os_info.c

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/*
 * OS info memory interface
 *
 * Copyright IBM Corp. 2012
 * Author(s): Michael Holzheu <[email protected]>
 */

#define KMSG_COMPONENT "os_info"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/crash_dump.h>
#include <linux/kernel.h>
#include <asm/checksum.h>
#include <asm/lowcore.h>
#include <asm/os_info.h>

/*
 * OS info structure has to be page aligned
 */
static struct os_info os_info __page_aligned_data;

/*
 * Compute checksum over OS info structure
 */
u32 os_info_csum(struct os_info *os_info)
{
    int size = sizeof(*os_info) - offsetof(struct os_info, version_major);
    return csum_partial(&os_info->version_major, size, 0);
}

/*
 * Add crashkernel info to OS info and update checksum
 */
void os_info_crashkernel_add(unsigned long base, unsigned long size)
{
    os_info.crashkernel_addr = (u64)(unsigned long)base;
    os_info.crashkernel_size = (u64)(unsigned long)size;
    os_info.csum = os_info_csum(&os_info);
}

/*
 * Add OS info entry and update checksum
 */
void os_info_entry_add(int nr, void *ptr, u64 size)
{
    os_info.entry[nr].addr = (u64)(unsigned long)ptr;
    os_info.entry[nr].size = size;
    os_info.entry[nr].csum = csum_partial(ptr, size, 0);
    os_info.csum = os_info_csum(&os_info);
}

/*
 * Initialize OS info struture and set lowcore pointer
 */
void __init os_info_init(void)
{
    void *ptr = &os_info;

    os_info.version_major = OS_INFO_VERSION_MAJOR;
    os_info.version_minor = OS_INFO_VERSION_MINOR;
    os_info.magic = OS_INFO_MAGIC;
    os_info.csum = os_info_csum(&os_info);
    mem_assign_absolute(S390_lowcore.os_info, (unsigned long) ptr);
}

#ifdef CONFIG_CRASH_DUMP

static struct os_info *os_info_old;

/*
 * Allocate and copy OS info entry from oldmem
 */
static void os_info_old_alloc(int nr, int align)
{
    unsigned long addr, size = 0;
    char *buf, *buf_align, *msg;
    u32 csum;

    addr = os_info_old->entry[nr].addr;
    if (!addr) {
        msg = "not available";
        goto fail;
    }
    size = os_info_old->entry[nr].size;
    buf = kmalloc(size + align - 1, GFP_KERNEL);
    if (!buf) {
        msg = "alloc failed";
        goto fail;
    }
    buf_align = PTR_ALIGN(buf, align);
    if (copy_from_oldmem(buf_align, (void *) addr, size)) {
        msg = "copy failed";
        goto fail_free;
    }
    csum = csum_partial(buf_align, size, 0);
    if (csum != os_info_old->entry[nr].csum) {
        msg = "checksum failed";
        goto fail_free;
    }
    os_info_old->entry[nr].addr = (u64)(unsigned long)buf_align;
    msg = "copied";
    goto out;
fail_free:
    kfree(buf);
fail:
    os_info_old->entry[nr].addr = 0;
out:
    pr_info("entry %i: %s (addr=0x%lx size=%lu)\n",
        nr, msg, addr, size);
}

/*
 * Initialize os info and os info entries from oldmem
 */
static void os_info_old_init(void)
{
    static int os_info_init;
    unsigned long addr;

    if (os_info_init)
        return;
    if (!OLDMEM_BASE)
        goto fail;
    if (copy_from_oldmem(&addr, &S390_lowcore.os_info, sizeof(addr)))
        goto fail;
    if (addr == 0 || addr % PAGE_SIZE)
        goto fail;
    os_info_old = kzalloc(sizeof(*os_info_old), GFP_KERNEL);
    if (!os_info_old)
        goto fail;
    if (copy_from_oldmem(os_info_old, (void *) addr, sizeof(*os_info_old)))
        goto fail_free;
    if (os_info_old->magic != OS_INFO_MAGIC)
        goto fail_free;
    if (os_info_old->csum != os_info_csum(os_info_old))
        goto fail_free;
    if (os_info_old->version_major > OS_INFO_VERSION_MAJOR)
        goto fail_free;
    os_info_old_alloc(OS_INFO_VMCOREINFO, 1);
    os_info_old_alloc(OS_INFO_REIPL_BLOCK, 1);
    pr_info("crashkernel: addr=0x%lx size=%lu\n",
        (unsigned long) os_info_old->crashkernel_addr,
        (unsigned long) os_info_old->crashkernel_size);
    os_info_init = 1;
    return;
fail_free:
    kfree(os_info_old);
fail:
    os_info_init = 1;
    os_info_old = NULL;
}

/*
 * Return pointer to os infor entry and its size
 */
void *os_info_old_entry(int nr, unsigned long *size)
{
    os_info_old_init();

    if (!os_info_old)
        return NULL;
    if (!os_info_old->entry[nr].addr)
        return NULL;
    *size = (unsigned long) os_info_old->entry[nr].size;
    return (void *)(unsigned long)os_info_old->entry[nr].addr;
}
#endif