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    objtool: Enable compilation of objtool for all architectures · 0decf1f8
    Matt Helsley authored
    
    
    Objtool currently only compiles for x86 architectures. This is
    fine as it presently does not support tooling for other
    architectures. However, we would like to be able to convert other
    kernel tools to run as objtool sub commands because they too
    process ELF object files. This will allow us to convert tools
    such as recordmcount to use objtool's ELF code.
    
    Since much of recordmcount's ELF code is copy-paste code to/from
    a variety of other kernel tools (look at modpost for example) this
    means that if we can convert recordmcount we can convert more.
    
    We define weak definitions for subcommand entry functions and other weak
    definitions for shared functions critical to building existing
    subcommands. These return 127 when the command is missing which signify
    tools that do not exist on all architectures.  In this case the "check"
    and "orc" tools do not exist on all architectures so we only add them
    for x86. Future changes adding support for "check", to arm64 for
    example, can then modify the SUBCMD_CHECK variable when building for
    arm64.
    
    Objtool is not currently wired in to KConfig to be built for other
    architectures because it's not needed for those architectures and
    there are no commands it supports other than those for x86. As more
    command support is enabled on various architectures the necessary
    KConfig changes can be made (e.g. adding "STACK_VALIDATION") to
    trigger building objtool.
    
    [ jpoimboe: remove aliases, add __weak macro, add error messages ]
    
    Cc: Julien Thierry <jthierry@redhat.com>
    Signed-off-by: default avatarMatt Helsley <mhelsley@vmware.com>
    Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
    0decf1f8