linux-kernel - Re: [GIT PULL] x86/iopl changes for v5.5

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Message-ID: <20191125192456.GA46001@gmail.com>
Date:   Mon, 25 Nov 2019 20:24:56 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [GIT PULL] x86/iopl changes for v5.5


* Ingo Molnar <mingo@...nel.org> wrote:

> Linus,
> 
> Please pull the latest x86-iopl-for-linus git tree from:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-iopl-for-linus
> 
>    # HEAD: e3cb0c7102f04c83bf1a7cb1d052e92749310b46 x86/ioperm: Fix use of deprecated config option
> 
> This tree implements a nice simplification of the iopl and ioperm code 
> that Thomas Gleixner discovered: we can implement the IO privilege 
> features of the iopl system call by using the IO permission bitmap in 
> permissive mode, while trapping CLI/STI/POPF/PUSHF uses in user-space if 
> they change the interrupt flag.
> 
> This tree implements that feature, with testing facilities and related 
> cleanups.

Forgot to list the conflicts that may arise if you merge this after the 
other x86 bits.

Firstly the symbol bits would conflict here:

            arch/x86/entry/entry_32.S
            arch/x86/kernel/head_32.S
            arch/x86/xen/xen-asm_32.S

I've resolved them in tip:WIP.x86/asm if you want to double check:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.x86/asm

but usually you do the resolutions better. :-)

There's also a conflict in arch/x86/include/asm/pgtable_32_types.h.

But there's also a semantic conflict that would trigger if you pull this 
after the x86/urgent bits, interacting with:

  05b042a19443: ("x86/pti/32: Calculate the various PTI cpu_entry_area sizes correctly, make the CPU_ENTRY_AREA_PAGES assert precise")

After that commit the CPU_ENTRY_AREA_PAGES value has to be precise, and 
edited to 41 in the merge commit if I did everything write with the pull 
requests.

This too is resolved in tip:WIP.x86/asm, in the following merge commits:

  22d7b9359a9a: ("Merge branch 'x86/iopl' into x86/asm, to resolve conflicts")
  7543765dd362: ("Merge branch 'x86/urgent' into x86/iopl, to resolve conflicts")

Thanks,

	Ingo