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From: Robin Murphy <robin.murphy@arm.com>
To: Mark Rutland <mark.rutland@arm.com>,
	linux-arm-kernel@lists.infradead.org
Cc: catalin.marinas@arm.com, james.morse@arm.com, hch@lst.de,
	will@kernel.org
Subject: Re: [PATCHv3 10/17] arm64: uaccess: simplify __copy_user_flushcache()
Date: Tue, 27 Oct 2020 17:33:31 +0000	[thread overview]
Message-ID: <bc671c33-bf9f-f6d7-0ef5-7ef1ed229cce@arm.com> (raw)
In-Reply-To: <20201026133156.44186-11-mark.rutland@arm.com>

On 2020-10-26 13:31, Mark Rutland wrote:
> Currently __copy_user_flushcache() open-codes raw_copy_from_user(), and
> doesn't use uaccess_mask_ptr() on the user address. Let's have it call
> raw_copy_from_user(), which is both a simplification and ensures that
> user pointers are masked under speculation.

I think this originally stems from the fact that "raw_*" were merely 
generic aliases for "__arch_*" at the time. Then whichever chump 
subsequently implemented uaccess_mask_ptr() for arm64 clearly did a 
terrible job... ;)

> There should be no functional change as a result of this patch.

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Will Deacon <will@kernel.org>
> ---
>   arch/arm64/lib/uaccess_flushcache.c | 4 +---
>   1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/lib/uaccess_flushcache.c b/arch/arm64/lib/uaccess_flushcache.c
> index bfa30b75b2b8e..c83bb5a4aad2c 100644
> --- a/arch/arm64/lib/uaccess_flushcache.c
> +++ b/arch/arm64/lib/uaccess_flushcache.c
> @@ -30,9 +30,7 @@ unsigned long __copy_user_flushcache(void *to, const void __user *from,
>   {
>   	unsigned long rc;
>   
> -	uaccess_enable_not_uao();
> -	rc = __arch_copy_from_user(to, from, n);
> -	uaccess_disable_not_uao();
> +	rc = raw_copy_from_user(to, from, n);
>   
>   	/* See above */
>   	__clean_dcache_area_pop(to, n - rc);
> 

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  reply	other threads:[~2020-10-27 17:35 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-26 13:31 [PATCHv3 00/17] arm64: remove set_fs() and friends Mark Rutland
2020-10-26 13:31 ` [PATCHv3 01/17] arm64: ensure ERET from kthread is illegal Mark Rutland
2020-10-26 13:31 ` [PATCHv3 02/17] arm64: add C wrappers for SET_PSTATE_*() Mark Rutland
2020-10-26 13:31 ` [PATCHv3 03/17] arm64: head.S: rename el2_setup -> init_kernel_el Mark Rutland
2020-10-26 13:31 ` [PATCHv3 04/17] arm64: head.S: cleanup SCTLR_ELx initialization Mark Rutland
2020-10-26 13:31 ` [PATCHv3 05/17] arm64: head.S: always initialize PSTATE Mark Rutland
2020-10-26 13:31 ` [PATCHv3 06/17] arm64: sdei: move uaccess logic to arch/arm64/ Mark Rutland
2020-10-26 13:31 ` [PATCHv3 07/17] arm64: sdei: explicitly simulate PAN/UAO entry Mark Rutland
2020-10-26 13:31 ` [PATCHv3 08/17] arm64: uaccess: move uao_* alternatives to asm-uaccess.h Mark Rutland
2020-11-03 14:26   ` Will Deacon
2020-11-03 14:41     ` Mark Rutland
2020-10-26 13:31 ` [PATCHv3 09/17] arm64: uaccess: rename privileged uaccess routines Mark Rutland
2020-10-26 13:31 ` [PATCHv3 10/17] arm64: uaccess: simplify __copy_user_flushcache() Mark Rutland
2020-10-27 17:33   ` Robin Murphy [this message]
2020-11-02 10:14     ` Mark Rutland
2020-10-26 13:31 ` [PATCHv3 11/17] arm64: uaccess: refactor __{get,put}_user Mark Rutland
2020-10-27 18:03   ` Robin Murphy
2020-11-02 10:25     ` Mark Rutland
2020-10-26 13:31 ` [PATCHv3 12/17] arm64: uaccess: split user/kernel routines Mark Rutland
2020-11-02 10:48   ` Mark Rutland
2020-10-26 13:31 ` [PATCHv3 13/17] arm64: uaccess cleanup macro naming Mark Rutland
2020-10-27 18:45   ` Robin Murphy
2020-11-02 10:35     ` Mark Rutland
2020-10-26 13:31 ` [PATCHv3 14/17] arm64: uaccess: remove set_fs() Mark Rutland
2020-10-26 13:31 ` [PATCHv3 15/17] arm64: uaccess: remove addr_limit_user_check() Mark Rutland
2020-10-26 13:31 ` [PATCHv3 16/17] arm64: uaccess: remove redundant PAN toggling Mark Rutland
2020-10-26 13:31 ` [PATCHv3 17/17] arm64: uaccess: remove vestigal UAO support Mark Rutland

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