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  1. 11 12月, 2014 1 次提交
    • P
      kernel: add panic_on_warn · 9e3961a0
      由 Prarit Bhargava 提交于 
      There have been several times where I have had to rebuild a kernel to
cause a panic when hitting a WARN() in the code in order to get a crash
dump from a system.  Sometimes this is easy to do, other times (such as
in the case of a remote admin) it is not trivial to send new images to
the user.

A much easier method would be a switch to change the WARN() over to a
panic.  This makes debugging easier in that I can now test the actual
image the WARN() was seen on and I do not have to engage in remote
debugging.

This patch adds a panic_on_warn kernel parameter and
/proc/sys/kernel/panic_on_warn calls panic() in the
warn_slowpath_common() path.  The function will still print out the
location of the warning.

An example of the panic_on_warn output:

The first line below is from the WARN_ON() to output the WARN_ON()'s
location.  After that the panic() output is displayed.

    WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]()
    Kernel panic - not syncing: panic_on_warn set ...

    CPU: 30 PID: 11698 Comm: insmod Tainted: G        W  OE  3.17.0+ #57
    Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013
     0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190
     0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec
     ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df
    Call Trace:
     [<ffffffff81665190>] dump_stack+0x46/0x58
     [<ffffffff8165e2ec>] panic+0xd0/0x204
     [<ffffffffa038e05f>] ? init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81076b90>] warn_slowpath_common+0xd0/0xd0
     [<ffffffffa038e040>] ? dummy_greetings+0x40/0x40 [dummy_module]
     [<ffffffff81076c8a>] warn_slowpath_null+0x1a/0x20
     [<ffffffffa038e05f>] init_dummy+0x1f/0x30 [dummy_module]
     [<ffffffff81002144>] do_one_initcall+0xd4/0x210
     [<ffffffff811b52c2>] ? __vunmap+0xc2/0x110
     [<ffffffff810f8889>] load_module+0x16a9/0x1b30
     [<ffffffff810f3d30>] ? store_uevent+0x70/0x70
     [<ffffffff810f49b9>] ? copy_module_from_fd.isra.44+0x129/0x180
     [<ffffffff810f8ec6>] SyS_finit_module+0xa6/0xd0
     [<ffffffff8166cf29>] system_call_fastpath+0x12/0x17

Successfully tested by me.

hpa said: There is another very valid use for this: many operators would
rather a machine shuts down than being potentially compromised either
functionally or security-wise.
Signed-off-by: NPrarit Bhargava <prarit@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: NYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9e3961a0
  3. 09 12月, 2014 11 次提交
  5. 08 12月, 2014 1 次提交
  7. 05 12月, 2014 1 次提交
  9. 04 12月, 2014 2 次提交
  11. 02 12月, 2014 2 次提交
  13. 28 11月, 2014 1 次提交
    • A
      arm64: ptrace: add NT_ARM_SYSTEM_CALL regset · 766a85d7
      由 AKASHI Takahiro 提交于 
      This regeset is intended to be used to get and set a system call number
while tracing.
There was some discussion about possible approaches to do so:

(1) modify x8 register with ptrace(PTRACE_SETREGSET) indirectly,
    and update regs->syscallno later on in syscall_trace_enter(), or
(2) define a dedicated regset for this purpose as on s390, or
(3) support ptrace(PTRACE_SET_SYSCALL) as on arch/arm

Thinking of the fact that user_pt_regs doesn't expose 'syscallno' to
tracer as well as that secure_computing() expects a changed syscall number,
especially case of -1, to be visible before this function returns in
syscall_trace_enter(), (1) doesn't work well.
We will take (2) since it looks much cleaner.
Signed-off-by: NAKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
      766a85d7
  15. 25 11月, 2014 1 次提交
  17. 20 11月, 2014 3 次提交
    • D
      dlm: adopt orphan locks · 2ab4bd8e
      由 David Teigland 提交于 
      A process may exit, leaving an orphan lock in the lockspace.
This adds the capability for another process to acquire the
orphan lock.  Acquiring the orphan just moves the lock from
the orphan list onto the acquiring process's list of locks.

An adopting process must specify the resource name and mode
of the lock it wants to adopt.  If a matching lock is found,
the lock is moved to the caller's 's list of locks, and the
lkid of the lock is returned like the lkid of a new lock.

If an orphan with a different mode is found, then -EAGAIN is
returned.  If no orphan lock is found on the resource, then
-ENOENT is returned.  No async completion is used because
the result is immediately available.

Also, when orphans are purged, allow a zero nodeid to refer
to the local nodeid so the caller does not need to look up
the local nodeid.
Signed-off-by: NDavid Teigland <teigland@redhat.com>
      2ab4bd8e
    • M
      dm: enhance internal suspend and resume interface · ffcc3936
      由 Mike Snitzer 提交于 
      Rename dm_internal_{suspend,resume} to dm_internal_{suspend,resume}_fast
-- dm-stats will continue using these methods to avoid all the extra
suspend/resume logic that is not needed in order to quickly flush IO.

Introduce dm_internal_suspend_noflush() variant that actually calls the
mapped_device's target callbacks -- otherwise target-specific hooks are
avoided (e.g. dm-thin's thin_presuspend and thin_postsuspend).  Common
code between dm_internal_{suspend_noflush,resume} and
dm_{suspend,resume} was factored out as __dm_{suspend,resume}.

Update dm_internal_{suspend_noflush,resume} to always take and release
the mapped_device's suspend_lock.  Also update dm_{suspend,resume} to be
aware of potential for DM_INTERNAL_SUSPEND_FLAG to be set and respond
accordingly by interruptibly waiting for the DM_INTERNAL_SUSPEND_FLAG to
be cleared.  Add lockdep annotation to dm_suspend() and dm_resume().

The existing DM_SUSPEND_FLAG remains unchanged.
DM_INTERNAL_SUSPEND_FLAG is set by dm_internal_suspend_noflush() and
cleared by dm_internal_resume().

Both DM_SUSPEND_FLAG and DM_INTERNAL_SUSPEND_FLAG may be set if a device
was already suspended when dm_internal_suspend_noflush() was called --
this can be thought of as a "nested suspend".  A "nested suspend" can
occur with legacy userspace dm-thin code that might suspend all active
thin volumes before suspending the pool for resize.

But otherwise, in the normal dm-thin-pool suspend case moving forward:
the thin-pool will have DM_SUSPEND_FLAG set and all active thins from
that thin-pool will have DM_INTERNAL_SUSPEND_FLAG set.

Also add DM_INTERNAL_SUSPEND_FLAG to status report.  This new
DM_INTERNAL_SUSPEND_FLAG state is being reported to assist with
debugging (e.g. 'dmsetup info' will report an internally suspended
device accordingly).
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NJoe Thornber <ejt@redhat.com>
      ffcc3936
    • M
      dm: add presuspend_undo hook to target_type · d67ee213
      由 Mike Snitzer 提交于 
      The DM thin-pool target now must undo the changes performed during
pool_presuspend() so introduce presuspend_undo hook in target_type.
Signed-off-by: NMike Snitzer <snitzer@redhat.com>
Acked-by: NJoe Thornber <ejt@redhat.com>
      d67ee213
  19. 18 11月, 2014 1 次提交
    • D
      x86, mpx: On-demand kernel allocation of bounds tables · fe3d197f
      由 Dave Hansen 提交于 
      This is really the meat of the MPX patch set.  If there is one patch to
review in the entire series, this is the one.  There is a new ABI here
and this kernel code also interacts with userspace memory in a
relatively unusual manner.  (small FAQ below).

Long Description:

This patch adds two prctl() commands to provide enable or disable the
management of bounds tables in kernel, including on-demand kernel
allocation (See the patch "on-demand kernel allocation of bounds tables")
and cleanup (See the patch "cleanup unused bound tables"). Applications
do not strictly need the kernel to manage bounds tables and we expect
some applications to use MPX without taking advantage of this kernel
support. This means the kernel can not simply infer whether an application
needs bounds table management from the MPX registers.  The prctl() is an
explicit signal from userspace.

PR_MPX_ENABLE_MANAGEMENT is meant to be a signal from userspace to
require kernel's help in managing bounds tables.

PR_MPX_DISABLE_MANAGEMENT is the opposite, meaning that userspace don't
want kernel's help any more. With PR_MPX_DISABLE_MANAGEMENT, the kernel
won't allocate and free bounds tables even if the CPU supports MPX.

PR_MPX_ENABLE_MANAGEMENT will fetch the base address of the bounds
directory out of a userspace register (bndcfgu) and then cache it into
a new field (->bd_addr) in  the 'mm_struct'.  PR_MPX_DISABLE_MANAGEMENT
will set "bd_addr" to an invalid address.  Using this scheme, we can
use "bd_addr" to determine whether the management of bounds tables in
kernel is enabled.

Also, the only way to access that bndcfgu register is via an xsaves,
which can be expensive.  Caching "bd_addr" like this also helps reduce
the cost of those xsaves when doing table cleanup at munmap() time.
Unfortunately, we can not apply this optimization to #BR fault time
because we need an xsave to get the value of BNDSTATUS.

==== Why does the hardware even have these Bounds Tables? ====

MPX only has 4 hardware registers for storing bounds information.
If MPX-enabled code needs more than these 4 registers, it needs to
spill them somewhere. It has two special instructions for this
which allow the bounds to be moved between the bounds registers
and some new "bounds tables".

They are similar conceptually to a page fault and will be raised by
the MPX hardware during both bounds violations or when the tables
are not present. This patch handles those #BR exceptions for
not-present tables by carving the space out of the normal processes
address space (essentially calling the new mmap() interface indroduced
earlier in this patch set.) and then pointing the bounds-directory
over to it.

The tables *need* to be accessed and controlled by userspace because
the instructions for moving bounds in and out of them are extremely
frequent. They potentially happen every time a register pointing to
memory is dereferenced. Any direct kernel involvement (like a syscall)
to access the tables would obviously destroy performance.

==== Why not do this in userspace? ====

This patch is obviously doing this allocation in the kernel.
However, MPX does not strictly *require* anything in the kernel.
It can theoretically be done completely from userspace. Here are
a few ways this *could* be done. I don't think any of them are
practical in the real-world, but here they are.

Q: Can virtual space simply be reserved for the bounds tables so
   that we never have to allocate them?
A: As noted earlier, these tables are *HUGE*. An X-GB virtual
   area needs 4*X GB of virtual space, plus 2GB for the bounds
   directory. If we were to preallocate them for the 128TB of
   user virtual address space, we would need to reserve 512TB+2GB,
   which is larger than the entire virtual address space today.
   This means they can not be reserved ahead of time. Also, a
   single process's pre-popualated bounds directory consumes 2GB
   of virtual *AND* physical memory. IOW, it's completely
   infeasible to prepopulate bounds directories.

Q: Can we preallocate bounds table space at the same time memory
   is allocated which might contain pointers that might eventually
   need bounds tables?
A: This would work if we could hook the site of each and every
   memory allocation syscall. This can be done for small,
   constrained applications. But, it isn't practical at a larger
   scale since a given app has no way of controlling how all the
   parts of the app might allocate memory (think libraries). The
   kernel is really the only place to intercept these calls.

Q: Could a bounds fault be handed to userspace and the tables
   allocated there in a signal handler instead of in the kernel?
A: (thanks to tglx) mmap() is not on the list of safe async
   handler functions and even if mmap() would work it still
   requires locking or nasty tricks to keep track of the
   allocation state there.

Having ruled out all of the userspace-only approaches for managing
bounds tables that we could think of, we create them on demand in
the kernel.
Based-on-patch-by: NQiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151829.AD4310DE@viggo.jf.intel.comSigned-off-by: NThomas Gleixner <tglx@linutronix.de>
      fe3d197f
  21. 16 11月, 2014 2 次提交
  23. 15 11月, 2014 3 次提交
  25. 06 11月, 2014 1 次提交
  27. 04 11月, 2014 1 次提交
  29. 28 10月, 2014 2 次提交
  31. 24 10月, 2014 2 次提交
  33. 21 10月, 2014 1 次提交
  35. 15 10月, 2014 1 次提交
  37. 14 10月, 2014 1 次提交
  39. 10 10月, 2014 2 次提交
    • K
      mm/balloon_compaction: add vmstat counters and kpageflags bit · 09316c09
      由 Konstantin Khlebnikov 提交于 
      Always mark pages with PageBalloon even if balloon compaction is disabled
and expose this mark in /proc/kpageflags as KPF_BALLOON.

Also this patch adds three counters into /proc/vmstat: "balloon_inflate",
"balloon_deflate" and "balloon_migrate".  They accumulate balloon
activity.  Current size of balloon is (balloon_inflate - balloon_deflate)
pages.

All generic balloon code now gathered under option CONFIG_MEMORY_BALLOON.
It should be selected by ballooning driver which wants use this feature.
Currently virtio-balloon is the only user.
Signed-off-by: NKonstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      09316c09
    • C
      prctl: PR_SET_MM -- introduce PR_SET_MM_MAP operation · f606b77f
      由 Cyrill Gorcunov 提交于 
      During development of c/r we've noticed that in case if we need to support
user namespaces we face a problem with capabilities in prctl(PR_SET_MM,
...) call, in particular once new user namespace is created
capable(CAP_SYS_RESOURCE) no longer passes.

A approach is to eliminate CAP_SYS_RESOURCE check but pass all new values
in one bundle, which would allow the kernel to make more intensive test
for sanity of values and same time allow us to support checkpoint/restore
of user namespaces.

Thus a new command PR_SET_MM_MAP introduced. It takes a pointer of
prctl_mm_map structure which carries all the members to be updated.

	prctl(PR_SET_MM, PR_SET_MM_MAP, struct prctl_mm_map *, size)

	struct prctl_mm_map {
		__u64	start_code;
		__u64	end_code;
		__u64	start_data;
		__u64	end_data;
		__u64	start_brk;
		__u64	brk;
		__u64	start_stack;
		__u64	arg_start;
		__u64	arg_end;
		__u64	env_start;
		__u64	env_end;
		__u64	*auxv;
		__u32	auxv_size;
		__u32	exe_fd;
	};

All members except @exe_fd correspond ones of struct mm_struct.  To figure
out which available values these members may take here are meanings of the
members.

 - start_code, end_code: represent bounds of executable code area
 - start_data, end_data: represent bounds of data area
 - start_brk, brk: used to calculate bounds for brk() syscall
 - start_stack: used when accounting space needed for command
   line arguments, environment and shmat() syscall
 - arg_start, arg_end, env_start, env_end: represent memory area
   supplied for command line arguments and environment variables
 - auxv, auxv_size: carries auxiliary vector, Elf format specifics
 - exe_fd: file descriptor number for executable link (/proc/self/exe)

Thus we apply the following requirements to the values

1) Any member except @auxv, @auxv_size, @exe_fd is rather an address
   in user space thus it must be laying inside [mmap_min_addr, mmap_max_addr)
   interval.

2) While @[start|end]_code and @[start|end]_data may point to an nonexisting
   VMAs (say a program maps own new .text and .data segments during execution)
   the rest of members should belong to VMA which must exist.

3) Addresses must be ordered, ie @start_ member must not be greater or
   equal to appropriate @end_ member.

4) As in regular Elf loading procedure we require that @start_brk and
   @brk be greater than @end_data.

5) If RLIMIT_DATA rlimit is set to non-infinity new values should not
   exceed existing limit. Same applies to RLIMIT_STACK.

6) Auxiliary vector size must not exceed existing one (which is
   predefined as AT_VECTOR_SIZE and depends on architecture).

7) File descriptor passed in @exe_file should be pointing
   to executable file (because we use existing prctl_set_mm_exe_file_locked
   helper it ensures that the file we are going to use as exe link has all
   required permission granted).

Now about where these members are involved inside kernel code:

 - @start_code and @end_code are used in /proc/$pid/[stat|statm] output;

 - @start_data and @end_data are used in /proc/$pid/[stat|statm] output,
   also they are considered if there enough space for brk() syscall
   result if RLIMIT_DATA is set;

 - @start_brk shown in /proc/$pid/stat output and accounted in brk()
   syscall if RLIMIT_DATA is set; also this member is tested to
   find a symbolic name of mmap event for perf system (we choose
   if event is generated for "heap" area); one more aplication is
   selinux -- we test if a process has PROCESS__EXECHEAP permission
   if trying to make heap area being executable with mprotect() syscall;

 - @brk is a current value for brk() syscall which lays inside heap
   area, it's shown in /proc/$pid/stat. When syscall brk() succesfully
   provides new memory area to a user space upon brk() completion the
   mm::brk is updated to carry new value;

   Both @start_brk and @brk are actively used in /proc/$pid/maps
   and /proc/$pid/smaps output to find a symbolic name "heap" for
   VMA being scanned;

 - @start_stack is printed out in /proc/$pid/stat and used to
   find a symbolic name "stack" for task and threads in
   /proc/$pid/maps and /proc/$pid/smaps output, and as the same
   as with @start_brk -- perf system uses it for event naming.
   Also kernel treat this member as a start address of where
   to map vDSO pages and to check if there is enough space
   for shmat() syscall;

 - @arg_start, @arg_end, @env_start and @env_end are printed out
   in /proc/$pid/stat. Another access to the data these members
   represent is to read /proc/$pid/environ or /proc/$pid/cmdline.
   Any attempt to read these areas kernel tests with access_process_vm
   helper so a user must have enough rights for this action;

 - @auxv and @auxv_size may be read from /proc/$pid/auxv. Strictly
   speaking kernel doesn't care much about which exactly data is
   sitting there because it is solely for userspace;

 - @exe_fd is referred from /proc/$pid/exe and when generating
   coredump. We uses prctl_set_mm_exe_file_locked helper to update
   this member, so exe-file link modification remains one-shot
   action.

Still note that updating exe-file link now doesn't require sys-resource
capability anymore, after all there is no much profit in preventing setup
own file link (there are a number of ways to execute own code -- ptrace,
ld-preload, so that the only reliable way to find which exactly code is
executed is to inspect running program memory).  Still we require the
caller to be at least user-namespace root user.

I believe the old interface should be deprecated and ripped off in a
couple of kernel releases if no one against.

To test if new interface is implemented in the kernel one can pass
PR_SET_MM_MAP_SIZE opcode and the kernel returns the size of currently
supported struct prctl_mm_map.

[akpm@linux-foundation.org: fix 80-col wordwrap in macro definitions]
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: NAndrew Vagin <avagin@openvz.org>
Tested-by: NAndrew Vagin <avagin@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Acked-by: NSerge Hallyn <serge.hallyn@canonical.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Julien Tinnes <jln@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      f606b77f