[PATCH] x86: Fix build of UML with KASAN

[PATCH] x86: Fix build of UML with KASAN

[Vincent Whitchurch]

Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
x86: Disallow overriding mem*() functions") with the following errors:

 $ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
 ...
 ld: mm/kasan/shadow.o: in function `memset':
 shadow.c:(.text+0x40): multiple definition of `memset';
 arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
 ld: mm/kasan/shadow.o: in function `memmove':
 shadow.c:(.text+0x90): multiple definition of `memmove';
 arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
 ld: mm/kasan/shadow.o: in function `memcpy':
 shadow.c:(.text+0x110): multiple definition of `memcpy';
 arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here

If I'm reading that commit right, the !GENERIC_ENTRY case is still
supposed to be allowed to override the mem*() functions, so use weak
aliases in that case.

Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
 arch/x86/lib/memcpy_64.S  | 4 ++++
 arch/x86/lib/memmove_64.S | 4 ++++
 arch/x86/lib/memset_64.S  | 4 ++++
 3 files changed, 12 insertions(+)

diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 8f95fb267caa7..5dc265b36ef0b 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -40,7 +40,11 @@ SYM_TYPED_FUNC_START(__memcpy)
 SYM_FUNC_END(__memcpy)
 EXPORT_SYMBOL(__memcpy)
 
+#ifdef CONFIG_GENERIC_ENTRY
 SYM_FUNC_ALIAS(memcpy, __memcpy)
+#else
+SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
+#endif
 EXPORT_SYMBOL(memcpy)
 
 SYM_FUNC_START_LOCAL(memcpy_orig)
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 02661861e5dd9..3b1a02357fb29 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -215,5 +215,9 @@ SYM_FUNC_START(__memmove)
 SYM_FUNC_END(__memmove)
 EXPORT_SYMBOL(__memmove)
 
+#ifdef CONFIG_GENERIC_ENTRY
 SYM_FUNC_ALIAS(memmove, __memmove)
+#else
+SYM_FUNC_ALIAS_WEAK(memmove, __memmove)
+#endif
 EXPORT_SYMBOL(memmove)
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 7c59a704c4584..fe27538a355db 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -40,7 +40,11 @@ SYM_FUNC_START(__memset)
 SYM_FUNC_END(__memset)
 EXPORT_SYMBOL(__memset)
 
+#ifdef CONFIG_GENERIC_ENTRY
 SYM_FUNC_ALIAS(memset, __memset)
+#else
+SYM_FUNC_ALIAS_WEAK(memset, __memset)
+#endif
 EXPORT_SYMBOL(memset)
 
 SYM_FUNC_START_LOCAL(memset_orig)

---
base-commit: 9561de3a55bed6bdd44a12820ba81ec416e705a7
change-id: 20230609-uml-kasan-2392dd4c3858

Best regards,
-- 
Vincent Whitchurch <vincent.whitchurch@axis.com>

Re: [PATCH] x86: Fix build of UML with KASAN

[David Gow]

[-- Attachment #1: Type: text/plain, Size: 3420 bytes --]

On Fri, 9 Jun 2023 at 19:19, Vincent Whitchurch
<vincent.whitchurch@axis.com> wrote:
>
> Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
> x86: Disallow overriding mem*() functions") with the following errors:
>
>  $ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
>  ...
>  ld: mm/kasan/shadow.o: in function `memset':
>  shadow.c:(.text+0x40): multiple definition of `memset';
>  arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
>  ld: mm/kasan/shadow.o: in function `memmove':
>  shadow.c:(.text+0x90): multiple definition of `memmove';
>  arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
>  ld: mm/kasan/shadow.o: in function `memcpy':
>  shadow.c:(.text+0x110): multiple definition of `memcpy';
>  arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here
>
> If I'm reading that commit right, the !GENERIC_ENTRY case is still
> supposed to be allowed to override the mem*() functions, so use weak
> aliases in that case.
>
> Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
> ---

Thanks: I stumbled into this the other day and ran out of time to debug it.

I've tested that it works here.

Tested-by: David Gow <davidgow@google.com>

Cheers,
-- David

>  arch/x86/lib/memcpy_64.S  | 4 ++++
>  arch/x86/lib/memmove_64.S | 4 ++++
>  arch/x86/lib/memset_64.S  | 4 ++++
>  3 files changed, 12 insertions(+)
>
> diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
> index 8f95fb267caa7..5dc265b36ef0b 100644
> --- a/arch/x86/lib/memcpy_64.S
> +++ b/arch/x86/lib/memcpy_64.S
> @@ -40,7 +40,11 @@ SYM_TYPED_FUNC_START(__memcpy)
>  SYM_FUNC_END(__memcpy)
>  EXPORT_SYMBOL(__memcpy)
>
> +#ifdef CONFIG_GENERIC_ENTRY
>  SYM_FUNC_ALIAS(memcpy, __memcpy)
> +#else
> +SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
> +#endif
>  EXPORT_SYMBOL(memcpy)
>
>  SYM_FUNC_START_LOCAL(memcpy_orig)
> diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
> index 02661861e5dd9..3b1a02357fb29 100644
> --- a/arch/x86/lib/memmove_64.S
> +++ b/arch/x86/lib/memmove_64.S
> @@ -215,5 +215,9 @@ SYM_FUNC_START(__memmove)
>  SYM_FUNC_END(__memmove)
>  EXPORT_SYMBOL(__memmove)
>
> +#ifdef CONFIG_GENERIC_ENTRY
>  SYM_FUNC_ALIAS(memmove, __memmove)
> +#else
> +SYM_FUNC_ALIAS_WEAK(memmove, __memmove)
> +#endif
>  EXPORT_SYMBOL(memmove)
> diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
> index 7c59a704c4584..fe27538a355db 100644
> --- a/arch/x86/lib/memset_64.S
> +++ b/arch/x86/lib/memset_64.S
> @@ -40,7 +40,11 @@ SYM_FUNC_START(__memset)
>  SYM_FUNC_END(__memset)
>  EXPORT_SYMBOL(__memset)
>
> +#ifdef CONFIG_GENERIC_ENTRY
>  SYM_FUNC_ALIAS(memset, __memset)
> +#else
> +SYM_FUNC_ALIAS_WEAK(memset, __memset)
> +#endif
>  EXPORT_SYMBOL(memset)
>
>  SYM_FUNC_START_LOCAL(memset_orig)
>
> ---
> base-commit: 9561de3a55bed6bdd44a12820ba81ec416e705a7
> change-id: 20230609-uml-kasan-2392dd4c3858
>
> Best regards,
> --
> Vincent Whitchurch <vincent.whitchurch@axis.com>
>
> --
> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20230609-uml-kasan-v1-1-5fac8d409d4f%40axis.com.

[-- Attachment #2: S/MIME Cryptographic Signature --]
[-- Type: application/pkcs7-signature, Size: 4003 bytes --]

Re: [PATCH] x86: Fix build of UML with KASAN

[Vincent Whitchurch]

On Sat, 2023-06-10 at 16:34 +0800, David Gow wrote:
> On Fri, 9 Jun 2023 at 19:19, Vincent Whitchurch
> <vincent.whitchurch@axis.com> wrote:
> > 
> > Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
> > x86: Disallow overriding mem*() functions") with the following errors:
> > 
> >  $ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
> >  ...
> >  ld: mm/kasan/shadow.o: in function `memset':
> >  shadow.c:(.text+0x40): multiple definition of `memset';
> >  arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
> >  ld: mm/kasan/shadow.o: in function `memmove':
> >  shadow.c:(.text+0x90): multiple definition of `memmove';
> >  arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
> >  ld: mm/kasan/shadow.o: in function `memcpy':
> >  shadow.c:(.text+0x110): multiple definition of `memcpy';
> >  arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here
> > 
> > If I'm reading that commit right, the !GENERIC_ENTRY case is still
> > supposed to be allowed to override the mem*() functions, so use weak
> > aliases in that case.
> > 
> > Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
> > ---
> 
> Thanks: I stumbled into this the other day and ran out of time to debug it.
> 
> I've tested that it works here.
> 
> Tested-by: David Gow <davidgow@google.com>

Thanks.  Perhaps someone could pick this up?  It's been a few months,
and the build problem is still present on v6.6-rc1.

Re: [PATCH] x86: Fix build of UML with KASAN

[Richard Weinberger]

----- Ursprüngliche Mail -----
> Von: "Vincent Whitchurch" <Vincent.Whitchurch@axis.com>
>> Thanks: I stumbled into this the other day and ran out of time to debug it.
>> 
>> I've tested that it works here.
>> 
>> Tested-by: David Gow <davidgow@google.com>
> 
> Thanks.  Perhaps someone could pick this up?  It's been a few months,
> and the build problem is still present on v6.6-rc1.

I'll happily carry it though the UML tree if we get an ACK from x86 maintainers.

Thanks,
//richard

Re: [PATCH] x86: Fix build of UML with KASAN

[Peter Zijlstra]

On Fri, Jun 09, 2023 at 01:18:54PM +0200, Vincent Whitchurch wrote:
> Building UML with KASAN fails since commit 69d4c0d32186 ("entry, kasan,
> x86: Disallow overriding mem*() functions") with the following errors:
> 
>  $ tools/testing/kunit/kunit.py run --kconfig_add CONFIG_KASAN=y
>  ...
>  ld: mm/kasan/shadow.o: in function `memset':
>  shadow.c:(.text+0x40): multiple definition of `memset';
>  arch/x86/lib/memset_64.o:(.noinstr.text+0x0): first defined here
>  ld: mm/kasan/shadow.o: in function `memmove':
>  shadow.c:(.text+0x90): multiple definition of `memmove';
>  arch/x86/lib/memmove_64.o:(.noinstr.text+0x0): first defined here
>  ld: mm/kasan/shadow.o: in function `memcpy':
>  shadow.c:(.text+0x110): multiple definition of `memcpy';
>  arch/x86/lib/memcpy_64.o:(.noinstr.text+0x0): first defined here
> 
> If I'm reading that commit right, the !GENERIC_ENTRY case is still
> supposed to be allowed to override the mem*() functions, so use weak
> aliases in that case.
> 
> Fixes: 69d4c0d32186 ("entry, kasan, x86: Disallow overriding mem*() functions")
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
> ---
>  arch/x86/lib/memcpy_64.S  | 4 ++++
>  arch/x86/lib/memmove_64.S | 4 ++++
>  arch/x86/lib/memset_64.S  | 4 ++++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
> index 8f95fb267caa7..5dc265b36ef0b 100644
> --- a/arch/x86/lib/memcpy_64.S
> +++ b/arch/x86/lib/memcpy_64.S
> @@ -40,7 +40,11 @@ SYM_TYPED_FUNC_START(__memcpy)
>  SYM_FUNC_END(__memcpy)
>  EXPORT_SYMBOL(__memcpy)
>  
> +#ifdef CONFIG_GENERIC_ENTRY
>  SYM_FUNC_ALIAS(memcpy, __memcpy)
> +#else
> +SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
> +#endif
>  EXPORT_SYMBOL(memcpy)
>  
>  SYM_FUNC_START_LOCAL(memcpy_orig)

Urgh... 

Can we use CONFIG_UML here to clarify things? It's a bit of a bother UML
is diverging to much, but oh well.