Date: Fri, 9 Jun 2017 01:40:59 +0300
From: Yury Norov <ynorov@caviumnetworks.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH 05/20] arm64: rename COMPAT to AARCH32_EL0 in Kconfig
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Hi Catalin, thanks for review.

On Thu, Jun 08, 2017 at 03:09:12PM +0100, Catalin Marinas wrote:
> On Sun, Jun 04, 2017 at 02:59:54PM +0300, Yury Norov wrote:
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -402,7 +402,7 @@ config ARM64_ERRATUM_834220
> >  
> >  config ARM64_ERRATUM_845719
> >  	bool "Cortex-A53: 845719: a load might read incorrect data"
> > -	depends on COMPAT
> > +	depends on AARCH32_EL0
> >  	default y
> >  	help
> >  	  This option adds an alternative code sequence to work around ARM
> > @@ -784,7 +784,7 @@ config FORCE_MAX_ZONEORDER
> >  
> >  menuconfig ARMV8_DEPRECATED
> >  	bool "Emulate deprecated/obsolete ARMv8 instructions"
> > -	depends on COMPAT
> > +	depends on AARCH32_EL0
> >  	help
> >  	  Legacy software support may require certain instructions
> >  	  that have been deprecated or obsoleted in the architecture.
> > @@ -1062,9 +1062,15 @@ menu "Userspace binary formats"
> >  source "fs/Kconfig.binfmt"
> >  
> >  config COMPAT
> > +	bool
> > +	depends on AARCH32_EL0
> 
> You could just use "def_bool y" here
> 
> > +
> > +config AARCH32_EL0
> >  	bool "Kernel support for 32-bit EL0"
> > +	def_bool y
> >  	depends on ARM64_4K_PAGES || EXPERT
> >  	select COMPAT_BINFMT_ELF if BINFMT_ELF
> > +	select COMPAT
> 
> and avoid the explicit select.

in patch 20 COMPAT becomes depending also on ARM64_ILP32, like this:
-       depends on AARCH32_EL0
+       depends on AARCH32_EL0 || ARM64_ILP32

So this is a preparation for it. If it looks confusing, I think it's
better to underline it in the description to the patch in addition to
this:

> From now, AARCH32_EL0 (former COMPAT) config option means the support of
> AARCH32 userspace, ARM64_ILP32 - support of ILP32 ABI (see next patches),
> and COMPAT indicates that one of them, or both, is enabled.

But if you prefer, I can do like you suggested here and make COMPAT
depend on AARCH32_EL0 in the last patch.

> 
> >  	select HAVE_UID16
> >  	select OLD_SIGSUSPEND3
> >  	select COMPAT_OLD_SIGACTION
> [...]
> > --- a/arch/arm64/kernel/cpuinfo.c
> > +++ b/arch/arm64/kernel/cpuinfo.c
> > @@ -139,15 +139,17 @@ static int c_show(struct seq_file *m, void *v)
> >  		 */
> >  		seq_puts(m, "Features\t:");
> >  		if (compat) {
> > -#ifdef CONFIG_COMPAT
> > -			for (j = 0; compat_hwcap_str[j]; j++)
> > -				if (compat_elf_hwcap & (1 << j))
> > -					seq_printf(m, " %s", compat_hwcap_str[j]);
> > -
> > -			for (j = 0; compat_hwcap2_str[j]; j++)
> > -				if (compat_elf_hwcap2 & (1 << j))
> > -					seq_printf(m, " %s", compat_hwcap2_str[j]);
> > -#endif /* CONFIG_COMPAT */
> > +#ifdef CONFIG_AARCH32_EL0
> > +			if (personality(current->personality) == PER_LINUX32) {
> > +				for (j = 0; compat_hwcap_str[j]; j++)
> > +					if (compat_elf_hwcap & (1 << j))
> > +						seq_printf(m, " %s", compat_hwcap_str[j]);
> > +
> > +				for (j = 0; compat_hwcap2_str[j]; j++)
> > +					if (compat_elf_hwcap2 & (1 << j))
> > +						seq_printf(m, " %s", compat_hwcap2_str[j]);
> > +			}
> > +#endif /* CONFIG_AARCH32_EL0 */
> 
> I don't understand this hunk. Why do you need another check on
> personality? "compat" is already true if PER_LINUX32.

I think it's rebase issue. I'll fix it.

Yury