linux-kernel - Re: [PATCHv5 1/4] arm64: io: Use asm-generic high level MMIO accessors

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: <2efe933e-de1e-0dfc-959a-c0003e28f830@quicinc.com>
Date:   Mon, 6 Dec 2021 19:22:47 +0530
From:   Sai Prakash Ranjan <quic_saipraka@...cinc.com>
To:     Arnd Bergmann <arnd@...db.de>
CC:     Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Marc Zyngier <maz@...nel.org>,
        gregkh <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        <quic_psodagud@...cinc.com>
Subject: Re: [PATCHv5 1/4] arm64: io: Use asm-generic high level MMIO
 accessors

On 12/6/2021 5:00 PM, Arnd Bergmann wrote:
> On Mon, Dec 6, 2021 at 12:12 PM Sai Prakash Ranjan
> <quic_saipraka@...cinc.com> wrote:
>> On 12/6/2021 2:20 PM, Arnd Bergmann wrote:
>>> I think it would be even better to flip these around and make the low-level
>>> definitions __io_ar() and __io_bw(), and then defining the arm64 specific
>>> macros based on those:
>>>
>>> /* arm64-specific, don't use in portable drivers */
>>> #define __iormb(v)     __io_ar(v)
>>> #define __iowmb()      __io_bw()
>>> #define __iomb()        dma_mb()
>>>
>>>
>> So __iormb on arm64 has some dummy control dependency stuff as well based on
>> ("arm64: io: Ensure calls to delay routines are ordered against prior
>> readX()") and then we would need to change __iormb definition to __io_ar which
>> doesn't seem like __iormb definition to be exact right?
> I'm not sure what you are asking here. As far as I can tell, __io_ar()
> and __iormb() have the same calling conventions and the same barrier
> requirements, so they should be interchangeable, we just need to decide
> which one is the primary definition.
>
>         Arnd

Sorry, what I meant was the literal name of these macros, i.e., 
__iormb() has more explicit naming as
IO read memory barrier and __io_ar() is IO after read? So doesn't it 
make more sense that __iormb()
should be the primary definition which is already the case and ar/bw 
should be based on them.

Thanks,
Sai