blob: 34a1e5aa848ce601f4d76911d0618f8ac6469cc3 [file] [log] [blame]
/*
* 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(sizeof(struct page *) * page_count, 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);
}