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    Subject[patch 5/9] kdump: Allow vmcore ELF header to be created in new kernel
    From: Michael Holzheu <holzheu@linux.vnet.ibm.com>

    For s390 we create the ELF header for /proc/vmcore in the second (kdump)
    kernel. Currently vmcore gets the ELF header from oldmem using the global
    variable "elfcorehdr_addr". This patch introduces a new value
    ELFCORE_ADDR_NEWMEM for "elfcorehdr_addr" that indicates that the ELF header
    is allocated in the new kernel. In this case a new architecture function
    "arch_vmcore_get_elf_hdr()" is called to obtain address and length of the
    ELF header.

    Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
    ---
    fs/proc/vmcore.c | 66 ++++++++++++++++++++++++++++++++++++---------
    include/linux/crash_dump.h | 1
    2 files changed, 55 insertions(+), 12 deletions(-)

    --- a/fs/proc/vmcore.c
    +++ b/fs/proc/vmcore.c
    @@ -494,14 +494,10 @@ static void __init set_vmcore_list_offse
    struct list_head *vc_list)
    {
    loff_t vmcore_off;
    - Elf64_Ehdr *ehdr_ptr;
    struct vmcore *m;

    - ehdr_ptr = (Elf64_Ehdr *)elfptr;
    -
    /* Skip Elf header and program headers. */
    - vmcore_off = sizeof(Elf64_Ehdr) +
    - (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
    + vmcore_off = elfcorebuf_sz;

    list_for_each_entry(m, vc_list, list) {
    m->offset = vmcore_off;
    @@ -514,14 +510,10 @@ static void __init set_vmcore_list_offse
    struct list_head *vc_list)
    {
    loff_t vmcore_off;
    - Elf32_Ehdr *ehdr_ptr;
    struct vmcore *m;

    - ehdr_ptr = (Elf32_Ehdr *)elfptr;
    -
    /* Skip Elf header and program headers. */
    - vmcore_off = sizeof(Elf32_Ehdr) +
    - (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
    + vmcore_off = elfcorebuf_sz;

    list_for_each_entry(m, vc_list, list) {
    m->offset = vmcore_off;
    @@ -641,7 +633,7 @@ static int __init parse_crash_elf32_head
    return 0;
    }

    -static int __init parse_crash_elf_headers(void)
    +static int __init parse_crash_elf_headers_oldmem(void)
    {
    unsigned char e_ident[EI_NIDENT];
    u64 addr;
    @@ -679,6 +671,53 @@ static int __init parse_crash_elf_header
    return 0;
    }

    +/*
    + * provide an empty default implementation here -- architecture
    + * code may override this
    + */
    +int __weak arch_vmcore_get_elf_hdr(char **elfcorebuf, size_t *elfcorebuf_sz)
    +{
    + return -EOPNOTSUPP;
    +}
    +
    +static int __init parse_crash_elf_headers_newmem(void)
    +{
    + unsigned char e_ident[EI_NIDENT];
    + int rc;
    +
    + rc = arch_vmcore_get_elf_hdr(&elfcorebuf, &elfcorebuf_sz);
    + if (rc)
    + return rc;
    + memcpy(e_ident, elfcorebuf, EI_NIDENT);
    + if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
    + printk(KERN_WARNING "Warning: Core image elf header "
    + "not found\n");
    + rc = -EINVAL;
    + goto fail;
    + }
    + if (e_ident[EI_CLASS] == ELFCLASS64) {
    + rc = process_ptload_program_headers_elf64(elfcorebuf,
    + elfcorebuf_sz,
    + &vmcore_list);
    + if (rc)
    + goto fail;
    + set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
    + vmcore_size = get_vmcore_size_elf64(elfcorebuf);
    + } else if (e_ident[EI_CLASS] == ELFCLASS32) {
    + rc = process_ptload_program_headers_elf32(elfcorebuf,
    + elfcorebuf_sz,
    + &vmcore_list);
    + if (rc)
    + goto fail;
    + set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
    + vmcore_size = get_vmcore_size_elf32(elfcorebuf);
    + }
    + return 0;
    +fail:
    + kfree(elfcorebuf);
    + return rc;
    +}
    +
    /* Init function for vmcore module. */
    static int __init vmcore_init(void)
    {
    @@ -687,7 +726,10 @@ static int __init vmcore_init(void)
    /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
    if (!(is_vmcore_usable()))
    return rc;
    - rc = parse_crash_elf_headers();
    + if (elfcorehdr_addr == ELFCORE_ADDR_NEWMEM)
    + rc = parse_crash_elf_headers_newmem();
    + else
    + rc = parse_crash_elf_headers_oldmem();
    if (rc) {
    printk(KERN_WARNING "Kdump: vmcore not initialized\n");
    return rc;
    --- a/include/linux/crash_dump.h
    +++ b/include/linux/crash_dump.h
    @@ -8,6 +8,7 @@

    #define ELFCORE_ADDR_MAX (-1ULL)
    #define ELFCORE_ADDR_ERR (-2ULL)
    +#define ELFCORE_ADDR_NEWMEM (-3ULL)

    extern unsigned long long elfcorehdr_addr;



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