linux-stable.git/kernel/jump_label.c, branch v5.2.5

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred()

2019-04-29T06:29:21+00:00

Changing jump_label state is protected by jump_label_lock().
Rate limited static_key_slow_dec(), however, will never
directly call jump_label_update(), it will schedule a delayed
work instead.  Therefore it's unnecessary to take both the
cpus_read_lock() and jump_label_lock().

This allows static_key_slow_dec_deferred() to be called
from atomic contexts, like socket destructing in net/tls,
without the need for another indirection.

Signed-off-by: Jakub Kicinski 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Simon Horman 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: alexei.starovoitov@gmail.com
Cc: ard.biesheuvel@linaro.org
Cc: oss-drivers@netronome.com
Cc: yamada.masahiro@socionext.com
Link: https://lkml.kernel.org/r/20190330000854.30142-4-jakub.kicinski@netronome.com
Signed-off-by: Ingo Molnar

locking/static_key: Factor out the fast path of static_key_slow_dec()

2019-04-29T06:29:21+00:00

static_key_slow_dec() checks if the atomic enable count is larger
than 1, and if so there decrements it before taking the jump_label_lock.
Move this logic into a helper for reuse in rate limitted keys.

Signed-off-by: Jakub Kicinski 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Simon Horman 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: alexei.starovoitov@gmail.com
Cc: ard.biesheuvel@linaro.org
Cc: oss-drivers@netronome.com
Cc: yamada.masahiro@socionext.com
Link: https://lkml.kernel.org/r/20190330000854.30142-3-jakub.kicinski@netronome.com
Signed-off-by: Ingo Molnar

locking/static_key: Add support for deferred static branches

2019-04-29T06:29:20+00:00

Add deferred static branches.  We can't unfortunately use the
nice trick of encapsulating the entire structure in true/false
variants, because the inside has to be either struct static_key_true
or struct static_key_false.  Use defines to pass the appropriate
members to the helpers separately.

Signed-off-by: Jakub Kicinski 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Simon Horman 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: alexei.starovoitov@gmail.com
Cc: ard.biesheuvel@linaro.org
Cc: oss-drivers@netronome.com
Cc: yamada.masahiro@socionext.com
Link: https://lkml.kernel.org/r/20190330000854.30142-2-jakub.kicinski@netronome.com
Signed-off-by: Ingo Molnar

locking/static_key: Fix false positive warnings on concurrent dec/inc

2019-04-03T09:42:33+00:00

Even though the atomic_dec_and_mutex_lock() in
__static_key_slow_dec_cpuslocked() can never see a negative value in
key->enabled the subsequent sanity check is re-reading key->enabled, which may
have been set to -1 in the meantime by static_key_slow_inc_cpuslocked().

                CPU  A                               CPU B

 __static_key_slow_dec_cpuslocked():          static_key_slow_inc_cpuslocked():
                               # enabled = 1
   atomic_dec_and_mutex_lock()
                               # enabled = 0
                                              atomic_read() == 0
                                              atomic_set(-1)
                               # enabled = -1
   val = atomic_read()
   # Oops - val == -1!

The test case is TCP's clean_acked_data_enable() / clean_acked_data_disable()
as tickled by KTLS (net/ktls).

Suggested-by: Jakub Kicinski 
Reported-by: Jakub Kicinski 
Tested-by: Jakub Kicinski 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Will Deacon 
Cc: ard.biesheuvel@linaro.org
Cc: oss-drivers@netronome.com
Cc: pbonzini@redhat.com
Signed-off-by: Ingo Molnar

jump_label: move 'asm goto' support test to Kconfig

2019-01-06T00:46:51+00:00

Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".

The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:

  #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
  # define HAVE_JUMP_LABEL
  #endif

We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.

Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.

Signed-off-by: Masahiro Yamada 
Acked-by: Michael Ellerman  (powerpc)
Tested-by: Sedat Dilek

Merge branch 'x86/build' into locking/core, to pick up dependent patches and unify jump-label work

2018-10-16T15:30:11+00:00

Signed-off-by: Ingo Molnar

jump_label: Fix NULL dereference bug in __jump_label_mod_update()

2018-10-02T06:08:18+00:00

Commit 19483677684b ("jump_label: Annotate entries that operate on
__init code earlier") refactored the code that manages runtime
patching of jump labels in modules that are tied to static keys
defined in other modules or in the core kernel.

In the latter case, we may iterate over the static_key_mod linked
list until we hit the entry for the core kernel, whose 'mod' field
will be NULL, and attempt to dereference it to get at its 'state'
member.

So let's add a non-NULL check: this forces the 'init' argument of
__jump_label_update() to false for static keys that are defined in
the core kernel, which is appropriate given that __init annotated
jump_label entries in the core kernel should no longer be active
at this point (i.e., when loading modules).

Fixes: 19483677684b ("jump_label: Annotate entries that operate on ...")
Reported-by: Dan Carpenter 
Signed-off-by: Ard Biesheuvel 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Kees Cook 
Cc: Jessica Yu 
Cc: Peter Zijlstra 
Link: https://lkml.kernel.org/r/20181001081324.11553-1-ard.biesheuvel@linaro.org

jump_label: Annotate entries that operate on __init code earlier

2018-09-27T15:56:48+00:00

Jump table entries are mostly read-only, with the exception of the
init and module loader code that defuses entries that point into init
code when the code being referred to is freed.

For robustness, it would be better to move these entries into the
ro_after_init section, but clearing the 'code' member of each jump
table entry referring to init code at module load time races with the
module_enable_ro() call that remaps the ro_after_init section read
only, so we'd like to do it earlier.

So given that whether such an entry refers to init code can be decided
much earlier, we can pull this check forward. Since we may still need
the code entry at this point, let's switch to setting a low bit in the
'key' member just like we do to annotate the default state of a jump
table entry.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Kees Cook 
Acked-by: Peter Zijlstra (Intel) 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Will Deacon 
Cc: Catalin Marinas 
Cc: Steven Rostedt 
Cc: Martin Schwidefsky 
Cc: Jessica Yu 
Link: https://lkml.kernel.org/r/20180919065144.25010-8-ard.biesheuvel@linaro.org

jump_label: Implement generic support for relative references

2018-09-27T15:56:47+00:00

To reduce the size taken up by absolute references in jump label
entries themselves and the associated relocation records in the
.init segment, add support for emitting them as relative references
instead.

Note that this requires some extra care in the sorting routine, given
that the offsets change when entries are moved around in the jump_entry
table.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann 
Cc: Heiko Carstens 
Cc: Kees Cook 
Cc: Will Deacon 
Cc: Catalin Marinas 
Cc: Steven Rostedt 
Cc: Martin Schwidefsky 
Cc: Jessica Yu 
Link: https://lkml.kernel.org/r/20180919065144.25010-3-ard.biesheuvel@linaro.org