[Crash-utility] [PATCH] crash-gcore-command extension module: ARM64 support

[Dave Anderson]

Hello Daisuke,

Attached is a patch to introduce support for the ARM64 architecture
for the gcore extension module.   

The patch is fairly straight-forward other than the fact that on
ARM64 machines, the chain of headers included from the crash utility's
"defs.h" looks like this:

  /usr/include/crash/defs.h 
    /usr/include/signal.h 
      /usr/include/sys/ucontext.h 
        /usr/include/sys/procfs.h 

The <sys/procfs.h> file defines several of the ELF-related structures that
are hard-coded in gcore_defs.h, causing compile failures due to duplicate 
structure declarations.

Note that the <sys/ucontext.h> file on the other three architectures does 
not #include <sys/procfs.h> so there are no conflicts.  It would be possible
to move all architectures to include <sys/procfs.h>, but for example, that 
would also bring in the <sys/user.h> definition of the user_regs_struct,
which in turn causes a myriad of register name mismatches in gcore_x86.c.
So for the sake of simplicity, wherever there is an ARM64-only duplicate
structure or definition in gcore_defs.h, I've encapsulated them by:

  #if defined(X86) || defined(X86_64) || defined(ARM)

Also, there are two generic fixes, one where the gcore module fails on
Linux 3.11 and later kernels due to a structure member name change,
and another that changes the getopt() return variable to an "int" instead
of a "char".

Here are the details:
  
  gcore.mk:
  
    - Introduce ARM64 as a supported architecture
    - Add libgcore/gcore_arm64 to GCORE_CFILES
  
  gcore.c:
  
    - In cmd_gcore() change "c" type to "int" to correctly match
      the return type of getopt(); without it, the while loop
      spins indefinitely on ARM64.
    - In gcore_offset_table_init(), account for the Linux 3.11 
      structure member name-change from ns_proxy.pid_ns to 
      ns_proxy.pid_ns_for_children; without it, the gcore command
      fails during initialization.
  
  libgcore/gcore_defs.h:
  
    - Add ARM64 ELF- and REGSET_VIEW-related #defines required for
      each architecture.
    - Account for variable page sizes in ARM64.
    - Restrict the hard-coded ELF_NGREG, elf_siginfo, elf_prstatus, 
      __kernel_old_uid_t and __kernel_old_gid_t, and elf_prsinfo 
      definitions to X86, X86_64 and ARM architectures.
    - Add ARM64 thread_struct_fpsmid_state and thread_struct_tp_value
      offsets to gcore_offset_table.
  
  libgcore/gcore_coredump.c:
  
    - In fill_prstatus_note(), account for the ARM64 usage of 
      "user_pt_regs" structure instead of the "user_regs_struct" 
      used by the other architectures.
  
  libgcore/gcore_arm64.c:
  
    - Implement ARM64-specific user_regset and user_regset_view
      structures and all required support functions.
  
Please accept these changes into an new package version.
  
Thanks,
  Dave
  
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