1. 24 12月, 2017 1 次提交
    • T
      x86/ldt: Make the LDT mapping RO · 9f5cb6b3
      Thomas Gleixner 提交于
      Now that the LDT mapping is in a known area when PAGE_TABLE_ISOLATION is
      enabled its a primary target for attacks, if a user space interface fails
      to validate a write address correctly. That can never happen, right?
      
      The SDM states:
      
          If the segment descriptors in the GDT or an LDT are placed in ROM, the
          processor can enter an indefinite loop if software or the processor
          attempts to update (write to) the ROM-based segment descriptors. To
          prevent this problem, set the accessed bits for all segment descriptors
          placed in a ROM. Also, remove operating-system or executive code that
          attempts to modify segment descriptors located in ROM.
      
      So its a valid approach to set the ACCESS bit when setting up the LDT entry
      and to map the table RO. Fixup the selftest so it can handle that new mode.
      
      Remove the manual ACCESS bit setter in set_tls_desc() as this is now
      pointless. Folded the patch from Peter Ziljstra.
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      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: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      9f5cb6b3
  2. 23 12月, 2017 1 次提交
    • T
      x86/cpu_entry_area: Move it out of the fixmap · 92a0f81d
      Thomas Gleixner 提交于
      Put the cpu_entry_area into a separate P4D entry. The fixmap gets too big
      and 0-day already hit a case where the fixmap PTEs were cleared by
      cleanup_highmap().
      
      Aside of that the fixmap API is a pain as it's all backwards.
      Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
      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: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      92a0f81d
  3. 17 12月, 2017 3 次提交
  4. 02 11月, 2017 1 次提交
    • G
      License cleanup: add SPDX GPL-2.0 license identifier to files with no license · b2441318
      Greg Kroah-Hartman 提交于
      Many source files in the tree are missing licensing information, which
      makes it harder for compliance tools to determine the correct license.
      
      By default all files without license information are under the default
      license of the kernel, which is GPL version 2.
      
      Update the files which contain no license information with the 'GPL-2.0'
      SPDX license identifier.  The SPDX identifier is a legally binding
      shorthand, which can be used instead of the full boiler plate text.
      
      This patch is based on work done by Thomas Gleixner and Kate Stewart and
      Philippe Ombredanne.
      
      How this work was done:
      
      Patches were generated and checked against linux-4.14-rc6 for a subset of
      the use cases:
       - file had no licensing information it it.
       - file was a */uapi/* one with no licensing information in it,
       - file was a */uapi/* one with existing licensing information,
      
      Further patches will be generated in subsequent months to fix up cases
      where non-standard license headers were used, and references to license
      had to be inferred by heuristics based on keywords.
      
      The analysis to determine which SPDX License Identifier to be applied to
      a file was done in a spreadsheet of side by side results from of the
      output of two independent scanners (ScanCode & Windriver) producing SPDX
      tag:value files created by Philippe Ombredanne.  Philippe prepared the
      base worksheet, and did an initial spot review of a few 1000 files.
      
      The 4.13 kernel was the starting point of the analysis with 60,537 files
      assessed.  Kate Stewart did a file by file comparison of the scanner
      results in the spreadsheet to determine which SPDX license identifier(s)
      to be applied to the file. She confirmed any determination that was not
      immediately clear with lawyers working with the Linux Foundation.
      
      Criteria used to select files for SPDX license identifier tagging was:
       - Files considered eligible had to be source code files.
       - Make and config files were included as candidates if they contained >5
         lines of source
       - File already had some variant of a license header in it (even if <5
         lines).
      
      All documentation files were explicitly excluded.
      
      The following heuristics were used to determine which SPDX license
      identifiers to apply.
      
       - when both scanners couldn't find any license traces, file was
         considered to have no license information in it, and the top level
         COPYING file license applied.
      
         For non */uapi/* files that summary was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0                                              11139
      
         and resulted in the first patch in this series.
      
         If that file was a */uapi/* path one, it was "GPL-2.0 WITH
         Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|-------
         GPL-2.0 WITH Linux-syscall-note                        930
      
         and resulted in the second patch in this series.
      
       - if a file had some form of licensing information in it, and was one
         of the */uapi/* ones, it was denoted with the Linux-syscall-note if
         any GPL family license was found in the file or had no licensing in
         it (per prior point).  Results summary:
      
         SPDX license identifier                            # files
         ---------------------------------------------------|------
         GPL-2.0 WITH Linux-syscall-note                       270
         GPL-2.0+ WITH Linux-syscall-note                      169
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
         ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
         LGPL-2.1+ WITH Linux-syscall-note                      15
         GPL-1.0+ WITH Linux-syscall-note                       14
         ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
         LGPL-2.0+ WITH Linux-syscall-note                       4
         LGPL-2.1 WITH Linux-syscall-note                        3
         ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
         ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1
      
         and that resulted in the third patch in this series.
      
       - when the two scanners agreed on the detected license(s), that became
         the concluded license(s).
      
       - when there was disagreement between the two scanners (one detected a
         license but the other didn't, or they both detected different
         licenses) a manual inspection of the file occurred.
      
       - In most cases a manual inspection of the information in the file
         resulted in a clear resolution of the license that should apply (and
         which scanner probably needed to revisit its heuristics).
      
       - When it was not immediately clear, the license identifier was
         confirmed with lawyers working with the Linux Foundation.
      
       - If there was any question as to the appropriate license identifier,
         the file was flagged for further research and to be revisited later
         in time.
      
      In total, over 70 hours of logged manual review was done on the
      spreadsheet to determine the SPDX license identifiers to apply to the
      source files by Kate, Philippe, Thomas and, in some cases, confirmation
      by lawyers working with the Linux Foundation.
      
      Kate also obtained a third independent scan of the 4.13 code base from
      FOSSology, and compared selected files where the other two scanners
      disagreed against that SPDX file, to see if there was new insights.  The
      Windriver scanner is based on an older version of FOSSology in part, so
      they are related.
      
      Thomas did random spot checks in about 500 files from the spreadsheets
      for the uapi headers and agreed with SPDX license identifier in the
      files he inspected. For the non-uapi files Thomas did random spot checks
      in about 15000 files.
      
      In initial set of patches against 4.14-rc6, 3 files were found to have
      copy/paste license identifier errors, and have been fixed to reflect the
      correct identifier.
      
      Additionally Philippe spent 10 hours this week doing a detailed manual
      inspection and review of the 12,461 patched files from the initial patch
      version early this week with:
       - a full scancode scan run, collecting the matched texts, detected
         license ids and scores
       - reviewing anything where there was a license detected (about 500+
         files) to ensure that the applied SPDX license was correct
       - reviewing anything where there was no detection but the patch license
         was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
         SPDX license was correct
      
      This produced a worksheet with 20 files needing minor correction.  This
      worksheet was then exported into 3 different .csv files for the
      different types of files to be modified.
      
      These .csv files were then reviewed by Greg.  Thomas wrote a script to
      parse the csv files and add the proper SPDX tag to the file, in the
      format that the file expected.  This script was further refined by Greg
      based on the output to detect more types of files automatically and to
      distinguish between header and source .c files (which need different
      comment types.)  Finally Greg ran the script using the .csv files to
      generate the patches.
      Reviewed-by: NKate Stewart <kstewart@linuxfoundation.org>
      Reviewed-by: NPhilippe Ombredanne <pombredanne@nexb.com>
      Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
      Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b2441318
  5. 13 9月, 2017 1 次提交
  6. 29 8月, 2017 16 次提交
  7. 23 3月, 2017 3 次提交
  8. 16 3月, 2017 2 次提交
    • T
      x86: Make the GDT remapping read-only on 64-bit · 45fc8757
      Thomas Garnier 提交于
      This patch makes the GDT remapped pages read-only, to prevent accidental
      (or intentional) corruption of this key data structure.
      
      This change is done only on 64-bit, because 32-bit needs it to be writable
      for TSS switches.
      
      The native_load_tr_desc function was adapted to correctly handle a
      read-only GDT. The LTR instruction always writes to the GDT TSS entry.
      This generates a page fault if the GDT is read-only. This change checks
      if the current GDT is a remap and swap GDTs as needed. This function was
      tested by booting multiple machines and checking hibernation works
      properly.
      
      KVM SVM and VMX were adapted to use the writeable GDT. On VMX, the
      per-cpu variable was removed for functions to fetch the original GDT.
      Instead of reloading the previous GDT, VMX will reload the fixmap GDT as
      expected. For testing, VMs were started and restored on multiple
      configurations.
      Signed-off-by: NThomas Garnier <thgarnie@google.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Jiri Kosina <jikos@kernel.org>
      Cc: Joerg Roedel <joro@8bytes.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Lorenzo Stoakes <lstoakes@gmail.com>
      Cc: Luis R . Rodriguez <mcgrof@kernel.org>
      Cc: Matt Fleming <matt@codeblueprint.co.uk>
      Cc: Michal Hocko <mhocko@suse.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Pavel Machek <pavel@ucw.cz>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Stanislaw Gruszka <sgruszka@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Tim Chen <tim.c.chen@linux.intel.com>
      Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
      Cc: kasan-dev@googlegroups.com
      Cc: kernel-hardening@lists.openwall.com
      Cc: kvm@vger.kernel.org
      Cc: lguest@lists.ozlabs.org
      Cc: linux-doc@vger.kernel.org
      Cc: linux-efi@vger.kernel.org
      Cc: linux-mm@kvack.org
      Cc: linux-pm@vger.kernel.org
      Cc: xen-devel@lists.xenproject.org
      Cc: zijun_hu <zijun_hu@htc.com>
      Link: http://lkml.kernel.org/r/20170314170508.100882-3-thgarnie@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      45fc8757
    • T
      x86: Remap GDT tables in the fixmap section · 69218e47
      Thomas Garnier 提交于
      Each processor holds a GDT in its per-cpu structure. The sgdt
      instruction gives the base address of the current GDT. This address can
      be used to bypass KASLR memory randomization. With another bug, an
      attacker could target other per-cpu structures or deduce the base of
      the main memory section (PAGE_OFFSET).
      
      This patch relocates the GDT table for each processor inside the
      fixmap section. The space is reserved based on number of supported
      processors.
      
      For consistency, the remapping is done by default on 32 and 64-bit.
      
      Each processor switches to its remapped GDT at the end of
      initialization. For hibernation, the main processor returns with the
      original GDT and switches back to the remapping at completion.
      
      This patch was tested on both architectures. Hibernation and KVM were
      both tested specially for their usage of the GDT.
      
      Thanks to Boris Ostrovsky <boris.ostrovsky@oracle.com> for testing and
      recommending changes for Xen support.
      Signed-off-by: NThomas Garnier <thgarnie@google.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@suse.de>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Frederic Weisbecker <fweisbec@gmail.com>
      Cc: Jiri Kosina <jikos@kernel.org>
      Cc: Joerg Roedel <joro@8bytes.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Len Brown <len.brown@intel.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Lorenzo Stoakes <lstoakes@gmail.com>
      Cc: Luis R . Rodriguez <mcgrof@kernel.org>
      Cc: Matt Fleming <matt@codeblueprint.co.uk>
      Cc: Michal Hocko <mhocko@suse.com>
      Cc: Paolo Bonzini <pbonzini@redhat.com>
      Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
      Cc: Pavel Machek <pavel@ucw.cz>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Radim Krčmář <rkrcmar@redhat.com>
      Cc: Rafael J . Wysocki <rjw@rjwysocki.net>
      Cc: Rusty Russell <rusty@rustcorp.com.au>
      Cc: Stanislaw Gruszka <sgruszka@redhat.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Tim Chen <tim.c.chen@linux.intel.com>
      Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
      Cc: kasan-dev@googlegroups.com
      Cc: kernel-hardening@lists.openwall.com
      Cc: kvm@vger.kernel.org
      Cc: lguest@lists.ozlabs.org
      Cc: linux-doc@vger.kernel.org
      Cc: linux-efi@vger.kernel.org
      Cc: linux-mm@kvack.org
      Cc: linux-pm@vger.kernel.org
      Cc: xen-devel@lists.xenproject.org
      Cc: zijun_hu <zijun_hu@htc.com>
      Link: http://lkml.kernel.org/r/20170314170508.100882-2-thgarnie@google.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      69218e47
  9. 02 3月, 2017 1 次提交
    • A
      x86/asm: Tidy up TSS limit code · b7ceaec1
      Andy Lutomirski 提交于
      In an earlier version of the patch ("x86/kvm/vmx: Defer TR reload
      after VM exit") that introduced TSS limit validity tracking, I
      confused which helper was which.  On reflection, the names I chose
      sucked.  Rename the helpers to make it more obvious what's going on
      and add some comments.
      
      While I'm at it, clear __tss_limit_invalid when force-reloading as
      well as when contitionally reloading, since any TR reload fixes the
      limit.
      Signed-off-by: NAndy Lutomirski <luto@kernel.org>
      Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      b7ceaec1
  10. 21 2月, 2017 2 次提交
    • A
      x86/kvm/vmx: Defer TR reload after VM exit · b7ffc44d
      Andy Lutomirski 提交于
      Intel's VMX is daft and resets the hidden TSS limit register to 0x67
      on VMX reload, and the 0x67 is not configurable.  KVM currently
      reloads TR using the LTR instruction on every exit, but this is quite
      slow because LTR is serializing.
      
      The 0x67 limit is entirely harmless unless ioperm() is in use, so
      defer the reload until a task using ioperm() is actually running.
      
      Here's some poorly done benchmarking using kvm-unit-tests:
      
      Before:
      
      cpuid 1313
      vmcall 1195
      mov_from_cr8 11
      mov_to_cr8 17
      inl_from_pmtimer 6770
      inl_from_qemu 6856
      inl_from_kernel 2435
      outl_to_kernel 1402
      
      After:
      
      cpuid 1291
      vmcall 1181
      mov_from_cr8 11
      mov_to_cr8 16
      inl_from_pmtimer 6457
      inl_from_qemu 6209
      inl_from_kernel 2339
      outl_to_kernel 1391
      Signed-off-by: NAndy Lutomirski <luto@kernel.org>
      [Force-reload TR in invalidate_tss_limit. - Paolo]
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b7ffc44d
    • A
      x86/asm: Define the kernel TSS limit in a macro · 4f53ab14
      Andy Lutomirski 提交于
      Rather than open-coding the kernel TSS limit in set_tss_desc(), make
      it a real macro near the TSS layout definition.
      
      This is purely a cleanup.
      
      Cc: Thomas Garnier <thgarnie@google.com>
      Cc: Jim Mattson <jmattson@google.com>
      Signed-off-by: NAndy Lutomirski <luto@kernel.org>
      Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      4f53ab14
  11. 10 8月, 2016 1 次提交
    • K
      x86: Apply more __ro_after_init and const · 404f6aac
      Kees Cook 提交于
      Guided by grsecurity's analogous __read_only markings in arch/x86,
      this applies several uses of __ro_after_init to structures that are
      only updated during __init, and const for some structures that are
      never updated.  Additionally extends __init markings to some functions
      that are only used during __init, and cleans up some missing C99 style
      static initializers.
      Signed-off-by: NKees Cook <keescook@chromium.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Arnd Bergmann <arnd@arndb.de>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brad Spengler <spender@grsecurity.net>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: David Brown <david.brown@linaro.org>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Emese Revfy <re.emese@gmail.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Mathias Krause <minipli@googlemail.com>
      Cc: Michael Ellerman <mpe@ellerman.id.au>
      Cc: PaX Team <pageexec@freemail.hu>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: kernel-hardening@lists.openwall.com
      Link: http://lkml.kernel.org/r/20160808232906.GA29731@www.outflux.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      404f6aac
  12. 31 7月, 2015 1 次提交
    • A
      x86/ldt: Make modify_ldt synchronous · 37868fe1
      Andy Lutomirski 提交于
      modify_ldt() has questionable locking and does not synchronize
      threads.  Improve it: redesign the locking and synchronize all
      threads' LDTs using an IPI on all modifications.
      
      This will dramatically slow down modify_ldt in multithreaded
      programs, but there shouldn't be any multithreaded programs that
      care about modify_ldt's performance in the first place.
      
      This fixes some fallout from the CVE-2015-5157 fixes.
      Signed-off-by: NAndy Lutomirski <luto@kernel.org>
      Reviewed-by: NBorislav Petkov <bp@suse.de>
      Cc: Andrew Cooper <andrew.cooper3@citrix.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Jan Beulich <jbeulich@suse.com>
      Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Sasha Levin <sasha.levin@oracle.com>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: security@kernel.org <security@kernel.org>
      Cc: <stable@vger.kernel.org>
      Cc: xen-devel <xen-devel@lists.xen.org>
      Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.luto@kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>
      37868fe1
  13. 05 3月, 2015 1 次提交
  14. 23 1月, 2015 2 次提交
  15. 09 11月, 2013 3 次提交
  16. 23 6月, 2013 1 次提交
    • S
      trace,x86: Do not call local_irq_save() in load_current_idt() · 2b4bc789
      Steven Rostedt (Red Hat) 提交于
      As load_current_idt() is now what is used to update the IDT for the
      switches needed for NMI, lockdep debug, and for tracing, it must not
      call local_irq_save(). This is because one of the users of this is
      lockdep, which does tracing of local_irq_save() and when the debug
      trap is hit, we need to update the IDT before tracing interrupts
      being disabled. As load_current_idt() is used to do this, calling
      local_irq_save() which lockdep traces, defeats the point of calling
      load_current_idt().
      
      As interrupts are already disabled when used by lockdep and NMI, the
      only other user is tracing that can disable interrupts itself. Simply
      have the tracing update disable interrupts before calling load_current_idt()
      instead of breaking the other users.
      
      Here's the dump that happened:
      
      ------------[ cut here ]------------
      WARNING: at /work/autotest/nobackup/linux-test.git/kernel/fork.c:1196 copy_process+0x2c3/0x1398()
      DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled)
      Modules linked in:
      CPU: 1 PID: 4570 Comm: gdm-simple-gree Not tainted 3.10.0-rc3-test+ #5
      Hardware name:                  /DG965MQ, BIOS MQ96510J.86A.0372.2006.0605.1717 06/05/2006
       ffffffff81d2a7a5 ffff88006ed13d50 ffffffff8192822b ffff88006ed13d90
       ffffffff81035f25 ffff8800721c6000 ffff88006ed13da0 0000000001200011
       0000000000000000 ffff88006ed5e000 ffff8800721c6000 ffff88006ed13df0
      Call Trace:
       [<ffffffff8192822b>] dump_stack+0x19/0x1b
       [<ffffffff81035f25>] warn_slowpath_common+0x67/0x80
       [<ffffffff81035fe1>] warn_slowpath_fmt+0x46/0x48
       [<ffffffff812bfc5d>] ? __raw_spin_lock_init+0x31/0x52
       [<ffffffff810341f7>] copy_process+0x2c3/0x1398
       [<ffffffff8103539d>] do_fork+0xa8/0x260
       [<ffffffff810ca7b1>] ? trace_preempt_on+0x2a/0x2f
       [<ffffffff812afb3e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
       [<ffffffff81937fe7>] ? sysret_check+0x1b/0x56
       [<ffffffff81937fe7>] ? sysret_check+0x1b/0x56
       [<ffffffff810355cf>] SyS_clone+0x16/0x18
       [<ffffffff81938369>] stub_clone+0x69/0x90
       [<ffffffff81937fc2>] ? system_call_fastpath+0x16/0x1b
      ---[ end trace 8b157a9d20ca1aa2 ]---
      
      in fork.c:
      
       #ifdef CONFIG_PROVE_LOCKING
      	DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled); <-- bug here
      	DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
       #endif
      
      Cc: Seiji Aguchi <seiji.aguchi@hds.com>
      Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      2b4bc789