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Commit 7d46d9e6 authored by Vegard Nossum's avatar Vegard Nossum
Browse files

kmemcheck: enable in the x86 Kconfig 



let it rip!

Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>

[rebased for mainline inclusion]
Signed-off-by: default avatarVegard Nossum <vegardno@ifi.uio.no>
parent b1eeab67

arch/x86/Kconfig.debug

+88 −0
Original line number Diff line number Diff line
@@ -260,6 +260,94 @@ config DEFAULT_IO_DELAY_TYPE 
	default IO_DELAY_TYPE_NONE

endif



menuconfig KMEMCHECK

	bool "kmemcheck: trap use of uninitialized memory"

	depends on DEBUG_KERNEL

	depends on !X86_USE_3DNOW

	depends on SLUB || SLAB

	depends on !CC_OPTIMIZE_FOR_SIZE

	depends on !FUNCTION_TRACER

	select FRAME_POINTER

	select STACKTRACE

	default n

	help

	  This option enables tracing of dynamically allocated kernel memory

	  to see if memory is used before it has been given an initial value.

	  Be aware that this requires half of your memory for bookkeeping and

	  will insert extra code at *every* read and write to tracked memory

	  thus slow down the kernel code (but user code is unaffected).



	  The kernel may be started with kmemcheck=0 or kmemcheck=1 to disable

	  or enable kmemcheck at boot-time. If the kernel is started with

	  kmemcheck=0, the large memory and CPU overhead is not incurred.



choice

	prompt "kmemcheck: default mode at boot"

	depends on KMEMCHECK

	default KMEMCHECK_ONESHOT_BY_DEFAULT

	help

	  This option controls the default behaviour of kmemcheck when the

	  kernel boots and no kmemcheck= parameter is given.



config KMEMCHECK_DISABLED_BY_DEFAULT

	bool "disabled"

	depends on KMEMCHECK



config KMEMCHECK_ENABLED_BY_DEFAULT

	bool "enabled"

	depends on KMEMCHECK



config KMEMCHECK_ONESHOT_BY_DEFAULT

	bool "one-shot"

	depends on KMEMCHECK

	help

	  In one-shot mode, only the first error detected is reported before

	  kmemcheck is disabled.



endchoice



config KMEMCHECK_QUEUE_SIZE

	int "kmemcheck: error queue size"

	depends on KMEMCHECK

	default 64

	help

	  Select the maximum number of errors to store in the queue. Since

	  errors can occur virtually anywhere and in any context, we need a

	  temporary storage area which is guarantueed not to generate any

	  other faults. The queue will be emptied as soon as a tasklet may

	  be scheduled. If the queue is full, new error reports will be

	  lost.



config KMEMCHECK_SHADOW_COPY_SHIFT

	int "kmemcheck: shadow copy size (5 => 32 bytes, 6 => 64 bytes)"

	depends on KMEMCHECK

	range 2 8

	default 5

	help

	  Select the number of shadow bytes to save along with each entry of

	  the queue. These bytes indicate what parts of an allocation are

	  initialized, uninitialized, etc. and will be displayed when an

	  error is detected to help the debugging of a particular problem.



config KMEMCHECK_PARTIAL_OK

	bool "kmemcheck: allow partially uninitialized memory"

	depends on KMEMCHECK

	default y

	help

	  This option works around certain GCC optimizations that produce

	  32-bit reads from 16-bit variables where the upper 16 bits are

	  thrown away afterwards. This may of course also hide some real

	  bugs.



config KMEMCHECK_BITOPS_OK

	bool "kmemcheck: allow bit-field manipulation"

	depends on KMEMCHECK

	default n

	help

	  This option silences warnings that would be generated for bit-field

	  accesses where not all the bits are initialized at the same time.

	  This may also hide some real bugs.



config DEBUG_BOOT_PARAMS

	bool "Debug boot parameters"

	depends on DEBUG_KERNEL

lib/Kconfig.debug

+2 −2
Original line number Diff line number Diff line
@@ -300,7 +300,7 @@ config DEBUG_OBJECTS_ENABLE_DEFAULT 


config DEBUG_SLAB

	bool "Debug slab memory allocations"

	depends on DEBUG_KERNEL && SLAB

	depends on DEBUG_KERNEL && SLAB && !KMEMCHECK

	help

	  Say Y here to have the kernel do limited verification on memory

	  allocation as well as poisoning memory on free to catch use of freed
@@ -312,7 +312,7 @@ config DEBUG_SLAB_LEAK 


config SLUB_DEBUG_ON

	bool "SLUB debugging on by default"

	depends on SLUB && SLUB_DEBUG

	depends on SLUB && SLUB_DEBUG && !KMEMCHECK

	default n

	help

	  Boot with debugging on by default. SLUB boots by default with

mm/Kconfig.debug

+1 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ config DEBUG_PAGEALLOC 
	bool "Debug page memory allocations"

	depends on DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC

	depends on !HIBERNATION || !PPC && !SPARC

	depends on !KMEMCHECK

	---help---

	  Unmap pages from the kernel linear mapping after free_pages().

	  This results in a large slowdown, but helps to find certain types