// 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/rslib.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <asm/page.h>
#include "ram_internal.h"
/**
* struct persistent_ram_buffer - persistent circular RAM buffer
*
* @sig: Signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
* @start: First valid byte in the buffer.
* @size: Number of valid bytes in the buffer.
* @data: The contents of the buffer.
*/
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;
size_t 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_ratelimited("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, ""
"\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
prz->corrected_bytes, prz->bad_blocks);
else
ret = snprintf(str, len, "\nECC: No 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 = kvzalloc(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)
{
kvfree(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);
}
#define MEM_TYPE_WCOMBINE 0
#define MEM_TYPE_NONCACHED 1
#define MEM_TYPE_NORMAL 2
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);
switch (memtype) {
case MEM_TYPE_NORMAL:
prot = PAGE_KERNEL;
break;
case MEM_TYPE_NONCACHED:
prot = pgprot_noncached(PAGE_KERNEL);
break;
case MEM_TYPE_WCOMBINE:
prot = pgprot_writecombine(PAGE_KERNEL);
break;
default:
pr_err("invalid mem_type=%d\n", memtype);
return NULL;
}
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);
}
/*
* VM_IOREMAP used here to bypass this region during vread()
* and kmap_atomic() (i.e. kcore) to avoid __va() failures.
*/
vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, 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 && buffer_start(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)
{
struct persistent_ram_zone *prz;
if (!_prz)
return;
prz = *_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);
*_prz = NULL;
}
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);
if (!prz->label)
goto err;
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);
}
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