From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: jmorris@namei.org, sashal@kernel.org,
linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
will@kernel.org, steve.capper@arm.com,
linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com,
james.morse@arm.com, vladimir.murzin@arm.com,
mark.rutland@arm.com, tglx@linutronix.de,
gregkh@linuxfoundation.org, allison@lohutok.net, info@metux.net,
alexios.zavras@intel.com, sstabellini@kernel.org,
boris.ostrovsky@oracle.com, jgross@suse.com, stefan@agner.ch,
yamada.masahiro@socionext.com, xen-devel@lists.xenproject.org
Subject: Re: [PATCH 1/3] arm/arm64/xen: use C inlines for privcmd_call
Date: Fri, 22 Nov 2019 00:22:58 +0000 [thread overview]
Message-ID: <20191122002258.GD25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20191121184805.414758-2-pasha.tatashin@soleen.com>
On Thu, Nov 21, 2019 at 01:48:03PM -0500, Pavel Tatashin wrote:
> privcmd_call requires to enable access to userspace for the
> duration of the hypercall.
>
> Currently, this is done via assembly macros. Change it to C
> inlines instead.
>
> Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
> ---
> arch/arm/include/asm/assembler.h | 2 +-
> arch/arm/include/asm/uaccess.h | 32 ++++++++++++++++++++++++++------
> arch/arm/xen/enlighten.c | 2 +-
> arch/arm/xen/hypercall.S | 15 ++-------------
> arch/arm64/xen/hypercall.S | 19 ++-----------------
> include/xen/arm/hypercall.h | 23 ++++++++++++++++++++---
> 6 files changed, 52 insertions(+), 41 deletions(-)
>
> diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
> index 99929122dad7..8e9262a0f016 100644
> --- a/arch/arm/include/asm/assembler.h
> +++ b/arch/arm/include/asm/assembler.h
> @@ -480,7 +480,7 @@ THUMB( orr \reg , \reg , #PSR_T_BIT )
> .macro uaccess_disable, tmp, isb=1
> #ifdef CONFIG_CPU_SW_DOMAIN_PAN
> /*
> - * Whenever we re-enter userspace, the domains should always be
> + * Whenever we re-enter kernel, the domains should always be
> * set appropriately.
> */
> mov \tmp, #DACR_UACCESS_DISABLE
> diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
> index 98c6b91be4a8..79d4efa3eb62 100644
> --- a/arch/arm/include/asm/uaccess.h
> +++ b/arch/arm/include/asm/uaccess.h
> @@ -16,6 +16,23 @@
>
> #include <asm/extable.h>
>
> +#ifdef CONFIG_CPU_SW_DOMAIN_PAN
> +static __always_inline void uaccess_enable(void)
> +{
> + unsigned long val = DACR_UACCESS_ENABLE;
> +
> + asm volatile("mcr p15, 0, %0, c3, c0, 0" : : "r" (val));
> + isb();
> +}
> +
> +static __always_inline void uaccess_disable(void)
> +{
> + unsigned long val = DACR_UACCESS_ENABLE;
> +
> + asm volatile("mcr p15, 0, %0, c3, c0, 0" : : "r" (val));
> + isb();
> +}
Rather than inventing these, why not use uaccess_save_and_enable()..
uaccess_restore() around the Xen call?
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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next prev parent reply other threads:[~2019-11-22 0:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-21 18:48 [PATCH 0/3] Use C inlines for uaccess Pavel Tatashin
2019-11-21 18:48 ` [PATCH 1/3] arm/arm64/xen: use C inlines for privcmd_call Pavel Tatashin
2019-11-22 0:22 ` Russell King - ARM Linux admin [this message]
2019-11-22 0:30 ` Pavel Tatashin
2019-11-22 0:34 ` Russell King - ARM Linux admin
2019-11-22 0:35 ` Russell King - ARM Linux admin
2019-11-22 0:39 ` Pavel Tatashin
2019-11-22 0:53 ` Russell King - ARM Linux admin
2019-11-21 18:48 ` [PATCH 2/3] arm64: remove uaccess_ttbr0 asm macros from cache functions Pavel Tatashin
2019-11-21 18:48 ` [PATCH 3/3] arm64: remove the rest of asm-uaccess.h Pavel Tatashin
2019-11-22 1:26 ` Max Filippov
2019-11-22 2:20 ` Pavel Tatashin
-- strict thread matches above, loose matches on Subject: below --
2019-11-27 18:44 [PATCH 0/3] Use C inlines for uaccess Pavel Tatashin
2019-11-27 18:44 ` [PATCH 1/3] arm/arm64/xen: use C inlines for privcmd_call Pavel Tatashin
2019-11-29 15:05 ` Julien Grall
2019-12-04 17:58 ` Pavel Tatashin
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