linux.git/lib, branch v6.8-rc4

Merge tag 'linux_kselftest-kunit-fixes-6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2024-01-30T23:12:58+00:00

Pull kunit fixes from Shuah Khan:
 "NULL vs IS_ERR() bug fixes, documentation update, MAINTAINERS file
  update to add Rae Moar as a reviewer, and a fix to run test suites
  only after module initialization completes"

* tag 'linux_kselftest-kunit-fixes-6.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
  Documentation: KUnit: Update the instructions on how to test static functions
  kunit: run test suites only after module initialization completes
  MAINTAINERS: kunit: Add Rae Moar as a reviewer
  kunit: device: Fix a NULL vs IS_ERR() check in init()
  kunit: Fix a NULL vs IS_ERR() bug

stackdepot: make fast paths lock-less again

2024-01-26T07:52:21+00:00

With the introduction of the pool_rwlock (reader-writer lock), several
fast paths end up taking the pool_rwlock as readers.  Furthermore,
stack_depot_put() unconditionally takes the pool_rwlock as a writer.

Despite allowing readers to make forward-progress concurrently,
reader-writer locks have inherent cache contention issues, which does not
scale well on systems with large CPU counts.

Rework the synchronization story of stack depot to again avoid taking any
locks in the fast paths.  This is done by relying on RCU-protected list
traversal, and the NMI-safe subset of RCU to delay reuse of freed stack
records.  See code comments for more details.

Along with the performance issues, this also fixes incorrect nesting of
rwlock within a raw_spinlock, given that stack depot should still be
usable from anywhere:

 | [ BUG: Invalid wait context ]
 | -----------------------------
 | swapper/0/1 is trying to lock:
 | ffffffff89869be8 (pool_rwlock){..--}-{3:3}, at: stack_depot_save_flags
 | other info that might help us debug this:
 | context-{5:5}
 | 2 locks held by swapper/0/1:
 |  #0: ffffffff89632440 (rcu_read_lock){....}-{1:3}, at: __queue_work
 |  #1: ffff888100092018 (&pool->lock){-.-.}-{2:2}, at: __queue_work  <-- raw_spin_lock

Stack depot usage stats are similar to the previous version after a KASAN
kernel boot:

 $ cat /sys/kernel/debug/stackdepot/stats
 pools: 838
 allocations: 29865
 frees: 6604
 in_use: 23261
 freelist_size: 1879

The number of pools is the same as previously.  The freelist size is
minimally larger, but this may also be due to variance across system
boots.  This shows that even though we do not eagerly wait for the next
RCU grace period (such as with synchronize_rcu() or call_rcu()) after
freeing a stack record - requiring depot_pop_free() to "poll" if an entry
may be used - new allocations are very likely to happen in later RCU grace
periods.

Link: https://lkml.kernel.org/r/20240118110216.2539519-2-elver@google.com
Fixes: 108be8def46e ("lib/stackdepot: allow users to evict stack traces")
Reported-by: Andi Kleen 
Signed-off-by: Marco Elver 
Reviewed-by: Andrey Konovalov 
Cc: Alexander Potapenko 
Cc: Andrey Konovalov 
Cc: Dmitry Vyukov 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

stackdepot: add stats counters exported via debugfs

2024-01-26T07:52:21+00:00

Add a few basic stats counters for stack depot that can be used to derive
if stack depot is working as intended.  This is a snapshot of the new
stats after booting a system with a KASAN-enabled kernel:

 $ cat /sys/kernel/debug/stackdepot/stats
 pools: 838
 allocations: 29861
 frees: 6561
 in_use: 23300
 freelist_size: 1840

Generally, "pools" should be well below the max; once the system is
booted, "in_use" should remain relatively steady.

Link: https://lkml.kernel.org/r/20240118110216.2539519-1-elver@google.com
Signed-off-by: Marco Elver 
Reviewed-by: Andrey Konovalov 
Cc: Andi Kleen 
Cc: Dmitry Vyukov 
Cc: Vlastimil Babka 
Cc: Alexander Potapenko 
Signed-off-by: Andrew Morton

kunit: run test suites only after module initialization completes

2024-01-22T14:58:54+00:00

Commit 2810c1e99867 ("kunit: Fix wild-memory-access bug in
kunit_free_suite_set()") fixed a wild-memory-access bug that could have
happened during the loading phase of test suites built and executed as
loadable modules. However, it also introduced a problematic side effect
that causes test suites modules to crash when they attempt to register
fake devices.

When a module is loaded, it traverses the MODULE_STATE_UNFORMED and
MODULE_STATE_COMING states before reaching the normal operating state
MODULE_STATE_LIVE. Finally, when the module is removed, it moves to
MODULE_STATE_GOING before being released. However, if the loading
function load_module() fails between complete_formation() and
do_init_module(), the module goes directly from MODULE_STATE_COMING to
MODULE_STATE_GOING without passing through MODULE_STATE_LIVE.

This behavior was causing kunit_module_exit() to be called without
having first executed kunit_module_init(). Since kunit_module_exit() is
responsible for freeing the memory allocated by kunit_module_init()
through kunit_filter_suites(), this behavior was resulting in a
wild-memory-access bug.

Commit 2810c1e99867 ("kunit: Fix wild-memory-access bug in
kunit_free_suite_set()") fixed this issue by running the tests when the
module is still in MODULE_STATE_COMING. However, modules in that state
are not fully initialized, lacking sysfs kobjects. Therefore, if a test
module attempts to register a fake device, it will inevitably crash.

This patch proposes a different approach to fix the original
wild-memory-access bug while restoring the normal module execution flow
by making kunit_module_exit() able to detect if kunit_module_init() has
previously initialized the tests suite set. In this way, test modules
can once again register fake devices without crashing.

This behavior is achieved by checking whether mod->kunit_suites is a
virtual or direct mapping address. If it is a virtual address, then
kunit_module_init() has allocated the suite_set in kunit_filter_suites()
using kmalloc_array(). On the contrary, if mod->kunit_suites is still
pointing to the original address that was set when looking up the
.kunit_test_suites section of the module, then the loading phase has
failed and there's no memory to be freed.

v4:
- rebased on 6.8
- noted that kunit_filter_suites() must return a virtual address
v3:
- add a comment to clarify why the start address is checked
v2:
- add include 

Fixes: 2810c1e99867 ("kunit: Fix wild-memory-access bug in kunit_free_suite_set()")
Reviewed-by: David Gow 
Tested-by: Rae Moar 
Tested-by: Richard Fitzgerald 
Reviewed-by: Javier Martinez Canillas 
Signed-off-by: Marco Pagani 
Signed-off-by: Shuah Khan

kunit: device: Fix a NULL vs IS_ERR() check in init()

2024-01-22T14:58:22+00:00

The root_device_register() function does not return NULL, it returns
error pointers.  Fix the check to match.

Fixes: d03c720e03bd ("kunit: Add APIs for managing devices")
Signed-off-by: Dan Carpenter 
Reviewed-by: Rae Moar 
Reviewed-by: David Gow 
Signed-off-by: Shuah Khan

kunit: Fix a NULL vs IS_ERR() bug

2024-01-22T14:58:12+00:00

The kunit_device_register() function doesn't return NULL, it returns
error pointers.  Change the KUNIT_ASSERT_NOT_NULL() to check for
ERR_OR_NULL().

Fixes: d03c720e03bd ("kunit: Add APIs for managing devices")
Signed-off-by: Dan Carpenter 
Reviewed-by: Rae Moar 
Reviewed-by: David Gow 
Signed-off-by: Shuah Khan

Merge tag 'riscv-for-linus-6.8-mw4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2024-01-20T19:06:04+00:00

Pull more RISC-V updates from Palmer Dabbelt:

 - Support for tuning for systems with fast misaligned accesses.

 - Support for SBI-based suspend.

 - Support for the new SBI debug console extension.

 - The T-Head CMOs now use PA-based flushes.

 - Support for enabling the V extension in kernel code.

 - Optimized IP checksum routines.

 - Various ftrace improvements.

 - Support for archrandom, which depends on the Zkr extension.

 - The build is no longer broken under NET=n, KUNIT=y for ports that
   don't define their own ipv6 checksum.

* tag 'riscv-for-linus-6.8-mw4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (56 commits)
  lib: checksum: Fix build with CONFIG_NET=n
  riscv: lib: Check if output in asm goto supported
  riscv: Fix build error on rv32 + XIP
  riscv: optimize ELF relocation function in riscv
  RISC-V: Implement archrandom when Zkr is available
  riscv: Optimize hweight API with Zbb extension
  riscv: add dependency among Image(.gz), loader(.bin), and vmlinuz.efi
  samples: ftrace: Add RISC-V support for SAMPLE_FTRACE_DIRECT[_MULTI]
  riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support
  riscv: ftrace: Make function graph use ftrace directly
  riscv: select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY
  lib/Kconfig.debug: Update AS_HAS_NON_CONST_LEB128 comment and name
  riscv: Restrict DWARF5 when building with LLVM to known working versions
  riscv: Hoist linker relaxation disabling logic into Kconfig
  kunit: Add tests for csum_ipv6_magic and ip_fast_csum
  riscv: Add checksum library
  riscv: Add checksum header
  riscv: Add static key for misaligned accesses
  asm-generic: Improve csum_fold
  RISC-V: selftests: cbo: Ensure asm operands match constraints
  ...

Merge tag 'strlcpy-removal-v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2024-01-19T21:49:16+00:00

Pull strlcpy removal from Kees Cook:
 "As promised, this is 'part 2' of the hardening tree, late in -rc1 now
  that all the other trees with strlcpy() removals have landed. One new
  user appeared (in bcachefs) but was a trivial refactor. The kernel is
  now free of the strlcpy() API!

   - Remove of the final (very recent) user of strlcpy() (in bcachefs)

   - Remove the strlcpy() API. Long live strscpy()"

* tag 'strlcpy-removal-v6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  string: Remove strlcpy()
  bcachefs: Replace strlcpy() with strscpy()

string: Remove strlcpy()

2024-01-19T19:59:11+00:00

With all the users of strlcpy() removed[1] from the kernel, remove the
API, self-tests, and other references. Leave mentions in Documentation
(about its deprecation), and in checkpatch.pl (to help migrate host-only
tools/ usage). Long live strscpy().

Link: https://github.com/KSPP/linux/issues/89 [1]
Cc: Azeem Shaikh 
Cc: Andrew Morton 
Cc: Andy Whitcroft 
Cc: Joe Perches 
Cc: Dwaipayan Ray 
Cc: Lukas Bulwahn 
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Andy Shevchenko 
Signed-off-by: Kees Cook

lib: checksum: Fix build with CONFIG_NET=n

2024-01-19T16:12:38+00:00

The generic ipv6 checksums are only defined with CONFIG_NET=y, so gate
the test as well.

Fixes: 6f4c45cbcb00 ("kunit: Add tests for csum_ipv6_magic and ip_fast_csum")
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202401192143.jLdjbIy3-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202401192357.WU4nPRdN-lkp@intel.com/
Reviewed-By: Charlie Jenkins 
Link: https://lore.kernel.org/r/20240119145600.3093-2-palmer@rivosinc.com
Signed-off-by: Palmer Dabbelt