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  1. 12 3月, 2017 2 次提交
    • D
      x86/tlb: Fix tlb flushing when lguest clears PGE · 2c4ea6e2
      由 Daniel Borkmann 提交于 
      Fengguang reported random corruptions from various locations on x86-32
after commits d2852a22 ("arch: add ARCH_HAS_SET_MEMORY config") and
9d876e79 ("bpf: fix unlocking of jited image when module ronx not set")
that uses the former. While x86-32 doesn't have a JIT like x86_64, the
bpf_prog_lock_ro() and bpf_prog_unlock_ro() got enabled due to
ARCH_HAS_SET_MEMORY, whereas Fengguang's test kernel doesn't have module
support built in and therefore never had the DEBUG_SET_MODULE_RONX setting
enabled.

After investigating the crashes further, it turned out that using
set_memory_ro() and set_memory_rw() didn't have the desired effect, for
example, setting the pages as read-only on x86-32 would still let
probe_kernel_write() succeed without error. This behavior would manifest
itself in situations where the vmalloc'ed buffer was accessed prior to
set_memory_*() such as in case of bpf_prog_alloc(). In cases where it
wasn't, the page attribute changes seemed to have taken effect, leading to
the conclusion that a TLB invalidate didn't happen. Moreover, it turned out
that this issue reproduced with qemu in "-cpu kvm64" mode, but not for
"-cpu host". When the issue occurs, change_page_attr_set_clr() did trigger
a TLB flush as expected via __flush_tlb_all() through cpa_flush_range(),
though.

There are 3 variants for issuing a TLB flush: invpcid_flush_all() (depends
on CPU feature bits X86_FEATURE_INVPCID, X86_FEATURE_PGE), cr4 based flush
(depends on X86_FEATURE_PGE), and cr3 based flush.  For "-cpu host" case in
my setup, the flush used invpcid_flush_all() variant, whereas for "-cpu
kvm64", the flush was cr4 based. Switching the kvm64 case to cr3 manually
worked fine, and further investigating the cr4 one turned out that
X86_CR4_PGE bit was not set in cr4 register, meaning the
__native_flush_tlb_global_irq_disabled() wrote cr4 twice with the same
value instead of clearing X86_CR4_PGE in the first write to trigger the
flush.

It turned out that X86_CR4_PGE was cleared from cr4 during init from
lguest_arch_host_init() via adjust_pge(). The X86_FEATURE_PGE bit is also
cleared from there due to concerns of using PGE in guest kernel that can
lead to hard to trace bugs (see bff672e6 ("lguest: documentation V:
Host") in init()). The CPU feature bits are cleared in dynamic
boot_cpu_data, but they never propagated to __flush_tlb_all() as it uses
static_cpu_has() instead of boot_cpu_has() for testing which variant of TLB
flushing to use, meaning they still used the old setting of the host
kernel.

Clearing via setup_clear_cpu_cap(X86_FEATURE_PGE) so this would propagate
to static_cpu_has() checks is too late at this point as sections have been
patched already, so for now, it seems reasonable to switch back to
boot_cpu_has(X86_FEATURE_PGE) as it was prior to commit c109bf95
("x86/cpufeature: Remove cpu_has_pge"). This lets the TLB flush trigger via
cr3 as originally intended, properly makes the new page attributes visible
and thus fixes the crashes seen by Fengguang.

Fixes: c109bf95 ("x86/cpufeature: Remove cpu_has_pge")
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Cc: bp@suse.de
Cc: Kees Cook <keescook@chromium.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: lkp@01.org
Cc: Laura Abbott <labbott@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernrl.org/r/20170301125426.l4nf65rx4wahohyl@wfg-t540p.sh.intel.com
Link: http://lkml.kernel.org/r/25c41ad9eca164be4db9ad84f768965b7eb19d9e.1489191673.git.daniel@iogearbox.netSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      2c4ea6e2
    • G
      score: Fix implicit includes now failing build after extable change · 0acf6119
      由 Guenter Roeck 提交于 
      After changing from module.h to extable.h, score builds fail with:

  arch/score/kernel/traps.c: In function 'do_ri':
  arch/score/kernel/traps.c:248:4: error: implicit declaration of function 'user_disable_single_step'
  arch/score/mm/extable.c: In function 'fixup_exception':
  arch/score/mm/extable.c:32:38: error: dereferencing pointer to incomplete type
  arch/score/mm/extable.c:34:24: error: dereferencing pointer to incomplete type

because extable.h doesn't drag in the same amount of headers as the
module.h did.  Add in the headers which were implicitly expected.

Fixes: 90858794 ("module.h: remove extable.h include now users have migrated")
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
[PG: tweak commit log; refresh for sched header refactoring.]
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
      0acf6119
  3. 11 3月, 2017 1 次提交
    • T
      kexec, x86/purgatory: Unbreak it and clean it up · 40c50c1f
      由 Thomas Gleixner 提交于 
      The purgatory code defines global variables which are referenced via a
symbol lookup in the kexec code (core and arch).

A recent commit addressing sparse warnings made these static and thereby
broke kexec_file.

Why did this happen? Simply because the whole machinery is undocumented and
lacks any form of forward declarations. The variable names are unspecific
and lack a prefix, so adding forward declarations creates shadow variables
in the core code. Aside of that the code relies on magic constants and
duplicate struct definitions with no way to ensure that these things stay
in sync. The section placement of the purgatory variables happened by
chance and not by design.

Unbreak kexec and cleanup the mess:

 - Add proper forward declarations and document the usage
 - Use common struct definition
 - Use the proper common defines instead of magic constants
 - Add a purgatory_ prefix to have a proper name space
 - Use ARRAY_SIZE() instead of a homebrewn reimplementation
 - Add proper sections to the purgatory variables [ From Mike ]

Fixes: 72042a8c ("x86/purgatory: Make functions and variables static")
Reported-by: NMike Galbraith <&lt;efault@gmx.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Tobin C. Harding" <me@tobin.cc>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1703101315140.3681@nanosSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      40c50c1f
  5. 10 3月, 2017 10 次提交
  7. 09 3月, 2017 5 次提交
    • R
      KVM: nVMX: do not warn when MSR bitmap address is not backed · 05d8d346
      由 Radim Krčmář 提交于 
      Before trying to do nested_get_page() in nested_vmx_merge_msr_bitmap(),
we have already checked that the MSR bitmap address is valid (4k aligned
and within physical limits).  SDM doesn't specify what happens if the
there is no memory mapped at the valid address, but Intel CPUs treat the
situation as if the bitmap was configured to trap all MSRs.

KVM already does that by returning false and a correct handling doesn't
need the guest-trigerrable warning that was reported by syzkaller:
(The warning was originally there to catch some possible bugs in nVMX.)

  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 7832 at arch/x86/kvm/vmx.c:9709
  nested_vmx_merge_msr_bitmap arch/x86/kvm/vmx.c:9709 [inline]
  WARNING: CPU: 0 PID: 7832 at arch/x86/kvm/vmx.c:9709
  nested_get_vmcs12_pages+0xfb6/0x15c0 arch/x86/kvm/vmx.c:9640
  Kernel panic - not syncing: panic_on_warn set ...
  CPU: 0 PID: 7832 Comm: syz-executor1 Not tainted 4.10.0+ #229
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
   __dump_stack lib/dump_stack.c:15 [inline]
   dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
   panic+0x1fb/0x412 kernel/panic.c:179
   __warn+0x1c4/0x1e0 kernel/panic.c:540
   warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
   nested_vmx_merge_msr_bitmap arch/x86/kvm/vmx.c:9709 [inline]
   nested_get_vmcs12_pages+0xfb6/0x15c0 arch/x86/kvm/vmx.c:9640
   enter_vmx_non_root_mode arch/x86/kvm/vmx.c:10471 [inline]
   nested_vmx_run+0x6186/0xaab0 arch/x86/kvm/vmx.c:10561
   handle_vmlaunch+0x1a/0x20 arch/x86/kvm/vmx.c:7312
   vmx_handle_exit+0xfc0/0x3f00 arch/x86/kvm/vmx.c:8526
   vcpu_enter_guest arch/x86/kvm/x86.c:6982 [inline]
   vcpu_run arch/x86/kvm/x86.c:7044 [inline]
   kvm_arch_vcpu_ioctl_run+0x1418/0x4840 arch/x86/kvm/x86.c:7205
   kvm_vcpu_ioctl+0x673/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2570
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Reviewed-by: NJim Mattson <jmattson@google.com>
[Jim Mattson explained the bare metal behavior: "I believe this behavior
 would be documented in the chipset data sheet rather than the SDM,
 since the chipset returns all 1s for an unclaimed read."]
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      05d8d346
    • L
      KVM: arm64: Increase number of user memslots to 512 · 955a3fc6
      由 Linu Cherian 提交于 
      Having only 32 memslots is a real constraint for the maximum
number of PCI devices that can be assigned to a single guest.
Assuming each PCI device/virtual function having two memory BAR
regions, we could assign only 15 devices/virtual functions to a
guest.

Hence increase KVM_USER_MEM_SLOTS to 512 as done in other archs like
powerpc.
Reviewed-by: NChristoffer Dall <cdall@linaro.org>
Signed-off-by: NLinu Cherian <linu.cherian@cavium.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      955a3fc6
    • L
      KVM: arm/arm64: Remove KVM_PRIVATE_MEM_SLOTS definition that are unused · 3e92f94a
      由 Linu Cherian 提交于 
      arm/arm64 architecture doesnt use private memslots, hence removing
KVM_PRIVATE_MEM_SLOTS macro definition.
Reviewed-by: NChristoffer Dall <cdall@linaro.org>
Signed-off-by: NLinu Cherian <linu.cherian@cavium.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      3e92f94a
    • L
      KVM: arm/arm64: Enable KVM_CAP_NR_MEMSLOTS on arm/arm64 · 7af4df85
      由 Linu Cherian 提交于 
      Return KVM_USER_MEM_SLOTS for userspace capability query on
NR_MEMSLOTS.
Reviewed-by: NChristoffer Dall <cdall@linaro.org>
Signed-off-by: NLinu Cherian <linu.cherian@cavium.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      7af4df85
    • J
      axonram: Fix gendisk handling · 672a2c87
      由 Jan Kara 提交于 
      It is invalid to call del_gendisk() when disk->queue is NULL. Fix error
handling in axon_ram_probe() to avoid doing that.

Also del_gendisk() does not drop a reference to gendisk allocated by
alloc_disk(). That has to be done by put_disk(). Add that call where
needed.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@fb.com>
      672a2c87
  9. 08 3月, 2017 1 次提交
  11. 07 3月, 2017 7 次提交
    • M
      arm64: KVM: Survive unknown traps from guests · ba4dd156
      由 Mark Rutland 提交于 
      Currently we BUG() if we see an ESR_EL2.EC value we don't recognise. As
configurable disables/enables are added to the architecture (controlled
by RES1/RES0 bits respectively), with associated synchronous exceptions,
it may be possible for a guest to trigger exceptions with classes that
we don't recognise.

While we can't service these exceptions in a manner useful to the guest,
we can avoid bringing down the host. Per ARM DDI 0487A.k_iss10775, page
D7-1937, EC values within the range 0x00 - 0x2c are reserved for future
use with synchronous exceptions, and EC values within the range 0x2d -
0x3f may be used for either synchronous or asynchronous exceptions.

The patch makes KVM handle any unknown EC by injecting an UNDEFINED
exception into the guest, with a corresponding (ratelimited) warning in
the host dmesg. We could later improve on this with with a new (opt-in)
exit to the host userspace.

Cc: Dave Martin <dave.martin@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      ba4dd156
    • M
      arm: KVM: Survive unknown traps from guests · f050fe7a
      由 Mark Rutland 提交于 
      Currently we BUG() if we see a HSR.EC value we don't recognise. As
configurable disables/enables are added to the architecture (controlled
by RES1/RES0 bits respectively), with associated synchronous exceptions,
it may be possible for a guest to trigger exceptions with classes that
we don't recognise.

While we can't service these exceptions in a manner useful to the guest,
we can avoid bringing down the host. Per ARM DDI 0406C.c, all currently
unallocated HSR EC encodings are reserved, and per ARM DDI
0487A.k_iss10775, page G6-4395, EC values within the range 0x00 - 0x2c
are reserved for future use with synchronous exceptions, and EC values
within the range 0x2d - 0x3f may be used for either synchronous or
asynchronous exceptions.

The patch makes KVM handle any unknown EC by injecting an UNDEFINED
exception into the guest, with a corresponding (ratelimited) warning in
the host dmesg. We could later improve on this with with a new (opt-in)
exit to the host userspace.

Cc: Dave Martin <dave.martin@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      f050fe7a
    • W
      KVM: nVMX: reset nested_run_pending if the vCPU is going to be reset · 2f707d97
      由 Wanpeng Li 提交于 
      Reported by syzkaller:

    WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
    nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
    CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
    Call Trace:
     __dump_stack lib/dump_stack.c:15 [inline]
     dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
     panic+0x1fb/0x412 kernel/panic.c:179
     __warn+0x1c4/0x1e0 kernel/panic.c:540
     warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
     nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
     vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
     vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
     kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
     do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
     __msr_io arch/x86/kvm/x86.c:2577 [inline]
     msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
     kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
     kvm_vcpu_ioctl+0x232/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
     vfs_ioctl fs/ioctl.c:43 [inline]
     do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
     SYSC_ioctl fs/ioctl.c:698 [inline]
     SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
     entry_SYSCALL_64_fastpath+0x1f/0xc2

The syzkaller folks reported a nested_run_pending warning during userspace
clear VMX capability which is exposed to L1 before.

The warning gets thrown while doing

(*(uint32_t*)0x20aecfe8 = (uint32_t)0x1);
(*(uint32_t*)0x20aecfec = (uint32_t)0x0);
(*(uint32_t*)0x20aecff0 = (uint32_t)0x3a);
(*(uint32_t*)0x20aecff4 = (uint32_t)0x0);
(*(uint64_t*)0x20aecff8 = (uint64_t)0x0);
r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul,
		0x20aecfe8ul, 0, 0, 0, 0, 0, 0);

i.e. KVM_SET_MSR ioctl with

struct kvm_msrs {
	.nmsrs = 1,
		.pad = 0,
		.entries = {
			{.index = MSR_IA32_FEATURE_CONTROL,
			 .reserved = 0,
			 .data = 0}
		}
}

The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to
reset here. This patch resets the nested_run_pending since the CPU is going
to be reset hence there should be nothing pending.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Suggested-by: NRadim Krčmář <rkrcmar@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: NWanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Reviewed-by: NJim Mattson <jmattson@google.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      2f707d97
    • S
      irqchip/gicv3-its: Add workaround for QDF2400 ITS erratum 0065 · 90922a2d
      由 Shanker Donthineni 提交于 
      On Qualcomm Datacenter Technologies QDF2400 SoCs, the ITS hardware
implementation uses 16Bytes for Interrupt Translation Entry (ITE),
but reports an incorrect value of 8Bytes in GITS_TYPER.ITTE_size.

It might cause kernel memory corruption depending on the number
of MSI(x) that are configured and the amount of memory that has
been allocated for ITEs in its_create_device().

This patch fixes the potential memory corruption by setting the
correct ITE size to 16Bytes.

Cc: stable@vger.kernel.org
Signed-off-by: NShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
      90922a2d
    • G
      h8300: Fix build breakage caused by header file changes · 80aa1a54
      由 Guenter Roeck 提交于 
      Fix the following h8300 build failures:

  arch/h8300/kernel/ptrace_h.c: In function ‘trace_trap’:
  arch/h8300/kernel/ptrace_h.c:253:3: error: implicit declaration of function ‘force_sig’
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Fixes: c3edc401 ("sched/headers: Move task_struct::signal and ...")
Link: http://lkml.kernel.org/r/1488738434-3504-1-git-send-email-linux@roeck-us.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      80aa1a54
    • G
      avr32: Fix build error caused by include file reshuffling · 1fbdbcea
      由 Guenter Roeck 提交于 
      Various avr32 builds fail:

  arch/avr32/oprofile/backtrace.c:58: error: dereferencing pointer to incomplete type
  arch/avr32/oprofile/backtrace.c:60: error: implicit declaration of function 'user_mode'
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Acked-by: NHans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: oprofile-list@lists.sf.net
Fixes: f780d89a ("sched/headers: Remove <asm/ptrace.h> from ...")
Link: http://lkml.kernel.org/r/1488762357-4500-1-git-send-email-linux@roeck-us.netSigned-off-by: NIngo Molnar <mingo@kernel.org>
      1fbdbcea
    • J
      kvm: nVMX: VMCLEAR should not cause the vCPU to shut down · 587d7e72
      由 Jim Mattson 提交于 
      VMCLEAR should silently ignore a failure to clear the launch state of
the VMCS referenced by the operand.
Signed-off-by: NJim Mattson <jmattson@google.com>
[Changed "kvm_write_guest(vcpu->kvm" to "kvm_vcpu_write_guest(vcpu".]
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
      587d7e72
  13. 06 3月, 2017 9 次提交
  15. 04 3月, 2017 2 次提交
  17. 03 3月, 2017 3 次提交
    • D
      statx: Add a system call to make enhanced file info available · a528d35e
      由 David Howells 提交于 
      Add a system call to make extended file information available, including
file creation and some attribute flags where available through the
underlying filesystem.

The getattr inode operation is altered to take two additional arguments: a
u32 request_mask and an unsigned int flags that indicate the
synchronisation mode.  This change is propagated to the vfs_getattr*()
function.

Functions like vfs_stat() are now inline wrappers around new functions
vfs_statx() and vfs_statx_fd() to reduce stack usage.

========
OVERVIEW
========

The idea was initially proposed as a set of xattrs that could be retrieved
with getxattr(), but the general preference proved to be for a new syscall
with an extended stat structure.

A number of requests were gathered for features to be included.  The
following have been included:

 (1) Make the fields a consistent size on all arches and make them large.

 (2) Spare space, request flags and information flags are provided for
     future expansion.

 (3) Better support for the y2038 problem [Arnd Bergmann] (tv_sec is an
     __s64).

 (4) Creation time: The SMB protocol carries the creation time, which could
     be exported by Samba, which will in turn help CIFS make use of
     FS-Cache as that can be used for coherency data (stx_btime).

     This is also specified in NFSv4 as a recommended attribute and could
     be exported by NFSD [Steve French].

 (5) Lightweight stat: Ask for just those details of interest, and allow a
     netfs (such as NFS) to approximate anything not of interest, possibly
     without going to the server [Trond Myklebust, Ulrich Drepper, Andreas
     Dilger] (AT_STATX_DONT_SYNC).

 (6) Heavyweight stat: Force a netfs to go to the server, even if it thinks
     its cached attributes are up to date [Trond Myklebust]
     (AT_STATX_FORCE_SYNC).

And the following have been left out for future extension:

 (7) Data version number: Could be used by userspace NFS servers [Aneesh
     Kumar].

     Can also be used to modify fill_post_wcc() in NFSD which retrieves
     i_version directly, but has just called vfs_getattr().  It could get
     it from the kstat struct if it used vfs_xgetattr() instead.

     (There's disagreement on the exact semantics of a single field, since
     not all filesystems do this the same way).

 (8) BSD stat compatibility: Including more fields from the BSD stat such
     as creation time (st_btime) and inode generation number (st_gen)
     [Jeremy Allison, Bernd Schubert].

 (9) Inode generation number: Useful for FUSE and userspace NFS servers
     [Bernd Schubert].

     (This was asked for but later deemed unnecessary with the
     open-by-handle capability available and caused disagreement as to
     whether it's a security hole or not).

(10) Extra coherency data may be useful in making backups [Andreas Dilger].

     (No particular data were offered, but things like last backup
     timestamp, the data version number and the DOS archive bit would come
     into this category).

(11) Allow the filesystem to indicate what it can/cannot provide: A
     filesystem can now say it doesn't support a standard stat feature if
     that isn't available, so if, for instance, inode numbers or UIDs don't
     exist or are fabricated locally...

     (This requires a separate system call - I have an fsinfo() call idea
     for this).

(12) Store a 16-byte volume ID in the superblock that can be returned in
     struct xstat [Steve French].

     (Deferred to fsinfo).

(13) Include granularity fields in the time data to indicate the
     granularity of each of the times (NFSv4 time_delta) [Steve French].

     (Deferred to fsinfo).

(14) FS_IOC_GETFLAGS value.  These could be translated to BSD's st_flags.
     Note that the Linux IOC flags are a mess and filesystems such as Ext4
     define flags that aren't in linux/fs.h, so translation in the kernel
     may be a necessity (or, possibly, we provide the filesystem type too).

     (Some attributes are made available in stx_attributes, but the general
     feeling was that the IOC flags were to ext[234]-specific and shouldn't
     be exposed through statx this way).

(15) Mask of features available on file (eg: ACLs, seclabel) [Brad Boyer,
     Michael Kerrisk].

     (Deferred, probably to fsinfo.  Finding out if there's an ACL or
     seclabal might require extra filesystem operations).

(16) Femtosecond-resolution timestamps [Dave Chinner].

     (A __reserved field has been left in the statx_timestamp struct for
     this - if there proves to be a need).

(17) A set multiple attributes syscall to go with this.

===============
NEW SYSTEM CALL
===============

The new system call is:

	int ret = statx(int dfd,
			const char *filename,
			unsigned int flags,
			unsigned int mask,
			struct statx *buffer);

The dfd, filename and flags parameters indicate the file to query, in a
similar way to fstatat().  There is no equivalent of lstat() as that can be
emulated with statx() by passing AT_SYMLINK_NOFOLLOW in flags.  There is
also no equivalent of fstat() as that can be emulated by passing a NULL
filename to statx() with the fd of interest in dfd.

Whether or not statx() synchronises the attributes with the backing store
can be controlled by OR'ing a value into the flags argument (this typically
only affects network filesystems):

 (1) AT_STATX_SYNC_AS_STAT tells statx() to behave as stat() does in this
     respect.

 (2) AT_STATX_FORCE_SYNC will require a network filesystem to synchronise
     its attributes with the server - which might require data writeback to
     occur to get the timestamps correct.

 (3) AT_STATX_DONT_SYNC will suppress synchronisation with the server in a
     network filesystem.  The resulting values should be considered
     approximate.

mask is a bitmask indicating the fields in struct statx that are of
interest to the caller.  The user should set this to STATX_BASIC_STATS to
get the basic set returned by stat().  It should be noted that asking for
more information may entail extra I/O operations.

buffer points to the destination for the data.  This must be 256 bytes in
size.

======================
MAIN ATTRIBUTES RECORD
======================

The following structures are defined in which to return the main attribute
set:

	struct statx_timestamp {
		__s64	tv_sec;
		__s32	tv_nsec;
		__s32	__reserved;
	};

	struct statx {
		__u32	stx_mask;
		__u32	stx_blksize;
		__u64	stx_attributes;
		__u32	stx_nlink;
		__u32	stx_uid;
		__u32	stx_gid;
		__u16	stx_mode;
		__u16	__spare0[1];
		__u64	stx_ino;
		__u64	stx_size;
		__u64	stx_blocks;
		__u64	__spare1[1];
		struct statx_timestamp	stx_atime;
		struct statx_timestamp	stx_btime;
		struct statx_timestamp	stx_ctime;
		struct statx_timestamp	stx_mtime;
		__u32	stx_rdev_major;
		__u32	stx_rdev_minor;
		__u32	stx_dev_major;
		__u32	stx_dev_minor;
		__u64	__spare2[14];
	};

The defined bits in request_mask and stx_mask are:

	STATX_TYPE		Want/got stx_mode & S_IFMT
	STATX_MODE		Want/got stx_mode & ~S_IFMT
	STATX_NLINK		Want/got stx_nlink
	STATX_UID		Want/got stx_uid
	STATX_GID		Want/got stx_gid
	STATX_ATIME		Want/got stx_atime{,_ns}
	STATX_MTIME		Want/got stx_mtime{,_ns}
	STATX_CTIME		Want/got stx_ctime{,_ns}
	STATX_INO		Want/got stx_ino
	STATX_SIZE		Want/got stx_size
	STATX_BLOCKS		Want/got stx_blocks
	STATX_BASIC_STATS	[The stuff in the normal stat struct]
	STATX_BTIME		Want/got stx_btime{,_ns}
	STATX_ALL		[All currently available stuff]

stx_btime is the file creation time, stx_mask is a bitmask indicating the
data provided and __spares*[] are where as-yet undefined fields can be
placed.

Time fields are structures with separate seconds and nanoseconds fields
plus a reserved field in case we want to add even finer resolution.  Note
that times will be negative if before 1970; in such a case, the nanosecond
fields will also be negative if not zero.

The bits defined in the stx_attributes field convey information about a
file, how it is accessed, where it is and what it does.  The following
attributes map to FS_*_FL flags and are the same numerical value:

	STATX_ATTR_COMPRESSED		File is compressed by the fs
	STATX_ATTR_IMMUTABLE		File is marked immutable
	STATX_ATTR_APPEND		File is append-only
	STATX_ATTR_NODUMP		File is not to be dumped
	STATX_ATTR_ENCRYPTED		File requires key to decrypt in fs

Within the kernel, the supported flags are listed by:

	KSTAT_ATTR_FS_IOC_FLAGS

[Are any other IOC flags of sufficient general interest to be exposed
through this interface?]

New flags include:

	STATX_ATTR_AUTOMOUNT		Object is an automount trigger

These are for the use of GUI tools that might want to mark files specially,
depending on what they are.

Fields in struct statx come in a number of classes:

 (0) stx_dev_*, stx_blksize.

     These are local system information and are always available.

 (1) stx_mode, stx_nlinks, stx_uid, stx_gid, stx_[amc]time, stx_ino,
     stx_size, stx_blocks.

     These will be returned whether the caller asks for them or not.  The
     corresponding bits in stx_mask will be set to indicate whether they
     actually have valid values.

     If the caller didn't ask for them, then they may be approximated.  For
     example, NFS won't waste any time updating them from the server,
     unless as a byproduct of updating something requested.

     If the values don't actually exist for the underlying object (such as
     UID or GID on a DOS file), then the bit won't be set in the stx_mask,
     even if the caller asked for the value.  In such a case, the returned
     value will be a fabrication.

     Note that there are instances where the type might not be valid, for
     instance Windows reparse points.

 (2) stx_rdev_*.

     This will be set only if stx_mode indicates we're looking at a
     blockdev or a chardev, otherwise will be 0.

 (3) stx_btime.

     Similar to (1), except this will be set to 0 if it doesn't exist.

=======
TESTING
=======

The following test program can be used to test the statx system call:

	samples/statx/test-statx.c

Just compile and run, passing it paths to the files you want to examine.
The file is built automatically if CONFIG_SAMPLES is enabled.

Here's some example output.  Firstly, an NFS directory that crosses to
another FSID.  Note that the AUTOMOUNT attribute is set because transiting
this directory will cause d_automount to be invoked by the VFS.

	[root@andromeda ~]# /tmp/test-statx -A /warthog/data
	statx(/warthog/data) = 0
	results=7ff
	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
	Device: 00:26           Inode: 1703937     Links: 125
	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
	Access: 2016-11-24 09:02:12.219699527+0000
	Modify: 2016-11-17 10:44:36.225653653+0000
	Change: 2016-11-17 10:44:36.225653653+0000
	Attributes: 0000000000001000 (-------- -------- -------- -------- -------- -------- ---m---- --------)

Secondly, the result of automounting on that directory.

	[root@andromeda ~]# /tmp/test-statx /warthog/data
	statx(/warthog/data) = 0
	results=7ff
	  Size: 4096            Blocks: 8          IO Block: 1048576  directory
	Device: 00:27           Inode: 2           Links: 125
	Access: (3777/drwxrwxrwx)  Uid:     0   Gid:  4041
	Access: 2016-11-24 09:02:12.219699527+0000
	Modify: 2016-11-17 10:44:36.225653653+0000
	Change: 2016-11-17 10:44:36.225653653+0000
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      a528d35e
    • I
      sched/headers: Remove the <linux/topology.h> include from <linux/sched.h> · ee6a3d19
      由 Ingo Molnar 提交于 
      It's used only by a single (rarely used) inline function (task_node(p)),
which we can move to <linux/sched/topology.h>.

( Add <linux/nodemask.h>, because we rely on that. )
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      ee6a3d19
    • I
      sched/headers, x86/apic: Remove the <linux/pm.h> header inclusion from <asm/apic.h> · 1a79a72c
      由 Ingo Molnar 提交于 
      We want to simplify <linux/sched.h>'s header dependencies, but one
roadblock to that is <asm/apic.h>'s inclusion of pm.h,
which brings in other, problematic headers.

Remove it, as it appears to be entirely spurious, apic.h does not
actually make use of any PM facilities.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      1a79a72c