1. 10 Jan, 2018 17 commits
  2. 05 Jan, 2018 23 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.4.110 · b3e3db15
      Greg Kroah-Hartman authored
      b3e3db15
    • Guenter Roeck's avatar
      kaiser: Set _PAGE_NX only if supported · b33c3c64
      Guenter Roeck authored
      This resolves a crash if loaded under qemu + haxm under windows.
      See https://www.spinics.net/lists/kernel/msg2689835.html for details.
      Here is a boot log (the log is from chromeos-4.4, but Tao Wu says that
      the same log is also seen with vanilla v4.4.110-rc1).
      
      [    0.712750] Freeing unused kernel memory: 552K
      [    0.721821] init: Corrupted page table at address 57b029b332e0
      [    0.722761] PGD 80000000bb238067 PUD bc36a067 PMD bc369067 PTE 45d2067
      [    0.722761] Bad pagetable: 000b [#1] PREEMPT SMP 
      [    0.722761] Modules linked in:
      [    0.722761] CPU: 1 PID: 1 Comm: init Not tainted 4.4.96 #31
      [    0.722761] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
      rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
      [    0.722761] task: ffff8800bc290000 ti: ffff8800bc28c000 task.ti: ffff8800bc28c000
      [    0.722761] RIP: 0010:[<ffffffff83f4129e>]  [<ffffffff83f4129e>] __clear_user+0x42/0x67
      [    0.722761] RSP: 0000:ffff8800bc28fcf8  EFLAGS: 00010202
      [    0.722761] RAX: 0000000000000000 RBX: 00000000000001a4 RCX: 00000000000001a4
      [    0.722761] RDX: 0000000000000000 RSI: 0000000000000008 RDI: 000057b029b332e0
      [    0.722761] RBP: ffff8800bc28fd08 R08: ffff8800bc290000 R09: ffff8800bb2f4000
      [    0.722761] R10: ffff8800bc290000 R11: ffff8800bb2f4000 R12: 000057b029b332e0
      [    0.722761] R13: 0000000000000000 R14: 000057b029b33340 R15: ffff8800bb1e2a00
      [    0.722761] FS:  0000000000000000(0000) GS:ffff8800bfb00000(0000) knlGS:0000000000000000
      [    0.722761] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
      [    0.722761] CR2: 000057b029b332e0 CR3: 00000000bb2f8000 CR4: 00000000000006e0
      [    0.722761] Stack:
      [    0.722761]  000057b029b332e0 ffff8800bb95fa80 ffff8800bc28fd18 ffffffff83f4120c
      [    0.722761]  ffff8800bc28fe18 ffffffff83e9e7a1 ffff8800bc28fd68 0000000000000000
      [    0.722761]  ffff8800bc290000 ffff8800bc290000 ffff8800bc290000 ffff8800bc290000
      [    0.722761] Call Trace:
      [    0.722761]  [<ffffffff83f4120c>] clear_user+0x2e/0x30
      [    0.722761]  [<ffffffff83e9e7a1>] load_elf_binary+0xa7f/0x18f7
      [    0.722761]  [<ffffffff83de2088>] search_binary_handler+0x86/0x19c
      [    0.722761]  [<ffffffff83de389e>] do_execveat_common.isra.26+0x909/0xf98
      [    0.722761]  [<ffffffff844febe0>] ? rest_init+0x87/0x87
      [    0.722761]  [<ffffffff83de40be>] do_execve+0x23/0x25
      [    0.722761]  [<ffffffff83c002e3>] run_init_process+0x2b/0x2d
      [    0.722761]  [<ffffffff844fec4d>] kernel_init+0x6d/0xda
      [    0.722761]  [<ffffffff84505b2f>] ret_from_fork+0x3f/0x70
      [    0.722761]  [<ffffffff844febe0>] ? rest_init+0x87/0x87
      [    0.722761] Code: 86 84 be 12 00 00 00 e8 87 0d e8 ff 66 66 90 48 89 d8 48 c1
      eb 03 4c 89 e7 83 e0 07 48 89 d9 be 08 00 00 00 31 d2 48 85 c9 74 0a <48> 89 17
      48 01 f7 ff c9 75 f6 48 89 c1 85 c9 74 09 88 17 48 ff 
      [    0.722761] RIP  [<ffffffff83f4129e>] __clear_user+0x42/0x67
      [    0.722761]  RSP <ffff8800bc28fcf8>
      [    0.722761] ---[ end trace def703879b4ff090 ]---
      [    0.722761] BUG: sleeping function called from invalid context at /mnt/host/source/src/third_party/kernel/v4.4/kernel/locking/rwsem.c:21
      [    0.722761] in_atomic(): 0, irqs_disabled(): 1, pid: 1, name: init
      [    0.722761] CPU: 1 PID: 1 Comm: init Tainted: G      D         4.4.96 #31
      [    0.722761] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014
      [    0.722761]  0000000000000086 dcb5d76098c89836 ffff8800bc28fa30 ffffffff83f34004
      [    0.722761]  ffffffff84839dc2 0000000000000015 ffff8800bc28fa40 ffffffff83d57dc9
      [    0.722761]  ffff8800bc28fa68 ffffffff83d57e6a ffffffff84a53640 0000000000000000
      [    0.722761] Call Trace:
      [    0.722761]  [<ffffffff83f34004>] dump_stack+0x4d/0x63
      [    0.722761]  [<ffffffff83d57dc9>] ___might_sleep+0x13a/0x13c
      [    0.722761]  [<ffffffff83d57e6a>] __might_sleep+0x9f/0xa6
      [    0.722761]  [<ffffffff84502788>] down_read+0x20/0x31
      [    0.722761]  [<ffffffff83cc5d9b>] __blocking_notifier_call_chain+0x35/0x63
      [    0.722761]  [<ffffffff83cc5ddd>] blocking_notifier_call_chain+0x14/0x16
      [    0.800374] usb 1-1: new full-speed USB device number 2 using uhci_hcd
      [    0.722761]  [<ffffffff83cefe97>] profile_task_exit+0x1a/0x1c
      [    0.802309]  [<ffffffff83cac84e>] do_exit+0x39/0xe7f
      [    0.802309]  [<ffffffff83ce5938>] ? vprintk_default+0x1d/0x1f
      [    0.802309]  [<ffffffff83d7bb95>] ? printk+0x57/0x73
      [    0.802309]  [<ffffffff83c46e25>] oops_end+0x80/0x85
      [    0.802309]  [<ffffffff83c7b747>] pgtable_bad+0x8a/0x95
      [    0.802309]  [<ffffffff83ca7f4a>] __do_page_fault+0x8c/0x352
      [    0.802309]  [<ffffffff83eefba5>] ? file_has_perm+0xc4/0xe5
      [    0.802309]  [<ffffffff83ca821c>] do_page_fault+0xc/0xe
      [    0.802309]  [<ffffffff84507682>] page_fault+0x22/0x30
      [    0.802309]  [<ffffffff83f4129e>] ? __clear_user+0x42/0x67
      [    0.802309]  [<ffffffff83f4127f>] ? __clear_user+0x23/0x67
      [    0.802309]  [<ffffffff83f4120c>] clear_user+0x2e/0x30
      [    0.802309]  [<ffffffff83e9e7a1>] load_elf_binary+0xa7f/0x18f7
      [    0.802309]  [<ffffffff83de2088>] search_binary_handler+0x86/0x19c
      [    0.802309]  [<ffffffff83de389e>] do_execveat_common.isra.26+0x909/0xf98
      [    0.802309]  [<ffffffff844febe0>] ? rest_init+0x87/0x87
      [    0.802309]  [<ffffffff83de40be>] do_execve+0x23/0x25
      [    0.802309]  [<ffffffff83c002e3>] run_init_process+0x2b/0x2d
      [    0.802309]  [<ffffffff844fec4d>] kernel_init+0x6d/0xda
      [    0.802309]  [<ffffffff84505b2f>] ret_from_fork+0x3f/0x70
      [    0.802309]  [<ffffffff844febe0>] ? rest_init+0x87/0x87
      [    0.830559] Kernel panic - not syncing: Attempted to kill init!  exitcode=0x00000009
      [    0.830559] 
      [    0.831305] Kernel Offset: 0x2c00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
      [    0.831305] ---[ end Kernel panic - not syncing: Attempted to kill init!  exitcode=0x00000009
      
      The crash part of this problem may be solved with the following patch
      (thanks to Hugh for the hint). There is still another problem, though -
      with this patch applied, the qemu session aborts with "VCPU Shutdown
      request", whatever that means.
      
      Cc: lepton <ytht.net@gmail.com>
      Signed-off-by: default avatarGuenter Roeck <groeck@chromium.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b33c3c64
    • Andrey Ryabinin's avatar
      x86/kasan: Clear kasan_zero_page after TLB flush · 2b24fe5c
      Andrey Ryabinin authored
      commit 69e0210f upstream.
      
      Currently we clear kasan_zero_page before __flush_tlb_all(). This
      works with current implementation of native_flush_tlb[_global]()
      because it doesn't cause do any writes to kasan shadow memory.
      But any subtle change made in native_flush_tlb*() could break this.
      Also current code seems doesn't work for paravirt guests (lguest).
      
      Only after the TLB flush we can be sure that kasan_zero_page is not
      used as early shadow anymore (instrumented code will not write to it).
      So it should cleared it only after the TLB flush.
      Signed-off-by: default avatarAndrey Ryabinin <aryabinin@virtuozzo.com>
      Reviewed-by: default avatarBorislav Petkov <bp@suse.de>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Dave Hansen <dave.hansen@linux.intel.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Luis R. Rodriguez <mcgrof@suse.com>
      Cc: Oleg Nesterov <oleg@redhat.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Toshi Kani <toshi.kani@hp.com>
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/1452516679-32040-2-git-send-email-aryabinin@virtuozzo.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Cc: Jamie Iles <jamie.iles@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2b24fe5c
    • Andy Lutomirski's avatar
      x86/vdso: Get pvclock data from the vvar VMA instead of the fixmap · 755bd549
      Andy Lutomirski authored
      commit dac16fba upstream.
      Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
      Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Cc: Andy Lutomirski <luto@amacapital.net>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/9d37826fdc7e2d2809efe31d5345f97186859284.1449702533.git.luto@kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Cc: Jamie Iles <jamie.iles@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      755bd549
    • Andy Lutomirski's avatar
      x86, vdso, pvclock: Simplify and speed up the vdso pvclock reader · 64e23980
      Andy Lutomirski authored
      commit 6b078f5d upstream.
      
      The pvclock vdso code was too abstracted to understand easily
      and excessively paranoid.  Simplify it for a huge speedup.
      
      This opens the door for additional simplifications, as the vdso
      no longer accesses the pvti for any vcpu other than vcpu 0.
      
      Before, vclock_gettime using kvm-clock took about 45ns on my
      machine. With this change, it takes 29ns, which is almost as
      fast as the pure TSC implementation.
      Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
      Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Brian Gerst <brgerst@gmail.com>
      Cc: Denys Vlasenko <dvlasenk@redhat.com>
      Cc: H. Peter Anvin <hpa@zytor.com>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-mm@kvack.org
      Link: http://lkml.kernel.org/r/6b51dcc41f1b101f963945c5ec7093d72bdac429.1449702533.git.luto@kernel.orgSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      Cc: Jamie Iles <jamie.iles@oracle.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      64e23980
    • Kees Cook's avatar
      KPTI: Report when enabled · bfd51a4d
      Kees Cook authored
      Make sure dmesg reports when KPTI is enabled.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bfd51a4d
    • Kees Cook's avatar
      KPTI: Rename to PAGE_TABLE_ISOLATION · 3e1457d6
      Kees Cook authored
      This renames CONFIG_KAISER to CONFIG_PAGE_TABLE_ISOLATION.
      Signed-off-by: default avatarKees Cook <keescook@chromium.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3e1457d6
    • Borislav Petkov's avatar
      x86/kaiser: Move feature detection up · 7f79599d
      Borislav Petkov authored
      
      ... before the first use of kaiser_enabled as otherwise funky
      things happen:
      
        about to get started...
        (XEN) d0v0 Unhandled page fault fault/trap [#14, ec=0000]
        (XEN) Pagetable walk from ffff88022a449090:
        (XEN)  L4[0x110] = 0000000229e0e067 0000000000001e0e
        (XEN)  L3[0x008] = 0000000000000000 ffffffffffffffff
        (XEN) domain_crash_sync called from entry.S: fault at ffff82d08033fd08
        entry.o#create_bounce_frame+0x135/0x14d
        (XEN) Domain 0 (vcpu#0) crashed on cpu#0:
        (XEN) ----[ Xen-4.9.1_02-3.21  x86_64  debug=n   Not tainted ]----
        (XEN) CPU:    0
        (XEN) RIP:    e033:[<ffffffff81007460>]
        (XEN) RFLAGS: 0000000000000286   EM: 1   CONTEXT: pv guest (d0v0)
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      7f79599d
    • Jiri Kosina's avatar
      kaiser: disabled on Xen PV · e4ba212e
      Jiri Kosina authored
      
      Kaiser cannot be used on paravirtualized MMUs (namely reading and writing CR3).
      This does not work with KAISER as the CR3 switch from and to user space PGD
      would require to map the whole XEN_PV machinery into both.
      
      More importantly, enabling KAISER on Xen PV doesn't make too much sense, as PV
      guests use distinct %cr3 values for kernel and user already.
      Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e4ba212e
    • Borislav Petkov's avatar
      x86/kaiser: Reenable PARAVIRT · 750fb627
      Borislav Petkov authored
      
      Now that the required bits have been addressed, reenable
      PARAVIRT.
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      750fb627
    • Thomas Gleixner's avatar
      x86/paravirt: Dont patch flush_tlb_single · 3e809caf
      Thomas Gleixner authored
      
      commit a0357954 upstream
      
      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>
      Acked-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3e809caf
    • Hugh Dickins's avatar
      kaiser: kaiser_flush_tlb_on_return_to_user() check PCID · 8eaca4c7
      Hugh Dickins authored
      
      Let kaiser_flush_tlb_on_return_to_user() do the X86_FEATURE_PCID
      check, instead of each caller doing it inline first: nobody needs
      to optimize for the noPCID case, it's clearer this way, and better
      suits later changes.  Replace those no-op X86_CR3_PCID_KERN_FLUSH lines
      by a BUILD_BUG_ON() in load_new_mm_cr3(), in case something changes.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      8eaca4c7
    • Hugh Dickins's avatar
      kaiser: asm/tlbflush.h handle noPGE at lower level · 0651b3ad
      Hugh Dickins authored
      
      I found asm/tlbflush.h too twisty, and think it safer not to avoid
      __native_flush_tlb_global_irq_disabled() in the kaiser_enabled case,
      but instead let it handle kaiser_enabled along with cr3: it can just
      use __native_flush_tlb() for that, no harm in re-disabling preemption.
      
      (This is not the same change as Kirill and Dave have suggested for
      upstream, flipping PGE in cr4: that's neat, but needs a cpu_has_pge
      check; cr3 is enough for kaiser, and thought to be cheaper than cr4.)
      
      Also delete the X86_FEATURE_INVPCID invpcid_flush_all_nonglobals()
      preference from __native_flush_tlb(): unlike the invpcid_flush_all()
      preference in __native_flush_tlb_global(), it's not seen in upstream
      4.14, and was recently reported to be surprisingly slow.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0651b3ad
    • Hugh Dickins's avatar
      kaiser: drop is_atomic arg to kaiser_pagetable_walk() · 28c6de54
      Hugh Dickins authored
      
      I have not observed a might_sleep() warning from setup_fixmap_gdt()'s
      use of kaiser_add_mapping() in our tree (why not?), but like upstream
      we have not provided a way for that to pass is_atomic true down to
      kaiser_pagetable_walk(), and at startup it's far from a likely source
      of trouble: so just delete the walk's is_atomic arg and might_sleep().
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      28c6de54
    • Hugh Dickins's avatar
      kaiser: use ALTERNATIVE instead of x86_cr3_pcid_noflush · 2dff99eb
      Hugh Dickins authored
      
      Now that we're playing the ALTERNATIVE game, use that more efficient
      method: instead of user-mapping an extra page, and reading an extra
      cacheline each time for x86_cr3_pcid_noflush.
      
      Neel has found that __stringify(bts $X86_CR3_PCID_NOFLUSH_BIT, %rax)
      is a working substitute for the "bts $63, %rax" in these ALTERNATIVEs;
      but the one line with $63 in looks clearer, so let's stick with that.
      
      Worried about what happens with an ALTERNATIVE between the jump and
      jump label in another ALTERNATIVE?  I was, but have checked the
      combinations in SWITCH_KERNEL_CR3_NO_STACK at entry_SYSCALL_64,
      and it does a good job.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      2dff99eb
    • Borislav Petkov's avatar
      x86/kaiser: Check boottime cmdline params · e405a064
      Borislav Petkov authored
      
      AMD (and possibly other vendors) are not affected by the leak
      KAISER is protecting against.
      
      Keep the "nopti" for traditional reasons and add pti=<on|off|auto>
      like upstream.
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e405a064
    • Borislav Petkov's avatar
      x86/kaiser: Rename and simplify X86_FEATURE_KAISER handling · dea9aa9f
      Borislav Petkov authored
      
      Concentrate it in arch/x86/mm/kaiser.c and use the upstream string "nopti".
      Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      dea9aa9f
    • Hugh Dickins's avatar
      kaiser: add "nokaiser" boot option, using ALTERNATIVE · e345dcc9
      Hugh Dickins authored
      
      Added "nokaiser" boot option: an early param like "noinvpcid".
      Most places now check int kaiser_enabled (#defined 0 when not
      CONFIG_KAISER) instead of #ifdef CONFIG_KAISER; but entry_64.S
      and entry_64_compat.S are using the ALTERNATIVE technique, which
      patches in the preferred instructions at runtime.  That technique
      is tied to x86 cpu features, so X86_FEATURE_KAISER is fabricated.
      
      Prior to "nokaiser", Kaiser #defined _PAGE_GLOBAL 0: revert that,
      but be careful with both _PAGE_GLOBAL and CR4.PGE: setting them when
      nokaiser like when !CONFIG_KAISER, but not setting either when kaiser -
      neither matters on its own, but it's hard to be sure that _PAGE_GLOBAL
      won't get set in some obscure corner, or something add PGE into CR4.
      By omitting _PAGE_GLOBAL from __supported_pte_mask when kaiser_enabled,
      all page table setup which uses pte_pfn() masks it out of the ptes.
      
      It's slightly shameful that the same declaration versus definition of
      kaiser_enabled appears in not one, not two, but in three header files
      (asm/kaiser.h, asm/pgtable.h, asm/tlbflush.h).  I felt safer that way,
      than with #including any of those in any of the others; and did not
      feel it worth an asm/kaiser_enabled.h - kernel/cpu/common.c includes
      them all, so we shall hear about it if they get out of synch.
      
      Cleanups while in the area: removed the silly #ifdef CONFIG_KAISER
      from kaiser.c; removed the unused native_get_normal_pgd(); removed
      the spurious reg clutter from SWITCH_*_CR3 macro stubs; corrected some
      comments.  But more interestingly, set CR4.PSE in secondary_startup_64:
      the manual is clear that it does not matter whether it's 0 or 1 when
      4-level-pts are enabled, but I was distracted to find cr4 different on
      BSP and auxiliaries - BSP alone was adding PSE, in probe_page_size_mask().
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e345dcc9
    • Hugh Dickins's avatar
      kaiser: fix unlikely error in alloc_ldt_struct() · 500943e5
      Hugh Dickins authored
      
      An error from kaiser_add_mapping() here is not at all likely, but
      Eric Biggers rightly points out that __free_ldt_struct() relies on
      new_ldt->size being initialized: move that up.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      500943e5
    • Hugh Dickins's avatar
      kaiser: _pgd_alloc() without __GFP_REPEAT to avoid stalls · d41f46f7
      Hugh Dickins authored
      
      Synthetic filesystem mempressure testing has shown softlockups, with
      hour-long page allocation stalls, and pgd_alloc() trying for order:1
      with __GFP_REPEAT in one of the backtraces each time.
      
      That's _pgd_alloc() going for a Kaiser double-pgd, using the __GFP_REPEAT
      common to all page table allocations, but actually having no effect on
      order:0 (see should_alloc_oom() and should_continue_reclaim() in this
      tree, but beware that ports to another tree might behave differently).
      
      Order:1 stack allocation has been working satisfactorily without
      __GFP_REPEAT forever, and page table allocation only asks __GFP_REPEAT
      for awkward occasions in a long-running process: it's not appropriate
      at fork or exec time, and seems to be doing much more harm than good:
      getting those contiguous pages under very heavy mempressure can be
      hard (though even without it, Kaiser does generate more mempressure).
      
      Mask out that __GFP_REPEAT inside _pgd_alloc().  Why not take it out
      of the PGALLOG_GFP altogether, as v4.7 commit a3a9a59d ("x86: get
      rid of superfluous __GFP_REPEAT") did?  Because I think that might
      make a difference to our page table memcg charging, which I'd prefer
      not to interfere with at this time.
      
      hughd adds: __alloc_pages_slowpath() in the 4.4.89-stable tree handles
      __GFP_REPEAT a little differently than in prod kernel or 3.18.72-stable,
      so it may not always be exactly a no-op on order:0 pages, as said above;
      but I think still appropriate to omit it from Kaiser or non-Kaiser pgd.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      d41f46f7
    • Hugh Dickins's avatar
      kaiser: paranoid_entry pass cr3 need to paranoid_exit · fc8334e6
      Hugh Dickins authored
      
      Neel Natu points out that paranoid_entry() was wrong to assume that
      an entry that did not need swapgs would not need SWITCH_KERNEL_CR3:
      paranoid_entry (used for debug breakpoint, int3, double fault or MCE;
      though I think it's only the MCE case that is cause for concern here)
      can break in at an awkward time, between cr3 switch and swapgs, but
      its handling always needs kernel gs and kernel cr3.
      
      Easy to fix in itself, but paranoid_entry() also needs to convey to
      paranoid_exit() (and my reading of macro idtentry says paranoid_entry
      and paranoid_exit are always paired) how to restore the prior state.
      The swapgs state is already conveyed by %ebx (0 or 1), so extend that
      also to convey when SWITCH_USER_CR3 will be needed (2 or 3).
      
      (Yes, I'd much prefer that 0 meant no swapgs, whereas it's the other
      way round: and a convention shared with error_entry() and error_exit(),
      which I don't want to touch.  Perhaps I should have inverted the bit
      for switch cr3 too, but did not.)
      
      paranoid_exit() would be straightforward, except for TRACE_IRQS: it
      did TRACE_IRQS_IRETQ when doing swapgs, but TRACE_IRQS_IRETQ_DEBUG
      when not: which is it supposed to use when SWITCH_USER_CR3 is split
      apart from that?  As best as I can determine, commit 5963e317
      ("ftrace/x86: Do not change stacks in DEBUG when calling lockdep")
      missed the swapgs case, and should have used TRACE_IRQS_IRETQ_DEBUG
      there too (the discrepancy has nothing to do with the liberal use
      of _NO_STACK and _UNSAFE_STACK hereabouts: TRACE_IRQS_OFF_DEBUG has
      just been used in all cases); discrepancy lovingly preserved across
      several paranoid_exit() cleanups, but I'm now removing it.
      
      Neel further indicates that to use SWITCH_USER_CR3_NO_STACK there in
      paranoid_exit() is now not only unnecessary but unsafe: might corrupt
      syscall entry's unsafe_stack_register_backup of %rax.  Just use
      SWITCH_USER_CR3: and delete SWITCH_USER_CR3_NO_STACK altogether,
      before we make the mistake of using it again.
      
      hughd adds: this commit fixes an issue in the Kaiser-without-PCIDs
      part of the series, and ought to be moved earlier, if you decided
      to make a release of Kaiser-without-PCIDs.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      fc8334e6
    • Hugh Dickins's avatar
      kaiser: x86_cr3_pcid_noflush and x86_cr3_pcid_user · 20268a10
      Hugh Dickins authored
      
      Mostly this commit is just unshouting X86_CR3_PCID_KERN_VAR and
      X86_CR3_PCID_USER_VAR: we usually name variables in lower-case.
      
      But why does x86_cr3_pcid_noflush need to be __aligned(PAGE_SIZE)?
      Ah, it's a leftover from when kaiser_add_user_map() once complained
      about mapping the same page twice.  Make it __read_mostly instead.
      (I'm a little uneasy about all the unrelated data which shares its
      page getting user-mapped too, but that was so before, and not a big
      deal: though we call it user-mapped, it's not mapped with _PAGE_USER.)
      
      And there is a little change around the two calls to do_nmi().
      Previously they set the NOFLUSH bit (if PCID supported) when
      forcing to kernel context before do_nmi(); now they also have the
      NOFLUSH bit set (if PCID supported) when restoring context after:
      nothing done in do_nmi() should require a TLB to be flushed here.
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      20268a10
    • Hugh Dickins's avatar
      kaiser: PCID 0 for kernel and 128 for user · 3b4ce0e1
      Hugh Dickins authored
      
      Why was 4 chosen for kernel PCID and 6 for user PCID?
      No good reason in a backport where PCIDs are only used for Kaiser.
      
      If we continue with those, then we shall need to add Andy Lutomirski's
      4.13 commit 6c690ee1 ("x86/mm: Split read_cr3() into read_cr3_pa()
      and __read_cr3()"), which deals with the problem of read_cr3() callers
      finding stray bits in the cr3 that they expected to be page-aligned;
      and for hibernation, his 4.14 commit f34902c5 ("x86/hibernate/64:
      Mask off CR3's PCID bits in the saved CR3").
      
      But if 0 is used for kernel PCID, then there's no need to add in those
      commits - whenever the kernel looks, it sees 0 in the lower bits; and
      0 for kernel seems an obvious choice.
      
      And I naughtily propose 128 for user PCID.  Because there's a place
      in _SWITCH_TO_USER_CR3 where it takes note of the need for TLB FLUSH,
      but needs to reset that to NOFLUSH for the next occasion.  Currently
      it does so with a "movb $(0x80)" into the high byte of the per-cpu
      quadword, but that will cause a machine without PCID support to crash.
      Now, if %al just happened to have 0x80 in it at that point, on a
      machine with PCID support, but 0 on a machine without PCID support...
      
      (That will go badly wrong once the pgd can be at a physical address
      above 2^56, but even with 5-level paging, physical goes up to 2^52.)
      Signed-off-by: default avatarHugh Dickins <hughd@google.com>
      Acked-by: default avatarJiri Kosina <jkosina@suse.cz>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      3b4ce0e1