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  1. 19 5月, 2020 1 次提交
  3. 08 4月, 2020 1 次提交
  5. 03 4月, 2020 3 次提交
    • P
      mm: allow VM_FAULT_RETRY for multiple times · 4064b982
      由 Peter Xu 提交于 
      The idea comes from a discussion between Linus and Andrea [1].

Before this patch we only allow a page fault to retry once.  We achieved
this by clearing the FAULT_FLAG_ALLOW_RETRY flag when doing
handle_mm_fault() the second time.  This was majorly used to avoid
unexpected starvation of the system by looping over forever to handle the
page fault on a single page.  However that should hardly happen, and after
all for each code path to return a VM_FAULT_RETRY we'll first wait for a
condition (during which time we should possibly yield the cpu) to happen
before VM_FAULT_RETRY is really returned.

This patch removes the restriction by keeping the FAULT_FLAG_ALLOW_RETRY
flag when we receive VM_FAULT_RETRY.  It means that the page fault handler
now can retry the page fault for multiple times if necessary without the
need to generate another page fault event.  Meanwhile we still keep the
FAULT_FLAG_TRIED flag so page fault handler can still identify whether a
page fault is the first attempt or not.

Then we'll have these combinations of fault flags (only considering
ALLOW_RETRY flag and TRIED flag):

  - ALLOW_RETRY and !TRIED:  this means the page fault allows to
                             retry, and this is the first try

  - ALLOW_RETRY and TRIED:   this means the page fault allows to
                             retry, and this is not the first try

  - !ALLOW_RETRY and !TRIED: this means the page fault does not allow
                             to retry at all

  - !ALLOW_RETRY and TRIED:  this is forbidden and should never be used

In existing code we have multiple places that has taken special care of
the first condition above by checking against (fault_flags &
FAULT_FLAG_ALLOW_RETRY).  This patch introduces a simple helper to detect
the first retry of a page fault by checking against both (fault_flags &
FAULT_FLAG_ALLOW_RETRY) and !(fault_flag & FAULT_FLAG_TRIED) because now
even the 2nd try will have the ALLOW_RETRY set, then use that helper in
all existing special paths.  One example is in __lock_page_or_retry(), now
we'll drop the mmap_sem only in the first attempt of page fault and we'll
keep it in follow up retries, so old locking behavior will be retained.

This will be a nice enhancement for current code [2] at the same time a
supporting material for the future userfaultfd-writeprotect work, since in
that work there will always be an explicit userfault writeprotect retry
for protected pages, and if that cannot resolve the page fault (e.g., when
userfaultfd-writeprotect is used in conjunction with swapped pages) then
we'll possibly need a 3rd retry of the page fault.  It might also benefit
other potential users who will have similar requirement like userfault
write-protection.

GUP code is not touched yet and will be covered in follow up patch.

Please read the thread below for more information.

[1] https://lore.kernel.org/lkml/20171102193644.GB22686@redhat.com/
[2] https://lore.kernel.org/lkml/20181230154648.GB9832@redhat.com/Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Suggested-by: NAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: NPeter Xu <peterx@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Tested-by: NBrian Geffon <bgeffon@google.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220160246.9790-1-peterx@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4064b982
    • P
      mm: introduce FAULT_FLAG_DEFAULT · dde16072
      由 Peter Xu 提交于 
      Although there're tons of arch-specific page fault handlers, most of them
are still sharing the same initial value of the page fault flags.  Say,
merely all of the page fault handlers would allow the fault to be retried,
and they also allow the fault to respond to SIGKILL.

Let's define a default value for the fault flags to replace those initial
page fault flags that were copied over.  With this, it'll be far easier to
introduce new fault flag that can be used by all the architectures instead
of touching all the archs.
Signed-off-by: NPeter Xu <peterx@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Tested-by: NBrian Geffon <bgeffon@google.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220160238.9694-1-peterx@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dde16072
    • P
      x86/mm: use helper fault_signal_pending() · 39678191
      由 Peter Xu 提交于 
      Let's move the fatal signal check even earlier so that we can directly use
the new fault_signal_pending() in x86 mm code.
Signed-off-by: NPeter Xu <peterx@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Tested-by: NBrian Geffon <bgeffon@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220155353.8676-5-peterx@redhat.comSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      39678191
  7. 22 3月, 2020 1 次提交
  9. 07 1月, 2020 1 次提交
    • F
      x86/context-tracking: Remove exception_enter/exit() from do_page_fault() · ee6352b2
      由 Frederic Weisbecker 提交于 
      do_page_fault(), like other exceptions, is already covered by
user_enter() and user_exit() when the exception triggers in userspace.

As explained in:

  8c84014f ("x86/entry: Remove exception_enter() from most trap handlers")

exception_enter/exit() only remained to handle possible page fault from
kernel mode while context tracking is in CONTEXT_USER mode, ie: on
kernel entry before we manage to call user_exit(). The only known
offender was do_fast_syscall_32() fetching EBP register from where
vDSO stashed it.

Meanwhile this got fixed in:

  9999c8c0 ("x86/entry: Call enter_from_user_mode() with IRQs off")

that moved enter_from_user_mode() before the call to get_user().

So we can safely remove it now.
Signed-off-by: NFrederic Weisbecker <frederic@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jim Mattson <jmattson@google.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Link: https://lkml.kernel.org/r/20191227163612.10039-2-frederic@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      ee6352b2
  11. 10 12月, 2019 1 次提交
    • I
      mm, x86/mm: Untangle address space layout definitions from basic pgtable type definitions · 186525bd
      由 Ingo Molnar 提交于 
      - Untangle the somewhat incestous way of how VMALLOC_START is used all across the
  kernel, but is, on x86, defined deep inside one of the lowest level page table headers.
  It doesn't help that vmalloc.h only includes a single asm header:

     #include <asm/page.h>           /* pgprot_t */

  So there was no existing cross-arch way to decouple address layout
  definitions from page.h details. I used this:

   #ifndef VMALLOC_START
   # include <asm/vmalloc.h>
   #endif

  This way every architecture that wants to simplify page.h can do so.

- Also on x86 we had a couple of LDT related inline functions that used
  the late-stage address space layout positions - but these could be
  uninlined without real trouble - the end result is cleaner this way as
  well.
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      186525bd
  13. 27 11月, 2019 1 次提交
    • J
      x86/mm/32: Sync only to VMALLOC_END in vmalloc_sync_all() · 9a62d200
      由 Joerg Roedel 提交于 
      The job of vmalloc_sync_all() is to help the lazy freeing of vmalloc()
ranges: before such vmap ranges are reused we make sure that they are
unmapped from every task's page tables.

This is really easy on pagetable setups where the kernel page tables
are shared between all tasks - this is the case on 32-bit kernels
with SHARED_KERNEL_PMD = 1.

But on !SHARED_KERNEL_PMD 32-bit kernels this involves iterating
over the pgd_list and clearing all pmd entries in the pgds that
are cleared in the init_mm.pgd, which is the reference pagetable
that the vmalloc() code uses.

In that context the current practice of vmalloc_sync_all() iterating
until FIX_ADDR_TOP is buggy:

        for (address = VMALLOC_START & PMD_MASK;
             address >= TASK_SIZE_MAX && address < FIXADDR_TOP;
             address += PMD_SIZE) {
                struct page *page;

Because iterating up to FIXADDR_TOP will involve a lot of non-vmalloc
address ranges:

	VMALLOC -> PKMAP -> LDT -> CPU_ENTRY_AREA -> FIX_ADDR

This is mostly harmless for the FIX_ADDR and CPU_ENTRY_AREA ranges
that don't clear their pmds, but it's lethal for the LDT range,
which relies on having different mappings in different processes,
and 'synchronizing' them in the vmalloc sense corrupts those
pagetable entries (clearing them).

This got particularly prominent with PTI, which turns SHARED_KERNEL_PMD
off and makes this the dominant mapping mode on 32-bit.

To make LDT working again vmalloc_sync_all() must only iterate over
the volatile parts of the kernel address range that are identical
between all processes.

So the correct check in vmalloc_sync_all() is "address < VMALLOC_END"
to make sure the VMALLOC areas are synchronized and the LDT
mapping is not falsely overwritten.

The CPU_ENTRY_AREA and the FIXMAP area are no longer synced either,
but this is not really a proplem since their PMDs get established
during bootup and never change.

This change fixes the ldt_gdt selftest in my setup.

[ mingo: Fixed up the changelog to explain the logic and modified the
         copying to only happen up until VMALLOC_END. ]
Reported-by: NBorislav Petkov <bp@suse.de>
Tested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NJoerg Roedel <jroedel@suse.de>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com
Fixes: 7757d607: ("x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32")
Link: https://lkml.kernel.org/r/20191126111119.GA110513@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      9a62d200
  15. 22 7月, 2019 2 次提交
  17. 18 7月, 2019 1 次提交
  19. 17 7月, 2019 1 次提交
    • A
      mm, kprobes: generalize and rename notify_page_fault() as kprobe_page_fault() · b98cca44
      由 Anshuman Khandual 提交于 
      Architectures which support kprobes have very similar boilerplate around
calling kprobe_fault_handler().  Use a helper function in kprobes.h to
unify them, based on the x86 code.

This changes the behaviour for other architectures when preemption is
enabled.  Previously, they would have disabled preemption while calling
the kprobe handler.  However, preemption would be disabled if this fault
was due to a kprobe, so we know the fault was not due to a kprobe
handler and can simply return failure.

This behaviour was introduced in commit a980c0ef ("x86/kprobes:
Refactor kprobes_fault() like kprobe_exceptions_notify()")

[anshuman.khandual@arm.com: export kprobe_fault_handler()]
  Link: http://lkml.kernel.org/r/1561133358-8876-1-git-send-email-anshuman.khandual@arm.com
Link: http://lkml.kernel.org/r/1560420444-25737-1-git-send-email-anshuman.khandual@arm.comSigned-off-by: NAnshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b98cca44
  21. 28 6月, 2019 2 次提交
  23. 03 6月, 2019 1 次提交
    • E
      signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus · 318759b4
      由 Eric W. Biederman 提交于 
      Stephen Rothwell <sfr@canb.auug.org.au> reported:
> After merging the userns tree, today's linux-next build (i386 defconfig)
> produced this warning:
>
> arch/x86/mm/fault.c: In function 'do_sigbus':
> arch/x86/mm/fault.c:1017:22: warning: unused variable 'tsk' [-Wunused-variable]
>   struct task_struct *tsk = current;
>                       ^~~
>
> Introduced by commit
>
>   351b6825 ("signal: Explicitly call force_sig_fault on current")
>
> The remaining used of "tsk" are protected by CONFIG_MEMORY_FAILURE.

So do the obvious thing and move tsk inside of CONFIG_MEMORY_FAILURE
to prevent introducing new warnings into the build.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      318759b4
  25. 29 5月, 2019 2 次提交
    • E
      signal: Remove the task parameter from force_sig_fault · 2e1661d2
      由 Eric W. Biederman 提交于 
      As synchronous exceptions really only make sense against the current
task (otherwise how are you synchronous) remove the task parameter
from from force_sig_fault to make it explicit that is what is going
on.

The two known exceptions that deliver a synchronous exception to a
stopped ptraced task have already been changed to
force_sig_fault_to_task.

The callers have been changed with the following emacs regular expression
(with obvious variations on the architectures that take more arguments)
to avoid typos:

force_sig_fault[(]\([^,]+\)[,]\([^,]+\)[,]\([^,]+\)[,]\W+current[)]
->
force_sig_fault(\1,\2,\3)
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      2e1661d2
    • E
      signal: Explicitly call force_sig_fault on current · 351b6825
      由 Eric W. Biederman 提交于 
      Update the calls of force_sig_fault that pass in a variable that is
set to current earlier to explicitly use current.

This is to make the next change that removes the task parameter
from force_sig_fault easier to verify.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      351b6825
  27. 27 5月, 2019 1 次提交
  29. 24 4月, 2019 1 次提交
  31. 22 4月, 2019 1 次提交
    • B
      x86/fault: Make fault messages more succinct · ea2f8d60
      由 Borislav Petkov 提交于 
      So we are going to be staring at those in the next years, let's make
them more succinct. In particular:

 - change "address = " to "address: "

 - "-privileged" reads funny. It should be simply "kernel" or "user"

 - "from kernel code" reads funny too. "kernel mode" or "user mode" is
   more natural.

An actual example says more than 1000 words, of course:

  [    0.248370] BUG: kernel NULL pointer dereference, address: 00000000000005b8
  [    0.249120] #PF: supervisor write access in kernel mode
  [    0.249717] #PF: error_code(0x0002) - not-present page
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dave.hansen@linux.intel.com
Cc: luto@kernel.org
Cc: riel@surriel.com
Cc: sean.j.christopherson@intel.com
Cc: yu-cheng.yu@intel.com
Link: http://lkml.kernel.org/r/20190421183524.GC6048@zn.tnicSigned-off-by: NIngo Molnar <mingo@kernel.org>
      ea2f8d60
  33. 20 4月, 2019 2 次提交
    • S
      x86/fault: Decode and print #PF oops in human readable form · 18ea35c5
      由 Sean Christopherson 提交于 
      Linus pointed out that deciphering the raw #PF error code and printing
a more human readable message are two different things, and also that
printing the negative cases is mostly just noise[1].  For example, the
USER bit doesn't mean the fault originated in user code and stating
that an oops wasn't due to a protection keys violation isn't interesting
since an oops on a keys violation is a one-in-a-million scenario.

Remove the per-bit decoding of the error code and instead print:
  - the raw error code
  - why the fault occurred
  - the effective privilege level of the access
  - the type of access
  - whether the fault originated in user code or kernel code

This provides the user with the information needed to triage 99.9% of
oopses without polluting the log with useless information or conflating
the error_code with the CPL.

Sample output:

    BUG: kernel NULL pointer dereference, address = 0000000000000008
    #PF: supervisor-privileged instruction fetch from kernel code
    #PF: error_code(0x0010) - not-present page

    BUG: unable to handle page fault for address = ffffbeef00000000
    #PF: supervisor-privileged instruction fetch from kernel code
    #PF: error_code(0x0010) - not-present page

    BUG: unable to handle page fault for address = ffffc90000230000
    #PF: supervisor-privileged write access from kernel code
    #PF: error_code(0x000b) - reserved bit violation

[1] https://lkml.kernel.org/r/CAHk-=whk_fsnxVMvF1T2fFCaP2WrvSybABrLQCWLJyCvHw6NKA@mail.gmail.comSuggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20181221213657.27628-3-sean.j.christopherson@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      18ea35c5
    • S
      x86/fault: Reword initial BUG message for unhandled page faults · f28b11a2
      由 Sean Christopherson 提交于 
      Reword the NULL pointer dereference case to simply state that a NULL
pointer was dereferenced, i.e. drop "unable to handle" as that implies
that there are instances where the kernel actual does handle NULL
pointer dereferences, which is not true barring funky exception fixup.

For the non-NULL case, replace "kernel paging request" with "page fault"
as the kernel can technically oops on faults that originated in user
code.  Dropping "kernel" also allows future patches to provide detailed
information on where the fault occurred, e.g. user vs. kernel, without
conflicting with the initial BUG message.

In both cases, replace "at address=" with wording more appropriate to
the oops, as "at" may be interpreted as stating that the address is the
RIP of the instruction that faulted.

Last, and probably least, further qualify the NULL-pointer path by
checking that the fault actually originated in kernel code.  It's
technically possible for userspace to map address 0, and not printing
a super specific message is the least of our worries if the kernel does
manage to oops on an actual NULL pointer dereference from userspace.

Before:
    BUG: unable to handle kernel NULL pointer dereference at ffffbeef00000000
    BUG: unable to handle kernel paging request at ffffbeef00000000

After:
    BUG: kernel NULL pointer dereference, address = 0000000000000008
    BUG: unable to handle page fault for address = ffffbeef00000000
Suggested-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20181221213657.27628-2-sean.j.christopherson@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      f28b11a2
  35. 17 4月, 2019 2 次提交
    • T
      x86/traps: Use cpu_entry_area instead of orig_ist · d876b673
      由 Thomas Gleixner 提交于 
      The orig_ist[] array is a shadow copy of the IST array in the TSS. The
reason why it exists is that older kernels used two TSS variants with
different pointers into the debug stack. orig_ist[] contains the real
starting points.

There is no point anymore to do so because the same information can be
retrieved using the base address of the cpu entry area mapping and the
offsets of the various exception stacks.

No functional change. Preparation for removing orig_ist.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160144.784487230@linutronix.de
      d876b673
    • T
      x86/exceptions: Make IST index zero based · 8f34c5b5
      由 Thomas Gleixner 提交于 
      The defines for the exception stack (IST) array in the TSS are using the
SDM convention IST1 - IST7. That causes all sorts of code to subtract 1 for
array indices related to IST. That's confusing at best and does not provide
any value.

Make the indices zero based and fixup the usage sites. The only code which
needs to adjust the 0 based index is the interrupt descriptor setup which
needs to add 1 now.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NSean Christopherson <sean.j.christopherson@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Chang S. Bae" <chang.seok.bae@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: linux-doc@vger.kernel.org
Cc: Nicolai Stange <nstange@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qian Cai <cai@lca.pw>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190414160144.331772825@linutronix.de
      8f34c5b5
  37. 08 3月, 2019 1 次提交
  39. 30 1月, 2019 1 次提交
    • C
      x86/fault: Fix sign-extend unintended sign extension · 5ccd3528
      由 Colin Ian King 提交于 
      show_ldttss() shifts desc.base2 by 24 bit, but base2 is 8 bits of a
bitfield in a u16.

Due to the really great idea of integer promotion in C99 base2 is promoted
to an int, because that's the standard defined behaviour when all values
which can be represented by base2 fit into an int.

Now if bit 7 is set in desc.base2 the result of the shift left by 24 makes
the resulting integer negative and the following conversion to unsigned
long legitmately sign extends first causing the upper bits 32 bits to be
set in the result.

Fix this by casting desc.base2 to unsigned long before the shift.

Detected by CoverityScan, CID#1475635 ("Unintended sign extension")

[ tglx: Reworded the changelog a bit as I actually had to lookup
  	the standard (again) to decode the original one. ]

Fixes: a1a371c4 ("x86/fault: Decode page fault OOPSes better")
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: kernel-janitors@vger.kernel.org
Link: https://lkml.kernel.org/r/20181222191116.21831-1-colin.king@canonical.com
      5ccd3528
  41. 22 11月, 2018 4 次提交
    • I
      x86/fault: Clean up the page fault oops decoder a bit · a2aa52ab
      由 Ingo Molnar 提交于 
       - Make the oops messages a bit less scary (don't mention 'HW errors')

 - Turn 'PROT USER' (which is visually easily confused with PROT_USER)
   into individual bit descriptors: "[PROT] [USER]".
   This also makes "[normal kernel read fault]" more apparent.

 - De-abbreviate variables to make the code easier to read

 - Use vertical alignment where appropriate.

 - Add comment about string size limits and the helper function.

 - Remove unnecessary line breaks.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a2aa52ab
    • A
      x86/fault: Decode page fault OOPSes better · a1a371c4
      由 Andy Lutomirski 提交于 
      One of Linus' favorite hobbies seems to be looking at OOPSes and
decoding the error code in his head.  This is not one of my favorite
hobbies :)

Teach the page fault OOPS hander to decode the error code.  If it's
a !USER fault from user mode, print an explicit note to that effect
and print out the addresses of various tables that might cause such
an error.

With this patch applied, if I intentionally point the LDT at 0x0 and
run the x86 selftests, I get:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
  HW error: normal kernel read fault
  This was a system access from user code
  IDT: 0xfffffe0000000000 (limit=0xfff) GDT: 0xfffffe0000001000 (limit=0x7f)
  LDTR: 0x50 -- base=0x0 limit=0xfff7
  TR: 0x40 -- base=0xfffffe0000003000 limit=0x206f
  PGD 800000000456e067 P4D 800000000456e067 PUD 4623067 PMD 0
  SMP PTI
  CPU: 0 PID: 153 Comm: ldt_gdt_64 Not tainted 4.19.0+ #1317
  Hardware name: ...
  RIP: 0033:0x401454
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/11212acb25980cd1b3030875cd9502414fbb214d.1542841400.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      a1a371c4
    • A
      x86/fault: Don't try to recover from an implicit supervisor access · ebb53e25
      由 Andy Lutomirski 提交于 
      This avoids a situation in which we attempt to apply various fixups
that are not intended to handle implicit supervisor accesses from
user mode if we screw up in a way that causes this type of fault.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/9999f151d72ff352265f3274c5ab3a4105090f49.1542841400.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      ebb53e25
    • A
      x86/fault: Remove sw_error_code · 0ed32f1a
      由 Andy Lutomirski 提交于 
      All of the fault handling code now corrently checks user_mode(regs)
as needed, and nothing depends on the X86_PF_USER bit being munged.
Get rid of the sw_error code and use hw_error_code everywhere.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/078f5b8ae6e8c79ff8ee7345b5c476c45003e5ac.1542841400.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      0ed32f1a
  43. 20 11月, 2018 7 次提交
    • A
      x86/fault: Don't set thread.cr2, etc before OOPSing · 1ad33f5a
      由 Andy Lutomirski 提交于 
      The fault handling code sets the cr2, trap_nr, and error_code fields
in thread_struct before OOPSing.  No one reads those fields during
an OOPS, so remove the code to set them.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/d418022aa0fad9cb40467aa7acaf4e95be50ee96.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      1ad33f5a
    • A
      x86/fault: Make error_code sanitization more robust · e49d3cbe
      由 Andy Lutomirski 提交于 
      The error code in a page fault on a kernel address indicates
whether that address is mapped, which should not be revealed in a signal.

The normal code path for a page fault on a kernel address sanitizes the bit,
but the paths for vsyscall emulation and SIGBUS do not.  Both are
harmless, but for subtle reasons.  SIGBUS is never sent for a kernel
address, and vsyscall emulation will never fault on a kernel address
per se because it will fail an access_ok() check instead.

Make the code more robust by adding a helper that sets the relevant
fields and sanitizing the error code in the helper.  This also
cleans up the code -- we had three copies of roughly the same thing.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/b31159bd55bd0c4fa061a20dfd6c429c094bebaa.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      e49d3cbe
    • A
      x86/fault: Improve the condition for signalling vs OOPSing · 6ea59b07
      由 Andy Lutomirski 提交于 
      __bad_area_nosemaphore() currently checks the X86_PF_USER bit in the
error code to decide whether to send a signal or to treat the fault
as a kernel error.  This can cause somewhat erratic behavior.  The
straightforward cases where the CPL agrees with the hardware USER
bit are all correct, but the other cases are confusing.

 - A user instruction accessing a kernel address with supervisor
   privilege (e.g. a descriptor table access failed).  The USER bit
   will be clear, and we OOPS.  This is correct, because it indicates
   a kernel bug, not a user error.

 - A user instruction accessing a user address with supervisor
   privilege (e.g. a descriptor table was incorrectly pointing at
   user memory).  __bad_area_nosemaphore() will be passed a modified
   error code with the user bit set, and we will send a signal.
   Sending the signal will work (because the regs and the entry
   frame genuinely come from user mode), but we really ought to
   OOPS, as this event indicates a severe kernel bug.

 - A kernel instruction with user privilege (i.e. WRUSS).  This
   should OOPS or get fixed up.  The current code would instead try
   send a signal and malfunction.

Change the logic: a signal should be sent if the faulting context is
user mode *and* the access has user privilege.  Otherwise it's
either a kernel mode fault or a failed implicit access, either of
which should end up in no_context().

Note to -stable maintainers: don't backport this unless you backport
CET.  The bug it fixes is unobservable in current kernels unless
something is extremely wrong.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/10e509c43893170e262e82027ea399130ae81159.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6ea59b07
    • A
      x86/fault: Fix SMAP #PF handling buglet for implicit supervisor accesses · e50928d7
      由 Andy Lutomirski 提交于 
      Currently, if a user program somehow triggers an implicit supervisor
access to a user address (e.g. if the kernel somehow sets LDTR to a
user address), it will be incorrectly detected as a SMAP violation
if AC is clear and SMAP is enabled.  This is incorrect -- the error
has nothing to do with SMAP.  Fix the condition so that only
accesses with the hardware USER bit set are diagnosed as SMAP
violations.

With the logic fixed, an implicit supervisor access to a user address
will hit the code lower in the function that is intended to handle it
even if SMAP is enabled.  That logic is still a bit buggy, and later
patches will clean it up.

I *think* this code is still correct for WRUSS, and I've added a
comment to that effect.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/d1d1b2e66ef31f884dba172084486ea9423ddcdb.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      e50928d7
    • A
      x86/fault: Fold smap_violation() into do_user_addr_fault() · a15781b5
      由 Andy Lutomirski 提交于 
      smap_violation() has a single caller, and the contents are a bit
nonsensical.  I'm going to fix it, but first let's fold it into its
caller for ease of comprehension.

In this particular case, the user_mode(regs) check is incorrect --
it will cause false positives in the case of a user-initiated
kernel-privileged access.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/806c366f6ca861152398ce2c01744d59d9aceb6d.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      a15781b5
    • A
      x86/cpufeatures, x86/fault: Mark SMAP as disabled when configured out · dae0a105
      由 Andy Lutomirski 提交于 
      Add X86_FEATURE_SMAP to the disabled features mask as appropriate
and use cpu_feature_enabled() in the fault code.  This lets us get
rid of a redundant IS_ENABLED(CONFIG_X86_SMAP).
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/fe93332eded3d702f0b0b4cf83928d6830739ba3.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      dae0a105
    • A
      x86/fault: Check user_mode(regs) when avoiding an mmap_sem deadlock · 6344be60
      由 Andy Lutomirski 提交于 
      The fault-handling code that takes mmap_sem needs to avoid a
deadlock that could occur if the kernel took a bad (OOPS-worthy)
page fault on a user address while holding mmap_sem.  This can only
happen if the faulting instruction was in the kernel
(i.e. user_mode(regs)).  Rather than checking the sw_error_code
(which will have the USER bit set if the fault was a USER-permission
access *or* if user_mode(regs)), just check user_mode(regs)
directly.

The old code would have malfunctioned if the kernel executed a bogus
WRUSS instruction while holding mmap_sem.  Fortunately, that is
extremely unlikely in current kernels, which don't use WRUSS.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/4b89b542e8ceba9bd6abde2f386afed6d99244a9.1542667307.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6344be60
  45. 12 11月, 2018 1 次提交
    • W
      x86/mm/fault: Allow stack access below %rsp · 1d8ca3be
      由 Waiman Long 提交于 
      The current x86 page fault handler allows stack access below the stack
pointer if it is no more than 64k+256 bytes. Any access beyond the 64k+
limit will cause a segmentation fault.

The gcc -fstack-check option generates code to probe the stack for
large stack allocation to see if the stack is accessible. The newer gcc
does that while updating the %rsp simultaneously. Older gcc's like gcc4
doesn't do that. As a result, an application compiled with an old gcc
and the -fstack-check option may fail to start at all:

  $ cat test.c
  int main() {
	char tmp[1024*128];
	printf("### ok\n");
	return 0;
  }

  $ gcc -fstack-check -g -o test test.c

  $ ./test
  Segmentation fault

The old binary was working in older kernels where expand_stack() was
somehow called before the check. But it is not working in newer kernels.
Besides, the 64k+ limit check is kind of crude and will not catch a
lot of mistakes that userspace applications may be misbehaving anyway.
I think the kernel isn't the right place for this kind of tests. We
should leave it to userspace instrumentation tools to perform them.

The 64k+ limit check is now removed to just let expand_stack() decide
if a segmentation fault should happen, when the RLIMIT_STACK limit is
exceeded, for example.
Signed-off-by: NWaiman Long <longman@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1541535149-31963-1-git-send-email-longman@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      1d8ca3be
  47. 31 10月, 2018 1 次提交