linux-kernel - Re: [PATCH] x86/sgx: Replace kmap/kunmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d64e6e9f-27b9-9bbb-aaf8-fca1681eada5@intel.com>
Date:   Thu, 6 Oct 2022 13:45:56 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        linux-kernel@...r.kernel.org, linux-sgx@...r.kernel.org,
        Jarkko Sakkinen <jarkko@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>
Cc:     ira.weiny@...el.com
Subject: Re: [PATCH] x86/sgx: Replace kmap/kunmap_atomic calls

On 10/6/22 13:37, Fabio M. De Francesco wrote:
> kmap() were not suited in those cases because it might sleep. If the intents 
> of the author are simply map a page while in atomic, so to avoid sleeping in 
> atomic bugs, your conversions looks good. 
> 
> For the reasons above, can you please say something more about why this code 
> needed a kmap_atomic() instead of calling kmap()?

This question is backwards.  kmap_atomic() is the default that folks
use.  You use kmap_atomic() *always* unless you _need_ to sleep or one
of the other kmap()-only things.

Folks don't and shouldn't have to explain why this was using kmap_atomic().