1. 18 Dec, 2017 2 commits
    • Linus Torvalds's avatar
      Merge branch 'WIP.x86-pti.entry-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 64a48099
      Linus Torvalds authored
      Pull x86 syscall entry code changes for PTI from Ingo Molnar:
       "The main changes here are Andy Lutomirski's changes to switch the
        x86-64 entry code to use the 'per CPU entry trampoline stack'. This,
        besides helping fix KASLR leaks (the pending Page Table Isolation
        (PTI) work), also robustifies the x86 entry code"
      
      * 'WIP.x86-pti.entry-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
        x86/cpufeatures: Make CPU bugs sticky
        x86/paravirt: Provide a way to check for hypervisors
        x86/paravirt: Dont patch flush_tlb_single
        x86/entry/64: Make cpu_entry_area.tss read-only
        x86/entry: Clean up the SYSENTER_stack code
        x86/entry/64: Remove the SYSENTER stack canary
        x86/entry/64: Move the IST stacks into struct cpu_entry_area
        x86/entry/64: Create a per-CPU SYSCALL entry trampoline
        x86/entry/64: Return to userspace from the trampoline stack
        x86/entry/64: Use a per-CPU trampoline stack for IDT entries
        x86/espfix/64: Stop assuming that pt_regs is on the entry stack
        x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0
        x86/entry: Remap the TSS into the CPU entry area
        x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct
        x86/dumpstack: Handle stack overflow on all stacks
        x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss
        x86/kasan/64: Teach KASAN about the cpu_entry_area
        x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce struct cpu_entry_area
        x86/entry/gdt: Put per-CPU GDT remaps in ascending order
        x86/dumpstack: Add get_stack_info() support for the SYSENTER stack
        ...
      64a48099
    • Linus Torvalds's avatar
      Linux 4.15-rc4 · 1291a0d5
      Linus Torvalds authored
      1291a0d5
  2. 17 Dec, 2017 38 commits
    • Kees Cook's avatar
      Revert "exec: avoid RLIMIT_STACK races with prlimit()" · 779f4e1c
      Kees Cook authored
      This reverts commit 04e35f44.
      
      SELinux runs with secureexec for all non-"noatsecure" domain transitions,
      which means lots of processes end up hitting the stack hard-limit change
      that was introduced in order to fix a race with prlimit(). That race fix
      will need to be redesigned.
      Reported-by: default avatarLaura Abbott <labbott@redhat.com>
      Reported-by: default avatarTomáš Trnka <trnka@scm.com>
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      779f4e1c
    • Linus Torvalds's avatar
      Merge branch 'WIP.x86-pti.base-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · f8940a0f
      Linus Torvalds authored
      Pull Page Table Isolation (PTI) v4.14 backporting base tree from Ingo Molnar:
       "This tree contains the v4.14 PTI backport preparatory tree, which
        consists of four merges of upstream trees and 7 cherry-picked commits,
        which the upcoming PTI work depends on"
      
      NOTE! The resulting tree is exactly the same as the original base tree
      (ie the diff between this commit and its immediate first parent is
      empty).
      
      The only reason for this merge is literally to have a common point for
      the actual PTI changes so that the commits can be shared in both the
      4.15 and 4.14 trees.
      
      * 'WIP.x86-pti.base-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow
        locking/barriers: Convert users of lockless_dereference() to READ_ONCE()
        locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()
        bpf: fix build issues on um due to mising bpf_perf_event.h
        perf/x86: Enable free running PEBS for REGS_USER/INTR
        x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD
        x86/cpufeature: Add User-Mode Instruction Prevention definitions
      f8940a0f
    • Linus Torvalds's avatar
      Merge branch 'WIP.x86-pti.base.prep-for-linus' of... · 6ba64fef
      Linus Torvalds authored
      Merge branch 'WIP.x86-pti.base.prep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
      
      Pull Page Table Isolation (PTI) preparatory tree from Ingo Molnar:
       "This does a rename to free up linux/pti.h to be used by the upcoming
        page table isolation feature"
      
      * 'WIP.x86-pti.base.prep-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        drivers/misc/intel/pti: Rename the header file to free up the namespace
      6ba64fef
    • Linus Torvalds's avatar
      Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 2ffb448c
      Linus Torvalds authored
      Pull timer fix from Thomas Gleixner:
       "A single bugfix which prevents arbitrary sigev_notify values in
        posix-timers"
      
      * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        posix-timer: Properly check sigevent->sigev_notify
      2ffb448c
    • Linus Torvalds's avatar
      Merge tag 'dmaengine-fix-4.15-rc4' of git://git.infradead.org/users/vkoul/slave-dma · c4372790
      Linus Torvalds authored
      Pull dmaengine fixes from Vinod Koul:
       "This time consisting of fixes in a bunch of drivers and the dmatest
        module:
      
         - Fix for disable clk on error path in fsl-edma driver
         - Disable clk fail fix in jz4740 driver
         - Fix long pending bug in dmatest driver for dangling pointer
         - Fix potential NULL pointer dereference in at_hdmac driver
         - Error handling path in ioat driver"
      
      * tag 'dmaengine-fix-4.15-rc4' of git://git.infradead.org/users/vkoul/slave-dma:
        dmaengine: fsl-edma: disable clks on all error paths
        dmaengine: jz4740: disable/unprepare clk if probe fails
        dmaengine: dmatest: move callback wait queue to thread context
        dmaengine: at_hdmac: fix potential NULL pointer dereference in atc_prep_dma_interleaved
        dmaengine: ioat: Fix error handling path
      c4372790
    • Arnd Bergmann's avatar
      cramfs: fix MTD dependency · b9f5fb18
      Arnd Bergmann authored
      With CONFIG_MTD=m and CONFIG_CRAMFS=y, we now get a link failure:
      
        fs/cramfs/inode.o: In function `cramfs_mount': inode.c:(.text+0x220): undefined reference to `mount_mtd'
        fs/cramfs/inode.o: In function `cramfs_mtd_fill_super':
        inode.c:(.text+0x6d8): undefined reference to `mtd_point'
        inode.c:(.text+0xae4): undefined reference to `mtd_unpoint'
      
      This adds a more specific Kconfig dependency to avoid the broken
      configuration.
      
      Alternatively we could make CRAMFS itself depend on "MTD || !MTD" with a
      similar result.
      
      Fixes: 99c18ce5 ("cramfs: direct memory access support")
      Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
      Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b9f5fb18
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs · 73d080d3
      Linus Torvalds authored
      Pull vfs fixes from Al Viro:
       "The alloc_super() one is a regression in this merge window, lazytime
        thing is older..."
      
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
        VFS: Handle lazytime in do_mount()
        alloc_super(): do ->s_umount initialization earlier
      73d080d3
    • Linus Torvalds's avatar
      Merge tag 'ext4_for_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4 · 1c6b942d
      Linus Torvalds authored
      Pull ext4 fixes from Ted Ts'o:
       "Fix a regression which caused us to fail to interpret symlinks in very
        ancient ext3 file system images.
      
        Also fix two xfstests failures, one of which could cause an OOPS, plus
        an additional bug fix caught by fuzz testing"
      
      * tag 'ext4_for_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
        ext4: fix crash when a directory's i_size is too small
        ext4: add missing error check in __ext4_new_inode()
        ext4: fix fdatasync(2) after fallocate(2) operation
        ext4: support fast symlinks from ext3 file systems
      1c6b942d
    • Thomas Gleixner's avatar
      x86/cpufeatures: Make CPU bugs sticky · 6cbd2171
      Thomas Gleixner authored
      There is currently no way to force CPU bug bits like CPU feature bits. That
      makes it impossible to set a bug bit once at boot and have it stick for all
      upcoming CPUs.
      
      Extend the force set/clear arrays to handle bug bits as well.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.992156574@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      6cbd2171
    • Thomas Gleixner's avatar
      x86/paravirt: Provide a way to check for hypervisors · 79cc7415
      Thomas Gleixner authored
      There is no generic way to test whether a kernel is running on a specific
      hypervisor. But that's required to prevent the upcoming user address space
      separation feature in certain guest modes.
      
      Make the hypervisor type enum unconditionally available and provide a
      helper function which allows to test for a specific type.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.912938129@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      79cc7415
    • Thomas Gleixner's avatar
      x86/paravirt: Dont patch flush_tlb_single · a0357954
      Thomas Gleixner authored
      native_flush_tlb_single() will be changed with the upcoming
      PAGE_TABLE_ISOLATION feature. This requires to have more code in
      there than INVLPG.
      
      Remove the paravirt patching for it.
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
      Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Cc: linux-mm@kvack.org
      Cc: michael.schwarz@iaik.tugraz.at
      Cc: moritz.lipp@iaik.tugraz.at
      Cc: richard.fellner@student.tugraz.at
      Link: https://lkml.kernel.org/r/20171204150606.828111617@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      a0357954
    • Andy Lutomirski's avatar
      x86/entry/64: Make cpu_entry_area.tss read-only · c482feef
      Andy Lutomirski authored
      The TSS is a fairly juicy target for exploits, and, now that the TSS
      is in the cpu_entry_area, it's no longer protected by kASLR.  Make it
      read-only on x86_64.
      
      On x86_32, it can't be RO because it's written by the CPU during task
      switches, and we use a task gate for double faults.  I'd also be
      nervous about errata if we tried to make it RO even on configurations
      without double fault handling.
      
      [ tglx: AMD confirmed that there is no problem on 64-bit with TSS RO.  So
        	it's probably safe to assume that it's a non issue, though Intel
        	might have been creative in that area. Still waiting for
        	confirmation. ]
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bpetkov@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Kees Cook <keescook@chromium.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.733700132@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      c482feef
    • Andy Lutomirski's avatar
      x86/entry: Clean up the SYSENTER_stack code · 0f9a4810
      Andy Lutomirski authored
      The existing code was a mess, mainly because C arrays are nasty.  Turn
      SYSENTER_stack into a struct, add a helper to find it, and do all the
      obvious cleanups this enables.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bpetkov@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.653244723@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      0f9a4810
    • Andy Lutomirski's avatar
      x86/entry/64: Remove the SYSENTER stack canary · 7fbbd5cb
      Andy Lutomirski authored
      Now that the SYSENTER stack has a guard page, there's no need for a canary
      to detect overflow after the fact.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.572577316@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7fbbd5cb
    • Andy Lutomirski's avatar
      x86/entry/64: Move the IST stacks into struct cpu_entry_area · 40e7f949
      Andy Lutomirski authored
      The IST stacks are needed when an IST exception occurs and are accessed
      before any kernel code at all runs.  Move them into struct cpu_entry_area.
      
      The IST stacks are unlike the rest of cpu_entry_area: they're used even for
      entries from kernel mode.  This means that they should be set up before we
      load the final IDT.  Move cpu_entry_area setup to trap_init() for the boot
      CPU and set it up for all possible CPUs at once in native_smp_prepare_cpus().
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.480598743@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      40e7f949
    • Andy Lutomirski's avatar
      x86/entry/64: Create a per-CPU SYSCALL entry trampoline · 3386bc8a
      Andy Lutomirski authored
      Handling SYSCALL is tricky: the SYSCALL handler is entered with every
      single register (except FLAGS), including RSP, live.  It somehow needs
      to set RSP to point to a valid stack, which means it needs to save the
      user RSP somewhere and find its own stack pointer.  The canonical way
      to do this is with SWAPGS, which lets us access percpu data using the
      %gs prefix.
      
      With PAGE_TABLE_ISOLATION-like pagetable switching, this is
      problematic.  Without a scratch register, switching CR3 is impossible, so
      %gs-based percpu memory would need to be mapped in the user pagetables.
      Doing that without information leaks is difficult or impossible.
      
      Instead, use a different sneaky trick.  Map a copy of the first part
      of the SYSCALL asm at a different address for each CPU.  Now RIP
      varies depending on the CPU, so we can use RIP-relative memory access
      to access percpu memory.  By putting the relevant information (one
      scratch slot and the stack address) at a constant offset relative to
      RIP, we can make SYSCALL work without relying on %gs.
      
      A nice thing about this approach is that we can easily switch it on
      and off if we want pagetable switching to be configurable.
      
      The compat variant of SYSCALL doesn't have this problem in the first
      place -- there are plenty of scratch registers, since we don't care
      about preserving r8-r15.  This patch therefore doesn't touch SYSCALL32
      at all.
      
      This patch actually seems to be a small speedup.  With this patch,
      SYSCALL touches an extra cache line and an extra virtual page, but
      the pipeline no longer stalls waiting for SWAPGS.  It seems that, at
      least in a tight loop, the latter outweights the former.
      
      Thanks to David Laight for an optimization tip.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bpetkov@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.403607157@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      3386bc8a
    • Andy Lutomirski's avatar
      x86/entry/64: Return to userspace from the trampoline stack · 3e3b9293
      Andy Lutomirski authored
      By itself, this is useless.  It gives us the ability to run some final code
      before exit that cannnot run on the kernel stack.  This could include a CR3
      switch a la PAGE_TABLE_ISOLATION or some kernel stack erasing, for
      example.  (Or even weird things like *changing* which kernel stack gets
      used as an ASLR-strengthening mechanism.)
      
      The SYSRET32 path is not covered yet.  It could be in the future or
      we could just ignore it and force the slow path if needed.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.306546484@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      3e3b9293
    • Andy Lutomirski's avatar
      x86/entry/64: Use a per-CPU trampoline stack for IDT entries · 7f2590a1
      Andy Lutomirski authored
      Historically, IDT entries from usermode have always gone directly
      to the running task's kernel stack.  Rearrange it so that we enter on
      a per-CPU trampoline stack and then manually switch to the task's stack.
      This touches a couple of extra cachelines, but it gives us a chance
      to run some code before we touch the kernel stack.
      
      The asm isn't exactly beautiful, but I think that fully refactoring
      it can wait.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.225330557@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7f2590a1
    • Andy Lutomirski's avatar
      x86/espfix/64: Stop assuming that pt_regs is on the entry stack · 6d9256f0
      Andy Lutomirski authored
      When we start using an entry trampoline, a #GP from userspace will
      be delivered on the entry stack, not on the task stack.  Fix the
      espfix64 #DF fixup to set up #GP according to TSS.SP0, rather than
      assuming that pt_regs + 1 == SP0.  This won't change anything
      without an entry stack, but it will make the code continue to work
      when an entry stack is added.
      
      While we're at it, improve the comments to explain what's actually
      going on.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.130778051@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      6d9256f0
    • Andy Lutomirski's avatar
      x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 · 9aaefe7b
      Andy Lutomirski authored
      On 64-bit kernels, we used to assume that TSS.sp0 was the current
      top of stack.  With the addition of an entry trampoline, this will
      no longer be the case.  Store the current top of stack in TSS.sp1,
      which is otherwise unused but shares the same cacheline.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150606.050864668@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      9aaefe7b
    • Andy Lutomirski's avatar
      x86/entry: Remap the TSS into the CPU entry area · 72f5e08d
      Andy Lutomirski authored
      This has a secondary purpose: it puts the entry stack into a region
      with a well-controlled layout.  A subsequent patch will take
      advantage of this to streamline the SYSCALL entry code to be able to
      find it more easily.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bpetkov@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.962042855@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      72f5e08d
    • Andy Lutomirski's avatar
      x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct · 1a935bc3
      Andy Lutomirski authored
      SYSENTER_stack should have reliable overflow detection, which
      means that it needs to be at the bottom of a page, not the top.
      Move it to the beginning of struct tss_struct and page-align it.
      
      Also add an assertion to make sure that the fixed hardware TSS
      doesn't cross a page boundary.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.881827433@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      1a935bc3
    • Andy Lutomirski's avatar
      x86/dumpstack: Handle stack overflow on all stacks · 6e60e583
      Andy Lutomirski authored
      We currently special-case stack overflow on the task stack.  We're
      going to start putting special stacks in the fixmap with a custom
      layout, so they'll have guard pages, too.  Teach the unwinder to be
      able to unwind an overflow of any of the stacks.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.802057305@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      6e60e583
    • Andy Lutomirski's avatar
      x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss · 7fb983b4
      Andy Lutomirski authored
      A future patch will move SYSENTER_stack to the beginning of cpu_tss
      to help detect overflow.  Before this can happen, fix several code
      paths that hardcode assumptions about the old layout.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarDave Hansen <dave.hansen@intel.com>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.722425540@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      7fb983b4
    • Andy Lutomirski's avatar
      x86/kasan/64: Teach KASAN about the cpu_entry_area · 21506525
      Andy Lutomirski authored
      The cpu_entry_area will contain stacks.  Make sure that KASAN has
      appropriate shadow mappings for them.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: kasan-dev@googlegroups.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.642806442@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      21506525
    • Andy Lutomirski's avatar
      x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce struct cpu_entry_area · ef8813ab
      Andy Lutomirski authored
      Currently, the GDT is an ad-hoc array of pages, one per CPU, in the
      fixmap.  Generalize it to be an array of a new 'struct cpu_entry_area'
      so that we can cleanly add new things to it.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.563271721@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      ef8813ab
    • Andy Lutomirski's avatar
      x86/entry/gdt: Put per-CPU GDT remaps in ascending order · aaeed3ae
      Andy Lutomirski authored
      We currently have CPU 0's GDT at the top of the GDT range and
      higher-numbered CPUs at lower addresses.  This happens because the
      fixmap is upside down (index 0 is the top of the fixmap).
      
      Flip it so that GDTs are in ascending order by virtual address.
      This will simplify a future patch that will generalize the GDT
      remap to contain multiple pages.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.471561421@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      aaeed3ae
    • Andy Lutomirski's avatar
      x86/dumpstack: Add get_stack_info() support for the SYSENTER stack · 33a2f1a6
      Andy Lutomirski authored
      get_stack_info() doesn't currently know about the SYSENTER stack, so
      unwinding will fail if we entered the kernel on the SYSENTER stack
      and haven't fully switched off.  Teach get_stack_info() about the
      SYSENTER stack.
      
      With future patches applied that run part of the entry code on the
      SYSENTER stack and introduce an intentional BUG(), I would get:
      
        PANIC: double fault, error_code: 0x0
        ...
        RIP: 0010:do_error_trap+0x33/0x1c0
        ...
        Call Trace:
        Code: ...
      
      With this patch, I get:
      
        PANIC: double fault, error_code: 0x0
        ...
        Call Trace:
         <SYSENTER>
         ? async_page_fault+0x36/0x60
         ? invalid_op+0x22/0x40
         ? async_page_fault+0x36/0x60
         ? sync_regs+0x3c/0x40
         ? sync_regs+0x2e/0x40
         ? error_entry+0x6c/0xd0
         ? async_page_fault+0x36/0x60
         </SYSENTER>
        Code: ...
      
      which is a lot more informative.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.392711508@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      33a2f1a6
    • Andy Lutomirski's avatar
      x86/entry/64: Allocate and enable the SYSENTER stack · 1a79797b
      Andy Lutomirski authored
      This will simplify future changes that want scratch variables early in
      the SYSENTER handler -- they'll be able to spill registers to the
      stack.  It also lets us get rid of a SWAPGS_UNSAFE_STACK user.
      
      This does not depend on CONFIG_IA32_EMULATION=y because we'll want the
      stack space even without IA32 emulation.
      
      As far as I can tell, the reason that this wasn't done from day 1 is
      that we use IST for #DB and #BP, which is IMO rather nasty and causes
      a lot more problems than it solves.  But, since #DB uses IST, we don't
      actually need a real stack for SYSENTER (because SYSENTER with TF set
      will invoke #DB on the IST stack rather than the SYSENTER stack).
      
      I want to remove IST usage from these vectors some day, and this patch
      is a prerequisite for that as well.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.312726423@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      1a79797b
    • Andy Lutomirski's avatar
      x86/irq/64: Print the offending IP in the stack overflow warning · 4f3789e7
      Andy Lutomirski authored
      In case something goes wrong with unwind (not unlikely in case of
      overflow), print the offending IP where we detected the overflow.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.231677119@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      4f3789e7
    • Andy Lutomirski's avatar
      x86/irq: Remove an old outdated comment about context tracking races · 6669a692
      Andy Lutomirski authored
      That race has been fixed and code cleaned up for a while now.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.150551639@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      6669a692
    • Josh Poimboeuf's avatar
      x86/unwinder: Handle stack overflows more gracefully · b02fcf9b
      Josh Poimboeuf authored
      There are at least two unwinder bugs hindering the debugging of
      stack-overflow crashes:
      
      - It doesn't deal gracefully with the case where the stack overflows and
        the stack pointer itself isn't on a valid stack but the
        to-be-dereferenced data *is*.
      
      - The ORC oops dump code doesn't know how to print partial pt_regs, for the
        case where if we get an interrupt/exception in *early* entry code
        before the full pt_regs have been saved.
      
      Fix both issues.
      
      http://lkml.kernel.org/r/20171126024031.uxi4numpbjm5rlbr@trebleSigned-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarBorislav Petkov <bpetkov@suse.de>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Juergen Gross <jgross@suse.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150605.071425003@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      b02fcf9b
    • Andy Lutomirski's avatar
      x86/unwinder/orc: Dont bail on stack overflow · d3a09104
      Andy Lutomirski authored
      If the stack overflows into a guard page and the ORC unwinder should work
      well: by construction, there can't be any meaningful data in the guard page
      because no writes to the guard page will have succeeded.
      
      But there is a bug that prevents unwinding from working correctly: if the
      starting register state has RSP pointing into a stack guard page, the ORC
      unwinder bails out immediately.
      
      Instead of bailing out immediately check whether the next page up is a
      valid check page and if so analyze that. As a result the ORC unwinder will
      start the unwind.
      
      Tested by intentionally overflowing the task stack.  The result is an
      accurate call trace instead of a trace consisting purely of '?' entries.
      
      There are a few other bugs that are triggered if the unwinder encounters a
      stack overflow after the first step, but they are outside the scope of this
      fix.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      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: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Link: https://lkml.kernel.org/r/20171204150604.991389777@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      d3a09104
    • Boris Ostrovsky's avatar
      x86/entry/64/paravirt: Use paravirt-safe macro to access eflags · e17f8234
      Boris Ostrovsky authored
      Commit 1d3e53e8 ("x86/entry/64: Refactor IRQ stacks and make them
      NMI-safe") added DEBUG_ENTRY_ASSERT_IRQS_OFF macro that acceses eflags
      using 'pushfq' instruction when testing for IF bit. On PV Xen guests
      looking at IF flag directly will always see it set, resulting in 'ud2'.
      
      Introduce SAVE_FLAGS() macro that will use appropriate save_fl pv op when
      running paravirt.
      Signed-off-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Borislav Petkov <bpetkov@suse.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@intel.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: David Laight <David.Laight@aculab.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: Eduardo Valentin <eduval@amazon.com>
      Cc: Greg KH <gregkh@linuxfoundation.org>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Josh Poimboeuf <jpoimboe@redhat.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rik van Riel <riel@redhat.com>
      Cc: Will Deacon <will.deacon@arm.com>
      Cc: aliguori@amazon.com
      Cc: daniel.gruss@iaik.tugraz.at
      Cc: hughd@google.com
      Cc: keescook@google.com
      Cc: xen-devel@lists.xenproject.org
      Link: https://lkml.kernel.org/r/20171204150604.899457242@linutronix.deSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      e17f8234
    • Andrey Ryabinin's avatar
      x86/mm/kasan: Don't use vmemmap_populate() to initialize shadow · 2aeb0736
      Andrey Ryabinin authored
      [ Note, this is a Git cherry-pick of the following commit:
      
          d17a1d97: ("x86/mm/kasan: don't use vmemmap_populate() to initialize shadow")
      
        ... for easier x86 PTI code testing and back-porting. ]
      
      The KASAN shadow is currently mapped using vmemmap_populate() since that
      provides a semi-convenient way to map pages into init_top_pgt.  However,
      since that no longer zeroes the mapped pages, it is not suitable for
      KASAN, which requires zeroed shadow memory.
      
      Add kasan_populate_shadow() interface and use it instead of
      vmemmap_populate().  Besides, this allows us to take advantage of
      gigantic pages and use them to populate the shadow, which should save us
      some memory wasted on page tables and reduce TLB pressure.
      
      Link: http://lkml.kernel.org/r/20171103185147.2688-2-pasha.tatashin@oracle.comSigned-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Steven Sistare <steven.sistare@oracle.com>
      Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
      Cc: Bob Picco <bob.picco@oracle.com>
      Cc: Michal Hocko <mhocko@suse.com>
      Cc: Alexander Potapenko <glider@google.com>
      Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Christian Borntraeger <borntraeger@de.ibm.com>
      Cc: David S. Miller <davem@davemloft.net>
      Cc: Dmitry Vyukov <dvyukov@google.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Mark Rutland <mark.rutland@arm.com>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Cc: Michal Hocko <mhocko@kernel.org>
      Cc: Sam Ravnborg <sam@ravnborg.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Will Deacon <will.deacon@arm.com>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      2aeb0736
    • Will Deacon's avatar
      locking/barriers: Convert users of lockless_dereference() to READ_ONCE() · 3382290e
      Will Deacon authored
      [ Note, this is a Git cherry-pick of the following commit:
      
          506458ef ("locking/barriers: Convert users of lockless_dereference() to READ_ONCE()")
      
        ... for easier x86 PTI code testing and back-porting. ]
      
      READ_ONCE() now has an implicit smp_read_barrier_depends() call, so it
      can be used instead of lockless_dereference() without any change in
      semantics.
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/1508840570-22169-4-git-send-email-will.deacon@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      3382290e
    • Will Deacon's avatar
      locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE() · c2bc6608
      Will Deacon authored
      [ Note, this is a Git cherry-pick of the following commit:
      
          76ebbe78 ("locking/barriers: Add implicit smp_read_barrier_depends() to READ_ONCE()")
      
        ... for easier x86 PTI code testing and back-porting. ]
      
      In preparation for the removal of lockless_dereference(), which is the
      same as READ_ONCE() on all architectures other than Alpha, add an
      implicit smp_read_barrier_depends() to READ_ONCE() so that it can be
      used to head dependency chains on all architectures.
      Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Link: http://lkml.kernel.org/r/1508840570-22169-3-git-send-email-will.deacon@arm.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      c2bc6608
    • Daniel Borkmann's avatar
      bpf: fix build issues on um due to mising bpf_perf_event.h · ab95477e
      Daniel Borkmann authored
      [ Note, this is a Git cherry-pick of the following commit:
      
          a23f06f0 ("bpf: fix build issues on um due to mising bpf_perf_event.h")
      
        ... for easier x86 PTI code testing and back-porting. ]
      
      Since c895f6f7 ("bpf: correct broken uapi for
      BPF_PROG_TYPE_PERF_EVENT program type") um (uml) won't build
      on i386 or x86_64:
      
        [...]
          CC      init/main.o
        In file included from ../include/linux/perf_event.h:18:0,
                         from ../include/linux/trace_events.h:10,
                         from ../include/trace/syscall.h:7,
                         from ../include/linux/syscalls.h:82,
                         from ../init/main.c:20:
        ../include/uapi/linux/bpf_perf_event.h:11:32: fatal error:
        asm/bpf_perf_event.h: No such file or directory #include
        <asm/bpf_perf_event.h>
        [...]
      
      Lets add missing bpf_perf_event.h also to um arch. This seems
      to be the only one still missing.
      
      Fixes: c895f6f7 ("bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type")
      Reported-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Suggested-by: default avatarRichard Weinberger <richard@sigma-star.at>
      Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
      Tested-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
      Cc: Richard Weinberger <richard@sigma-star.at>
      Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Acked-by: default avatarRichard Weinberger <richard@nod.at>
      Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      ab95477e