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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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3c5c3cfb9e
Patch series "kasan: support backing vmalloc space with real shadow
memory", v11.
Currently, vmalloc space is backed by the early shadow page. This means
that kasan is incompatible with VMAP_STACK.
This series provides a mechanism to back vmalloc space with real,
dynamically allocated memory. I have only wired up x86, because that's
the only currently supported arch I can work with easily, but it's very
easy to wire up other architectures, and it appears that there is some
work-in-progress code to do this on arm64 and s390.
This has been discussed before in the context of VMAP_STACK:
- https://bugzilla.kernel.org/show_bug.cgi?id=202009
- https://lkml.org/lkml/2018/7/22/198
- https://lkml.org/lkml/2019/7/19/822
In terms of implementation details:
Most mappings in vmalloc space are small, requiring less than a full
page of shadow space. Allocating a full shadow page per mapping would
therefore be wasteful. Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.
Instead, share backing space across multiple mappings. Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region. This page can be shared by other vmalloc mappings
later on.
We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.
Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:
- Turning on KASAN, inline instrumentation, without vmalloc, introuduces
a 4.1x-4.2x slowdown in vmalloc operations.
- Turning this on introduces the following slowdowns over KASAN:
* ~1.76x slower single-threaded (test_vmalloc.sh performance)
* ~2.18x slower when both cpus are performing operations
simultaneously (test_vmalloc.sh sequential_test_order=1)
This is unfortunate but given that this is a debug feature only, not the
end of the world. The benchmarks are also a stress-test for the vmalloc
subsystem: they're not indicative of an overall 2x slowdown!
This patch (of 4):
Hook into vmalloc and vmap, and dynamically allocate real shadow memory
to back the mappings.
Most mappings in vmalloc space are small, requiring less than a full
page of shadow space. Allocating a full shadow page per mapping would
therefore be wasteful. Furthermore, to ensure that different mappings
use different shadow pages, mappings would have to be aligned to
KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE.
Instead, share backing space across multiple mappings. Allocate a
backing page when a mapping in vmalloc space uses a particular page of
the shadow region. This page can be shared by other vmalloc mappings
later on.
We hook in to the vmap infrastructure to lazily clean up unused shadow
memory.
To avoid the difficulties around swapping mappings around, this code
expects that the part of the shadow region that covers the vmalloc space
will not be covered by the early shadow page, but will be left unmapped.
This will require changes in arch-specific code.
This allows KASAN with VMAP_STACK, and may be helpful for architectures
that do not have a separate module space (e.g. powerpc64, which I am
currently working on). It also allows relaxing the module alignment
back to PAGE_SIZE.
Testing with test_vmalloc.sh on an x86 VM with 2 vCPUs shows that:
- Turning on KASAN, inline instrumentation, without vmalloc, introuduces
a 4.1x-4.2x slowdown in vmalloc operations.
- Turning this on introduces the following slowdowns over KASAN:
* ~1.76x slower single-threaded (test_vmalloc.sh performance)
* ~2.18x slower when both cpus are performing operations
simultaneously (test_vmalloc.sh sequential_test_order=3D1)
This is unfortunate but given that this is a debug feature only, not the
end of the world.
The full benchmark results are:
Performance
No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN
fix_size_alloc_test 662004 11404956 17.23 19144610 28.92 1.68
full_fit_alloc_test 710950 12029752 16.92 13184651 18.55 1.10
long_busy_list_alloc_test 9431875 43990172 4.66 82970178 8.80 1.89
random_size_alloc_test 5033626 23061762 4.58 47158834 9.37 2.04
fix_align_alloc_test 1252514 15276910 12.20 31266116 24.96 2.05
random_size_align_alloc_te 1648501 14578321 8.84 25560052 15.51 1.75
align_shift_alloc_test 147 830 5.65 5692 38.72 6.86
pcpu_alloc_test 80732 125520 1.55 140864 1.74 1.12
Total Cycles 119240774314 763211341128 6.40 1390338696894 11.66 1.82
Sequential, 2 cpus
No KASAN KASAN original x baseline KASAN vmalloc x baseline x KASAN
fix_size_alloc_test 1423150
14276550 10.03 27733022 19.49 1.94
full_fit_alloc_test 1754219 14722640 8.39 15030786 8.57 1.02
long_busy_list_alloc_test 11451858 52154973 4.55 107016027 9.34 2.05
random_size_alloc_test 5989020 26735276 4.46 68885923 11.50 2.58
fix_align_alloc_test 2050976 20166900 9.83 50491675 24.62 2.50
random_size_align_alloc_te 2858229 17971700 6.29 38730225 13.55 2.16
align_shift_alloc_test 405 6428 15.87 26253 64.82 4.08
pcpu_alloc_test 127183 151464 1.19 216263 1.70 1.43
Total Cycles 54181269392 308723699764 5.70 650772566394 12.01 2.11
fix_size_alloc_test 1420404 14289308 10.06 27790035 19.56 1.94
full_fit_alloc_test 1736145 14806234 8.53 15274301 8.80 1.03
long_busy_list_alloc_test 11404638 52270785 4.58 107550254 9.43 2.06
random_size_alloc_test 6017006 26650625 4.43 68696127 11.42 2.58
fix_align_alloc_test 2045504 20280985 9.91 50414862 24.65 2.49
random_size_align_alloc_te 2845338 17931018 6.30 38510276 13.53 2.15
align_shift_alloc_test 472 3760 7.97 9656 20.46 2.57
pcpu_alloc_test 118643 132732 1.12 146504 1.23 1.10
Total Cycles 54040011688 309102805492 5.72 651325675652 12.05 2.11
[dja@axtens.net: fixups]
Link: http://lkml.kernel.org/r/20191120052719.7201-1-dja@axtens.net
Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D202009
Link: http://lkml.kernel.org/r/20191031093909.9228-2-dja@axtens.net
Signed-off-by: Mark Rutland <mark.rutland@arm.com> [shadow rework]
Signed-off-by: Daniel Axtens <dja@axtens.net>
Co-developed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
251 lines
7.5 KiB
C
251 lines
7.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __MM_KASAN_KASAN_H
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#define __MM_KASAN_KASAN_H
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#include <linux/kasan.h>
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#include <linux/stackdepot.h>
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#define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
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#define KASAN_SHADOW_MASK (KASAN_SHADOW_SCALE_SIZE - 1)
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#define KASAN_TAG_KERNEL 0xFF /* native kernel pointers tag */
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#define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */
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#define KASAN_TAG_MAX 0xFD /* maximum value for random tags */
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#ifdef CONFIG_KASAN_GENERIC
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#define KASAN_FREE_PAGE 0xFF /* page was freed */
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#define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */
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#define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */
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#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */
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#else
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#define KASAN_FREE_PAGE KASAN_TAG_INVALID
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#define KASAN_PAGE_REDZONE KASAN_TAG_INVALID
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#define KASAN_KMALLOC_REDZONE KASAN_TAG_INVALID
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#define KASAN_KMALLOC_FREE KASAN_TAG_INVALID
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#endif
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#define KASAN_GLOBAL_REDZONE 0xFA /* redzone for global variable */
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#define KASAN_VMALLOC_INVALID 0xF9 /* unallocated space in vmapped page */
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/*
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* Stack redzone shadow values
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* (Those are compiler's ABI, don't change them)
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*/
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#define KASAN_STACK_LEFT 0xF1
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#define KASAN_STACK_MID 0xF2
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#define KASAN_STACK_RIGHT 0xF3
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#define KASAN_STACK_PARTIAL 0xF4
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/*
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* alloca redzone shadow values
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*/
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#define KASAN_ALLOCA_LEFT 0xCA
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#define KASAN_ALLOCA_RIGHT 0xCB
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#define KASAN_ALLOCA_REDZONE_SIZE 32
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/*
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* Stack frame marker (compiler ABI).
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*/
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#define KASAN_CURRENT_STACK_FRAME_MAGIC 0x41B58AB3
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/* Don't break randconfig/all*config builds */
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#ifndef KASAN_ABI_VERSION
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#define KASAN_ABI_VERSION 1
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#endif
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struct kasan_access_info {
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const void *access_addr;
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const void *first_bad_addr;
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size_t access_size;
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bool is_write;
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unsigned long ip;
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};
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/* The layout of struct dictated by compiler */
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struct kasan_source_location {
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const char *filename;
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int line_no;
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int column_no;
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};
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/* The layout of struct dictated by compiler */
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struct kasan_global {
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const void *beg; /* Address of the beginning of the global variable. */
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size_t size; /* Size of the global variable. */
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size_t size_with_redzone; /* Size of the variable + size of the red zone. 32 bytes aligned */
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const void *name;
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const void *module_name; /* Name of the module where the global variable is declared. */
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unsigned long has_dynamic_init; /* This needed for C++ */
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#if KASAN_ABI_VERSION >= 4
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struct kasan_source_location *location;
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#endif
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#if KASAN_ABI_VERSION >= 5
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char *odr_indicator;
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#endif
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};
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/**
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* Structures to keep alloc and free tracks *
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*/
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#define KASAN_STACK_DEPTH 64
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struct kasan_track {
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u32 pid;
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depot_stack_handle_t stack;
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};
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#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
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#define KASAN_NR_FREE_STACKS 5
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#else
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#define KASAN_NR_FREE_STACKS 1
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#endif
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struct kasan_alloc_meta {
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struct kasan_track alloc_track;
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struct kasan_track free_track[KASAN_NR_FREE_STACKS];
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#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
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u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
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u8 free_track_idx;
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#endif
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};
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struct qlist_node {
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struct qlist_node *next;
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};
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struct kasan_free_meta {
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/* This field is used while the object is in the quarantine.
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* Otherwise it might be used for the allocator freelist.
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*/
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struct qlist_node quarantine_link;
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};
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struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
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const void *object);
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struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
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const void *object);
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static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
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{
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return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
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<< KASAN_SHADOW_SCALE_SHIFT);
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}
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static inline bool addr_has_shadow(const void *addr)
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{
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return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
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}
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void kasan_poison_shadow(const void *address, size_t size, u8 value);
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/**
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* check_memory_region - Check memory region, and report if invalid access.
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* @addr: the accessed address
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* @size: the accessed size
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* @write: true if access is a write access
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* @ret_ip: return address
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* @return: true if access was valid, false if invalid
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*/
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bool check_memory_region(unsigned long addr, size_t size, bool write,
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unsigned long ret_ip);
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void *find_first_bad_addr(void *addr, size_t size);
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const char *get_bug_type(struct kasan_access_info *info);
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void kasan_report(unsigned long addr, size_t size,
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bool is_write, unsigned long ip);
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void kasan_report_invalid_free(void *object, unsigned long ip);
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struct page *kasan_addr_to_page(const void *addr);
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#if defined(CONFIG_KASAN_GENERIC) && \
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(defined(CONFIG_SLAB) || defined(CONFIG_SLUB))
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void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
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void quarantine_reduce(void);
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void quarantine_remove_cache(struct kmem_cache *cache);
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#else
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static inline void quarantine_put(struct kasan_free_meta *info,
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struct kmem_cache *cache) { }
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static inline void quarantine_reduce(void) { }
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static inline void quarantine_remove_cache(struct kmem_cache *cache) { }
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#endif
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#ifdef CONFIG_KASAN_SW_TAGS
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void print_tags(u8 addr_tag, const void *addr);
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u8 random_tag(void);
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#else
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static inline void print_tags(u8 addr_tag, const void *addr) { }
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static inline u8 random_tag(void)
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{
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return 0;
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}
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#endif
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#ifndef arch_kasan_set_tag
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static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
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{
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return addr;
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}
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#endif
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#ifndef arch_kasan_reset_tag
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#define arch_kasan_reset_tag(addr) ((void *)(addr))
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#endif
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#ifndef arch_kasan_get_tag
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#define arch_kasan_get_tag(addr) 0
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#endif
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#define set_tag(addr, tag) ((void *)arch_kasan_set_tag((addr), (tag)))
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#define reset_tag(addr) ((void *)arch_kasan_reset_tag(addr))
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#define get_tag(addr) arch_kasan_get_tag(addr)
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/*
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* Exported functions for interfaces called from assembly or from generated
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* code. Declarations here to avoid warning about missing declarations.
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*/
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asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
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void __asan_register_globals(struct kasan_global *globals, size_t size);
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void __asan_unregister_globals(struct kasan_global *globals, size_t size);
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void __asan_loadN(unsigned long addr, size_t size);
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void __asan_storeN(unsigned long addr, size_t size);
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void __asan_handle_no_return(void);
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void __asan_alloca_poison(unsigned long addr, size_t size);
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void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom);
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void __asan_load1(unsigned long addr);
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void __asan_store1(unsigned long addr);
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void __asan_load2(unsigned long addr);
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void __asan_store2(unsigned long addr);
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void __asan_load4(unsigned long addr);
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void __asan_store4(unsigned long addr);
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void __asan_load8(unsigned long addr);
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void __asan_store8(unsigned long addr);
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void __asan_load16(unsigned long addr);
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void __asan_store16(unsigned long addr);
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void __asan_load1_noabort(unsigned long addr);
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void __asan_store1_noabort(unsigned long addr);
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void __asan_load2_noabort(unsigned long addr);
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void __asan_store2_noabort(unsigned long addr);
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void __asan_load4_noabort(unsigned long addr);
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void __asan_store4_noabort(unsigned long addr);
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void __asan_load8_noabort(unsigned long addr);
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void __asan_store8_noabort(unsigned long addr);
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void __asan_load16_noabort(unsigned long addr);
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void __asan_store16_noabort(unsigned long addr);
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void __asan_set_shadow_00(const void *addr, size_t size);
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void __asan_set_shadow_f1(const void *addr, size_t size);
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void __asan_set_shadow_f2(const void *addr, size_t size);
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void __asan_set_shadow_f3(const void *addr, size_t size);
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void __asan_set_shadow_f5(const void *addr, size_t size);
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void __asan_set_shadow_f8(const void *addr, size_t size);
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#endif
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