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| author | Josh Poimboeuf <jpoimboe@redhat.com> | 2017-07-24 18:36:57 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-07-26 13:18:20 +0200 |
| commit | ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67 (patch) | |
| tree | be03fe86edb9ebd70b4d29ca2bc8a4d972ff6644 /arch/x86/Kconfig.debug | |
| parent | 1ee6f00d1164955b7bdadd36fc0f2736754784d9 (diff) | |
| download | lwn-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.tar.gz lwn-ee9f8fce99640811b2b8e79d0d1dbe8bab69ba67.zip | |
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 <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: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/Kconfig.debug')
| -rw-r--r-- | arch/x86/Kconfig.debug | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 353ed09f5fba..dc10ec6ead6e 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -355,4 +355,29 @@ config PUNIT_ATOM_DEBUG The current power state can be read from /sys/kernel/debug/punit_atom/dev_power_state +config ORC_UNWINDER + bool "ORC unwinder" + depends on X86_64 + select STACK_VALIDATION + ---help--- + This option enables the ORC (Oops Rewind Capability) unwinder for + unwinding kernel stack traces. It uses a custom data format which is + a simplified version of the DWARF Call Frame Information standard. + + This unwinder is more accurate across interrupt entry frames than the + frame pointer unwinder. It can also enable a 5-10% performance + improvement across the entire kernel if CONFIG_FRAME_POINTER is + disabled. + + Enabling this option will increase the kernel's runtime memory usage + by roughly 2-4MB, depending on your kernel config. + +config FRAME_POINTER_UNWINDER + def_bool y + depends on !ORC_UNWINDER && FRAME_POINTER + +config GUESS_UNWINDER + def_bool y + depends on !ORC_UNWINDER && !FRAME_POINTER + endmenu |