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    Subject[PATCH 4/6] persistent_ram: Move to fs/pstore/ram_core.c
    This is a first step for adding ECC support for pstore RAM backend: we
    will use the persistent_ram routines, kindly provided by Google.

    Basically, persistent_ram is a set of helper routines to deal with the
    [optionally] ECC-protected persistent ram regions.

    A bit of Makefile, Kconfig and header files adjustments were needed
    because of the move.

    Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
    Acked-by: Kees Cook <keescook@chromium.org>
    ---
    drivers/staging/android/Kconfig | 10 +-
    drivers/staging/android/Makefile | 1 -
    drivers/staging/android/persistent_ram.c | 532 ------------------------------
    drivers/staging/android/persistent_ram.h | 82 -----
    drivers/staging/android/ram_console.c | 2 +-
    fs/pstore/Kconfig | 7 +-
    fs/pstore/Makefile | 2 +-
    fs/pstore/ram_core.c | 532 ++++++++++++++++++++++++++++++
    include/linux/pstore_ram.h | 80 +++++
    9 files changed, 620 insertions(+), 628 deletions(-)
    delete mode 100644 drivers/staging/android/persistent_ram.c
    delete mode 100644 drivers/staging/android/persistent_ram.h
    create mode 100644 fs/pstore/ram_core.c

    diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
    index 42f0133..4bfcceb 100644
    --- a/drivers/staging/android/Kconfig
    +++ b/drivers/staging/android/Kconfig
    @@ -25,17 +25,9 @@ config ANDROID_LOGGER
    tristate "Android log driver"
    default n

    -config ANDROID_PERSISTENT_RAM
    - bool
    - depends on HAVE_MEMBLOCK
    - select REED_SOLOMON
    - select REED_SOLOMON_ENC8
    - select REED_SOLOMON_DEC8
    -
    config ANDROID_RAM_CONSOLE
    bool "Android RAM buffer console"
    - depends on !S390 && !UML && HAVE_MEMBLOCK
    - select ANDROID_PERSISTENT_RAM
    + depends on !S390 && !UML && HAVE_MEMBLOCK && PSTORE_RAM
    default n

    config ANDROID_TIMED_OUTPUT
    diff --git a/drivers/staging/android/Makefile b/drivers/staging/android/Makefile
    index 2de5c10..98711e2 100644
    --- a/drivers/staging/android/Makefile
    +++ b/drivers/staging/android/Makefile
    @@ -1,7 +1,6 @@
    obj-$(CONFIG_ANDROID_BINDER_IPC) += binder.o
    obj-$(CONFIG_ASHMEM) += ashmem.o
    obj-$(CONFIG_ANDROID_LOGGER) += logger.o
    -obj-$(CONFIG_ANDROID_PERSISTENT_RAM) += persistent_ram.o
    obj-$(CONFIG_ANDROID_RAM_CONSOLE) += ram_console.o
    obj-$(CONFIG_ANDROID_TIMED_OUTPUT) += timed_output.o
    obj-$(CONFIG_ANDROID_TIMED_GPIO) += timed_gpio.o
    diff --git a/drivers/staging/android/persistent_ram.c b/drivers/staging/android/persistent_ram.c
    deleted file mode 100644
    index 4b46eaa..0000000
    --- a/drivers/staging/android/persistent_ram.c
    +++ /dev/null
    @@ -1,532 +0,0 @@
    -/*
    - * 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.
    - *
    - */
    -
    -#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 <asm/page.h>
    -#include "persistent_ram.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 __initdata LIST_HEAD(persistent_ram_list);
    -
    -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 inline size_t buffer_start_add(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 inline void buffer_size_add(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 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_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_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_size];
    -
    - for (i = 0; i < prz->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_block_size;
    - int ecc_size = prz->ecc_size;
    - int size = prz->ecc_block_size;
    -
    - if (!prz->ecc)
    - return;
    -
    - block = buffer->data + (start & ~(ecc_block_size - 1));
    - par = prz->par_buffer + (start / ecc_block_size) * prz->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)
    - 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)
    - return;
    -
    - block = buffer->data;
    - par = prz->par_buffer;
    - while (block < buffer->data + buffer_size(prz)) {
    - int numerr;
    - int size = prz->ecc_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("persistent_ram: error in block %p, %d\n",
    - block, numerr);
    - prz->corrected_bytes += numerr;
    - } else if (numerr < 0) {
    - pr_devel("persistent_ram: uncorrectable error in block %p\n",
    - block);
    - prz->bad_blocks++;
    - }
    - block += prz->ecc_block_size;
    - par += prz->ecc_size;
    - }
    -}
    -
    -static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
    - size_t buffer_size)
    -{
    - int numerr;
    - struct persistent_ram_buffer *buffer = prz->buffer;
    - int ecc_blocks;
    -
    - if (!prz->ecc)
    - return 0;
    -
    - prz->ecc_block_size = 128;
    - prz->ecc_size = 16;
    - prz->ecc_symsize = 8;
    - prz->ecc_poly = 0x11d;
    -
    - ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
    - prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
    -
    - if (prz->buffer_size > buffer_size) {
    - pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
    - buffer_size, prz->buffer_size);
    - return -EINVAL;
    - }
    -
    - prz->par_buffer = buffer->data + prz->buffer_size;
    - prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
    -
    - /*
    - * first consecutive root is 0
    - * primitive element to generate roots = 1
    - */
    - prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
    - prz->ecc_size);
    - if (prz->rs_decoder == NULL) {
    - pr_info("persistent_ram: 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("persistent_ram: error in header, %d\n", numerr);
    - prz->corrected_bytes += numerr;
    - } else if (numerr < 0) {
    - pr_info("persistent_ram: 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->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);
    -}
    -
    -static void __init
    -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);
    - char *dest;
    -
    - persistent_ram_ecc_old(prz);
    -
    - dest = kmalloc(size, GFP_KERNEL);
    - if (dest == NULL) {
    - pr_err("persistent_ram: failed to allocate buffer\n");
    - return;
    - }
    -
    - prz->old_log = dest;
    - 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;
    -}
    -
    -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;
    - }
    -
    - 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 __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool ecc)
    -{
    - int ret;
    -
    - prz->ecc = ecc;
    -
    - ret = persistent_ram_init_ecc(prz, prz->buffer_size);
    - if (ret)
    - return ret;
    -
    - if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
    - if (buffer_size(prz) > prz->buffer_size ||
    - buffer_start(prz) > buffer_size(prz))
    - pr_info("persistent_ram: found existing invalid buffer,"
    - " size %zu, start %zu\n",
    - buffer_size(prz), buffer_start(prz));
    - else {
    - pr_info("persistent_ram: found existing buffer,"
    - " size %zu, start %zu\n",
    - buffer_size(prz), buffer_start(prz));
    - persistent_ram_save_old(prz);
    - }
    - } else {
    - pr_info("persistent_ram: no valid data in buffer"
    - " (sig = 0x%08x)\n", prz->buffer->sig);
    - }
    -
    - prz->buffer->sig = PERSISTENT_RAM_SIG;
    - atomic_set(&prz->buffer->start, 0);
    - atomic_set(&prz->buffer->size, 0);
    -
    - return 0;
    -}
    -
    -void persistent_ram_free(struct persistent_ram_zone *prz)
    -{
    - if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
    - vunmap(prz->vaddr);
    - } else {
    - iounmap(prz->vaddr);
    - release_mem_region(prz->paddr, prz->size);
    - }
    - persistent_ram_free_old(prz);
    - kfree(prz);
    -}
    -
    -struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
    - size_t size,
    - bool ecc)
    -{
    - struct persistent_ram_zone *prz;
    - int ret = -ENOMEM;
    -
    - prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
    - if (!prz) {
    - pr_err("persistent_ram: failed to allocate persistent ram zone\n");
    - goto err;
    - }
    -
    - ret = persistent_ram_buffer_map(start, size, prz);
    - if (ret)
    - goto err;
    -
    - persistent_ram_post_init(prz, ecc);
    - persistent_ram_update_header_ecc(prz);
    -
    - return prz;
    -err:
    - kfree(prz);
    - return ERR_PTR(ret);
    -}
    -
    -#ifndef MODULE
    -static int __init persistent_ram_buffer_init(const char *name,
    - struct persistent_ram_zone *prz)
    -{
    - int i;
    - struct persistent_ram *ram;
    - struct persistent_ram_descriptor *desc;
    - phys_addr_t start;
    -
    - list_for_each_entry(ram, &persistent_ram_list, node) {
    - start = ram->start;
    - for (i = 0; i < ram->num_descs; i++) {
    - desc = &ram->descs[i];
    - if (!strcmp(desc->name, name))
    - return persistent_ram_buffer_map(start,
    - desc->size, prz);
    - start += desc->size;
    - }
    - }
    -
    - return -EINVAL;
    -}
    -
    -static __init
    -struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
    -{
    - struct persistent_ram_zone *prz;
    - int ret = -ENOMEM;
    -
    - prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
    - if (!prz) {
    - pr_err("persistent_ram: failed to allocate persistent ram zone\n");
    - goto err;
    - }
    -
    - ret = persistent_ram_buffer_init(dev_name(dev), prz);
    - if (ret) {
    - pr_err("persistent_ram: failed to initialize buffer\n");
    - goto err;
    - }
    -
    - persistent_ram_post_init(prz, ecc);
    -
    - return prz;
    -err:
    - kfree(prz);
    - return ERR_PTR(ret);
    -}
    -
    -struct persistent_ram_zone * __init
    -persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
    -{
    - return __persistent_ram_init(dev, ecc);
    -}
    -
    -int __init persistent_ram_early_init(struct persistent_ram *ram)
    -{
    - int ret;
    -
    - ret = memblock_reserve(ram->start, ram->size);
    - if (ret) {
    - pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
    - (long)ram->start, (long)(ram->start + ram->size - 1));
    - return ret;
    - }
    -
    - list_add_tail(&ram->node, &persistent_ram_list);
    -
    - pr_info("Initialized persistent memory from %08lx-%08lx\n",
    - (long)ram->start, (long)(ram->start + ram->size - 1));
    -
    - return 0;
    -}
    -#endif
    diff --git a/drivers/staging/android/persistent_ram.h b/drivers/staging/android/persistent_ram.h
    deleted file mode 100644
    index d23850c..0000000
    --- a/drivers/staging/android/persistent_ram.h
    +++ /dev/null
    @@ -1,82 +0,0 @@
    -/*
    - * Copyright (C) 2011 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.
    - *
    - */
    -
    -#ifndef __LINUX_PERSISTENT_RAM_H__
    -#define __LINUX_PERSISTENT_RAM_H__
    -
    -#include <linux/device.h>
    -#include <linux/kernel.h>
    -#include <linux/list.h>
    -#include <linux/types.h>
    -#include <linux/init.h>
    -
    -struct persistent_ram_buffer;
    -
    -struct persistent_ram_descriptor {
    - const char *name;
    - phys_addr_t size;
    -};
    -
    -struct persistent_ram {
    - phys_addr_t start;
    - phys_addr_t size;
    -
    - int num_descs;
    - struct persistent_ram_descriptor *descs;
    -
    - struct list_head node;
    -};
    -
    -struct persistent_ram_zone {
    - phys_addr_t paddr;
    - size_t size;
    - void *vaddr;
    - struct persistent_ram_buffer *buffer;
    - size_t buffer_size;
    -
    - /* ECC correction */
    - bool ecc;
    - char *par_buffer;
    - char *par_header;
    - struct rs_control *rs_decoder;
    - int corrected_bytes;
    - int bad_blocks;
    - int ecc_block_size;
    - int ecc_size;
    - int ecc_symsize;
    - int ecc_poly;
    -
    - char *old_log;
    - size_t old_log_size;
    -};
    -
    -int persistent_ram_early_init(struct persistent_ram *ram);
    -
    -struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
    - size_t size,
    - bool ecc);
    -void persistent_ram_free(struct persistent_ram_zone *prz);
    -struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev,
    - bool ecc);
    -
    -int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
    - unsigned int count);
    -
    -size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
    -void *persistent_ram_old(struct persistent_ram_zone *prz);
    -void persistent_ram_free_old(struct persistent_ram_zone *prz);
    -ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
    - char *str, size_t len);
    -
    -#endif
    diff --git a/drivers/staging/android/ram_console.c b/drivers/staging/android/ram_console.c
    index ce140ff..82323bb 100644
    --- a/drivers/staging/android/ram_console.c
    +++ b/drivers/staging/android/ram_console.c
    @@ -21,7 +21,7 @@
    #include <linux/string.h>
    #include <linux/uaccess.h>
    #include <linux/io.h>
    -#include "persistent_ram.h"
    +#include <linux/pstore_ram.h>
    #include "ram_console.h"

    static struct persistent_ram_zone *ram_console_zone;
    diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
    index b75ee51..23ade26 100644
    --- a/fs/pstore/Kconfig
    +++ b/fs/pstore/Kconfig
    @@ -14,9 +14,12 @@ config PSTORE

    config PSTORE_RAM
    tristate "Log panic/oops to a RAM buffer"
    - depends on HAS_IOMEM
    depends on PSTORE
    - default n
    + depends on HAS_IOMEM
    + depends on HAVE_MEMBLOCK
    + select REED_SOLOMON
    + select REED_SOLOMON_ENC8
    + select REED_SOLOMON_DEC8
    help
    This enables panic and oops messages to be logged to a circular
    buffer in RAM where it can be read back at some later point.
    diff --git a/fs/pstore/Makefile b/fs/pstore/Makefile
    index 2ab3d0d..278a44e 100644
    --- a/fs/pstore/Makefile
    +++ b/fs/pstore/Makefile
    @@ -6,5 +6,5 @@ obj-y += pstore.o

    pstore-objs += inode.o platform.o

    -ramoops-objs += ram.o
    +ramoops-objs += ram.o ram_core.o
    obj-$(CONFIG_PSTORE_RAM) += ramoops.o
    diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
    new file mode 100644
    index 0000000..31f8d18
    --- /dev/null
    +++ b/fs/pstore/ram_core.c
    @@ -0,0 +1,532 @@
    +/*
    + * 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.
    + *
    + */
    +
    +#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 __initdata LIST_HEAD(persistent_ram_list);
    +
    +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 inline size_t buffer_start_add(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 inline void buffer_size_add(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 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_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_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_size];
    +
    + for (i = 0; i < prz->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_block_size;
    + int ecc_size = prz->ecc_size;
    + int size = prz->ecc_block_size;
    +
    + if (!prz->ecc)
    + return;
    +
    + block = buffer->data + (start & ~(ecc_block_size - 1));
    + par = prz->par_buffer + (start / ecc_block_size) * prz->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)
    + 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)
    + return;
    +
    + block = buffer->data;
    + par = prz->par_buffer;
    + while (block < buffer->data + buffer_size(prz)) {
    + int numerr;
    + int size = prz->ecc_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("persistent_ram: error in block %p, %d\n",
    + block, numerr);
    + prz->corrected_bytes += numerr;
    + } else if (numerr < 0) {
    + pr_devel("persistent_ram: uncorrectable error in block %p\n",
    + block);
    + prz->bad_blocks++;
    + }
    + block += prz->ecc_block_size;
    + par += prz->ecc_size;
    + }
    +}
    +
    +static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
    + size_t buffer_size)
    +{
    + int numerr;
    + struct persistent_ram_buffer *buffer = prz->buffer;
    + int ecc_blocks;
    +
    + if (!prz->ecc)
    + return 0;
    +
    + prz->ecc_block_size = 128;
    + prz->ecc_size = 16;
    + prz->ecc_symsize = 8;
    + prz->ecc_poly = 0x11d;
    +
    + ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
    + prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
    +
    + if (prz->buffer_size > buffer_size) {
    + pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
    + buffer_size, prz->buffer_size);
    + return -EINVAL;
    + }
    +
    + prz->par_buffer = buffer->data + prz->buffer_size;
    + prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
    +
    + /*
    + * first consecutive root is 0
    + * primitive element to generate roots = 1
    + */
    + prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
    + prz->ecc_size);
    + if (prz->rs_decoder == NULL) {
    + pr_info("persistent_ram: 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("persistent_ram: error in header, %d\n", numerr);
    + prz->corrected_bytes += numerr;
    + } else if (numerr < 0) {
    + pr_info("persistent_ram: 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->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);
    +}
    +
    +static void __init
    +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);
    + char *dest;
    +
    + persistent_ram_ecc_old(prz);
    +
    + dest = kmalloc(size, GFP_KERNEL);
    + if (dest == NULL) {
    + pr_err("persistent_ram: failed to allocate buffer\n");
    + return;
    + }
    +
    + prz->old_log = dest;
    + 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;
    +}
    +
    +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;
    + }
    +
    + 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 __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool ecc)
    +{
    + int ret;
    +
    + prz->ecc = ecc;
    +
    + ret = persistent_ram_init_ecc(prz, prz->buffer_size);
    + if (ret)
    + return ret;
    +
    + if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
    + if (buffer_size(prz) > prz->buffer_size ||
    + buffer_start(prz) > buffer_size(prz))
    + pr_info("persistent_ram: found existing invalid buffer,"
    + " size %zu, start %zu\n",
    + buffer_size(prz), buffer_start(prz));
    + else {
    + pr_info("persistent_ram: found existing buffer,"
    + " size %zu, start %zu\n",
    + buffer_size(prz), buffer_start(prz));
    + persistent_ram_save_old(prz);
    + }
    + } else {
    + pr_info("persistent_ram: no valid data in buffer"
    + " (sig = 0x%08x)\n", prz->buffer->sig);
    + }
    +
    + prz->buffer->sig = PERSISTENT_RAM_SIG;
    + atomic_set(&prz->buffer->start, 0);
    + atomic_set(&prz->buffer->size, 0);
    +
    + return 0;
    +}
    +
    +void persistent_ram_free(struct persistent_ram_zone *prz)
    +{
    + if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
    + vunmap(prz->vaddr);
    + } else {
    + iounmap(prz->vaddr);
    + release_mem_region(prz->paddr, prz->size);
    + }
    + persistent_ram_free_old(prz);
    + kfree(prz);
    +}
    +
    +struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
    + size_t size,
    + bool ecc)
    +{
    + struct persistent_ram_zone *prz;
    + int ret = -ENOMEM;
    +
    + prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
    + if (!prz) {
    + pr_err("persistent_ram: failed to allocate persistent ram zone\n");
    + goto err;
    + }
    +
    + ret = persistent_ram_buffer_map(start, size, prz);
    + if (ret)
    + goto err;
    +
    + persistent_ram_post_init(prz, ecc);
    + persistent_ram_update_header_ecc(prz);
    +
    + return prz;
    +err:
    + kfree(prz);
    + return ERR_PTR(ret);
    +}
    +
    +#ifndef MODULE
    +static int __init persistent_ram_buffer_init(const char *name,
    + struct persistent_ram_zone *prz)
    +{
    + int i;
    + struct persistent_ram *ram;
    + struct persistent_ram_descriptor *desc;
    + phys_addr_t start;
    +
    + list_for_each_entry(ram, &persistent_ram_list, node) {
    + start = ram->start;
    + for (i = 0; i < ram->num_descs; i++) {
    + desc = &ram->descs[i];
    + if (!strcmp(desc->name, name))
    + return persistent_ram_buffer_map(start,
    + desc->size, prz);
    + start += desc->size;
    + }
    + }
    +
    + return -EINVAL;
    +}
    +
    +static __init
    +struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
    +{
    + struct persistent_ram_zone *prz;
    + int ret = -ENOMEM;
    +
    + prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
    + if (!prz) {
    + pr_err("persistent_ram: failed to allocate persistent ram zone\n");
    + goto err;
    + }
    +
    + ret = persistent_ram_buffer_init(dev_name(dev), prz);
    + if (ret) {
    + pr_err("persistent_ram: failed to initialize buffer\n");
    + goto err;
    + }
    +
    + persistent_ram_post_init(prz, ecc);
    +
    + return prz;
    +err:
    + kfree(prz);
    + return ERR_PTR(ret);
    +}
    +
    +struct persistent_ram_zone * __init
    +persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
    +{
    + return __persistent_ram_init(dev, ecc);
    +}
    +
    +int __init persistent_ram_early_init(struct persistent_ram *ram)
    +{
    + int ret;
    +
    + ret = memblock_reserve(ram->start, ram->size);
    + if (ret) {
    + pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
    + (long)ram->start, (long)(ram->start + ram->size - 1));
    + return ret;
    + }
    +
    + list_add_tail(&ram->node, &persistent_ram_list);
    +
    + pr_info("Initialized persistent memory from %08lx-%08lx\n",
    + (long)ram->start, (long)(ram->start + ram->size - 1));
    +
    + return 0;
    +}
    +#endif
    diff --git a/include/linux/pstore_ram.h b/include/linux/pstore_ram.h
    index fa4cb02..ffe24a5 100644
    --- a/include/linux/pstore_ram.h
    +++ b/include/linux/pstore_ram.h
    @@ -1,6 +1,86 @@
    +/*
    + * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
    + * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
    + * Copyright (C) 2011 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.
    + *
    + */
    +
    #ifndef __LINUX_PSTORE_RAM_H__
    #define __LINUX_PSTORE_RAM_H__

    +#include <linux/device.h>
    +#include <linux/kernel.h>
    +#include <linux/list.h>
    +#include <linux/types.h>
    +#include <linux/init.h>
    +
    +struct persistent_ram_buffer;
    +
    +struct persistent_ram_descriptor {
    + const char *name;
    + phys_addr_t size;
    +};
    +
    +struct persistent_ram {
    + phys_addr_t start;
    + phys_addr_t size;
    +
    + int num_descs;
    + struct persistent_ram_descriptor *descs;
    +
    + struct list_head node;
    +};
    +
    +struct persistent_ram_zone {
    + phys_addr_t paddr;
    + size_t size;
    + void *vaddr;
    + struct persistent_ram_buffer *buffer;
    + size_t buffer_size;
    +
    + /* ECC correction */
    + bool ecc;
    + char *par_buffer;
    + char *par_header;
    + struct rs_control *rs_decoder;
    + int corrected_bytes;
    + int bad_blocks;
    + int ecc_block_size;
    + int ecc_size;
    + int ecc_symsize;
    + int ecc_poly;
    +
    + char *old_log;
    + size_t old_log_size;
    +};
    +
    +int persistent_ram_early_init(struct persistent_ram *ram);
    +
    +struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
    + size_t size,
    + bool ecc);
    +void persistent_ram_free(struct persistent_ram_zone *prz);
    +struct persistent_ram_zone *persistent_ram_init_ringbuffer(struct device *dev,
    + bool ecc);
    +
    +int persistent_ram_write(struct persistent_ram_zone *prz, const void *s,
    + unsigned int count);
    +
    +size_t persistent_ram_old_size(struct persistent_ram_zone *prz);
    +void *persistent_ram_old(struct persistent_ram_zone *prz);
    +void persistent_ram_free_old(struct persistent_ram_zone *prz);
    +ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
    + char *str, size_t len);
    +
    /*
    * Ramoops platform data
    * @mem_size memory size for ramoops
    --
    1.7.9.2


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