Messages in this thread | | | Date | Fri, 15 Sep 2023 11:32:38 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2] x86: Fix build of UML with KASAN |
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* 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
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.whitchurch@axis.com> > --- > Changes in v2: > - Use CONFIG_UML instead of CONFIG_GENERIC_ENTRY. > - Link to v1: https://lore.kernel.org/r/20230609-uml-kasan-v1-1-5fac8d409d4f@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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