staging: android: 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 538 insertions, 3 deletions

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index b75ee51b2714..23ade2680a4a 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 2ab3d0d55ef6..278a44e0d4e1 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 000000000000..31f8d184f3a0
--- /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