Convert the remaining 32bit users and remove the GLOBAL macro finally.
In particular, this means to use SYM_ENTRY for the singlestepping hack
region.

Exclude the global definition of GLOBAL from x86 too.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-20-jslaby@suse.cz

The GLOBAL macro had several meanings and is going away. Convert all the
inner function labels marked with GLOBAL to use SYM_INNER_LABEL instead.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-18-jslaby@suse.cz

* annotate functions properly by SYM_CODE_START, SYM_CODE_START_LOCAL*
  and SYM_CODE_END -- these are not C-like functions, so they have to
  be annotated using CODE.
* use SYM_INNER_LABEL* for labels being in the middle of other functions
  This prevents nested labels annotations.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-11-jslaby@suse.cz

Use the newly added SYM_CODE_START_LOCAL* to annotate beginnings of
all pseudo-functions (those ending with END until now) which do not
have ".globl" annotation. This is needed to balance END for tools that
generate debuginfo. Note that ENDs are switched to SYM_CODE_END too so
that everybody can see the pairing.

C-like functions (which handle frame ptr etc.) are not annotated here,
hence SYM_CODE_* macros are used here, not SYM_FUNC_*. Note that the
32bit version of early_idt_handler_common already had ENDPROC -- switch
that to SYM_CODE_END for the same reason as above (and to be the same as
64bit).

While early_idt_handler_common is LOCAL, it's name is not prepended with
".L" as it happens to appear in call traces.

bad_get_user*, and bad_put_user are now aligned, as they are separate
functions. They do not mind to be aligned -- no need to be compact
there.

early_idt_handler_common is aligned now too, as it is after
early_idt_handler_array, so as well no need to be compact there.

verify_cpu is self-standing and included in other .S files, so align it
too.

The others have alignment preserved to what it used to be (using the
_NOALIGN variant of macros).
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Alexios Zavras <alexios.zavras@intel.com>
Cc: Allison Randal <allison@lohutok.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: Enrico Weigelt <info@metux.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: linux-arch@vger.kernel.org
Cc: Maran Wilson <maran.wilson@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-6-jslaby@suse.cz

Place SYM_*_START_NOALIGN and SYM_*_END around the THUNK macro body.
Preserve @function by FUNC (64bit) and CODE (32bit). Given it was not
marked as aligned, use NOALIGN.

The result:
 Value  Size Type    Bind   Vis      Ndx Name
  0000    28 FUNC    GLOBAL DEFAULT    1 trace_hardirqs_on_thunk
  001c    28 FUNC    GLOBAL DEFAULT    1 trace_hardirqs_off_thunk
  0038    24 FUNC    GLOBAL DEFAULT    1 lockdep_sys_exit_thunk
  0050    24 FUNC    GLOBAL DEFAULT    1 ___preempt_schedule
  0068    24 FUNC    GLOBAL DEFAULT    1 ___preempt_schedule_notra

The annotation of .L_restore does not generate anything (at the moment).
Here, it just serves documentation purposes (as opening and closing
brackets of functions).
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-arch@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191011115108.12392-5-jslaby@suse.cz

During the assembly cleanup patchset review, I found more symbols which
are used only locally. So make them really local by prepending ".L" to
them. Namely:

 - wakeup_idt is used only in realmode/rm/wakeup_asm.S.
 - in_pm32 is used only in boot/pmjump.S.
 - retint_user is used only in entry/entry_64.S, perhaps since commit
   2ec67971 ("x86/entry/64/compat: Remove most of the fast system
   call machinery"), where entry_64_compat's caller was removed.

Drop GLOBAL from all of them too. I do not see more candidates in the
series.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Acked-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: bp@alien8.de
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20191011092213.31470-1-jslaby@suse.czSigned-off-by: NIngo Molnar <mingo@kernel.org>

Boris suggests to make a local label (prepend ".L") to these functions
to eliminate them from the symbol table. These are functions with very
local names and really should not be visible anywhere.

Note that objtool won't see these functions anymore (to generate ORC
debug info). But all the functions are not annotated with ENDPROC, so
they won't have objtool's attention anyway.
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steve Winslow <swinslow@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Huang <wei@redhat.com>
Cc: x86-ml <x86@kernel.org>
Cc: Xiaoyao Li <xiaoyao.li@linux.intel.com>
Link: https://lkml.kernel.org/r/20190906075550.23435-2-jslaby@suse.cz

Kbuild provides per-file compiler flag addition/removal:

  CFLAGS_<basetarget>.o
  CFLAGS_REMOVE_<basetarget>.o
  AFLAGS_<basetarget>.o
  AFLAGS_REMOVE_<basetarget>.o
  CPPFLAGS_<basetarget>.lds
  HOSTCFLAGS_<basetarget>.o
  HOSTCXXFLAGS_<basetarget>.o

The <basetarget> is the filename of the target with its directory and
suffix stripped.

This syntax comes into a trouble when two files with the same basename
appear in one Makefile, for example:

  obj-y += foo.o
  obj-y += dir/foo.o
  CFLAGS_foo.o := <some-flags>

Here, the <some-flags> applies to both foo.o and dir/foo.o

The real world problem is:

  scripts/kconfig/util.c
  scripts/kconfig/lxdialog/util.c

Both files are compiled into scripts/kconfig/mconf, but only the
latter should be given with the ncurses flags.

It is more sensible to use the relative path to the Makefile, like this:

  obj-y += foo.o
  CFLAGS_foo.o := <some-flags>
  obj-y += dir/foo.o
  CFLAGS_dir/foo.o := <other-flags>

At first, I attempted to replace $(basetarget) with $*. The $* variable
is replaced with the stem ('%') part in a pattern rule. This works with
most of cases, but does not for explicit rules.

For example, arch/ia64/lib/Makefile reuses rule_as_o_S in its own
explicit rules, so $* will be empty, resulting in ignoring the per-file
AFLAGS.

I introduced a new variable, target-stem, which can be used also from
explicit rules.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NMarc Zyngier <maz@kernel.org>

Prepare to add Hyper-V sched clock callback and move Hyper-V Reference TSC
initialization much earlier in the boot process.  Earlier initialization is
needed so that it happens while the timestamp value is still 0 and no
discontinuity in the timestamp will occur when pv_ops.time.sched_clock
calculates its offset.
    
The earlier initialization requires that the Hyper-V TSC page be allocated
statically instead of with vmalloc(), so fixup the references to the TSC
page and the method of getting its physical address.
Signed-off-by: NTianyu Lan <Tianyu.Lan@microsoft.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lkml.kernel.org/r/20190814123216.32245-2-Tianyu.Lan@microsoft.com

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by
CONFIG_PREEMPT_RT. Both PREEMPT and PREEMPT_RT require the same
functionality which today depends on CONFIG_PREEMPT.

Switch the entry code, preempt and kprobes conditionals over to
CONFIG_PREEMPTION.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20190726212124.608488448@linutronix.deSigned-off-by: NIngo Molnar <mingo@kernel.org>

Commit a0d14b89 ("x86/mm, tracing: Fix CR2 corruption") added the
address parameter to do_async_page_fault(), but does not pass it from the
32-bit entry point.  To plumb it through, factor-out
common_exception_read_cr2 in the same fashion as common_exception, and uses
it from both page_fault and async_page_fault.

For a 32-bit KVM guest, this fixes:

  Run /sbin/init as init process
  Starting init: /sbin/init exists but couldn't execute it (error -14)

Fixes: a0d14b89 ("x86/mm, tracing: Fix CR2 corruption")
Signed-off-by: NMatt Mullins <mmullins@fb.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190724042058.24506-1-mmullins@fb.com

For unfortunate historical reasons, the x32 syscalls and the x86_64
syscalls are not all numbered the same.  As an example, ioctl() is nr 16 on
x86_64 but 514 on x32.

This has potentially nasty consequences, since it means that there are two
valid RAX values to do ioctl(2) and two invalid RAX values.  The valid
values are 16 (i.e. ioctl(2) using the x86_64 ABI) and (514 | 0x40000000)
(i.e. ioctl(2) using the x32 ABI).

The invalid values are 514 and (16 | 0x40000000).  514 will enter the
"COMPAT_SYSCALL_DEFINE3(ioctl, ...)" entry point with in_compat_syscall()
and in_x32_syscall() returning false, whereas (16 | 0x40000000) will enter
the native entry point with in_compat_syscall() and in_x32_syscall()
returning true.  Both are bogus, and both will exercise code paths in the
kernel and in any running seccomp filters that really ought to be
unreachable.

Splitting out the x32 syscalls into their own tables, allows both bogus
invocations to return -ENOSYS.  I've checked glibc, musl, and Bionic, and
all of them appear to call syscalls with their correct numbers, so this
change should have no effect on them.

There is an added benefit going forward: new syscalls that need special
handling on x32 can share the same number on x32 and x86_64.  This means
that the special syscall range 512-547 can be treated as a legacy wart
instead of something that may need to be extended in the future.

Also add a selftest to verify the new behavior.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/208024256b764312598f014ebfb0a42472c19354.1562185330.git.luto@kernel.org

A "compat" entry in the syscall tables means to use a different entry on
32-bit and 64-bit builds.

This only makes sense for syscalls that exist in the first place in 32-bit
builds, so disallow it for anything other than i386.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/4b7565954c5a06530ac01d98cb1592538fd8ae51.1562185330.git.luto@kernel.org

I'm working on some code that detects at build time if there's a
COMPAT_SYSCALL_DEFINE() that is not referenced in the x86 syscall tables.
It catches three offenders: rt_sigsuspend(), rt_sigprocmask(), and
sendfile64().

For rt_sigsuspend() and rt_sigprocmask(), the only potential difference
between the native and compat versions is that the compat version converts
the sigset_t, but, on little endian architectures, the conversion is a
no-op.  This is why they both currently work on x86.

To make the code more consistent, and to make the upcoming patches work,
rewire x86 to use the compat vesions.

sendfile64() is more complicated, and will be addressed separately.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/51643ac3157b5921eae0e172a8a0b1d953e68ebb.1562185330.git.luto@kernel.org

The recent fix for CR2 corruption introduced a new way to reliably corrupt
the saved CR2 value.

CR2 is saved early in the entry code in RDX, which is the third argument to
the fault handling functions. But it missed that between saving and
invoking the fault handler enter_from_user_mode() can be called. RDX is a
caller saved register so the invoked function can freely clobber it with
the obvious consequences.

The TRACE_IRQS_OFF call is safe as it calls through the thunk which
preserves RDX, but TRACE_IRQS_OFF_DEBUG is not because it also calls into
C-code outside of the thunk.

Store CR2 in R12 instead which is a callee saved register and move R12 to
RDX just before calling the fault handler.

Fixes: a0d14b89 ("x86/mm, tracing: Fix CR2 corruption")
Reported-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907201020540.1782@nanos.tec.linutronix.de

In the sysctl code the proc_dointvec_minmax() function is often used to
validate the user supplied value between an allowed range.  This
function uses the extra1 and extra2 members from struct ctl_table as
minimum and maximum allowed value.

On sysctl handler declaration, in every source file there are some
readonly variables containing just an integer which address is assigned
to the extra1 and extra2 members, so the sysctl range is enforced.

The special values 0, 1 and INT_MAX are very often used as range
boundary, leading duplication of variables like zero=0, one=1,
int_max=INT_MAX in different source files:

    $ git grep -E '\.extra[12].*&(zero|one|int_max)' |wc -l
    248

Add a const int array containing the most commonly used values, some
macros to refer more easily to the correct array member, and use them
instead of creating a local one for every object file.

This is the bloat-o-meter output comparing the old and new binary
compiled with the default Fedora config:

    # scripts/bloat-o-meter -d vmlinux.o.old vmlinux.o
    add/remove: 2/2 grow/shrink: 0/2 up/down: 24/-188 (-164)
    Data                                         old     new   delta
    sysctl_vals                                    -      12     +12
    __kstrtab_sysctl_vals                          -      12     +12
    max                                           14      10      -4
    int_max                                       16       -     -16
    one                                           68       -     -68
    zero                                         128      28    -100
    Total: Before=20583249, After=20583085, chg -0.00%

[mcroce@redhat.com: tipc: remove two unused variables]
  Link: http://lkml.kernel.org/r/20190530091952.4108-1-mcroce@redhat.com
[akpm@linux-foundation.org: fix net/ipv6/sysctl_net_ipv6.c]
[arnd@arndb.de: proc/sysctl: make firmware loader table conditional]
  Link: http://lkml.kernel.org/r/20190617130014.1713870-1-arnd@arndb.de
[akpm@linux-foundation.org: fix fs/eventpoll.c]
Link: http://lkml.kernel.org/r/20190430180111.10688-1-mcroce@redhat.comSigned-off-by: NMatteo Croce <mcroce@redhat.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NAaron Tomlin <atomlin@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the following warnings:

  arch/x86/entry/thunk_64.o: warning: objtool: trace_hardirqs_on_thunk() is missing an ELF size annotation
  arch/x86/entry/thunk_64.o: warning: objtool: trace_hardirqs_off_thunk() is missing an ELF size annotation
  arch/x86/entry/thunk_64.o: warning: objtool: lockdep_sys_exit_thunk() is missing an ELF size annotation
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/89c97adc9f6cc44a0f5d03cde6d0357662938909.1563413318.git.jpoimboe@redhat.com

Despite the current efforts to read CR2 before tracing happens there still
exist a number of possible holes:

  idtentry page_fault             do_page_fault           has_error_code=1
    call error_entry
      TRACE_IRQS_OFF
        call trace_hardirqs_off*
          #PF // modifies CR2

      CALL_enter_from_user_mode
        __context_tracking_exit()
          trace_user_exit(0)
            #PF // modifies CR2

    call do_page_fault
      address = read_cr2(); /* whoopsie */

And similar for i386.

Fix it by pulling the CR2 read into the entry code, before any of that
stuff gets a chance to run and ruin things.
Reported-by: NHe Zhe <zhe.he@windriver.com>
Reported-by: NEiichi Tsukata <devel@etsukata.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAndy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: rostedt@goodmis.org
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: joel@joelfernandes.org
Link: https://lkml.kernel.org/r/20190711114336.116812491@infradead.orgDebugged-by: NSteven Rostedt <rostedt@goodmis.org>

Commit 2700fefd ("x86_64: Add gap to int3 to allow for call
emulation") forgot to update the comment, do so now.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114336.059780563@infradead.org

There's a bunch of duplication in idtentry, namely the
.Lfrom_usermode_switch_stack is a paranoid=0 copy of the normal flow.

Make this explicit by creating a idtentry_part helper macro.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NAndy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114336.002429503@infradead.org

Adding one more option to SAVE_ALL can be used in common_exception to
simplify things. This also saves duplication later where page_fault will no
longer use common_exception.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: NAndy Lutomirski <luto@kernel.org>
Cc: bp@alien8.de
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: jgross@suse.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114335.945136187@infradead.org

The one paravirt read_cr2() implementation (Xen) is actually quite trivial
and doesn't need to clobber anything other than the return register.

Making read_cr2() CALLEE_SAVE avoids all the PUSH/POP nonsense and allows
more convenient use from assembly.
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Cc: bp@alien8.de
Cc: rostedt@goodmis.org
Cc: luto@kernel.org
Cc: torvalds@linux-foundation.org
Cc: hpa@zytor.com
Cc: dave.hansen@linux.intel.com
Cc: zhe.he@windriver.com
Cc: joel@joelfernandes.org
Cc: devel@etsukata.com
Link: https://lkml.kernel.org/r/20190711114335.887392493@infradead.org

As commit 1e022137 ("mips: vdso: drop unnecessary cc-ldoption")
explained, these flags are supported by the minimal required version
of binutils. They are supported by ld.lld too.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NNathan Chancellor <natechancellor@gmail.com>
Tested-by: NNathan Chancellor <natechancellor@gmail.com>

Somehow the swapgs mitigation entry code patch ended up with a JMPQ
instruction instead of JMP, where only the short jump is needed.  Some
assembler versions apparently fail to optimize JMPQ into a two-byte JMP
when possible, instead always using a 7-byte JMP with relocation.  For
some reason that makes the entry code explode with a #GP during boot.

Change it back to "JMP" as originally intended.

Fixes: 18ec54fd ("x86/speculation: Prepare entry code for Spectre v1 swapgs mitigations")
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Commit 7457c0da ("x86/alternatives: Add int3_emulate_call()
selftest") is used to ensure there is a gap setup in int3 exception stack
which could be used for inserting call return address.

This gap is missed in XEN PV int3 exception entry path, then below panic
triggered:

[    0.772876] general protection fault: 0000 [#1] SMP NOPTI
[    0.772886] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0+ #11
[    0.772893] RIP: e030:int3_magic+0x0/0x7
[    0.772905] RSP: 3507:ffffffff82203e98 EFLAGS: 00000246
[    0.773334] Call Trace:
[    0.773334]  alternative_instructions+0x3d/0x12e
[    0.773334]  check_bugs+0x7c9/0x887
[    0.773334]  ? __get_locked_pte+0x178/0x1f0
[    0.773334]  start_kernel+0x4ff/0x535
[    0.773334]  ? set_init_arg+0x55/0x55
[    0.773334]  xen_start_kernel+0x571/0x57a

For 64bit PV guests, Xen's ABI enters the kernel with using SYSRET, with
%rcx/%r11 on the stack. To convert back to "normal" looking exceptions,
the xen thunks do 'xen_*: pop %rcx; pop %r11; jmp *'.

E.g. Extracting 'xen_pv_trap xenint3' we have:
xen_xenint3:
 pop %rcx;
 pop %r11;
 jmp xenint3

As xenint3 and int3 entry code are same except xenint3 doesn't generate
a gap, we can fix it by using int3 and drop useless xenint3.
Signed-off-by: NZhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: NJuergen Gross <jgross@suse.com>

Two consecutive "make" on an already compiled kernel tree will show
different behavior:

$ make
  CALL    scripts/checksyscalls.sh
  CALL    scripts/atomic/check-atomics.sh
  DESCEND  objtool
  CHK     include/generated/compile.h
  VDSOCHK arch/x86/entry/vdso/vdso64.so.dbg
  VDSOCHK arch/x86/entry/vdso/vdso32.so.dbg
Kernel: arch/x86/boot/bzImage is ready  (#3)
  Building modules, stage 2.
  MODPOST 12 modules

$ make
make
  CALL    scripts/checksyscalls.sh
  CALL    scripts/atomic/check-atomics.sh
  DESCEND  objtool
  CHK     include/generated/compile.h
  VDSO    arch/x86/entry/vdso/vdso64.so.dbg
  OBJCOPY arch/x86/entry/vdso/vdso64.so
  VDSO2C  arch/x86/entry/vdso/vdso-image-64.c
  CC      arch/x86/entry/vdso/vdso-image-64.o
  VDSO    arch/x86/entry/vdso/vdso32.so.dbg
  OBJCOPY arch/x86/entry/vdso/vdso32.so
  VDSO2C  arch/x86/entry/vdso/vdso-image-32.c
  CC      arch/x86/entry/vdso/vdso-image-32.o
  AR      arch/x86/entry/vdso/built-in.a
  AR      arch/x86/entry/built-in.a
  AR      arch/x86/built-in.a
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      init/version.o
  AR      init/built-in.a
  LD      vmlinux.o
<snip>

This is causing "LD vmlinux" once every two times even without any
modifications. This is the same bug fixed in commit 92a47286
("x86/boot: Fix if_changed build flip/flop bug"). Two "if_changed" cannot
be used in one target.

Fix this merging two commands into one function.

Fixes: 7ac87074 ("x86/vdso: Switch to generic vDSO implementation")
Signed-off-by: NNaohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Link: https://lkml.kernel.org/r/20190712101556.17833-1-naohiro.aota@wdc.com

common_spurious is currently ENDed erroneously. common_interrupt is used
in its ENDPROC. So fix this mistake.

Found by my asm macros rewrite patchset.

Fixes: f8a8fe61 ("x86/irq: Seperate unused system vectors from spurious entry again")
Signed-off-by: NJiri Slaby <jslaby@suse.cz>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190709063402.19847-1-jslaby@suse.cz

Spectre v1 isn't only about array bounds checks.  It can affect any
conditional checks.  The kernel entry code interrupt, exception, and NMI
handlers all have conditional swapgs checks.  Those may be problematic in
the context of Spectre v1, as kernel code can speculatively run with a user
GS.

For example:

	if (coming from user space)
		swapgs
	mov %gs:<percpu_offset>, %reg
	mov (%reg), %reg1

When coming from user space, the CPU can speculatively skip the swapgs, and
then do a speculative percpu load using the user GS value.  So the user can
speculatively force a read of any kernel value.  If a gadget exists which
uses the percpu value as an address in another load/store, then the
contents of the kernel value may become visible via an L1 side channel
attack.

A similar attack exists when coming from kernel space.  The CPU can
speculatively do the swapgs, causing the user GS to get used for the rest
of the speculative window.

The mitigation is similar to a traditional Spectre v1 mitigation, except:

  a) index masking isn't possible; because the index (percpu offset)
     isn't user-controlled; and

  b) an lfence is needed in both the "from user" swapgs path and the
     "from kernel" non-swapgs path (because of the two attacks described
     above).

The user entry swapgs paths already have SWITCH_TO_KERNEL_CR3, which has a
CR3 write when PTI is enabled.  Since CR3 writes are serializing, the
lfences can be skipped in those cases.

On the other hand, the kernel entry swapgs paths don't depend on PTI.

To avoid unnecessary lfences for the user entry case, create two separate
features for alternative patching:

  X86_FEATURE_FENCE_SWAPGS_USER
  X86_FEATURE_FENCE_SWAPGS_KERNEL

Use these features in entry code to patch in lfences where needed.

The features aren't enabled yet, so there's no functional change.
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NDave Hansen <dave.hansen@intel.com>

The FSGSBASE series turned out to have serious bugs and there is still an
open issue which is not fully understood yet.

The confidence in those changes has become close to zero especially as the
test cases which have been shipped with that series were obviously never
run before sending the final series out to LKML.

  ./fsgsbase_64 >/dev/null
  Segmentation fault

As the merge window is close, the only sane decision is to revert FSGSBASE
support. The revert is necessary as this branch has been merged into
perf/core already and rebasing all of that a few days before the merge
window is not the most brilliant idea.

I could definitely slap myself for not noticing the test case fail when
merging that series, but TBH my expectations weren't that low back
then. Won't happen again.

Revert the following commits:
539bca53 ("x86/entry/64: Fix and clean up paranoid_exit")
2c7b5ac5 ("Documentation/x86/64: Add documentation for GS/FS addressing mode")
f987c955 ("x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2")
2032f1f9 ("x86/cpu: Enable FSGSBASE on 64bit by default and add a chicken bit")
5bf0cab6 ("x86/entry/64: Document GSBASE handling in the paranoid path")
708078f6 ("x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit")
79e1932f ("x86/entry/64: Introduce the FIND_PERCPU_BASE macro")
1d07316b ("x86/entry/64: Switch CR3 before SWAPGS in paranoid entry")
f60a83df ("x86/process/64: Use FSGSBASE instructions on thread copy and ptrace")
1ab5f3f7 ("x86/process/64: Use FSBSBASE in switch_to() if available")
a86b4625 ("x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions")
8b71340d ("x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions")
b64ed19b ("x86/cpu: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE")
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@kernel.org>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>

Continue consolidating Hyper-V clock and timer code into an ISA
independent Hyper-V clocksource driver.

Move the existing clocksource code under drivers/hv and arch/x86 to the new
clocksource driver while separating out the ISA dependencies. Update
Hyper-V initialization to call initialization and cleanup routines since
the Hyper-V synthetic clock is not independently enumerated in ACPI.

Update Hyper-V clocksource users in KVM and VDSO to get definitions from
the new include file.

No behavior is changed and no new functionality is added.
Suggested-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMichael Kelley <mikelley@microsoft.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Cc: "bp@alien8.de" <bp@alien8.de>
Cc: "will.deacon@arm.com" <will.deacon@arm.com>
Cc: "catalin.marinas@arm.com" <catalin.marinas@arm.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: Sunil Muthuswamy <sunilmut@microsoft.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: "sashal@kernel.org" <sashal@kernel.org>
Cc: "vincenzo.frascino@arm.com" <vincenzo.frascino@arm.com>
Cc: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: "linux-kselftest@vger.kernel.org" <linux-kselftest@vger.kernel.org>
Cc: "arnd@arndb.de" <arnd@arndb.de>
Cc: "linux@armlinux.org.uk" <linux@armlinux.org.uk>
Cc: "ralf@linux-mips.org" <ralf@linux-mips.org>
Cc: "paul.burton@mips.com" <paul.burton@mips.com>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "salyzyn@android.com" <salyzyn@android.com>
Cc: "pcc@google.com" <pcc@google.com>
Cc: "shuah@kernel.org" <shuah@kernel.org>
Cc: "0x7f454c46@gmail.com" <0x7f454c46@gmail.com>
Cc: "linux@rasmusvillemoes.dk" <linux@rasmusvillemoes.dk>
Cc: "huw@codeweavers.com" <huw@codeweavers.com>
Cc: "sfr@canb.auug.org.au" <sfr@canb.auug.org.au>
Cc: "pbonzini@redhat.com" <pbonzini@redhat.com>
Cc: "rkrcmar@redhat.com" <rkrcmar@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>
Link: https://lkml.kernel.org/r/1561955054-1838-3-git-send-email-mikelley@microsoft.com

Quite some time ago the interrupt entry stubs for unused vectors in the
system vector range got removed and directly mapped to the spurious
interrupt vector entry point.

Sounds reasonable, but it's subtly broken. The spurious interrupt vector
entry point pushes vector number 0xFF on the stack which makes the whole
logic in __smp_spurious_interrupt() pointless.

As a consequence any spurious interrupt which comes from a vector != 0xFF
is treated as a real spurious interrupt (vector 0xFF) and not
acknowledged. That subsequently stalls all interrupt vectors of equal and
lower priority, which brings the system to a grinding halt.

This can happen because even on 64-bit the system vector space is not
guaranteed to be fully populated. A full compile time handling of the
unused vectors is not possible because quite some of them are conditonally
populated at runtime.

Bring the entry stubs back, which wastes 160 bytes if all stubs are unused,
but gains the proper handling back. There is no point to selectively spare
some of the stubs which are known at compile time as the required code in
the IDT management would be way larger and convoluted.

Do not route the spurious entries through common_interrupt and do_IRQ() as
the original code did. Route it to smp_spurious_interrupt() which evaluates
the vector number and acts accordingly now that the real vector numbers are
handed in.

Fixup the pr_warn so the actual spurious vector (0xff) is clearly
distiguished from the other vectors and also note for the vectored case
whether it was pending in the ISR or not.

 "Spurious APIC interrupt (vector 0xFF) on CPU#0, should never happen."
 "Spurious interrupt vector 0xed on CPU#1. Acked."
 "Spurious interrupt vector 0xee on CPU#1. Not pending!."

Fixes: 2414e021 ("x86: Avoid building unused IRQ entry stubs")
Reported-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jan Beulich <jbeulich@suse.com>
Link: https://lkml.kernel.org/r/20190628111440.550568228@linutronix.de

paranoid_exit needs to restore CR3 before GSBASE.  Doing it in the opposite
order crashes if the exception came from a context with user GSBASE and
user CR3 -- RESTORE_CR3 cannot resture user CR3 if run with user GSBASE.
This results in infinitely recursing exceptions if user code does SYSENTER
with TF set if both FSGSBASE and PTI are enabled.

The old code worked if user code just set TF without SYSENTER because #DB
from user mode is special cased in idtentry and paranoid_exit doesn't run.

Fix it by cleaning up the spaghetti code.  All that paranoid_exit needs to
do is to disable IRQs, handle IRQ tracing, then restore CR3, and restore
GSBASE.  Simply do those actions in that order.

Fixes: 708078f6 ("x86/entry/64: Handle FSGSBASE enabled paranoid entry/exit")
Reported-by: NVegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: NChang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lkml.kernel.org/r/59725ceb08977359489fbed979716949ad45f616.1562035429.git.luto@kernel.org

It's only used if !CONFIG_IA32_EMULATION, so disable it in normal
configs.  This will save a few bytes of text and reduce confusion.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc:  "BaeChang Seok" <chang.seok.bae@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Bae, Chang Seok" <chang.seok.bae@intel.com>
Link: https://lkml.kernel.org/r/0f7dafa72fe7194689de5ee8cfe5d83509fabcf5.1562035429.git.luto@kernel.org

This wires up the pidfd_open() syscall into all arches at once.
Signed-off-by: NChristian Brauner <christian@brauner.io>
Reviewed-by: NDavid Howells <dhowells@redhat.com>
Reviewed-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jann Horn <jannh@google.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org

The vDSO is only configurable by command-line options, so make its
global variables __ro_after_init.  This seems highly unlikely to
ever stop an exploit, but it's nicer anyway.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/a386925835e49d319e70c4d7404b1f6c3c2e3702.1561610354.git.luto@kernel.org

Just segfaulting the application when it tries to read the vsyscall page in
xonly mode is not helpful for those who need to debug it.

Emit a hint.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Link: https://lkml.kernel.org/r/8016afffe0eab497be32017ad7f6f7030dc3ba66.1561610354.git.luto@kernel.org

With vsyscall emulation on, a readable vsyscall page is still exposed that
contains syscall instructions that validly implement the vsyscalls.

This is required because certain dynamic binary instrumentation tools
attempt to read the call targets of call instructions in the instrumented
code.  If the instrumented code uses vsyscalls, then the vsyscall page needs
to contain readable code.

Unfortunately, leaving readable memory at a deterministic address can be
used to help various ASLR bypasses, so some hardening value can be gained
by disallowing vsyscall reads.

Given how rarely the vsyscall page needs to be readable, add a mechanism to
make the vsyscall page be execute only.
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/d17655777c21bc09a7af1bbcf74e6f2b69a51152.1561610354.git.luto@kernel.org

The usage of emulated and _TIF_SYSCALL_EMU flags in syscall_trace_enter
is more complicated than required.

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Acked-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Currently pt_regs on x86_32 has an oddity in that kernel regs
(!user_mode(regs)) are short two entries (esp/ss). This means that any
code trying to use them (typically: regs->sp) needs to jump through
some unfortunate hoops.

Change the entry code to fix this up and create a full pt_regs frame.

This then simplifies various trampolines in ftrace and kprobes, the
stack unwinder, ptrace, kdump and kgdb.

Much thanks to Josh for help with the cleanups!
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>

In preparation for wider use, move the ENCODE_FRAME_POINTER macros to
a common header and provide inline asm versions.

These macros are used to encode a pt_regs frame for the unwinder; see
unwind_frame.c:decode_frame_pointer().
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>