Re: [PATCH 3/3] x86: mm: add x86_64 support for page table check

From: Pasha Tatashin <pasha.tatashin@soleen.com>
To: Jiri Slaby <jirislaby@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Rientjes <rientjes@google.com>,
	Paul Turner <pjt@google.com>,
	weixugc@google.com, Greg Thelen <gthelen@google.com>,
	Ingo Molnar <mingo@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
	Will Deacon <will@kernel.org>, Mike Rapoport <rppt@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	masahiroy@kernel.org, Sami Tolvanen <samitolvanen@google.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>,
	frederic@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: Re: [PATCH 3/3] x86: mm: add x86_64 support for page table check
Date: Wed, 1 Dec 2021 08:55:21 -0500	[thread overview]
Message-ID: <CA+CK2bBfcrxDyxnV+xc680AP+sJGHSpong6a+b_vvWcRsB2CcA@mail.gmail.com> (raw)
In-Reply-To: <cadf2582-3004-92b9-ab5a-cb39259fa36c@kernel.org>

On Wed, Dec 1, 2021 at 3:44 AM Jiri Slaby <jirislaby@kernel.org> wrote:
>
> On 01. 12. 21, 9:00, Jiri Slaby wrote:
> > On 23. 11. 21, 22:48, Pasha Tatashin wrote:
> >> Add page table check hooks into routines that modify user page tables.
> >
> > Hi,
> >
> > I bisected to this as this causes crashes during modules load:
>
> And it's not enough to unset CONFIG_PAGE_TABLE_CHECK_ENFORCED. I had to
> unset CONFIG_PAGE_TABLE_CHECK completely to get rid of this.

Hi,

Thanks for reporting this. Seems like module load for some reasons
does not like the static branches. However, I was not able to repro
this. Could you please share your config and the module that you were
loading?

Thank you,
Pasha

>
> > #PF: supervisor write access in kernel mode
> > #PF: error_code(0x0003) - permissions violation
> > PGD 6d615067 P4D 6d615067 PUD 6d616063 PMD 800000006d2001e1
> > Oops: 0003 [#1] PREEMPT SMP PTI
> > CPU: 0 PID: 6189 Comm: modprobe Kdump: loaded Tainted: G          I E
> > 5.16.0-rc2-next-20211129-vanilla #3
> > 83846a405f0e3937f5c8dfbc7d449622b8f46369
> > Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be
> > filled by O.E.M., BIOS SDBLI944.86P 05/08/2007
> > RIP: 0010:jump_label_module_notify (kernel/jump_label.c:370
> > kernel/jump_label.c:670 kernel/jump_label.c:748)
> > Code: 00 48 8b 43 08 a8 02 0f 85 e9 00 00 00 48 83 e0 fc 48 c7 02 00 00
> > 00 00 48 89 42 08 48 8b 43 08 83 e0 03 48 09 c2 48 83 ca 02 <48> 89 53
> > 08 4d 89 66 10 49 89 6e 08 48 8b 43 08 a8 02 0f 84 98 00
> > All code
> > ========
> >     0:    00 48 8b                 add    %cl,-0x75(%rax)
> >     3:    43 08 a8 02 0f 85 e9     rex.XB or %bpl,-0x167af0fe(%r8)
> >     a:    00 00                    add    %al,(%rax)
> >     c:    00 48 83                 add    %cl,-0x7d(%rax)
> >     f:    e0 fc                    loopne 0xd
> >    11:    48 c7 02 00 00 00 00     movq   $0x0,(%rdx)
> >    18:    48 89 42 08              mov    %rax,0x8(%rdx)
> >    1c:    48 8b 43 08              mov    0x8(%rbx),%rax
> >    20:    83 e0 03                 and    $0x3,%eax
> >    23:    48 09 c2                 or     %rax,%rdx
> >    26:    48 83 ca 02              or     $0x2,%rdx
> >    2a:*    48 89 53 08              mov    %rdx,0x8(%rbx)        <--
> > trapping instruction
> >    2e:    4d 89 66 10              mov    %r12,0x10(%r14)
> >    32:    49 89 6e 08              mov    %rbp,0x8(%r14)
> >    36:    48 8b 43 08              mov    0x8(%rbx),%rax
> >    3a:    a8 02                    test   $0x2,%al
> >    3c:    0f                       .byte 0xf
> >    3d:    84                       .byte 0x84
> >    3e:    98                       cwtl
> >      ...
> >
> > Code starting with the faulting instruction
> > ===========================================
> >     0:    48 89 53 08              mov    %rdx,0x8(%rbx)
> >     4:    4d 89 66 10              mov    %r12,0x10(%r14)
> >     8:    49 89 6e 08              mov    %rbp,0x8(%r14)
> >     c:    48 8b 43 08              mov    0x8(%rbx),%rax
> >    10:    a8 02                    test   $0x2,%al
> >    12:    0f                       .byte 0xf
> >    13:    84                       .byte 0x84
> >    14:    98                       cwtl
> >      ...
> > RSP: 0018:ffffaf4dc051fbe8 EFLAGS: 00010282
> > RAX: 0000000000000001 RBX: ffffffff931ee760 RCX: 0000000000000001
> > RDX: ffff9d1aa7d43883 RSI: ffffffff91c50aa0 RDI: ffffffff931ee760
> > RBP: ffffffffc0782000 R08: 0000000000000020 R09: 0000000000000000
> > R10: ffff9d1aa7d43880 R11: 0000000000000000 R12: ffffffffc079a980
> > R13: ffffffffc0784080 R14: ffff9d1aa7d43ca0 R15: ffffffffc0782008
> > FS:  00007f87104b8740(0000) GS:ffff9d1b45c00000(0000)
> > knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: ffffffff931ee768 CR3: 000000010fdce000 CR4: 00000000000006f0
> > Call Trace:
> >   <TASK>
> > blocking_notifier_call_chain_robust (kernel/notifier.c:83
> > kernel/notifier.c:118 kernel/notifier.c:283 kernel/notifier.c:271)
> > load_module (./include/linux/notifier.h:198 kernel/module.c:3923
> > kernel/module.c:4100)
> > __do_sys_finit_module (kernel/module.c:4224)
> > do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
> > entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:113)
> >
> >> Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
> >> ---
> >>   arch/x86/Kconfig               |  1 +
> >>   arch/x86/include/asm/pgtable.h | 29 +++++++++++++++++++++++++++--
> >>   2 files changed, 28 insertions(+), 2 deletions(-)
> >>
> >
> > regards,
>
>
> --
> js
> suse labs