linux-kernel - Re: [PATCH] x86: Disable EXECMEM

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Message-ID: <Z4U1qqBekZ-_l1NS@intel.com>
Date: Mon, 13 Jan 2025 17:47:54 +0200
From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>, Mike Rapoport <rppt@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Luis Chamberlain <mcgrof@...nel.org>,
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	Geert Uytterhoeven <geert@...ux-m68k.org>,
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Subject: Re: [PATCH] x86: Disable EXECMEM_ROX support

On Mon, Jan 13, 2025 at 12:29:34PM +0100, Peter Zijlstra wrote:
> On Mon, Jan 13, 2025 at 12:11:16PM +0100, Peter Zijlstra wrote:
> 
> > There's definiltely breakage with that module_writable_address()
> > nonsense in alternative.c that will not be fixed by that patch.
> > 
> > The very simplest thing at this point is to remove:
> > 
> >      select ARCH_HAS_EXECMEM_ROX             if X86_64
> > 
> > and try again next cycle.
> 
> Boris asked I send it as a proper patch, so here goes. Perhaps next time
> let x86 merge x86 code :/
> 
> ---
> Subject: x86: Disable EXECMEM_ROX support
> 
> The whole module_writable_address() nonsense made a giant mess of
> alternative.c, not to mention it still contains bugs -- notable some of the CFI
> variants crash and burn.
> 
> Mike has been working on patches to clean all this up again, but given the
> current state of things, this stuff just isn't ready.
> 
> Disable for now, lets try again next cycle.
> 
> Fixes: 5185e7f9f3bd ("x86/module: enable ROX caches for module text on 64 bit")
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> ---
>  arch/x86/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9d7bd0ae48c4..ef6cfea9df73 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -83,7 +83,6 @@ config X86
>  	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
>  	select ARCH_HAS_EARLY_DEBUG		if KGDB
>  	select ARCH_HAS_ELF_RANDOMIZE
> -	select ARCH_HAS_EXECMEM_ROX		if X86_64
>  	select ARCH_HAS_FAST_MULTIPLIER
>  	select ARCH_HAS_FORTIFY_SOURCE
>  	select ARCH_HAS_GCOV_PROFILE_ALL

This one works for my hibernate woes.

In case you want it:
Tested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

-- 
Ville Syrjälä
Intel