From ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 24 Jul 2017 18:36:57 -0500 Subject: x86/unwind: Add the ORC unwinder 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: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jiri Slaby Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: live-patching@vger.kernel.org Link: http://lkml.kernel.org/r/0a6cbfb40f8da99b7a45a1a8302dc6aef16ec812.1500938583.git.jpoimboe@redhat.com [ Extended the changelog. ] Signed-off-by: Ingo Molnar --- lib/Kconfig.debug | 3 +++ 1 file changed, 3 insertions(+) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 98fe715522e8..0f0d019ffb99 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -374,6 +374,9 @@ config STACK_VALIDATION pointers (if CONFIG_FRAME_POINTER is enabled). This helps ensure that runtime stack traces are more reliable. + This is also a prerequisite for generation of ORC unwind data, which + is needed for CONFIG_ORC_UNWINDER. + For more information, see tools/objtool/Documentation/stack-validation.txt. -- cgit