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From: Thomas Gleixner <tglx@linutronix.de>
To: ira.weiny@intel.com, Dave Hansen <dave.hansen@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andy Lutomirski <luto@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	nvdimm@lists.linux.dev, linux-mm@kvack.org
Subject: Re: [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access()
Date: Thu, 25 Nov 2021 15:23:26 +0100	[thread overview]
Message-ID: <87o868l3fl.ffs@tglx> (raw)
In-Reply-To: <20210804043231.2655537-3-ira.weiny@intel.com>

On Tue, Aug 03 2021 at 21:32, ira weiny wrote:
> +/*
> + * Replace disable bits for @pkey with values from @flags
> + *
> + * Kernel users use the same flags as user space:
> + *     PKEY_DISABLE_ACCESS
> + *     PKEY_DISABLE_WRITE
> + */
> +u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags)

pkey_.... please.

> +{
> +	int pkey_shift = pkey * PKR_BITS_PER_PKEY;
> +
> +	/*  Mask out old bit values */
> +	pk_reg &= ~(((1 << PKR_BITS_PER_PKEY) - 1) << pkey_shift);
> +
> +	/*  Or in new values */
> +	if (flags & PKEY_DISABLE_ACCESS)
> +		pk_reg |= PKR_AD_BIT << pkey_shift;
> +	if (flags & PKEY_DISABLE_WRITE)
> +		pk_reg |= PKR_WD_BIT << pkey_shift;
> +
> +	return pk_reg;

Also this code is silly.

#define PKEY_ACCESS_MASK	(PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE)

u32 pkey_update_pkval(u32 pkval, int pkey, u32 accessbits)
{
	int shift = pkey * PKR_BITS_PER_PKEY;

        if (WARN_ON_ONCE(accessbits & ~PKEY_ACCESS_MASK))
        	accessbits &= PKEY_ACCESS_MASK;

        pkval &= ~(PKEY_ACCESS_MASK << shift);
	return pkval | accessbit << pkey_shift;
}

See? It does not even need comments because it's self explaining and
uses sensible argument names matching the function name.



  reply	other threads:[~2021-11-25 14:26 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-04  4:32 [PATCH V7 00/18] PKS/PMEM: Add Stray Write Protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 01/18] x86/pkeys: Create pkeys_common.h ira.weiny
2021-08-04  4:32 ` [PATCH V7 02/18] x86/fpu: Refactor arch_set_user_pkey_access() ira.weiny
2021-11-25 14:23   ` Thomas Gleixner [this message]
2021-08-04  4:32 ` [PATCH V7 03/18] x86/pks: Add additional PKEY helper macros ira.weiny
2021-11-25 14:25   ` Thomas Gleixner
2021-11-25 16:58     ` Thomas Gleixner
2021-12-08  0:51     ` Ira Weiny
2021-12-08 15:11       ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 04/18] x86/pks: Add PKS defines and Kconfig options ira.weiny
2021-08-04  4:32 ` [PATCH V7 05/18] x86/pks: Add PKS setup code ira.weiny
2021-11-25 15:15   ` Thomas Gleixner
2021-11-26  3:11     ` taoyi.ty
2021-11-26  9:57       ` Thomas Gleixner
2021-11-26 11:03     ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 06/18] x86/fault: Adjust WARN_ON for PKey fault ira.weiny
2021-08-04  4:32 ` [PATCH V7 07/18] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2021-11-25 15:25   ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 08/18] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2021-11-13  0:50   ` Ira Weiny
2021-11-25 11:19     ` Thomas Gleixner
2021-12-03  1:13     ` Andy Lutomirski
2021-11-25 14:12   ` Thomas Gleixner
2021-12-07  1:54     ` Ira Weiny
2021-12-07  4:45       ` Ira Weiny
2021-12-08  0:21       ` Thomas Gleixner
2021-08-04  4:32 ` [PATCH V7 09/18] x86/pks: Add PKS kernel API ira.weiny
2021-08-04  4:32 ` [PATCH V7 10/18] x86/pks: Introduce pks_abandon_protections() ira.weiny
2021-08-04  4:32 ` [PATCH V7 11/18] x86/pks: Add PKS Test code ira.weiny
2021-08-04  4:32 ` [PATCH V7 12/18] x86/pks: Add PKS fault callbacks ira.weiny
2021-08-11 21:18   ` Edgecombe, Rick P
2021-08-17  3:21     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 13/18] memremap_pages: Add access protection via supervisor Protection Keys (PKS) ira.weiny
2021-08-04  4:32 ` [PATCH V7 14/18] memremap_pages: Add memremap.pks_fault_mode ira.weiny
2021-08-04  4:57   ` Randy Dunlap
2021-08-07 19:32     ` Ira Weiny
2021-08-11 19:01   ` Edgecombe, Rick P
2021-08-17  3:12     ` Ira Weiny
2021-08-04  4:32 ` [PATCH V7 15/18] kmap: Add stray access protection for devmap pages ira.weiny
2021-08-04  4:32 ` [PATCH V7 16/18] dax: Stray access protection for dax_direct_access() ira.weiny
2021-08-04  4:32 ` [PATCH V7 17/18] nvdimm/pmem: Enable stray access protection ira.weiny
2021-08-04  4:32 ` [PATCH V7 18/18] devdax: " ira.weiny

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