linux-kernel - Re: [PATCH] x86/e820: fix the function type for e820__mapped

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Message-ID: <352fcf22-aa5d-8f4b-686e-44df25f3ff4a@infradead.org>
Date:   Fri, 13 Nov 2020 11:01:32 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Sami Tolvanen <samitolvanen@...gle.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Kees Cook <keescook@...omium.org>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Sedat Dilek <sedat.dilek@...il.com>
Subject: Re: [PATCH] x86/e820: fix the function type for e820__mapped_all

On 11/13/20 10:59 AM, Sami Tolvanen wrote:
> On Fri, Nov 13, 2020 at 10:35 AM Randy Dunlap <rdunlap@...radead.org> wrote:
>>
>> On 11/13/20 10:26 AM, Sami Tolvanen wrote:
>>> e820__mapped_all is passed as a callback to is_mmconf_reserved, which
>>> expects a function of type:
>>>
>>>   typedef bool (*check_reserved_t)(u64 start, u64 end, unsigned type);
>>>
>>> This trips indirect call checking with Clang's Control-Flow Integrity
>>> (CFI). Change the last argument from enum e820_type to unsigned to fix
>>> the type mismatch.
>>
>> Hi,
>>
>> Kernel style is no raw unsigned -- use unsigned int or unsigned long, please.
>>
>> checkpatch should or could have found that issue.
> 
> It did, but the existing type definition for the callback in
> pci/mmconfig-shared.c uses raw unsigned. I can add a patch to change
> that to unsigned int as well, if you prefer.

Hm. :)
Well, yes, I prefer, but I can't require it.

thanks for the explanation.

-- 
~Randy