4c6080cd6f
list_del() poisoning can generate 2 64-bit immediate loads but it also can generate one 64-bit immediate load and an addition: 48 b8 00 01 00 00 00 00 ad de movabs rax,0xdead000000000100 48 89 47 58 mov QWORD PTR [rdi+0x58],rax 48 05 00 01 00 00 <=====> add rax,0x100 48 89 47 60 mov QWORD PTR [rdi+0x60],rax However on x86_64 not all constants are equal: those within [-128, 127] range can be added with shorter "add r64, imm32" instruction: 48 b8 00 01 00 00 00 00 ad de movabs rax,0xdead000000000100 48 89 47 58 mov QWORD PTR [rdi+0x58],rax 48 83 c0 22 <======> add rax,0x22 48 89 47 60 mov QWORD PTR [rdi+0x60],rax Patch saves 2 bytes per some LIST_POISON2 usage. (Slightly disappointing) space savings on F29 x86_64 config: add/remove: 0/0 grow/shrink: 0/2164 up/down: 0/-5184 (-5184) Function old new delta zstd_get_workspace 548 546 -2 ... mlx4_delete_all_resources_for_slave 4826 4804 -22 Total: Before=83304131, After=83298947, chg -0.01% New constants are: 0xdead000000000100 0xdead000000000122 Note: LIST_POISON1 can't be changed to ...11 because something in page allocator requires low bit unset. Link: http://lkml.kernel.org/r/20190513191502.GA8492@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Vasiliy Kulikov <segoon@openwall.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
90 lines
2.6 KiB
C
90 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_POISON_H
|
|
#define _LINUX_POISON_H
|
|
|
|
/********** include/linux/list.h **********/
|
|
|
|
/*
|
|
* Architectures might want to move the poison pointer offset
|
|
* into some well-recognized area such as 0xdead000000000000,
|
|
* that is also not mappable by user-space exploits:
|
|
*/
|
|
#ifdef CONFIG_ILLEGAL_POINTER_VALUE
|
|
# define POISON_POINTER_DELTA _AC(CONFIG_ILLEGAL_POINTER_VALUE, UL)
|
|
#else
|
|
# define POISON_POINTER_DELTA 0
|
|
#endif
|
|
|
|
/*
|
|
* These are non-NULL pointers that will result in page faults
|
|
* under normal circumstances, used to verify that nobody uses
|
|
* non-initialized list entries.
|
|
*/
|
|
#define LIST_POISON1 ((void *) 0x100 + POISON_POINTER_DELTA)
|
|
#define LIST_POISON2 ((void *) 0x122 + POISON_POINTER_DELTA)
|
|
|
|
/********** include/linux/timer.h **********/
|
|
/*
|
|
* Magic number "tsta" to indicate a static timer initializer
|
|
* for the object debugging code.
|
|
*/
|
|
#define TIMER_ENTRY_STATIC ((void *) 0x300 + POISON_POINTER_DELTA)
|
|
|
|
/********** mm/page_poison.c **********/
|
|
#ifdef CONFIG_PAGE_POISONING_ZERO
|
|
#define PAGE_POISON 0x00
|
|
#else
|
|
#define PAGE_POISON 0xaa
|
|
#endif
|
|
|
|
/********** mm/page_alloc.c ************/
|
|
|
|
#define TAIL_MAPPING ((void *) 0x400 + POISON_POINTER_DELTA)
|
|
|
|
/********** mm/slab.c **********/
|
|
/*
|
|
* Magic nums for obj red zoning.
|
|
* Placed in the first word before and the first word after an obj.
|
|
*/
|
|
#define RED_INACTIVE 0x09F911029D74E35BULL /* when obj is inactive */
|
|
#define RED_ACTIVE 0xD84156C5635688C0ULL /* when obj is active */
|
|
|
|
#define SLUB_RED_INACTIVE 0xbb
|
|
#define SLUB_RED_ACTIVE 0xcc
|
|
|
|
/* ...and for poisoning */
|
|
#define POISON_INUSE 0x5a /* for use-uninitialised poisoning */
|
|
#define POISON_FREE 0x6b /* for use-after-free poisoning */
|
|
#define POISON_END 0xa5 /* end-byte of poisoning */
|
|
|
|
/********** arch/$ARCH/mm/init.c **********/
|
|
#define POISON_FREE_INITMEM 0xcc
|
|
|
|
/********** arch/ia64/hp/common/sba_iommu.c **********/
|
|
/*
|
|
* arch/ia64/hp/common/sba_iommu.c uses a 16-byte poison string with a
|
|
* value of "SBAIOMMU POISON\0" for spill-over poisoning.
|
|
*/
|
|
|
|
/********** fs/jbd/journal.c **********/
|
|
#define JBD_POISON_FREE 0x5b
|
|
#define JBD2_POISON_FREE 0x5c
|
|
|
|
/********** drivers/base/dmapool.c **********/
|
|
#define POOL_POISON_FREED 0xa7 /* !inuse */
|
|
#define POOL_POISON_ALLOCATED 0xa9 /* !initted */
|
|
|
|
/********** drivers/atm/ **********/
|
|
#define ATM_POISON_FREE 0x12
|
|
#define ATM_POISON 0xdeadbeef
|
|
|
|
/********** kernel/mutexes **********/
|
|
#define MUTEX_DEBUG_INIT 0x11
|
|
#define MUTEX_DEBUG_FREE 0x22
|
|
#define MUTEX_POISON_WW_CTX ((void *) 0x500 + POISON_POINTER_DELTA)
|
|
|
|
/********** security/ **********/
|
|
#define KEY_DESTROY 0xbd
|
|
|
|
#endif
|