linux.git/arch/s390/include/asm/processor.h, branch v6.5

s390/stackleak: provide fast __stackleak_poison() implementation

2023-04-20T09:36:35+00:00

Provide an s390 specific __stackleak_poison() implementation which is
faster than the generic variant.

For the original implementation with an enforced 4kb stackframe for the
getpid() system call the system call overhead increases by a factor of 3 if
the stackleak feature is enabled. Using the s390 mvc based variant this is
reduced to an increase of 25% instead.

This is within the expected area, since the mvc based implementation is
more or less a memset64() variant which comes with similar results. See
commit 0b77d6701cf8 ("s390: implement memset16, memset32 & memset64").

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Link: https://lore.kernel.org/r/20230405130841.1350565-3-hca@linux.ibm.com
Signed-off-by: Vasily Gorbik

s390: move on_thread_stack() to processor.h

2023-04-04T16:34:56+00:00

As preparation for the stackleak feature move on_thread_stack() to
processor.h like x86.

Also make it __always_inline, and slightly optimize it by reading
current task's kernel stack pointer from lowcore.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: remove __bpon()

2023-03-13T08:16:42+00:00

There is no point in changing branch prediction state of a cpu shortly
before it enters stop state. Therefore remove __bpon().

Acked-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: remove s390_isolate_bp_guest()

2023-03-13T08:16:42+00:00

s390_isolate_bp_guest() is unused. Remove it.

Reviewed-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: remove TIF_ISOLATE_BP

2023-03-13T08:16:42+00:00

TIF_ISOLATE_BP is unused since it was introduced with commit 6b73044b2b00
("s390: run user space and KVM guests with modified branch prediction").
Given that there is no use case remove it again.

Acked-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/processor: add test_and_set_cpu_flag() and test_and_clear_cpu_flag()

2023-02-15T10:07:01+00:00

Add test_and_set_cpu_flag() and test_and_clear_cpu_flag() helper functions.

Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens

s390/processor: let cpu helper functions return boolean values

2023-02-15T10:07:01+00:00

Let cpu helper functions return boolean values. This also allows to
make the code a bit simpler by getting rid of the "!!" construct.

Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens

s390/processor: always inline cpu flag helper functions

2023-02-09T19:11:22+00:00

arch_cpu_idle() is marked noinstr and therefore must only call functions
which are also not instrumented.

Make sure that cpu flag helper functions are always inlined to avoid that
the compiler generates an out-of-line function for e.g. the call within
arch_cpu_idle().

Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens

s390: avoid using global register for current_stack_pointer

2022-11-16T10:39:12+00:00

Commit 30de14b1884b ("s390: current_stack_pointer shouldn't be a
function") made current_stack_pointer a global register variable like
on many other architectures. Unfortunately on s390 it uncovers old
gcc bug which is fixed only since gcc-9.1 [gcc commit 3ad7fed1cc87
("S/390: Fix PR89775. Stackpointer save/restore instructions removed")]
and backported to gcc-8.4 and later. Due to this bug gcc versions prior
to 8.4 generate broken code which leads to stack corruptions.

Current minimal gcc version required to build the kernel is declared
as 5.1. It is not possible to fix all old gcc versions, so work
around this problem by avoiding using global register variable for
current_stack_pointer.

Fixes: 30de14b1884b ("s390: current_stack_pointer shouldn't be a function")
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Alexander Gordeev

Merge tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-10-12T18:00:22+00:00

Pull non-MM updates from Andrew Morton:

 - hfs and hfsplus kmap API modernization (Fabio Francesco)

 - make crash-kexec work properly when invoked from an NMI-time panic
   (Valentin Schneider)

 - ntfs bugfixes (Hawkins Jiawei)

 - improve IPC msg scalability by replacing atomic_t's with percpu
   counters (Jiebin Sun)

 - nilfs2 cleanups (Minghao Chi)

 - lots of other single patches all over the tree!

* tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (71 commits)
  include/linux/entry-common.h: remove has_signal comment of arch_do_signal_or_restart() prototype
  proc: test how it holds up with mapping'less process
  mailmap: update Frank Rowand email address
  ia64: mca: use strscpy() is more robust and safer
  init/Kconfig: fix unmet direct dependencies
  ia64: update config files
  nilfs2: replace WARN_ONs by nilfs_error for checkpoint acquisition failure
  fork: remove duplicate included header files
  init/main.c: remove unnecessary (void*) conversions
  proc: mark more files as permanent
  nilfs2: remove the unneeded result variable
  nilfs2: delete unnecessary checks before brelse()
  checkpatch: warn for non-standard fixes tag style
  usr/gen_init_cpio.c: remove unnecessary -1 values from int file
  ipc/msg: mitigate the lock contention with percpu counter
  percpu: add percpu_counter_add_local and percpu_counter_sub_local
  fs/ocfs2: fix repeated words in comments
  relay: use kvcalloc to alloc page array in relay_alloc_page_array
  proc: make config PROC_CHILDREN depend on PROC_FS
  fs: uninline inode_maybe_inc_iversion()
  ...