* Vincent Whitchurch <vincent.whitchu...@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
So the breakage was ~9 months ago, and apparently nobody build-tested UML?
Does UML boot with the fix?
> UML does not use GENERIC_ENTRY and 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.whitchu...@axis.com>
> ---
> Changes in v2:
> - Use CONFIG_UML instead of CONFIG_GENERIC_ENTRY.
> - Link to v1:
> https://lore.kernel.org/r/20230609-uml-kasan-v1-1-5fac8d409...@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 8f95fb267caa..47b004851cf3 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_UML
> +SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy)
> +#else
> SYM_FUNC_ALIAS(memcpy, __memcpy)
> +#endif
> EXPORT_SYMBOL(memcpy)
Meh, the extra 3 #ifdefs are rather ugly and don't really express UML's
expectations here.
So how about introducing a SYM_FUNC_ALIAS_MEMFUNC() variant on x86 in a
suitable header, which maps to the right thing, with a comment added that
explains that this is for UML's mem*() functions?
Thanks,
Ingo
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