linux-kernel - Re: [GIT PULL] x86/mm changes for v4.4

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Message-ID: <CA+55aFwa9XsM7bwoQUU01bh6884_84KiU8rhJ6=LC2QYyDneRQ@mail.gmail.com>
Date:	Thu, 5 Nov 2015 14:04:55 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dave Jones <davej@...emonkey.org.uk>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Denys Vlasenko <dvlasenk@...hat.com>
Subject: Re: [GIT PULL] x86/mm changes for v4.4

On Thu, Nov 5, 2015 at 1:27 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> No, I have that. I suspect CONFIG_EFI_PGT_DUMP instead.

Yes, that seems to show the tables, and agrees with the problem address.

So for me I have:

    WARNING: CPU: 1 PID: 1 at arch/x86/mm/dump_pagetables.c:225
note_page+0x5dc/0x780()
    x86/mm: Found insecure W+X mapping at address
ffff88000005f000/0xffff88000005f000

and that 005f000 address also shows up in the firmware tables:

    ACPI: 6 ACPI AML tables successfully acquired and loaded
    ---[ User Space ]---
    0x0000000000000000-0x000000000005f000         380K     RW
       GLB NX pte
    0x000000000005f000-0x0000000000060000           4K     RW
       GLB x  pte
    0x0000000000060000-0x0000000000200000        1664K     RW
       GLB NX pte
    ...
    ---[ Low Kernel Mapping ]---
    0xffff880000000000-0xffff88000005f000         380K     RW
       GLB NX pte
    0xffff88000005f000-0xffff880000060000           4K     RW
       GLB x  pte
    0xffff880000060000-0xffff880000200000        1664K     RW
       GLB NX pte
    ...

and there's quite a few other pages there that are RW but not marked
NX. I suspect they come from the EFI runtime services because the
pattern seems to match what I see in that area, but there's at least a
PSE mapping at START_KERNEL_map too, etc.

                   Linus
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