigned long long)size, (unsigned long long)start);
		return NULL;
	}

	if (memtype)
		va = ioremap(start, size);
	else
		va = ioremap_wc(start, size);

	/*
	 * Since request_mem_region() and ioremap() are byte-granularity
	 * there is no need handle anything special like we do when the
	 * vmap() case in persistent_ram_vmap() above.
	 */
	return va;
}

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

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

	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;
	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;
	bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);

	ret = persistent_ram_init_ecc(prz, ecc_info);
	if (ret) {
		pr_warn("ECC failed %s\n", prz->label);
		return ret;
	}

	sig ^= PERSISTENT_RAM_SIG;

	if (prz->buffer->sig == sig) {
		if (buffer_size(prz) == 0) {
			pr_debug("found existing empty buffer\n");
			return 0;
		}

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

	/* Reset missing, invalid, or single-use memory area. */
	if (zap)
		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)) {
			/* We must vunmap() at page-granularity. */
			vunmap(prz->vaddr - offset_in_page(prz->paddr));
		} else {
			iounmap(prz->vaddr);
			release_mem_region(prz->paddr, prz->size);
		}
		prz->vaddr = NULL;
	}
	if (prz->rs_decoder) {
		free_rs(prz->rs_decoder);
		prz->rs_decoder = NULL;
	}
	kfree(prz->ecc_info.par);
	prz->ecc_info.par = NULL;

	persistent_ram_free_old(prz);
	kfree(prz->label);
	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,
			unsigned int memtype, u32 flags, char *label)
{
	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;
	}

	/* Initialize general buffer state. */
	raw_spin_lock_init(&prz->buffer_lock);
	prz->flags = flags;
	prz->label = kstrdup(label, GFP_KERNEL);

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

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

	pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
		prz->label, prz->size, (unsigned long long)prz->paddr,
		sizeof(*prz->buffer), prz->buffer_size,
		prz->size - sizeof(*prz->buffer) - prz->buffer_size,
		prz->ecc_info.ecc_size, prz->ecc_info.block_size);

	return prz;
err:
	persistent_ram_free(prz);
	return ERR_PTR(ret);
}
Commit	Line	Data
9c92ab61	1	// SPDX-License-Identifier: GPL-2.0-only
c672528a CC	2	/*
c672528a CC	3	* Copyright (C) 2012 Google, Inc.
c672528a CC	4	*/
c672528a CC	5
9ee85b8b	6	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
ef748853	7
404a6043 CC	8	#include <linux/device.h>
404a6043 CC	9	#include <linux/err.h>
c672528a	10	#include <linux/errno.h>
c672528a CC	11	#include <linux/init.h>
c672528a CC	12	#include <linux/io.h>
5bf6d1b9	13	#include <linux/kernel.h>
404a6043 CC	14	#include <linux/list.h>
404a6043 CC	15	#include <linux/memblock.h>
5bf6d1b9	16	#include <linux/pstore_ram.h>
9cc05ad9	17	#include <linux/rslib.h>
c672528a	18	#include <linux/slab.h>
5bf6d1b9	19	#include <linux/uaccess.h>
404a6043	20	#include <linux/vmalloc.h>
24c3d2f3	21	#include <asm/page.h>
c672528a	22
c208f7d4 KC	23	/**
	24	* struct persistent_ram_buffer - persistent circular RAM buffer
	25	*
	26	* @sig:
	27	* signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
	28	* @start:
	29	* offset into @data where the beginning of the stored bytes begin
	30	* @size:
	31	* number of valid bytes stored in @data
	32	*/
c672528a CC	33	struct persistent_ram_buffer {
c672528a CC	34	uint32_t sig;
808d0387 CC	35	atomic_t start;
808d0387 CC	36	atomic_t size;
8128d3aa	37	uint8_t data[];
c672528a CC	38	};
	39
	40	#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
	41
808d0387 CC	42	static inline size_t buffer_size(struct persistent_ram_zone *prz)
	43	{
	44	return atomic_read(&prz->buffer->size);
	45	}
	46
	47	static inline size_t buffer_start(struct persistent_ram_zone *prz)
	48	{
	49	return atomic_read(&prz->buffer->start);
	50	}
	51
0405a5ce	52	/* increase and wrap the start pointer, returning the old value */
d5a9bf0b	53	static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
0405a5ce RH	54	{
	55	int old;
	56	int new;
663deb47	57	unsigned long flags = 0;
0405a5ce	58
663deb47 JF	59	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
663deb47 JF	60	raw_spin_lock_irqsave(&prz->buffer_lock, flags);
0405a5ce RH	61
	62	old = atomic_read(&prz->buffer->start);
	63	new = old + a;
017321cf	64	while (unlikely(new >= prz->buffer_size))
0405a5ce RH	65	new -= prz->buffer_size;
	66	atomic_set(&prz->buffer->start, new);
	67
663deb47 JF	68	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
663deb47 JF	69	raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
0405a5ce RH	70
	71	return old;
	72	}
	73
	74	/* increase the size counter until it hits the max size */
d5a9bf0b	75	static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
0405a5ce RH	76	{
	77	size_t old;
	78	size_t new;
663deb47	79	unsigned long flags = 0;
0405a5ce	80
663deb47 JF	81	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
663deb47 JF	82	raw_spin_lock_irqsave(&prz->buffer_lock, flags);
0405a5ce RH	83
	84	old = atomic_read(&prz->buffer->size);
	85	if (old == prz->buffer_size)
	86	goto exit;
	87
	88	new = old + a;
	89	if (new > prz->buffer_size)
	90	new = prz->buffer_size;
	91	atomic_set(&prz->buffer->size, new);
	92
	93	exit:
663deb47 JF	94	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
663deb47 JF	95	raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
0405a5ce RH	96	}
0405a5ce RH	97
a15d0b36	98	static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
c672528a CC	99	uint8_t data, size_t len, uint8_t ecc)
	100	{
	101	int i;
9cc05ad9	102
c672528a	103	/* Initialize the parity buffer */
f2531f19 KC	104	memset(prz->ecc_info.par, 0,
	105	prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
	106	encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
c31ad081	107	for (i = 0; i < prz->ecc_info.ecc_size; i++)
f2531f19	108	ecc[i] = prz->ecc_info.par[i];
c672528a CC	109	}
	110
	111	static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
	112	void data, size_t len, uint8_t ecc)
	113	{
	114	int i;
9cc05ad9	115
c31ad081	116	for (i = 0; i < prz->ecc_info.ecc_size; i++)
f2531f19 KC	117	prz->ecc_info.par[i] = ecc[i];
f2531f19 KC	118	return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
c672528a CC	119	NULL, 0, NULL, 0, NULL);
c672528a CC	120	}
c672528a	121
a15d0b36	122	static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
808d0387	123	unsigned int start, unsigned int count)
c672528a CC	124	{
c672528a CC	125	struct persistent_ram_buffer *buffer = prz->buffer;
c672528a CC	126	uint8_t *buffer_end = buffer->data + prz->buffer_size;
	127	uint8_t *block;
	128	uint8_t *par;
c31ad081 AH	129	int ecc_block_size = prz->ecc_info.block_size;
	130	int ecc_size = prz->ecc_info.ecc_size;
	131	int size = ecc_block_size;
9cc05ad9	132
c31ad081	133	if (!ecc_size)
9cc05ad9 CC	134	return;
9cc05ad9 CC	135
808d0387	136	block = buffer->data + (start & ~(ecc_block_size - 1));
c31ad081	137	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
808d0387	138
c672528a	139	do {
9cc05ad9	140	if (block + ecc_block_size > buffer_end)
c672528a CC	141	size = buffer_end - block;
c672528a CC	142	persistent_ram_encode_rs8(prz, block, size, par);
9cc05ad9 CC	143	block += ecc_block_size;
9cc05ad9 CC	144	par += ecc_size;
808d0387	145	} while (block < buffer->data + start + count);
c672528a CC	146	}
c672528a CC	147
9cc05ad9	148	static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
c672528a	149	{
c672528a CC	150	struct persistent_ram_buffer *buffer = prz->buffer;
c672528a CC	151
c31ad081	152	if (!prz->ecc_info.ecc_size)
9cc05ad9 CC	153	return;
9cc05ad9 CC	154
c672528a CC	155	persistent_ram_encode_rs8(prz, (uint8_t )buffer, sizeof(buffer),
c672528a CC	156	prz->par_header);
c672528a CC	157	}
c672528a CC	158
9cc05ad9	159	static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
c672528a CC	160	{
c672528a CC	161	struct persistent_ram_buffer *buffer = prz->buffer;
c672528a CC	162	uint8_t *block;
	163	uint8_t *par;
	164
c31ad081	165	if (!prz->ecc_info.ecc_size)
9cc05ad9 CC	166	return;
9cc05ad9 CC	167
c672528a CC	168	block = buffer->data;
c672528a CC	169	par = prz->par_buffer;
808d0387	170	while (block < buffer->data + buffer_size(prz)) {
c672528a	171	int numerr;
c31ad081	172	int size = prz->ecc_info.block_size;
c672528a CC	173	if (block + size > buffer->data + prz->buffer_size)
	174	size = buffer->data + prz->buffer_size - block;
	175	numerr = persistent_ram_decode_rs8(prz, block, size, par);
	176	if (numerr > 0) {
ef748853	177	pr_devel("error in block %p, %d\n", block, numerr);
c672528a CC	178	prz->corrected_bytes += numerr;
c672528a CC	179	} else if (numerr < 0) {
ef748853	180	pr_devel("uncorrectable error in block %p\n", block);
c672528a CC	181	prz->bad_blocks++;
c672528a CC	182	}
c31ad081 AH	183	block += prz->ecc_info.block_size;
c31ad081 AH	184	par += prz->ecc_info.ecc_size;
9cc05ad9 CC	185	}
	186	}
	187
5ca5d4e6	188	static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
c31ad081	189	struct persistent_ram_ecc_info *ecc_info)
9cc05ad9 CC	190	{
	191	int numerr;
	192	struct persistent_ram_buffer *buffer = prz->buffer;
	193	int ecc_blocks;
1e6a9e56	194	size_t ecc_total;
9cc05ad9	195
c31ad081	196	if (!ecc_info \|\| !ecc_info->ecc_size)
9cc05ad9 CC	197	return 0;
9cc05ad9 CC	198
c31ad081 AH	199	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
	200	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
	201	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
	202	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
9cc05ad9	203
c31ad081 AH	204	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
	205	prz->ecc_info.block_size +
	206	prz->ecc_info.ecc_size);
	207	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
1e6a9e56 AV	208	if (ecc_total >= prz->buffer_size) {
1e6a9e56 AV	209	pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
c31ad081 AH	210	__func__, prz->ecc_info.ecc_size,
c31ad081 AH	211	ecc_total, prz->buffer_size);
9cc05ad9 CC	212	return -EINVAL;
	213	}
	214
1e6a9e56	215	prz->buffer_size -= ecc_total;
9cc05ad9	216	prz->par_buffer = buffer->data + prz->buffer_size;
c31ad081 AH	217	prz->par_header = prz->par_buffer +
c31ad081 AH	218	ecc_blocks * prz->ecc_info.ecc_size;
9cc05ad9 CC	219
	220	/*
	221	* first consecutive root is 0
	222	* primitive element to generate roots = 1
	223	*/
c31ad081 AH	224	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
c31ad081 AH	225	0, 1, prz->ecc_info.ecc_size);
9cc05ad9	226	if (prz->rs_decoder == NULL) {
ef748853	227	pr_info("init_rs failed\n");
9cc05ad9	228	return -EINVAL;
c672528a	229	}
9cc05ad9	230
f2531f19 KC	231	/* allocate workspace instead of using stack VLA */
	232	prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
	233	sizeof(*prz->ecc_info.par),
	234	GFP_KERNEL);
	235	if (!prz->ecc_info.par) {
	236	pr_err("cannot allocate ECC parity workspace\n");
	237	return -ENOMEM;
	238	}
	239
9cc05ad9 CC	240	prz->corrected_bytes = 0;
	241	prz->bad_blocks = 0;
	242
	243	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
	244	prz->par_header);
	245	if (numerr > 0) {
ef748853	246	pr_info("error in header, %d\n", numerr);
9cc05ad9 CC	247	prz->corrected_bytes += numerr;
9cc05ad9 CC	248	} else if (numerr < 0) {
ef748853	249	pr_info("uncorrectable error in header\n");
9cc05ad9 CC	250	prz->bad_blocks++;
	251	}
	252
	253	return 0;
	254	}
	255
	256	ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
	257	char *str, size_t len)
	258	{
	259	ssize_t ret;
	260
bd08ec33 AH	261	if (!prz->ecc_info.ecc_size)
	262	return 0;
	263
9cc05ad9 CC	264	if (prz->corrected_bytes \|\| prz->bad_blocks)
	265	ret = snprintf(str, len, ""
	266	"\n%d Corrected bytes, %d unrecoverable blocks\n",
	267	prz->corrected_bytes, prz->bad_blocks);
	268	else
	269	ret = snprintf(str, len, "\nNo errors detected\n");
	270
	271	return ret;
	272	}
	273
a15d0b36	274	static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
808d0387	275	const void *s, unsigned int start, unsigned int count)
9cc05ad9 CC	276	{
9cc05ad9 CC	277	struct persistent_ram_buffer *buffer = prz->buffer;
7e75678d	278	memcpy_toio(buffer->data + start, s, count);
808d0387	279	persistent_ram_update_ecc(prz, start, count);
9cc05ad9 CC	280	}
9cc05ad9 CC	281
5bf6d1b9 MS	282	static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
	283	const void __user *s, unsigned int start, unsigned int count)
	284	{
	285	struct persistent_ram_buffer *buffer = prz->buffer;
ff847781	286	int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
5bf6d1b9 MS	287	-EFAULT : 0;
	288	persistent_ram_update_ecc(prz, start, count);
	289	return ret;
	290	}
	291
201e4aca	292	void persistent_ram_save_old(struct persistent_ram_zone *prz)
9cc05ad9 CC	293	{
9cc05ad9 CC	294	struct persistent_ram_buffer *buffer = prz->buffer;
808d0387 CC	295	size_t size = buffer_size(prz);
808d0387 CC	296	size_t start = buffer_start(prz);
9cc05ad9	297
201e4aca AV	298	if (!size)
201e4aca AV	299	return;
c672528a	300
201e4aca AV	301	if (!prz->old_log) {
	302	persistent_ram_ecc_old(prz);
	303	prz->old_log = kmalloc(size, GFP_KERNEL);
	304	}
	305	if (!prz->old_log) {
ef748853	306	pr_err("failed to allocate buffer\n");
c672528a CC	307	return;
	308	}
	309
808d0387	310	prz->old_log_size = size;
d771fdf9 AB	311	memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
d771fdf9 AB	312	memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
c672528a CC	313	}
c672528a CC	314
a15d0b36	315	int notrace persistent_ram_write(struct persistent_ram_zone *prz,
c672528a CC	316	const void *s, unsigned int count)
	317	{
	318	int rem;
	319	int c = count;
808d0387	320	size_t start;
c672528a	321
808d0387	322	if (unlikely(c > prz->buffer_size)) {
c672528a CC	323	s += c - prz->buffer_size;
	324	c = prz->buffer_size;
	325	}
808d0387	326
484dd30e	327	buffer_size_add(prz, c);
808d0387 CC	328
	329	start = buffer_start_add(prz, c);
	330
	331	rem = prz->buffer_size - start;
	332	if (unlikely(rem < c)) {
	333	persistent_ram_update(prz, s, start, rem);
c672528a CC	334	s += rem;
c672528a CC	335	c -= rem;
808d0387	336	start = 0;
c672528a	337	}
808d0387	338	persistent_ram_update(prz, s, start, c);
c672528a	339
9cc05ad9	340	persistent_ram_update_header_ecc(prz);
c672528a CC	341
	342	return count;
	343	}
	344
5bf6d1b9 MS	345	int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
	346	const void __user *s, unsigned int count)
	347	{
	348	int rem, ret = 0, c = count;
	349	size_t start;
	350
5bf6d1b9 MS	351	if (unlikely(c > prz->buffer_size)) {
	352	s += c - prz->buffer_size;
	353	c = prz->buffer_size;
	354	}
	355
	356	buffer_size_add(prz, c);
	357
	358	start = buffer_start_add(prz, c);
	359
	360	rem = prz->buffer_size - start;
	361	if (unlikely(rem < c)) {
	362	ret = persistent_ram_update_user(prz, s, start, rem);
	363	s += rem;
	364	c -= rem;
	365	start = 0;
	366	}
	367	if (likely(!ret))
	368	ret = persistent_ram_update_user(prz, s, start, c);
	369
	370	persistent_ram_update_header_ecc(prz);
	371
	372	return unlikely(ret) ? ret : count;
	373	}
	374
c672528a CC	375	size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
	376	{
	377	return prz->old_log_size;
	378	}
	379
	380	void persistent_ram_old(struct persistent_ram_zone prz)
	381	{
	382	return prz->old_log;
	383	}
	384
	385	void persistent_ram_free_old(struct persistent_ram_zone *prz)
	386	{
	387	kfree(prz->old_log);
	388	prz->old_log = NULL;
	389	prz->old_log_size = 0;
	390	}
	391
fce39793 AV	392	void persistent_ram_zap(struct persistent_ram_zone *prz)
	393	{
	394	atomic_set(&prz->buffer->start, 0);
	395	atomic_set(&prz->buffer->size, 0);
	396	persistent_ram_update_header_ecc(prz);
	397	}
	398
027bc8b0 TL	399	static void *persistent_ram_vmap(phys_addr_t start, size_t size,
027bc8b0 TL	400	unsigned int memtype)
c672528a	401	{
404a6043 CC	402	struct page **pages;
	403	phys_addr_t page_start;
	404	unsigned int page_count;
	405	pgprot_t prot;
	406	unsigned int i;
2b1321e4	407	void *vaddr;
404a6043 CC	408
	409	page_start = start - offset_in_page(start);
	410	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
	411
027bc8b0 TL	412	if (memtype)
	413	prot = pgprot_noncached(PAGE_KERNEL);
	414	else
	415	prot = pgprot_writecombine(PAGE_KERNEL);
404a6043	416
b8f52d89	417	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
404a6043	418	if (!pages) {
ef748853 FF	419	pr_err("%s: Failed to allocate array for %u pages\n",
ef748853 FF	420	__func__, page_count);
2b1321e4	421	return NULL;
404a6043 CC	422	}
	423
	424	for (i = 0; i < page_count; i++) {
	425	phys_addr_t addr = page_start + i * PAGE_SIZE;
	426	pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
	427	}
2b1321e4	428	vaddr = vmap(pages, page_count, VM_MAP, prot);
404a6043	429	kfree(pages);
2b1321e4	430
831b624d BY	431	/*
	432	* Since vmap() uses page granularity, we must add the offset
	433	* into the page here, to get the byte granularity address
	434	* into the mapping to represent the actual "start" location.
	435	*/
	436	return vaddr + offset_in_page(start);
2b1321e4 AV	437	}
2b1321e4 AV	438
027bc8b0	439	static void *persistent_ram_iomap(phys_addr_t start, size_t size,
1227daa4	440	unsigned int memtype, char *label)
24c3d2f3	441	{
027bc8b0 TL	442	void *va;
027bc8b0 TL	443
1227daa4	444	if (!request_mem_region(start, size, label ?: "ramoops")) {
9ee85b8b KC	445	pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
9ee85b8b KC	446	label ?: "ramoops",
24c3d2f3 AV	447	(unsigned long long)size, (unsigned long long)start);
	448	return NULL;
	449	}
	450
027bc8b0 TL	451	if (memtype)
	452	va = ioremap(start, size);
	453	else
	454	va = ioremap_wc(start, size);
	455
831b624d BY	456	/*
	457	* Since request_mem_region() and ioremap() are byte-granularity
	458	* there is no need handle anything special like we do when the
	459	* vmap() case in persistent_ram_vmap() above.
	460	*/
027bc8b0	461	return va;
24c3d2f3 AV	462	}
24c3d2f3 AV	463
2b1321e4	464	static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
027bc8b0	465	struct persistent_ram_zone *prz, int memtype)
2b1321e4	466	{
d3b48769 AV	467	prz->paddr = start;
	468	prz->size = size;
	469
24c3d2f3	470	if (pfn_valid(start >> PAGE_SHIFT))
027bc8b0	471	prz->vaddr = persistent_ram_vmap(start, size, memtype);
24c3d2f3	472	else
1227daa4 KC	473	prz->vaddr = persistent_ram_iomap(start, size, memtype,
1227daa4 KC	474	prz->label);
24c3d2f3	475
404a6043	476	if (!prz->vaddr) {
2b1321e4 AV	477	pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
2b1321e4 AV	478	(unsigned long long)size, (unsigned long long)start);
404a6043 CC	479	return -ENOMEM;
	480	}
	481
831b624d	482	prz->buffer = prz->vaddr;
404a6043 CC	483	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
	484
	485	return 0;
	486	}
	487
f568f6ca	488	static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
76d5692a	489	struct persistent_ram_ecc_info *ecc_info)
404a6043	490	{
bb4206f2	491	int ret;
7684bd33	492	bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
c672528a	493
c31ad081	494	ret = persistent_ram_init_ecc(prz, ecc_info);
0eed84ff KC	495	if (ret) {
0eed84ff KC	496	pr_warn("ECC failed %s\n", prz->label);
bb4206f2	497	return ret;
0eed84ff	498	}
c672528a	499
cbe7cbf5 AV	500	sig ^= PERSISTENT_RAM_SIG;
	501
	502	if (prz->buffer->sig == sig) {
30696378 JFG	503	if (buffer_size(prz) == 0) {
	504	pr_debug("found existing empty buffer\n");
	505	return 0;
	506	}
	507
808d0387	508	if (buffer_size(prz) > prz->buffer_size \|\|
7684bd33	509	buffer_start(prz) > buffer_size(prz)) {
ef748853 FF	510	pr_info("found existing invalid buffer, size %zu, start %zu\n",
ef748853 FF	511	buffer_size(prz), buffer_start(prz));
7684bd33 PW	512	zap = true;
7684bd33 PW	513	} else {
ef748853 FF	514	pr_debug("found existing buffer, size %zu, start %zu\n",
ef748853 FF	515	buffer_size(prz), buffer_start(prz));
c672528a CC	516	persistent_ram_save_old(prz);
	517	}
	518	} else {
ef748853 FF	519	pr_debug("no valid data in buffer (sig = 0x%08x)\n",
ef748853 FF	520	prz->buffer->sig);
7684bd33 PW	521	prz->buffer->sig = sig;
7684bd33 PW	522	zap = true;
c672528a CC	523	}
c672528a CC	524
7684bd33 PW	525	/* Reset missing, invalid, or single-use memory area. */
	526	if (zap)
	527	persistent_ram_zap(prz);
c672528a	528
bb4206f2 AV	529	return 0;
	530	}
	531
d3b48769 AV	532	void persistent_ram_free(struct persistent_ram_zone *prz)
d3b48769 AV	533	{
beeb9432 AV	534	if (!prz)
	535	return;
	536
	537	if (prz->vaddr) {
	538	if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
831b624d BY	539	/* We must vunmap() at page-granularity. */
831b624d BY	540	vunmap(prz->vaddr - offset_in_page(prz->paddr));
beeb9432 AV	541	} else {
	542	iounmap(prz->vaddr);
	543	release_mem_region(prz->paddr, prz->size);
	544	}
	545	prz->vaddr = NULL;
d3b48769	546	}
f2531f19 KC	547	if (prz->rs_decoder) {
	548	free_rs(prz->rs_decoder);
	549	prz->rs_decoder = NULL;
	550	}
	551	kfree(prz->ecc_info.par);
	552	prz->ecc_info.par = NULL;
	553
d3b48769	554	persistent_ram_free_old(prz);
1227daa4	555	kfree(prz->label);
d3b48769 AV	556	kfree(prz);
	557	}
	558
f568f6ca	559	struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
027bc8b0	560	u32 sig, struct persistent_ram_ecc_info *ecc_info,
1227daa4	561	unsigned int memtype, u32 flags, char *label)
8cf5aff8 AV	562	{
	563	struct persistent_ram_zone *prz;
	564	int ret = -ENOMEM;
	565
	566	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
	567	if (!prz) {
ef748853	568	pr_err("failed to allocate persistent ram zone\n");
8cf5aff8 AV	569	goto err;
	570	}
	571
76d5692a	572	/* Initialize general buffer state. */
e9a330c4	573	raw_spin_lock_init(&prz->buffer_lock);
76d5692a	574	prz->flags = flags;
e163fdb3	575	prz->label = kstrdup(label, GFP_KERNEL);
76d5692a	576
027bc8b0	577	ret = persistent_ram_buffer_map(start, size, prz, memtype);
8cf5aff8 AV	578	if (ret)
	579	goto err;
	580
76d5692a	581	ret = persistent_ram_post_init(prz, sig, ecc_info);
beeb9432 AV	582	if (ret)
beeb9432 AV	583	goto err;
8cf5aff8	584
dc80b1ea KC	585	pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
	586	prz->label, prz->size, (unsigned long long)prz->paddr,
	587	sizeof(*prz->buffer), prz->buffer_size,
	588	prz->size - sizeof(*prz->buffer) - prz->buffer_size,
	589	prz->ecc_info.ecc_size, prz->ecc_info.block_size);
	590
8cf5aff8 AV	591	return prz;
8cf5aff8 AV	592	err:
beeb9432	593	persistent_ram_free(prz);
8cf5aff8 AV	594	return ERR_PTR(ret);
8cf5aff8 AV	595	}