• Josh Poimboeuf's avatar
    x86/unwind: Add the ORC unwinder · ee9f8fce
    Josh Poimboeuf authored
    Add the new ORC unwinder which is enabled by CONFIG_ORC_UNWINDER=y.
    It plugs into the existing x86 unwinder framework.
    
    It relies on objtool to generate the needed .orc_unwind and
    .orc_unwind_ip sections.
    
    For more details on why ORC is used instead of DWARF, see
    Documentation/x86/orc-unwinder.txt - but the short version is
    that it's a simplified, fundamentally more robust debugninfo
    data structure, which also allows up to two orders of magnitude
    faster lookups than the DWARF unwinder - which matters to
    profiling workloads like perf.
    
    Thanks to Andy Lutomirski for the performance improvement ideas:
    splitting the ORC unwind table into two parallel arrays and creating a
    fast lookup table to search a subset of the unwind table.
    Signed-off-by: 's avatarJosh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Jiri Slaby <jslaby@suse.cz>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: live-patching@vger.kernel.org
    Link: http://lkml.kernel.org/r/0a6cbfb40f8da99b7a45a1a8302dc6aef16ec812.1500938583.git.jpoimboe@redhat.com
    [ Extended the changelog. ]
    Signed-off-by: 's avatarIngo Molnar <mingo@kernel.org>
    ee9f8fce
orc_lookup.h 1.63 KB