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From:   Daniel Axtens <dja@axtens.net>
To:     Christophe Leroy <christophe.leroy@c-s.fr>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        kasan-dev@googlegroups.com, linux-mm@kvack.org
Subject: Re: [PATCH v9 02/11] powerpc: prepare string/mem functions for KASAN
In-Reply-To: <a99c00f8-85c2-a581-afe6-9995ae84e47b@c-s.fr>
References: <cover.1551443452.git.christophe.leroy@c-s.fr> <45fb252fc1b27f2804109fa35ba2882ae29e6035.1551443453.git.christophe.leroy@c-s.fr> <87sgw31a85.fsf@dja-thinkpad.axtens.net> <a99c00f8-85c2-a581-afe6-9995ae84e47b@c-s.fr>
Date:   Fri, 08 Mar 2019 15:49:20 +1100
Message-ID: <87imwu9din.fsf@dja-thinkpad.axtens.net>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

>>> +#ifdef CONFIG_KASAN
>>> +#define _GLOBAL_KASAN(fn)	.weak fn ; _GLOBAL(__##fn) ; _GLOBAL(fn)
>>> +#define _GLOBAL_TOC_KASAN(fn)	.weak fn ; _GLOBAL_TOC(__##fn) ; _GLOBAL_TOC(fn)
>>> +#define EXPORT_SYMBOL_KASAN(fn)	EXPORT_SYMBOL(__##fn) ; EXPORT_SYMBOL(fn)
>> 
>> I'm having some trouble with this. I get warnings like this:
>> 
>> WARNING: EXPORT symbol "__memcpy" [vmlinux] version generation failed, symbol will not be versioned.
>
> I don't have this problem, neither with my PPC32 defconfigs nor with 
> ppc64e_defconfig - SPARSEMEM_VMEMMAP + KASAN
> Using GCC 8.1
>
> I've been looking into it in more details and can't understand the need 
> for a weak symbol. A weak symbol is to allow it's optional replacement 
> by other code. But here KASAN replaces it inconditionally, so I see no 
> point for a weak symbol here.

If you don't make it weak, and kasan and arch code will export it as
a regular symbol, and you will end up with a clash like this:

powerpc64-linux-gnu-ld: mm/kasan/common.o: in function `.memset':
(.text+0x210): multiple definition of `.memset'; arch/powerpc/lib/mem_64.o:(.text+0x0): first defined here
powerpc64-linux-gnu-ld: mm/kasan/common.o:(.opd+0x78): multiple definition of `memset'; arch/powerpc/lib/mem_64.o:(.opd+0x0): first defined here

But your patch doesn't do that, so don't worry :)

> Regarding the export of the functions, I believe that when the functions 
> are defined in KASAN, they should be exported by KASAN and not by the 
> arch. But such a change is out of scope for now. So lets have a double 
> export for now, one day we will drop it.
>
> Regarding export of __memcpy() etc..., there is at least the LKDTM 
> module which inhibits KASAN, so it really needs to be exported.
>
> What about the patch below ?

Yes, that works for me. After de-mangling it I have used it to replace
your patch 2 v9.

Thanks for bearing with me.

Regards,
Daniel

>
> Christophe
>
> diff --git a/arch/powerpc/include/asm/kasan.h 
> b/arch/powerpc/include/asm/kasan.h
> new file mode 100644
> index 000000000000..2c179a39d4ba
> --- /dev/null
> +++ b/arch/powerpc/include/asm/kasan.h
> @@ -0,0 +1,15 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __ASM_KASAN_H
> +#define __ASM_KASAN_H
> +
> +#ifdef CONFIG_KASAN
> +#define _GLOBAL_KASAN(fn)	_GLOBAL(__##fn)
> +#define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(__##fn)
> +#define EXPORT_SYMBOL_KASAN(fn)	EXPORT_SYMBOL(__##fn)
> +#else
> +#define _GLOBAL_KASAN(fn)	_GLOBAL(fn)
> +#define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(fn)
> +#define EXPORT_SYMBOL_KASAN(fn)
> +#endif
> +
> +#endif
> diff --git a/arch/powerpc/include/asm/string.h 
> b/arch/powerpc/include/asm/string.h
> index 1647de15a31e..9bf6dffb4090 100644
> --- a/arch/powerpc/include/asm/string.h
> +++ b/arch/powerpc/include/asm/string.h
> @@ -4,14 +4,17 @@
>
>   #ifdef __KERNEL__
>
> +#ifndef CONFIG_KASAN
>   #define __HAVE_ARCH_STRNCPY
>   #define __HAVE_ARCH_STRNCMP
> +#define __HAVE_ARCH_MEMCHR
> +#define __HAVE_ARCH_MEMCMP
> +#define __HAVE_ARCH_MEMSET16
> +#endif
> +
>   #define __HAVE_ARCH_MEMSET
>   #define __HAVE_ARCH_MEMCPY
>   #define __HAVE_ARCH_MEMMOVE
> -#define __HAVE_ARCH_MEMCMP
> -#define __HAVE_ARCH_MEMCHR
> -#define __HAVE_ARCH_MEMSET16
>   #define __HAVE_ARCH_MEMCPY_FLUSHCACHE
>
>   extern char * strcpy(char *,const char *);
> @@ -27,7 +30,27 @@ extern int memcmp(const void *,const void 
> *,__kernel_size_t);
>   extern void * memchr(const void *,int,__kernel_size_t);
>   extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>
> +void *__memset(void *s, int c, __kernel_size_t count);
> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
> +void *__memmove(void *to, const void *from, __kernel_size_t n);
> +
> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> +/*
> + * For files that are not instrumented (e.g. mm/slub.c) we
> + * should use not instrumented version of mem* functions.
> + */
> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
> +#define memmove(dst, src, len) __memmove(dst, src, len)
> +#define memset(s, c, n) __memset(s, c, n)
> +
> +#ifndef __NO_FORTIFY
> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
> +#endif
> +
> +#endif
> +
>   #ifdef CONFIG_PPC64
> +#ifndef CONFIG_KASAN
>   #define __HAVE_ARCH_MEMSET32
>   #define __HAVE_ARCH_MEMSET64
>
> @@ -49,8 +72,11 @@ static inline void *memset64(uint64_t *p, uint64_t v, 
> __kernel_size_t n)
>   {
>   	return __memset64(p, v, n * 8);
>   }
> +#endif
>   #else
> +#ifndef CONFIG_KASAN
>   #define __HAVE_ARCH_STRLEN
> +#endif
>
>   extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
>   #endif
> diff --git a/arch/powerpc/kernel/prom_init_check.sh 
> b/arch/powerpc/kernel/prom_init_check.sh
> index 667df97d2595..181fd10008ef 100644
> --- a/arch/powerpc/kernel/prom_init_check.sh
> +++ b/arch/powerpc/kernel/prom_init_check.sh
> @@ -16,8 +16,16 @@
>   # If you really need to reference something from prom_init.o add
>   # it to the list below:
>
> +grep "^CONFIG_KASAN=y$" .config >/dev/null
> +if [ $? -eq 0 ]
> +then
> +	MEM_FUNCS="__memcpy __memset"
> +else
> +	MEM_FUNCS="memcpy memset"
> +fi
> +
>   WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
> -_end enter_prom memcpy memset reloc_offset __secondary_hold
> +_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
>   __secondary_hold_acknowledge __secondary_hold_spinloop __start
>   strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
>   reloc_got2 kernstart_addr memstart_addr linux_banner _stext
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 79396e184bca..47a4de434c22 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -8,9 +8,14 @@ ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
>   CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
>   CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>
> -obj-y += string.o alloc.o code-patching.o feature-fixups.o
> +obj-y += alloc.o code-patching.o feature-fixups.o
>
> -obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o strlen_32.o
> +ifndef CONFIG_KASAN
> +obj-y	+=	string.o memcmp_$(BITS).o
> +obj-$(CONFIG_PPC32)	+= strlen_32.o
> +endif
> +
> +obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
>
>   obj-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
>
> @@ -34,7 +39,7 @@ obj64-$(CONFIG_KPROBES_SANITY_TEST)	+= 
> test_emulate_step.o \
>   					   test_emulate_step_exec_instr.o
>
>   obj-y			+= checksum_$(BITS).o checksum_wrappers.o \
> -			   string_$(BITS).o memcmp_$(BITS).o
> +			   string_$(BITS).o
>
>   obj-y			+= sstep.o ldstfp.o quad.o
>   obj64-y			+= quad.o
> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> index ba66846fe973..d5642481fb98 100644
> --- a/arch/powerpc/lib/copy_32.S
> +++ b/arch/powerpc/lib/copy_32.S
> @@ -14,6 +14,7 @@
>   #include <asm/ppc_asm.h>
>   #include <asm/export.h>
>   #include <asm/code-patching-asm.h>
> +#include <asm/kasan.h>
>
>   #define COPY_16_BYTES		\
>   	lwz	r7,4(r4);	\
> @@ -68,6 +69,7 @@ CACHELINE_BYTES = L1_CACHE_BYTES
>   LG_CACHELINE_BYTES = L1_CACHE_SHIFT
>   CACHELINE_MASK = (L1_CACHE_BYTES-1)
>
> +#ifndef CONFIG_KASAN
>   _GLOBAL(memset16)
>   	rlwinm.	r0 ,r5, 31, 1, 31
>   	addi	r6, r3, -4
> @@ -81,6 +83,7 @@ _GLOBAL(memset16)
>   	sth	r4, 4(r6)
>   	blr
>   EXPORT_SYMBOL(memset16)
> +#endif
>
>   /*
>    * Use dcbz on the complete cache lines in the destination
> @@ -91,7 +94,7 @@ EXPORT_SYMBOL(memset16)
>    * We therefore skip the optimised bloc that uses dcbz. This jump is
>    * replaced by a nop once cache is active. This is done in machine_init()
>    */
> -_GLOBAL(memset)
> +_GLOBAL_KASAN(memset)
>   	cmplwi	0,r5,4
>   	blt	7f
>
> @@ -151,6 +154,7 @@ _GLOBAL(memset)
>   	bdnz	9b
>   	blr
>   EXPORT_SYMBOL(memset)
> +EXPORT_SYMBOL_KASAN(memset)
>
>   /*
>    * This version uses dcbz on the complete cache lines in the
> @@ -163,12 +167,12 @@ EXPORT_SYMBOL(memset)
>    * We therefore jump to generic_memcpy which doesn't use dcbz. This 
> jump is
>    * replaced by a nop once cache is active. This is done in machine_init()
>    */
> -_GLOBAL(memmove)
> +_GLOBAL_KASAN(memmove)
>   	cmplw	0,r3,r4
>   	bgt	backwards_memcpy
>   	/* fall through */
>
> -_GLOBAL(memcpy)
> +_GLOBAL_KASAN(memcpy)
>   1:	b	generic_memcpy
>   	patch_site	1b, patch__memcpy_nocache
>
> @@ -244,6 +248,8 @@ _GLOBAL(memcpy)
>   65:	blr
>   EXPORT_SYMBOL(memcpy)
>   EXPORT_SYMBOL(memmove)
> +EXPORT_SYMBOL_KASAN(memcpy)
> +EXPORT_SYMBOL_KASAN(memmove)
>
>   generic_memcpy:
>   	srwi.	r7,r5,3
> diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
> index 3c3be02f33b7..7f6bd031c306 100644
> --- a/arch/powerpc/lib/mem_64.S
> +++ b/arch/powerpc/lib/mem_64.S
> @@ -12,7 +12,9 @@
>   #include <asm/errno.h>
>   #include <asm/ppc_asm.h>
>   #include <asm/export.h>
> +#include <asm/kasan.h>
>
> +#ifndef CONFIG_KASAN
>   _GLOBAL(__memset16)
>   	rlwimi	r4,r4,16,0,15
>   	/* fall through */
> @@ -29,8 +31,9 @@ _GLOBAL(__memset64)
>   EXPORT_SYMBOL(__memset16)
>   EXPORT_SYMBOL(__memset32)
>   EXPORT_SYMBOL(__memset64)
> +#endif
>
> -_GLOBAL(memset)
> +_GLOBAL_KASAN(memset)
>   	neg	r0,r3
>   	rlwimi	r4,r4,8,16,23
>   	andi.	r0,r0,7			/* # bytes to be 8-byte aligned */
> @@ -96,8 +99,9 @@ _GLOBAL(memset)
>   	stb	r4,0(r6)
>   	blr
>   EXPORT_SYMBOL(memset)
> +EXPORT_SYMBOL_KASAN(memset)
>
> -_GLOBAL_TOC(memmove)
> +_GLOBAL_TOC_KASAN(memmove)
>   	cmplw	0,r3,r4
>   	bgt	backwards_memcpy
>   	b	memcpy
> @@ -139,3 +143,4 @@ _GLOBAL(backwards_memcpy)
>   	mtctr	r7
>   	b	1b
>   EXPORT_SYMBOL(memmove)
> +EXPORT_SYMBOL_KASAN(memmove)
> diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
> index 273ea67e60a1..25c3772c1dfb 100644
> --- a/arch/powerpc/lib/memcpy_64.S
> +++ b/arch/powerpc/lib/memcpy_64.S
> @@ -11,6 +11,7 @@
>   #include <asm/export.h>
>   #include <asm/asm-compat.h>
>   #include <asm/feature-fixups.h>
> +#include <asm/kasan.h>
>
>   #ifndef SELFTEST_CASE
>   /* For big-endian, 0 == most CPUs, 1 == POWER6, 2 == Cell */
> @@ -18,7 +19,7 @@
>   #endif
>
>   	.align	7
> -_GLOBAL_TOC(memcpy)
> +_GLOBAL_TOC_KASAN(memcpy)
>   BEGIN_FTR_SECTION
>   #ifdef __LITTLE_ENDIAN__
>   	cmpdi	cr7,r5,0
> @@ -230,3 +231,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
>   	blr
>   #endif
>   EXPORT_SYMBOL(memcpy)
> +EXPORT_SYMBOL_KASAN(memcpy)
>
>
>> 
>> It seems to be related to the export line, as if I swap the exports to
>> do fn before __##fn I get:
>> 
>> WARNING: EXPORT symbol "memset" [vmlinux] version generation failed, symbol will not be versioned.
>> 
>> I have narrowed this down to combining 2 EXPORT_SYMBOL()s on one line.
>> This works - no warning:
>> 
>> EXPORT_SYMBOL(memset)
>> EXPORT_SYMBOL(__memset)
>> 
>> This throws a warning:
>> 
>> EXPORT_SYMBOL(memset) ; EXPORT_SYMBOL(__memset)
>> 
>> I notice in looking at the diff of preprocessed source we end up
>> invoking an asm macro that doesn't seem to have a full final argument, I
>> wonder if that's relevant...
>> 
>> -___EXPORT_SYMBOL __memset, __memset, ; ___EXPORT_SYMBOL memset, memset,
>> +___EXPORT_SYMBOL __memset, __memset,
>> +___EXPORT_SYMBOL memset, memset,
>> 
>> I also notice that nowhere else in the source do people have multiple
>> EXPORT_SYMBOLs on the same line, and other arches seem to just
>> unconditionally export both symbols on multiple lines.
>> 
>> I have no idea how this works for you - maybe it's affected by something 32bit.
>> 
>> How would you feel about this approach instead? I'm not tied to any of
>> the names or anything.
>> 
>> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
>> index e0637730a8e7..7b6a91b448dd 100644
>> --- a/arch/powerpc/include/asm/ppc_asm.h
>> +++ b/arch/powerpc/include/asm/ppc_asm.h
>> @@ -214,6 +214,9 @@ name: \
>>   
>>   #define DOTSYM(a)      a
>>   
>> +#define PROVIDE_WEAK_ALIAS(strongname, weakname) \
>> +       .weak weakname ; .set weakname, strongname ;
>> +
>>   #else
>>   
>>   #define XGLUE(a,b) a##b
>> @@ -236,6 +239,10 @@ GLUE(.,name):
>>   
>>   #define DOTSYM(a)      GLUE(.,a)
>>   
>> +#define PROVIDE_WEAK_ALIAS(strongname, weakname) \
>> +       .weak weakname ; .set weakname, strongname ; \
>> +       .weak DOTSYM(weakname) ; .set DOTSYM(weakname), DOTSYM(strongname) ;
>> +
>>   #endif
>>   
>>   #else /* 32-bit */
>> @@ -251,6 +258,9 @@ GLUE(.,name):
>>   
>>   #define _GLOBAL_TOC(name) _GLOBAL(name)
>>   
>> +#define PROVIDE_WEAK_ALIAS(strongname, weakname) \
>> +       .weak weakname ; .set weakname, strongname ;
>> +
>>   #endif
>>   
>>   /*
>> --- a/arch/powerpc/lib/mem_64.S
>> +++ b/arch/powerpc/lib/mem_64.S
>> @@ -33,7 +33,8 @@ EXPORT_SYMBOL(__memset32)
>>   EXPORT_SYMBOL(__memset64)
>>   #endif
>>   
>> -_GLOBAL_KASAN(memset)
>> +PROVIDE_WEAK_ALIAS(__memset,memset)
>> +_GLOBAL(__memset)
>>          neg     r0,r3
>>          rlwimi  r4,r4,8,16,23
>>          andi.   r0,r0,7                 /* # bytes to be 8-byte aligned */
>> @@ -98,9 +99,11 @@ _GLOBAL_KASAN(memset)
>>   10:    bflr    31
>>          stb     r4,0(r6)
>>          blr
>> -EXPORT_SYMBOL_KASAN(memset)
>> +EXPORT_SYMBOL(memset)
>> +EXPORT_SYMBOL(__memset)
>>   
>> -_GLOBAL_TOC_KASAN(memmove)
>> +PROVIDE_WEAK_ALIAS(__memmove,memove)
>> +_GLOBAL_TOC(__memmove)
>>          cmplw   0,r3,r4
>>          bgt     backwards_memcpy
>>          b       memcpy
>> @@ -141,4 +144,5 @@ _GLOBAL(backwards_memcpy)
>>          beq     2b
>>          mtctr   r7
>>          b       1b
>> -EXPORT_SYMBOL_KASAN(memmove)
>> +EXPORT_SYMBOL(memmove)
>> +EXPORT_SYMBOL(__memmove)
>> diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
>> index 862b515b8868..7c1b09556cad 100644
>> --- a/arch/powerpc/lib/memcpy_64.S
>> +++ b/arch/powerpc/lib/memcpy_64.S
>> @@ -19,7 +19,8 @@
>>   #endif
>>   
>>          .align  7
>> -_GLOBAL_TOC_KASAN(memcpy)
>> +PROVIDE_WEAK_ALIAS(__memcpy,memcpy)
>> +_GLOBAL_TOC(__memcpy)
>>   BEGIN_FTR_SECTION
>>   #ifdef __LITTLE_ENDIAN__
>>          cmpdi   cr7,r5,0
>> @@ -230,4 +231,5 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
>>   4:     ld      r3,-STACKFRAMESIZE+STK_REG(R31)(r1)     /* return dest pointer */
>>          blr
>>   #endif
>> -EXPORT_SYMBOL_KASAN(memcpy)
>> +EXPORT_SYMBOL(__memcpy)
>> +EXPORT_SYMBOL(memcpy)
>> 
>> 
>> Regards,
>> Daniel
>> 
>> 
>>> +#else
>>> +#define _GLOBAL_KASAN(fn)	_GLOBAL(fn)
>>> +#define _GLOBAL_TOC_KASAN(fn)	_GLOBAL_TOC(fn)
>>> +#define EXPORT_SYMBOL_KASAN(fn)	EXPORT_SYMBOL(fn)
>>> +#endif
>>> +
>>> +#endif
>>> diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
>>> index 1647de15a31e..9bf6dffb4090 100644
>>> --- a/arch/powerpc/include/asm/string.h
>>> +++ b/arch/powerpc/include/asm/string.h
>>> @@ -4,14 +4,17 @@
>>>   
>>>   #ifdef __KERNEL__
>>>   
>>> +#ifndef CONFIG_KASAN
>>>   #define __HAVE_ARCH_STRNCPY
>>>   #define __HAVE_ARCH_STRNCMP
>>> +#define __HAVE_ARCH_MEMCHR
>>> +#define __HAVE_ARCH_MEMCMP
>>> +#define __HAVE_ARCH_MEMSET16
>>> +#endif
>>> +
>>>   #define __HAVE_ARCH_MEMSET
>>>   #define __HAVE_ARCH_MEMCPY
>>>   #define __HAVE_ARCH_MEMMOVE
>>> -#define __HAVE_ARCH_MEMCMP
>>> -#define __HAVE_ARCH_MEMCHR
>>> -#define __HAVE_ARCH_MEMSET16
>>>   #define __HAVE_ARCH_MEMCPY_FLUSHCACHE
>>>   
>>>   extern char * strcpy(char *,const char *);
>>> @@ -27,7 +30,27 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
>>>   extern void * memchr(const void *,int,__kernel_size_t);
>>>   extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>>>   
>>> +void *__memset(void *s, int c, __kernel_size_t count);
>>> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
>>> +void *__memmove(void *to, const void *from, __kernel_size_t n);
>>> +
>>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>>> +/*
>>> + * For files that are not instrumented (e.g. mm/slub.c) we
>>> + * should use not instrumented version of mem* functions.
>>> + */
>>> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
>>> +#define memmove(dst, src, len) __memmove(dst, src, len)
>>> +#define memset(s, c, n) __memset(s, c, n)
>>> +
>>> +#ifndef __NO_FORTIFY
>>> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
>>> +#endif
>>> +
>>> +#endif
>>> +
>>>   #ifdef CONFIG_PPC64
>>> +#ifndef CONFIG_KASAN
>>>   #define __HAVE_ARCH_MEMSET32
>>>   #define __HAVE_ARCH_MEMSET64
>>>   
>>> @@ -49,8 +72,11 @@ static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n)
>>>   {
>>>   	return __memset64(p, v, n * 8);
>>>   }
>>> +#endif
>>>   #else
>>> +#ifndef CONFIG_KASAN
>>>   #define __HAVE_ARCH_STRLEN
>>> +#endif
>>>   
>>>   extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
>>>   #endif
>>> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
>>> index 667df97d2595..181fd10008ef 100644
>>> --- a/arch/powerpc/kernel/prom_init_check.sh
>>> +++ b/arch/powerpc/kernel/prom_init_check.sh
>>> @@ -16,8 +16,16 @@
>>>   # If you really need to reference something from prom_init.o add
>>>   # it to the list below:
>>>   
>>> +grep "^CONFIG_KASAN=y$" .config >/dev/null
>>> +if [ $? -eq 0 ]
>>> +then
>>> +	MEM_FUNCS="__memcpy __memset"
>>> +else
>>> +	MEM_FUNCS="memcpy memset"
>>> +fi
>>> +
>>>   WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
>>> -_end enter_prom memcpy memset reloc_offset __secondary_hold
>>> +_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
>>>   __secondary_hold_acknowledge __secondary_hold_spinloop __start
>>>   strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
>>>   reloc_got2 kernstart_addr memstart_addr linux_banner _stext
>>> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
>>> index 79396e184bca..47a4de434c22 100644
>>> --- a/arch/powerpc/lib/Makefile
>>> +++ b/arch/powerpc/lib/Makefile
>>> @@ -8,9 +8,14 @@ ccflags-$(CONFIG_PPC64)	:= $(NO_MINIMAL_TOC)
>>>   CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
>>>   CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>>>   
>>> -obj-y += string.o alloc.o code-patching.o feature-fixups.o
>>> +obj-y += alloc.o code-patching.o feature-fixups.o
>>>   
>>> -obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o strlen_32.o
>>> +ifndef CONFIG_KASAN
>>> +obj-y	+=	string.o memcmp_$(BITS).o
>>> +obj-$(CONFIG_PPC32)	+= strlen_32.o
>>> +endif
>>> +
>>> +obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o
>>>   
>>>   obj-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
>>>   
>>> @@ -34,7 +39,7 @@ obj64-$(CONFIG_KPROBES_SANITY_TEST)	+= test_emulate_step.o \
>>>   					   test_emulate_step_exec_instr.o
>>>   
>>>   obj-y			+= checksum_$(BITS).o checksum_wrappers.o \
>>> -			   string_$(BITS).o memcmp_$(BITS).o
>>> +			   string_$(BITS).o
>>>   
>>>   obj-y			+= sstep.o ldstfp.o quad.o
>>>   obj64-y			+= quad.o
>>> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
>>> index ba66846fe973..fc4fa7246200 100644
>>> --- a/arch/powerpc/lib/copy_32.S
>>> +++ b/arch/powerpc/lib/copy_32.S
>>> @@ -14,6 +14,7 @@
>>>   #include <asm/ppc_asm.h>
>>>   #include <asm/export.h>
>>>   #include <asm/code-patching-asm.h>
>>> +#include <asm/kasan.h>
>>>   
>>>   #define COPY_16_BYTES		\
>>>   	lwz	r7,4(r4);	\
>>> @@ -68,6 +69,7 @@ CACHELINE_BYTES = L1_CACHE_BYTES
>>>   LG_CACHELINE_BYTES = L1_CACHE_SHIFT
>>>   CACHELINE_MASK = (L1_CACHE_BYTES-1)
>>>   
>>> +#ifndef CONFIG_KASAN
>>>   _GLOBAL(memset16)
>>>   	rlwinm.	r0 ,r5, 31, 1, 31
>>>   	addi	r6, r3, -4
>>> @@ -81,6 +83,7 @@ _GLOBAL(memset16)
>>>   	sth	r4, 4(r6)
>>>   	blr
>>>   EXPORT_SYMBOL(memset16)
>>> +#endif
>>>   
>>>   /*
>>>    * Use dcbz on the complete cache lines in the destination
>>> @@ -91,7 +94,7 @@ EXPORT_SYMBOL(memset16)
>>>    * We therefore skip the optimised bloc that uses dcbz. This jump is
>>>    * replaced by a nop once cache is active. This is done in machine_init()
>>>    */
>>> -_GLOBAL(memset)
>>> +_GLOBAL_KASAN(memset)
>>>   	cmplwi	0,r5,4
>>>   	blt	7f
>>>   
>>> @@ -150,7 +153,7 @@ _GLOBAL(memset)
>>>   9:	stbu	r4,1(r6)
>>>   	bdnz	9b
>>>   	blr
>>> -EXPORT_SYMBOL(memset)
>>> +EXPORT_SYMBOL_KASAN(memset)
>>>   
>>>   /*
>>>    * This version uses dcbz on the complete cache lines in the
>>> @@ -163,12 +166,12 @@ EXPORT_SYMBOL(memset)
>>>    * We therefore jump to generic_memcpy which doesn't use dcbz. This jump is
>>>    * replaced by a nop once cache is active. This is done in machine_init()
>>>    */
>>> -_GLOBAL(memmove)
>>> +_GLOBAL_KASAN(memmove)
>>>   	cmplw	0,r3,r4
>>>   	bgt	backwards_memcpy
>>>   	/* fall through */
>>>   
>>> -_GLOBAL(memcpy)
>>> +_GLOBAL_KASAN(memcpy)
>>>   1:	b	generic_memcpy
>>>   	patch_site	1b, patch__memcpy_nocache
>>>   
>>> @@ -242,8 +245,8 @@ _GLOBAL(memcpy)
>>>   	stbu	r0,1(r6)
>>>   	bdnz	40b
>>>   65:	blr
>>> -EXPORT_SYMBOL(memcpy)
>>> -EXPORT_SYMBOL(memmove)
>>> +EXPORT_SYMBOL_KASAN(memcpy)
>>> +EXPORT_SYMBOL_KASAN(memmove)
>>>   
>>>   generic_memcpy:
>>>   	srwi.	r7,r5,3
>>> diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
>>> index 3c3be02f33b7..7cd6cf6822a2 100644
>>> --- a/arch/powerpc/lib/mem_64.S
>>> +++ b/arch/powerpc/lib/mem_64.S
>>> @@ -12,7 +12,9 @@
>>>   #include <asm/errno.h>
>>>   #include <asm/ppc_asm.h>
>>>   #include <asm/export.h>
>>> +#include <asm/kasan.h>
>>>   
>>> +#ifndef CONFIG_KASAN
>>>   _GLOBAL(__memset16)
>>>   	rlwimi	r4,r4,16,0,15
>>>   	/* fall through */
>>> @@ -29,8 +31,9 @@ _GLOBAL(__memset64)
>>>   EXPORT_SYMBOL(__memset16)
>>>   EXPORT_SYMBOL(__memset32)
>>>   EXPORT_SYMBOL(__memset64)
>>> +#endif
>>>   
>>> -_GLOBAL(memset)
>>> +_GLOBAL_KASAN(memset)
>>>   	neg	r0,r3
>>>   	rlwimi	r4,r4,8,16,23
>>>   	andi.	r0,r0,7			/* # bytes to be 8-byte aligned */
>>> @@ -95,9 +98,9 @@ _GLOBAL(memset)
>>>   10:	bflr	31
>>>   	stb	r4,0(r6)
>>>   	blr
>>> -EXPORT_SYMBOL(memset)
>>> +EXPORT_SYMBOL_KASAN(memset)
>>>   
>>> -_GLOBAL_TOC(memmove)
>>> +_GLOBAL_TOC_KASAN(memmove)
>>>   	cmplw	0,r3,r4
>>>   	bgt	backwards_memcpy
>>>   	b	memcpy
>>> @@ -138,4 +141,4 @@ _GLOBAL(backwards_memcpy)
>>>   	beq	2b
>>>   	mtctr	r7
>>>   	b	1b
>>> -EXPORT_SYMBOL(memmove)
>>> +EXPORT_SYMBOL_KASAN(memmove)
>>> diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
>>> index 273ea67e60a1..862b515b8868 100644
>>> --- a/arch/powerpc/lib/memcpy_64.S
>>> +++ b/arch/powerpc/lib/memcpy_64.S
>>> @@ -11,6 +11,7 @@
>>>   #include <asm/export.h>
>>>   #include <asm/asm-compat.h>
>>>   #include <asm/feature-fixups.h>
>>> +#include <asm/kasan.h>
>>>   
>>>   #ifndef SELFTEST_CASE
>>>   /* For big-endian, 0 == most CPUs, 1 == POWER6, 2 == Cell */
>>> @@ -18,7 +19,7 @@
>>>   #endif
>>>   
>>>   	.align	7
>>> -_GLOBAL_TOC(memcpy)
>>> +_GLOBAL_TOC_KASAN(memcpy)
>>>   BEGIN_FTR_SECTION
>>>   #ifdef __LITTLE_ENDIAN__
>>>   	cmpdi	cr7,r5,0
>>> @@ -229,4 +230,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
>>>   4:	ld	r3,-STACKFRAMESIZE+STK_REG(R31)(r1)	/* return dest pointer */
>>>   	blr
>>>   #endif
>>> -EXPORT_SYMBOL(memcpy)
>>> +EXPORT_SYMBOL_KASAN(memcpy)
>>> -- 
>>> 2.13.3