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Commit 81d38719 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
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x86/kconfig: Consolidate unwinders into multiple choice selection 



There are three mutually exclusive unwinders.  Make that more obvious by
combining them into a multiple-choice selection:

  CONFIG_FRAME_POINTER_UNWINDER
  CONFIG_ORC_UNWINDER
  CONFIG_GUESS_UNWINDER (if CONFIG_EXPERT=y)

Frame pointers are still the default (for now).

The old CONFIG_FRAME_POINTER option is still used in some
arch-independent places, so keep it around, but make it
invisible to the user on x86 - it's now selected by
CONFIG_FRAME_POINTER_UNWINDER=y.

Suggested-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default 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/20170725135424.zukjmgpz3plf5pmt@treble


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a34a766f

arch/x86/Kconfig

+1 −2
Original line number Diff line number Diff line
@@ -73,7 +73,6 @@ config X86 
	select ARCH_USE_QUEUED_RWLOCKS

	select ARCH_USE_QUEUED_SPINLOCKS

	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH

	select ARCH_WANT_FRAME_POINTERS

	select ARCH_WANTS_DYNAMIC_TASK_STRUCT

	select ARCH_WANTS_THP_SWAP		if X86_64

	select BUILDTIME_EXTABLE_SORT
@@ -168,7 +167,7 @@ config X86 
	select HAVE_PERF_REGS

	select HAVE_PERF_USER_STACK_DUMP

	select HAVE_REGS_AND_STACK_ACCESS_API

	select HAVE_RELIABLE_STACKTRACE		if X86_64 && FRAME_POINTER && STACK_VALIDATION

	select HAVE_RELIABLE_STACKTRACE		if X86_64 && FRAME_POINTER_UNWINDER && STACK_VALIDATION

	select HAVE_STACK_VALIDATION		if X86_64

	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_UNSTABLE_SCHED_CLOCK

arch/x86/Kconfig.debug

+40 −7
Original line number Diff line number Diff line
@@ -355,9 +355,32 @@ config PUNIT_ATOM_DEBUG 
	  The current power state can be read from

	  /sys/kernel/debug/punit_atom/dev_power_state



choice

	prompt "Choose kernel unwinder"

	default FRAME_POINTER_UNWINDER

	---help---

	  This determines which method will be used for unwinding kernel stack

	  traces for panics, oopses, bugs, warnings, perf, /proc/<pid>/stack,

	  livepatch, lockdep, and more.



config FRAME_POINTER_UNWINDER

	bool "Frame pointer unwinder"

	select FRAME_POINTER

	---help---

	  This option enables the frame pointer unwinder for unwinding kernel

	  stack traces.



	  The unwinder itself is fast and it uses less RAM than the ORC

	  unwinder, but the kernel text size will grow by ~3% and the kernel's

	  overall performance will degrade by roughly 5-10%.



	  This option is recommended if you want to use the livepatch

	  consistency model, as this is currently the only way to get a

	  reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).



config ORC_UNWINDER

	bool "ORC unwinder"

	depends on X86_64 && !FRAME_POINTER

	depends on X86_64

	select STACK_VALIDATION

	---help---

	  This option enables the ORC (Oops Rewind Capability) unwinder for
@@ -371,12 +394,22 @@ config ORC_UNWINDER 
	  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

	bool "Guess unwinder"

	depends on EXPERT

	---help---

	  This option enables the "guess" unwinder for unwinding kernel stack

	  traces.  It scans the stack and reports every kernel text address it

	  finds.  Some of the addresses it reports may be incorrect.



	  While this option often produces false positives, it can still be

	  useful in many cases.  Unlike the other unwinders, it has no runtime

	  overhead.



endchoice



config FRAME_POINTER

	depends on !ORC_UNWINDER && !GUESS_UNWINDER

	bool



endmenu

arch/x86/configs/tiny.config

+2 −0
Original line number Diff line number Diff line 
CONFIG_NOHIGHMEM=y

# CONFIG_HIGHMEM4G is not set

# CONFIG_HIGHMEM64G is not set

CONFIG_GUESS_UNWINDER=y

# CONFIG_FRAME_POINTER_UNWINDER is not set

arch/x86/include/asm/unwind.h

+2 −2
Original line number Diff line number Diff line
@@ -16,7 +16,7 @@ struct unwind_state { 
	bool signal, full_regs;

	unsigned long sp, bp, ip;

	struct pt_regs *regs;

#elif defined(CONFIG_FRAME_POINTER)

#elif defined(CONFIG_FRAME_POINTER_UNWINDER)

	bool got_irq;

	unsigned long *bp, *orig_sp, ip;

	struct pt_regs *regs;
@@ -50,7 +50,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task, 
	__unwind_start(state, task, regs, first_frame);

}



#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER)

#if defined(CONFIG_ORC_UNWINDER) || defined(CONFIG_FRAME_POINTER_UNWINDER)

static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)

{

	if (unwind_done(state))