linux-stable.git/kernel/kcsan/selftest.c, branch v6.7

mm: delete checks for xor_unlock_is_negative_byte()

2023-10-18T21:34:17+00:00

Architectures which don't define their own use the one in
asm-generic/bitops/lock.h.  Get rid of all the ifdefs around "maybe we
don't have it".

Link: https://lkml.kernel.org/r/20231004165317.1061855-15-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: Geert Uytterhoeven 
Cc: Albert Ou 
Cc: Alexander Gordeev 
Cc: Andreas Dilger 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Heiko Carstens 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Richard Henderson 
Cc: Sven Schnelle 
Cc: "Theodore Ts'o" 
Cc: Thomas Bogendoerfer 
Cc: Vasily Gorbik 
Signed-off-by: Andrew Morton

bitops: add xor_unlock_is_negative_byte()

2023-10-18T21:34:16+00:00

Replace clear_bit_and_unlock_is_negative_byte() with
xor_unlock_is_negative_byte().  We have a few places that like to lock a
folio, set a flag and unlock it again.  Allow for the possibility of
combining the latter two operations for efficiency.  We are guaranteed
that the caller holds the lock, so it is safe to unlock it with the xor. 
The caller must guarantee that nobody else will set the flag without
holding the lock; it is not safe to do this with the PG_dirty flag, for
example.

Link: https://lkml.kernel.org/r/20231004165317.1061855-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Cc: Albert Ou 
Cc: Alexander Gordeev 
Cc: Andreas Dilger 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Geert Uytterhoeven 
Cc: Heiko Carstens 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: Michael Ellerman 
Cc: Nicholas Piggin 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Richard Henderson 
Cc: Sven Schnelle 
Cc: "Theodore Ts'o" 
Cc: Thomas Bogendoerfer 
Cc: Vasily Gorbik 
Signed-off-by: Andrew Morton

treewide: use get_random_u32_inclusive() when possible

2022-11-18T01:18:02+00:00

These cases were done with this Coccinelle:

@@
expression H;
expression L;
@@
- (get_random_u32_below(H) + L)
+ get_random_u32_inclusive(L, H + L - 1)

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- + E
- - E
  )

@@
expression H;
expression L;
expression E;
@@
  get_random_u32_inclusive(L,
  H
- - E
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- - E
  + F
- + E
  )

@@
expression H;
expression L;
expression E;
expression F;
@@
  get_random_u32_inclusive(L,
  H
- + E
  + F
- - E
  )

And then subsequently cleaned up by hand, with several automatic cases
rejected if it didn't make sense contextually.

Reviewed-by: Kees Cook 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Jason Gunthorpe  # for infiniband
Signed-off-by: Jason A. Donenfeld

treewide: use get_random_u32_below() instead of deprecated function

2022-11-18T01:15:15+00:00

This is a simple mechanical transformation done by:

@@
expression E;
@@
- prandom_u32_max
+ get_random_u32_below
  (E)

Reviewed-by: Kees Cook 
Reviewed-by: Greg Kroah-Hartman 
Acked-by: Darrick J. Wong  # for xfs
Reviewed-by: SeongJae Park  # for damon
Reviewed-by: Jason Gunthorpe  # for infiniband
Reviewed-by: Russell King (Oracle)  # for arm
Acked-by: Ulf Hansson  # for mmc
Signed-off-by: Jason A. Donenfeld

kcsan: remove rng selftest

2022-11-17T16:36:47+00:00

The first test of the kcsan selftest appears to test if get_random_u32()
returns two zeros in a row, and requires that it doesn't. This seems
like a bogus criteron. Remove it.

Acked-by: Marco Elver 
Signed-off-by: Jason A. Donenfeld

treewide: use get_random_bytes() when possible

2022-10-11T23:42:58+00:00

The prandom_bytes() function has been a deprecated inline wrapper around
get_random_bytes() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. This was done as a basic find and replace.

Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Kees Cook 
Reviewed-by: Yury Norov 
Reviewed-by: Christophe Leroy  # powerpc
Acked-by: Jakub Kicinski 
Signed-off-by: Jason A. Donenfeld

treewide: use get_random_u32() when possible

2022-10-11T23:42:58+00:00

The prandom_u32() function has been a deprecated inline wrapper around
get_random_u32() for several releases now, and compiles down to the
exact same code. Replace the deprecated wrapper with a direct call to
the real function. The same also applies to get_random_int(), which is
just a wrapper around get_random_u32(). This was done as a basic find
and replace.

Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Kees Cook 
Reviewed-by: Yury Norov 
Reviewed-by: Jan Kara  # for ext4
Acked-by: Toke Høiland-Jørgensen  # for sch_cake
Acked-by: Chuck Lever  # for nfsd
Acked-by: Jakub Kicinski 
Acked-by: Mika Westerberg  # for thunderbolt
Acked-by: Darrick J. Wong  # for xfs
Acked-by: Helge Deller  # for parisc
Acked-by: Heiko Carstens  # for s390
Signed-off-by: Jason A. Donenfeld

kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it

2021-12-10T00:42:29+00:00

Some architectures do not define clear_bit_unlock_is_negative_byte().
Only test it when it is actually defined (similar to other usage, such
as in lib/test_kasan.c).

Link: https://lkml.kernel.org/r/202112050757.x67rHnFU-lkp@intel.com
Reported-by: kernel test robot 
Signed-off-by: Marco Elver 
Signed-off-by: Paul E. McKenney

kcsan: Make barrier tests compatible with lockdep

2021-12-10T00:42:28+00:00

The barrier tests in selftest and the kcsan_test module only need the
spinlock and mutex to test correct barrier instrumentation. Therefore,
these were initially placed on the stack.

However, lockdep asserts that locks are in static storage, and will
generate this warning:

 | INFO: trying to register non-static key.
 | The code is fine but needs lockdep annotation, or maybe
 | you didn't initialize this object before use?
 | turning off the locking correctness validator.
 | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc1+ #3208
 | Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
 | Call Trace:
 |  
 |  dump_stack_lvl+0x88/0xd8
 |  dump_stack+0x15/0x1b
 |  register_lock_class+0x6b3/0x840
 |  ...
 |  test_barrier+0x490/0x14c7
 |  kcsan_selftest+0x47/0xa0
 |  ...

To fix, move the test locks into static storage.

Fixing the above also revealed that lock operations are strengthened on
first use with lockdep enabled, due to lockdep calling out into
non-instrumented files (recall that kernel/locking/lockdep.c is not
instrumented with KCSAN).

Only kcsan_test checks for over-instrumentation of *_lock() operations,
where we can simply "warm up" the test locks to avoid the test case
failing with lockdep.

Reported-by: Paul E. McKenney 
Signed-off-by: Marco Elver 
Signed-off-by: Paul E. McKenney

kcsan: selftest: Add test case to check memory barrier instrumentation

2021-12-10T00:42:27+00:00

Memory barrier instrumentation is crucial to avoid false positives. To
avoid surprises, run a simple test case in the boot-time selftest to
ensure memory barriers are still instrumented correctly.

Signed-off-by: Marco Elver 
Signed-off-by: Paul E. McKenney