• Baoquan He's avatar
    kexec: export the value of phys_base instead of symbol address · 401721ec
    Baoquan He authored
    Currently in x86_64, the symbol address of phys_base is exported to
    vmcoreinfo.  Dave Anderson complained this is really useless for his
    Crash implementation.  Because in user-space utility Crash and
    Makedumpfile which exported vmcore information is mainly used for, value
    of phys_base is needed to covert virtual address of exported kernel
    symbol to physical address.  Especially init_level4_pgt, if we want to
    access and go over the page table to look up a PA corresponding to VA,
    firstly we need calculate
    
      page_dir = SYMBOL(init_level4_pgt) - __START_KERNEL_map + phys_base;
    
    Now in Crash and Makedumpfile, we have to analyze the vmcore elf program
    header to get value of phys_base.  As Dave said, it would be preferable
    if it were readily availabl in vmcoreinfo rather than depending upon the
    PT_LOAD semantics.
    
    Hence in this patch change to export the value of phys_base instead of
    its virtual address.
    
    And people also complained that KERNEL_IMAGE_SIZE exporting is x86_64
    only, should be moved into arch dependent function
    arch_crash_save_vmcoreinfo.  Do the moving in this patch.
    
    Link: http://lkml.kernel.org/r/1478568596-30060-2-git-send-email-bhe@redhat.comSigned-off-by: default avatarBaoquan He <bhe@redhat.com>
    Cc: Thomas Garnier <thgarnie@google.com>
    Cc: Baoquan He <bhe@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: "H . Peter Anvin" <hpa@zytor.com>
    Cc: Eric Biederman <ebiederm@xmission.com>
    Cc: Xunlei Pang <xlpang@redhat.com>
    Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: Eugene Surovegin <surovegin@google.com>
    Cc: Dave Young <dyoung@redhat.com>
    Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
    Cc: Atsushi Kumagai <ats-kumagai@wm.jp.nec.com>
    Cc: Dave Anderson <anderson@redhat.com>
    Cc: Pratyush Anand <panand@redhat.com>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    401721ec
machine_kexec_64.c 14.2 KB