linux-toradex.git/arch/s390/kernel, branch v6.3

s390/ptrace: fix PTRACE_GET_LAST_BREAK error handling

2023-03-27T15:23:08+00:00

Return -EFAULT if put_user() for the PTRACE_GET_LAST_BREAK
request fails, instead of silently ignoring it.

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

Merge tag 's390-6.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2023-03-03T17:38:01+00:00

Pull more s390 updates from Heiko Carstens:

 - Add empty command line parameter handling stubs to kernel for all
   command line parameters which are handled in the decompressor. This
   avoids invalid "Unknown kernel command line parameters" messages from
   the kernel, and also avoids that these will be incorrectly passed to
   user space. This caused already confusion, therefore add the empty
   stubs

 - Add missing phys_to_virt() handling to machine check handler

 - Introduce and use a union to be used for zcrypt inline assemblies.
   This makes sure that only a register wide member of the union is
   passed as input and output parameter to inline assemblies, while
   usual C code uses other members of the union to access bit fields of
   it

 - Add and use a READ_ONCE_ALIGNED_128() macro, which can be used to
   atomically read a 128-bit value from memory. This replaces the
   (mis-)use of the 128-bit cmpxchg operation to do the same in cpum_sf
   code. Currently gcc does not generate the used lpq instruction if
   __READ_ONCE() is used for aligned 128-bit accesses, therefore use
   this s390 specific helper

 - Simplify machine check handler code if a task needs to be killed
   because of e.g. register corruption due to a machine malfunction

 - Perform CPU reset to clear pending interrupts and TLB entries on an
   already stopped target CPU before delegating work to it

 - Generate arch/s390/boot/vmlinux.map link map for the decompressor,
   when CONFIG_VMLINUX_MAP is enabled for debugging purposes

 - Fix segment type handling for dcssblk devices. It incorrectly always
   returned type "READ/WRITE" even for read-only segements, which can
   result in a kernel panic if somebody tries to write to a read-only
   device

 - Sort config S390 select list again

 - Fix two kprobe reenter bugs revealed by a recently added kprobe kunit
   test

* tag 's390-6.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/kprobes: fix current_kprobe never cleared after kprobes reenter
  s390/kprobes: fix irq mask clobbering on kprobe reenter from post_handler
  s390/Kconfig: sort config S390 select list again
  s390/extmem: return correct segment type in __segment_load()
  s390/decompressor: add link map saving
  s390/smp: perform cpu reset before delegating work to target cpu
  s390/mcck: cleanup user process termination path
  s390/cpum_sf: use READ_ONCE_ALIGNED_128() instead of 128-bit cmpxchg
  s390/rwonce: add READ_ONCE_ALIGNED_128() macro
  s390/ap,zcrypt,vfio: introduce and use ap_queue_status_reg union
  s390/nmi: fix virtual-physical address confusion
  s390/setup: do not complain about parameters handled in decompressor

s390/kprobes: fix current_kprobe never cleared after kprobes reenter

2023-03-02T14:33:11+00:00

Recent test_kprobe_missed kprobes kunit test uncovers the following
problem. Once kprobe is triggered from another kprobe (kprobe reenter),
all future kprobes on this cpu are considered as kprobe reenter, thus
pre_handler and post_handler are not being called and kprobes are counted
as "missed".

Commit b9599798f953 ("[S390] kprobes: activation and deactivation")
introduced a simpler scheme for kprobes (de)activation and status
tracking by using push_kprobe/pop_kprobe, which supposed to work for
both initial kprobe entry as well as kprobe reentry and helps to avoid
handling those two cases differently. The problem is that a sequence of
calls in case of kprobes reenter:
push_kprobe() <- NULL (current_kprobe)
push_kprobe() <- kprobe1 (current_kprobe)
pop_kprobe() -> kprobe1 (current_kprobe)
pop_kprobe() -> kprobe1 (current_kprobe)
leaves "kprobe1" as "current_kprobe" on this cpu, instead of setting it
to NULL. In fact push_kprobe/pop_kprobe can only store a single state
(there is just one prev_kprobe in kprobe_ctlblk). Which is a hack but
sufficient, there is no need to have another prev_kprobe just to store
NULL. To make a simple and backportable fix simply reset "prev_kprobe"
when kprobe is poped from this "stack". No need to worry about
"kprobe_status" in this case, because its value is only checked when
current_kprobe != NULL.

Cc: stable@vger.kernel.org
Fixes: b9599798f953 ("[S390] kprobes: activation and deactivation")
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

s390/kprobes: fix irq mask clobbering on kprobe reenter from post_handler

2023-03-02T14:33:11+00:00

Recent test_kprobe_missed kprobes kunit test uncovers the following error
(reported when CONFIG_DEBUG_ATOMIC_SLEEP is enabled):

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:580
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 662, name: kunit_try_catch
preempt_count: 0, expected: 0
RCU nest depth: 0, expected: 0
no locks held by kunit_try_catch/662.
irq event stamp: 280
hardirqs last  enabled at (279): [<00000003e60a3d42>] __do_pgm_check+0x17a/0x1c0
hardirqs last disabled at (280): [<00000003e3bd774a>] kprobe_exceptions_notify+0x27a/0x318
softirqs last  enabled at (0): [<00000003e3c5c890>] copy_process+0x14a8/0x4c80
softirqs last disabled at (0): [<0000000000000000>] 0x0
CPU: 46 PID: 662 Comm: kunit_try_catch Tainted: G                 N 6.2.0-173644-g44c18d77f0c0 #2
Hardware name: IBM 3931 A01 704 (LPAR)
Call Trace:
 [<00000003e60a3a00>] dump_stack_lvl+0x120/0x198
 [<00000003e3d02e82>] __might_resched+0x60a/0x668
 [<00000003e60b9908>] __mutex_lock+0xc0/0x14e0
 [<00000003e60bad5a>] mutex_lock_nested+0x32/0x40
 [<00000003e3f7b460>] unregister_kprobe+0x30/0xd8
 [<00000003e51b2602>] test_kprobe_missed+0xf2/0x268
 [<00000003e51b5406>] kunit_try_run_case+0x10e/0x290
 [<00000003e51b7dfa>] kunit_generic_run_threadfn_adapter+0x62/0xb8
 [<00000003e3ce30f8>] kthread+0x2d0/0x398
 [<00000003e3b96afa>] __ret_from_fork+0x8a/0xe8
 [<00000003e60ccada>] ret_from_fork+0xa/0x40

The reason for this error report is that kprobes handling code failed
to restore irqs.

The problem is that when kprobe is triggered from another kprobe
post_handler current sequence of enable_singlestep / disable_singlestep
is the following:
enable_singlestep  <- original kprobe (saves kprobe_saved_imask)
enable_singlestep  <- kprobe triggered from post_handler (clobbers kprobe_saved_imask)
disable_singlestep <- kprobe triggered from post_handler (restores kprobe_saved_imask)
disable_singlestep <- original kprobe (restores wrong clobbered kprobe_saved_imask)

There is just one kprobe_ctlblk per cpu and both calls saves and
loads irq mask to kprobe_saved_imask. To fix the problem simply move
resume_execution (which calls disable_singlestep) before calling
post_handler. This also fixes the problem that post_handler is called
with pt_regs which were not yet adjusted after single-stepping.

Cc: stable@vger.kernel.org
Fixes: 4ba069b802c2 ("[S390] add kprobes support.")
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

s390/smp: perform cpu reset before delegating work to target cpu

2023-02-28T12:19:06+00:00

Clear CPU state (e.g. all TLB entries, prefetched instructions, etc.)
of the target CPU, however without clearing register contents before
starting any work on it.

This puts the target CPU in a more defined state compared to the
current Stop + Restart sigp orders.

Signed-off-by: Heiko Carstens

s390/mcck: cleanup user process termination path

2023-02-28T12:19:05+00:00

If a machine check interrupt hits while user process is
running __s390_handle_mcck() helper function is called
directly from the interrupt handler and terminates the
current process by calling make_task_dead() routine.

The make_task_dead() is not allowed to be called from
interrupt context which forces the machine check handler
switch to the kernel stack and enable local interrupts
first.

The __s390_handle_mcck() could also be called to service
pending work, but this time from the external interrupts
handler. It is the machine check handler that establishes
the work and schedules the external interrupt, therefore
the machine check interrupt itself should be disabled
while reading out the corresponding variable:

	local_mcck_disable();
	mcck = *this_cpu_ptr(&cpu_mcck);
	memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
	local_mcck_enable();

However, local_mcck_disable() does not have effect when
__s390_handle_mcck() is called directly form the machine
check handler, since the machine check interrupt is still
disabled. Therefore, it is not the opening bracket to the
following local_mcck_enable() function.

Simplify the user process termination flow by scheduling
the external interrupt and killing the affected process
from the interrupt context.

Assume a kernel-generated signal is always delivered and
ignore a value returned by do_send_sig_info() funciton.

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

s390/cpum_sf: use READ_ONCE_ALIGNED_128() instead of 128-bit cmpxchg

2023-02-28T12:19:05+00:00

Use READ_ONCE_ALIGNED_128() to read the previous value in front of a
128-bit cmpxchg loop, instead of (mis-)using a 128-bit cmpxchg operation to
do the same.

This makes the code more readable and is faster.

Link: https://lore.kernel.org/r/20230224100237.3247871-3-hca@linux.ibm.com
Signed-off-by: Heiko Carstens

s390/nmi: fix virtual-physical address confusion

2023-02-27T14:29:36+00:00

When a machine check is received while in SIE, it is reinjected into the
guest in some cases. The respective code needs to access the sie_block,
which is taken from the backed up R14.

Since reinjection only occurs while we are in SIE (i.e. between the
labels sie_entry and sie_leave in entry.S and thus if CIF_MCCK_GUEST is
set), the backed up R14 will always contain a physical address in
s390_backup_mcck_info.

This currently works, because virtual and physical addresses are
the same.

Add phys_to_virt() to resolve the virtual-physical confusion.

Signed-off-by: Nico Boehr 
Reviewed-by: Claudio Imbrenda 
Reviewed-by: Alexander Gordeev 
Link: https://lore.kernel.org/r/20230216121208.4390-2-nrb@linux.ibm.com
Signed-off-by: Janosch Frank 
Signed-off-by: Heiko Carstens

s390/setup: do not complain about parameters handled in decompressor

2023-02-27T14:29:36+00:00

Currently there are several kernel command line parameters which are
only parsed and handled in decompressor and not known to the kernel.
This leads to the following error message during kernel boot:

Unknown kernel command line parameters "mem=3G nokaslr", will be passed
to user space.

To avoid confusion, register those parameters with an empty stub so that
kernel does not complain about them.

Reported-by: Gerald Schaefer 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

Merge tag 'kbuild-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2023-02-26T19:53:25+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Change V=1 option to print both short log and full command log

 - Allow V=1 and V=2 to be combined as V=12

 - Make W=1 detect wrong .gitignore files

 - Tree-wide cleanups for unused command line arguments passed to Clang

 - Stop using -Qunused-arguments with Clang

 - Make scripts/setlocalversion handle only correct release tags instead
   of any arbitrary annotated tag

 - Create Debian and RPM source packages without cleaning the source
   tree

 - Various cleanups for packaging

* tag 'kbuild-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (74 commits)
  kbuild: rpm-pkg: remove unneeded KERNELRELEASE from modules/headers_install
  docs: kbuild: remove description of KBUILD_LDS_MODULE
  .gitattributes: use 'dts' diff driver for *.dtso files
  kbuild: deb-pkg: improve the usability of source package
  kbuild: deb-pkg: fix binary-arch and clean in debian/rules
  kbuild: tar-pkg: use tar rules in scripts/Makefile.package
  kbuild: make perf-tar*-src-pkg work without relying on git
  kbuild: deb-pkg: switch over to source format 3.0 (quilt)
  kbuild: deb-pkg: make .orig tarball a hard link if possible
  kbuild: deb-pkg: hide KDEB_SOURCENAME from Makefile
  kbuild: srcrpm-pkg: create source package without cleaning
  kbuild: rpm-pkg: build binary packages from source rpm
  kbuild: deb-pkg: create source package without cleaning
  kbuild: add a tool to list files ignored by git
  Documentation/llvm: add Chimera Linux, Google and Meta datacenters
  setlocalversion: use only the correct release tag for git-describe
  setlocalversion: clean up the construction of version output
  .gitignore: ignore *.cover and *.mbx
  kbuild: remove --include-dir MAKEFLAG from top Makefile
  kbuild: fix trivial typo in comment
  ...