crash_dump.c

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/*
 * S390 kdump implementation
 *
 * Copyright IBM Corp. 2011
 * Author(s): Michael Holzheu <[email protected]>
 */

#include <linux/crash_dump.h>
#include <asm/lowcore.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/bootmem.h>
#include <linux/elf.h>
#include <asm/os_info.h>
#include <asm/elf.h>
#include <asm/ipl.h>

#define PTR_ADD(x, y) (((char *) (x)) + ((unsigned long) (y)))
#define PTR_SUB(x, y) (((char *) (x)) - ((unsigned long) (y)))
#define PTR_DIFF(x, y) ((unsigned long)(((char *) (x)) - ((unsigned long) (y))))

/*
 * Copy one page from "oldmem"
 *
 * For the kdump reserved memory this functions performs a swap operation:
 *  - [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE] is mapped to [0 - OLDMEM_SIZE].
 *  - [0 - OLDMEM_SIZE] is mapped to [OLDMEM_BASE - OLDMEM_BASE + OLDMEM_SIZE]
 */
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
             size_t csize, unsigned long offset, int userbuf)
{
    unsigned long src;

    if (!csize)
        return 0;

    src = (pfn << PAGE_SHIFT) + offset;
    if (src < OLDMEM_SIZE)
        src += OLDMEM_BASE;
    else if (src > OLDMEM_BASE &&
         src < OLDMEM_BASE + OLDMEM_SIZE)
        src -= OLDMEM_BASE;
    if (userbuf)
        copy_to_user_real((void __force __user *) buf, (void *) src,
                  csize);
    else
        memcpy_real(buf, (void *) src, csize);
    return csize;
}

/*
 * Copy memory from old kernel
 */
int copy_from_oldmem(void *dest, void *src, size_t count)
{
    unsigned long copied = 0;
    int rc;

    if ((unsigned long) src < OLDMEM_SIZE) {
        copied = min(count, OLDMEM_SIZE - (unsigned long) src);
        rc = memcpy_real(dest, src + OLDMEM_BASE, copied);
        if (rc)
            return rc;
    }
    return memcpy_real(dest + copied, src + copied, count - copied);
}

/*
 * Alloc memory and panic in case of ENOMEM
 */
static void *kzalloc_panic(int len)
{
    void *rc;

    rc = kzalloc(len, GFP_KERNEL);
    if (!rc)
        panic("s390 kdump kzalloc (%d) failed", len);
    return rc;
}

/*
 * Get memory layout and create hole for oldmem
 */
static struct mem_chunk *get_memory_layout(void)
{
    struct mem_chunk *chunk_array;

    chunk_array = kzalloc_panic(MEMORY_CHUNKS * sizeof(struct mem_chunk));
    detect_memory_layout(chunk_array);
    create_mem_hole(chunk_array, OLDMEM_BASE, OLDMEM_SIZE, CHUNK_CRASHK);
    return chunk_array;
}

/*
 * Initialize ELF note
 */
static void *nt_init(void *buf, Elf64_Word type, void *desc, int d_len,
             const char *name)
{
    Elf64_Nhdr *note;
    u64 len;

    note = (Elf64_Nhdr *)buf;
    note->n_namesz = strlen(name) + 1;
    note->n_descsz = d_len;
    note->n_type = type;
    len = sizeof(Elf64_Nhdr);

    memcpy(buf + len, name, note->n_namesz);
    len = roundup(len + note->n_namesz, 4);

    memcpy(buf + len, desc, note->n_descsz);
    len = roundup(len + note->n_descsz, 4);

    return PTR_ADD(buf, len);
}

/*
 * Initialize prstatus note
 */
static void *nt_prstatus(void *ptr, struct save_area *sa)
{
    struct elf_prstatus nt_prstatus;
    static int cpu_nr = 1;

    memset(&nt_prstatus, 0, sizeof(nt_prstatus));
    memcpy(&nt_prstatus.pr_reg.gprs, sa->gp_regs, sizeof(sa->gp_regs));
    memcpy(&nt_prstatus.pr_reg.psw, sa->psw, sizeof(sa->psw));
    memcpy(&nt_prstatus.pr_reg.acrs, sa->acc_regs, sizeof(sa->acc_regs));
    nt_prstatus.pr_pid = cpu_nr;
    cpu_nr++;

    return nt_init(ptr, NT_PRSTATUS, &nt_prstatus, sizeof(nt_prstatus),
             "CORE");
}

/*
 * Initialize fpregset (floating point) note
 */
static void *nt_fpregset(void *ptr, struct save_area *sa)
{
    elf_fpregset_t nt_fpregset;

    memset(&nt_fpregset, 0, sizeof(nt_fpregset));
    memcpy(&nt_fpregset.fpc, &sa->fp_ctrl_reg, sizeof(sa->fp_ctrl_reg));
    memcpy(&nt_fpregset.fprs, &sa->fp_regs, sizeof(sa->fp_regs));

    return nt_init(ptr, NT_PRFPREG, &nt_fpregset, sizeof(nt_fpregset),
               "CORE");
}

/*
 * Initialize timer note
 */
static void *nt_s390_timer(void *ptr, struct save_area *sa)
{
    return nt_init(ptr, NT_S390_TIMER, &sa->timer, sizeof(sa->timer),
             KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize TOD clock comparator note
 */
static void *nt_s390_tod_cmp(void *ptr, struct save_area *sa)
{
    return nt_init(ptr, NT_S390_TODCMP, &sa->clk_cmp,
               sizeof(sa->clk_cmp), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize TOD programmable register note
 */
static void *nt_s390_tod_preg(void *ptr, struct save_area *sa)
{
    return nt_init(ptr, NT_S390_TODPREG, &sa->tod_reg,
               sizeof(sa->tod_reg), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize control register note
 */
static void *nt_s390_ctrs(void *ptr, struct save_area *sa)
{
    return nt_init(ptr, NT_S390_CTRS, &sa->ctrl_regs,
               sizeof(sa->ctrl_regs), KEXEC_CORE_NOTE_NAME);
}

/*
 * Initialize prefix register note
 */
static void *nt_s390_prefix(void *ptr, struct save_area *sa)
{
    return nt_init(ptr, NT_S390_PREFIX, &sa->pref_reg,
             sizeof(sa->pref_reg), KEXEC_CORE_NOTE_NAME);
}

/*
 * Fill ELF notes for one CPU with save area registers
 */
void *fill_cpu_elf_notes(void *ptr, struct save_area *sa)
{
    ptr = nt_prstatus(ptr, sa);
    ptr = nt_fpregset(ptr, sa);
    ptr = nt_s390_timer(ptr, sa);
    ptr = nt_s390_tod_cmp(ptr, sa);
    ptr = nt_s390_tod_preg(ptr, sa);
    ptr = nt_s390_ctrs(ptr, sa);
    ptr = nt_s390_prefix(ptr, sa);
    return ptr;
}

/*
 * Initialize prpsinfo note (new kernel)
 */
static void *nt_prpsinfo(void *ptr)
{
    struct elf_prpsinfo prpsinfo;

    memset(&prpsinfo, 0, sizeof(prpsinfo));
    prpsinfo.pr_sname = 'R';
    strcpy(prpsinfo.pr_fname, "vmlinux");
    return nt_init(ptr, NT_PRPSINFO, &prpsinfo, sizeof(prpsinfo),
               KEXEC_CORE_NOTE_NAME);
}

/*
 * Get vmcoreinfo using lowcore->vmcore_info (new kernel)
 */
static void *get_vmcoreinfo_old(unsigned long *size)
{
    char nt_name[11], *vmcoreinfo;
    Elf64_Nhdr note;
    void *addr;

    if (copy_from_oldmem(&addr, &S390_lowcore.vmcore_info, sizeof(addr)))
        return NULL;
    memset(nt_name, 0, sizeof(nt_name));
    if (copy_from_oldmem(&note, addr, sizeof(note)))
        return NULL;
    if (copy_from_oldmem(nt_name, addr + sizeof(note), sizeof(nt_name) - 1))
        return NULL;
    if (strcmp(nt_name, "VMCOREINFO") != 0)
        return NULL;
    vmcoreinfo = kzalloc_panic(note.n_descsz);
    if (copy_from_oldmem(vmcoreinfo, addr + 24, note.n_descsz))
        return NULL;
    *size = note.n_descsz;
    return vmcoreinfo;
}

/*
 * Initialize vmcoreinfo note (new kernel)
 */
static void *nt_vmcoreinfo(void *ptr)
{
    unsigned long size;
    void *vmcoreinfo;

    vmcoreinfo = os_info_old_entry(OS_INFO_VMCOREINFO, &size);
    if (!vmcoreinfo)
        vmcoreinfo = get_vmcoreinfo_old(&size);
    if (!vmcoreinfo)
        return ptr;
    return nt_init(ptr, 0, vmcoreinfo, size, "VMCOREINFO");
}

/*
 * Initialize ELF header (new kernel)
 */
static void *ehdr_init(Elf64_Ehdr *ehdr, int mem_chunk_cnt)
{
    memset(ehdr, 0, sizeof(*ehdr));
    memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
    ehdr->e_ident[EI_CLASS] = ELFCLASS64;
    ehdr->e_ident[EI_DATA] = ELFDATA2MSB;
    ehdr->e_ident[EI_VERSION] = EV_CURRENT;
    memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
    ehdr->e_type = ET_CORE;
    ehdr->e_machine = EM_S390;
    ehdr->e_version = EV_CURRENT;
    ehdr->e_phoff = sizeof(Elf64_Ehdr);
    ehdr->e_ehsize = sizeof(Elf64_Ehdr);
    ehdr->e_phentsize = sizeof(Elf64_Phdr);
    ehdr->e_phnum = mem_chunk_cnt + 1;
    return ehdr + 1;
}

/*
 * Return CPU count for ELF header (new kernel)
 */
static int get_cpu_cnt(void)
{
    int i, cpus = 0;

    for (i = 0; zfcpdump_save_areas[i]; i++) {
        if (zfcpdump_save_areas[i]->pref_reg == 0)
            continue;
        cpus++;
    }
    return cpus;
}

/*
 * Return memory chunk count for ELF header (new kernel)
 */
static int get_mem_chunk_cnt(void)
{
    struct mem_chunk *chunk_array, *mem_chunk;
    int i, cnt = 0;

    chunk_array = get_memory_layout();
    for (i = 0; i < MEMORY_CHUNKS; i++) {
        mem_chunk = &chunk_array[i];
        if (chunk_array[i].type != CHUNK_READ_WRITE &&
            chunk_array[i].type != CHUNK_READ_ONLY)
            continue;
        if (mem_chunk->size == 0)
            continue;
        cnt++;
    }
    kfree(chunk_array);
    return cnt;
}

/*
 * Relocate pointer in order to allow vmcore code access the data
 */
static inline unsigned long relocate(unsigned long addr)
{
    return OLDMEM_BASE + addr;
}

/*
 * Initialize ELF loads (new kernel)
 */
static int loads_init(Elf64_Phdr *phdr, u64 loads_offset)
{
    struct mem_chunk *chunk_array, *mem_chunk;
    int i;

    chunk_array = get_memory_layout();
    for (i = 0; i < MEMORY_CHUNKS; i++) {
        mem_chunk = &chunk_array[i];
        if (mem_chunk->size == 0)
            break;
        if (chunk_array[i].type != CHUNK_READ_WRITE &&
            chunk_array[i].type != CHUNK_READ_ONLY)
            continue;
        else
            phdr->p_filesz = mem_chunk->size;
        phdr->p_type = PT_LOAD;
        phdr->p_offset = mem_chunk->addr;
        phdr->p_vaddr = mem_chunk->addr;
        phdr->p_paddr = mem_chunk->addr;
        phdr->p_memsz = mem_chunk->size;
        phdr->p_flags = PF_R | PF_W | PF_X;
        phdr->p_align = PAGE_SIZE;
        phdr++;
    }
    kfree(chunk_array);
    return i;
}

/*
 * Initialize notes (new kernel)
 */
static void *notes_init(Elf64_Phdr *phdr, void *ptr, u64 notes_offset)
{
    struct save_area *sa;
    void *ptr_start = ptr;
    int i;

    ptr = nt_prpsinfo(ptr);

    for (i = 0; zfcpdump_save_areas[i]; i++) {
        sa = zfcpdump_save_areas[i];
        if (sa->pref_reg == 0)
            continue;
        ptr = fill_cpu_elf_notes(ptr, sa);
    }
    ptr = nt_vmcoreinfo(ptr);
    memset(phdr, 0, sizeof(*phdr));
    phdr->p_type = PT_NOTE;
    phdr->p_offset = relocate(notes_offset);
    phdr->p_filesz = (unsigned long) PTR_SUB(ptr, ptr_start);
    phdr->p_memsz = phdr->p_filesz;
    return ptr;
}

/*
 * Create ELF core header (new kernel)
 */
static void s390_elf_corehdr_create(char **elfcorebuf, size_t *elfcorebuf_sz)
{
    Elf64_Phdr *phdr_notes, *phdr_loads;
    int mem_chunk_cnt;
    void *ptr, *hdr;
    u32 alloc_size;
    u64 hdr_off;

    mem_chunk_cnt = get_mem_chunk_cnt();

    alloc_size = 0x1000 + get_cpu_cnt() * 0x300 +
        mem_chunk_cnt * sizeof(Elf64_Phdr);
    hdr = kzalloc_panic(alloc_size);
    /* Init elf header */
    ptr = ehdr_init(hdr, mem_chunk_cnt);
    /* Init program headers */
    phdr_notes = ptr;
    ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr));
    phdr_loads = ptr;
    ptr = PTR_ADD(ptr, sizeof(Elf64_Phdr) * mem_chunk_cnt);
    /* Init notes */
    hdr_off = PTR_DIFF(ptr, hdr);
    ptr = notes_init(phdr_notes, ptr, ((unsigned long) hdr) + hdr_off);
    /* Init loads */
    hdr_off = PTR_DIFF(ptr, hdr);
    loads_init(phdr_loads, ((unsigned long) hdr) + hdr_off);
    *elfcorebuf_sz = hdr_off;
    *elfcorebuf = (void *) relocate((unsigned long) hdr);
    BUG_ON(*elfcorebuf_sz > alloc_size);
}

/*
 * Create kdump ELF core header in new kernel, if it has not been passed via
 * the "elfcorehdr" kernel parameter
 */
static int setup_kdump_elfcorehdr(void)
{
    size_t elfcorebuf_sz;
    char *elfcorebuf;

    if (!OLDMEM_BASE || is_kdump_kernel())
        return -EINVAL;
    s390_elf_corehdr_create(&elfcorebuf, &elfcorebuf_sz);
    elfcorehdr_addr = (unsigned long long) elfcorebuf;
    elfcorehdr_size = elfcorebuf_sz;
    return 0;
}

subsys_initcall(setup_kdump_elfcorehdr);