A lot of system calls that pass a time_t somewhere have an implementation
using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
been reworked so that this implementation can now be used on 32-bit
architectures as well.
The missing step is to redefine them using the regular SYSCALL_DEFINEx()
to get them out of the compat namespace and make it possible to build them
on 32-bit architectures.
Any system call that ends in 'time' gets a '32' suffix on its name for
that version, while the others get a '_time32' suffix, to distinguish
them from the normal version, which takes a 64-bit time argument in the
future.
In this step, only 64-bit architectures are changed, doing this rename
first lets us avoid touching the 32-bit architectures twice.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
The patch implements a handler for GIB alert interruptions
on the host. Its task is to alert guests that interrupts are
pending for them.
A GIB alert interrupt statistic counter is added as well:
$ cat /proc/interrupts
CPU0 CPU1
...
GAL: 23 37 [I/O] GIB Alert
...
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Message-Id: <20190131085247.13826-14-mimu@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Add the Interruption Alert Mask (IAM) to the architecture specific
kvm struct. This mask in the GISA is used to define for which ISC
a GIB alert will be issued.
The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister()
are used to (un)register a GISC (guest ISC) with a virtual machine and
its GISA.
Upon successful completion, kvm_s390_gisc_register() returns the
ISC to be used for GIB alert interruptions. A negative return code
indicates an error during registration.
Theses functions will be used by other adapter types like AP and PCI to
request pass-through interruption support.
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20190131085247.13826-12-mimu@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
The Guest Information Block (GIB) links the GISA of all guests
that have adapter interrupts pending. These interrupts cannot be
delivered because all vcpus of these guests are currently in WAIT
state or have masked the respective Interruption Sub Class (ISC).
If enabled, a GIB alert is issued on the host to schedule these
guests to run suitable vcpus to consume the pending interruptions.
This mechanism allows to process adapter interrupts for currently
not running guests.
The GIB is created during host initialization and associated with
the Adapter Interruption Facility in case an Adapter Interruption
Virtualization Facility is available.
The GIB initialization and thus the activation of the related code
will be done in an upcoming patch of this series.
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Message-Id: <20190131085247.13826-10-mimu@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Commit 626a5f66da ("s390: bpf: implement jitting of JMP32") added
JMP32 code-gen support for s390. However it triggers the warning below
due to some unusual gotos in the original s390 bpf jit code.
Add a couple of additional "is_jmp32" initializations to fix this.
Also fix the wrong opcode for the "llilf" instruction that was
introduced with the same commit.
arch/s390/net/bpf_jit_comp.c: In function 'bpf_jit_insn':
arch/s390/net/bpf_jit_comp.c:248:55: warning: 'is_jmp32' may be used uninitialized in this function [-Wmaybe-uninitialized]
_EMIT6(op1 | reg(b1, b2) << 16 | (rel & 0xffff), op2 | mask); \
^
arch/s390/net/bpf_jit_comp.c:1211:8: note: 'is_jmp32' was declared here
bool is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
Fixes: 626a5f66da ("s390: bpf: implement jitting of JMP32")
Cc: Jiong Wang <jiong.wang@netronome.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Jiong Wang <jiong.wang@netronome.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Daniel Borkmann says:
====================
pull-request: bpf-next 2019-01-29
The following pull-request contains BPF updates for your *net-next* tree.
The main changes are:
1) Teach verifier dead code removal, this also allows for optimizing /
removing conditional branches around dead code and to shrink the
resulting image. Code store constrained architectures like nfp would
have hard time doing this at JIT level, from Jakub.
2) Add JMP32 instructions to BPF ISA in order to allow for optimizing
code generation for 32-bit sub-registers. Evaluation shows that this
can result in code reduction of ~5-20% compared to 64 bit-only code
generation. Also add implementation for most JITs, from Jiong.
3) Add support for __int128 types in BTF which is also needed for
vmlinux's BTF conversion to work, from Yonghong.
4) Add a new command to bpftool in order to dump a list of BPF-related
parameters from the system or for a specific network device e.g. in
terms of available prog/map types or helper functions, from Quentin.
5) Add AF_XDP sock_diag interface for querying sockets from user
space which provides information about the RX/TX/fill/completion
rings, umem, memory usage etc, from Björn.
6) Add skb context access for skb_shared_info->gso_segs field, from Eric.
7) Add support for testing flow dissector BPF programs by extending
existing BPF_PROG_TEST_RUN infrastructure, from Stanislav.
8) Split BPF kselftest's test_verifier into various subgroups of tests
in order better deal with merge conflicts in this area, from Jakub.
9) Add support for queue/stack manipulations in bpftool, from Stanislav.
10) Document BTF, from Yonghong.
11) Dump supported ELF section names in libbpf on program load
failure, from Taeung.
12) Silence a false positive compiler warning in verifier's BTF
handling, from Peter.
13) Fix help string in bpftool's feature probing, from Prashant.
14) Remove duplicate includes in BPF kselftests, from Yue.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The s390x diagnose 318 instruction sets the control program name code (CPNC)
and control program version code (CPVC) to provide useful information
regarding the OS during debugging. The CPNC is explicitly set to 4 to
indicate a Linux/KVM environment.
The CPVC is a 7-byte value containing:
- 3-byte Linux version code, currently set to 0
- 3-byte unique value, currently set to 0
- 1-byte trailing null
Signed-off-by: Collin Walling <walling@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <1544135405-22385-2-git-send-email-walling@linux.ibm.com>
[set version code to 0 until the structure is fully defined]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The patch that added support for the virtually mapped kernel stacks changed
swsusp_arch_suspend to switch to the nodat-stack as the vmap stack is not
available while going in and out of suspend.
Unfortunately the switch to the nodat-stack is incorrect which breaks
suspend to disk.
Cc: stable@vger.kernel.org # v4.20
Fixes: ce3dc44749 ("s390: add support for virtually mapped kernel stacks")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
In Kbuild, if_changed and friends must have FORCE as a prerequisite.
Hence, $(filter-out FORCE,$^) or $(filter-out $(PHONY),$^) is a common
idiom to get the names of all the prerequisites except phony targets.
Add real-prereqs as a shorthand.
Note:
We cannot replace $(filter %.o,$^) in cmd_link_multi-m because $^ may
include auto-generated dependencies from the .*.cmd file when a single
object module is changed into a multi object module. Refer to commit
69ea912fda ("kbuild: remove unneeded link_multi_deps"). I added some
comment to avoid accidental breakage.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Rob Herring <robh@kernel.org>
When I was refactoring cmd_ar_builtin in scripts/Makefile.build,
I noticed the build breakage of s390.
Some Makefiles of s390 add extra dependencies to built-in.a;
built-in.a depends on timestamp files *.o.chkbss, but $(AR) does
not want to include them into built-in.a.
Insert a phony target 'chkbss' in between so that $(AR) can take
$(filter-out $(PHONY), $^) as input.
While I was here, I refactored Makefile.chkbss a little bit.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Most architectures define system call numbers for the rseq and pkey system
calls, even when they don't support the features, and perhaps never will.
Only a few architectures are missing these, so just define them anyway
for consistency. If we decide to add them later to one of these, the
system call numbers won't get out of sync then.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
The IPC system call handling is highly inconsistent across architectures,
some use sys_ipc, some use separate calls, and some use both. We also
have some architectures that require passing IPC_64 in the flags, and
others that set it implicitly.
For the addition of a y2038 safe semtimedop() system call, I chose to only
support the separate entry points, but that requires first supporting
the regular ones with their own syscall numbers.
The IPC_64 is now implied by the new semctl/shmctl/msgctl system
calls even on the architectures that require passing it with the ipc()
multiplexer.
I'm not adding the new semtimedop() or semop() on 32-bit architectures,
those will get implemented using the new semtimedop_time64() version
that gets added along with the other time64 calls.
Three 64-bit architectures (powerpc, s390 and sparc) get semtimedop().
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
CRYPTO_TFM_REQ_WEAK_KEY confuses newcomers to the crypto API because it
sounds like it is requesting a weak key. Actually, it is requesting
that weak keys be forbidden (for algorithms that have the notion of
"weak keys"; currently only DES and XTS do).
Also it is only one letter away from CRYPTO_TFM_RES_WEAK_KEY, with which
it can be easily confused. (This in fact happened in the UX500 driver,
though just in some debugging messages.)
Therefore, make the intent clear by renaming it to
CRYPTO_TFM_REQ_FORBID_WEAK_KEYS.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
In order to have a common code base for fscrypt "post read" processing
for all filesystems which support encryption, this commit removes
filesystem specific build config option (e.g. CONFIG_EXT4_FS_ENCRYPTION)
and replaces it with a build option (i.e. CONFIG_FS_ENCRYPTION) whose
value affects all the filesystems making use of fscrypt.
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
When converting to autogenerated compat syscall wrappers all system
call entry points got a different symbol name: they all got a __s390x_
prefix.
This caused breakage with system call tracing, since an appropriate
arch_syscall_match_sym_name() was not provided. Add this function, and
while at it also add code to avoid compat system call tracing. s390
has different system call tables for native 64 bit system calls and
compat system calls. This isn't really supported in the common
code. However there are hardly any compat binaries left, therefore
just ignore compat system calls, like x86 and arm64 also do for the
same reason.
Fixes: aa0d6e70d3 ("s390: autogenerate compat syscall wrappers")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
One of the more common cases of allocation size calculations is finding the
size of a structure that has a zero-sized array at the end, along with memory
for some number of elements for that array. For example:
struct foo {
int stuff;
void *entry[];
};
instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can now
use the new struct_size() helper:
instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Avoid using arch specific implementations of string/memory functions
with KASAN since gcc cannot instrument asm code memory accesses and
many bugs could be missed.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
These two functions are only used by core MM code, so no need to export
them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Any system call that takes a pointer argument on s390 requires
a wrapper function to do a 31-to-64 zero-extension, these are
currently generated in arch/s390/kernel/compat_wrapper.c.
On arm64 and x86, we already generate similar wrappers for all
system calls in the place of their definition, just for a different
purpose (they load the arguments from pt_regs).
We can do the same thing here, by adding an asm/syscall_wrapper.h
file with a copy of all the relevant macros to override the generic
version. Besides the addition of the compat entry point, these also
rename the entry points with a __s390_ or __s390x_ prefix, similar
to what we do on arm64 and x86. This in turn requires renaming
a few things, and adding a proper ni_syscall() entry point.
In order to still compile system call definitions that pass an
loff_t argument, the __SC_COMPAT_CAST() macro checks for that
and forces an -ENOSYS error, which was the best I could come up
with. Those functions must obviously not get called from user
space, but instead require hand-written compat_sys_*() handlers,
which fortunately already exist.
Link: https://lore.kernel.org/lkml/20190116131527.2071570-5-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
[heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
s390 has an almost identical copy of the code in kernel/uid16.c.
The problem here is that it requires calling the regular system calls,
which the generic implementation handles correctly, but the internal
interfaces are not declared in a global header for this.
The best way forward here seems to be to just use the generic code and
delete the s390 specific implementation.
I keep the changes to uapi/asm/posix_types.h inside of an #ifdef check
so user space does not observe any changes. As some of the system calls
pass pointers, we also need wrappers in compat_wrapper.c, which I add
for all calls with at least one argument. All those wrappers can be
removed in a later step.
Link: https://lore.kernel.org/lkml/20190116131527.2071570-4-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The sys_ipc() and compat_ksys_ipc() functions are meant to only
be used from the system call table, not called by another function.
Introduce ksys_*() interfaces for this purpose, as we have done
for many other system calls.
Link: https://lore.kernel.org/lkml/20190116131527.2071570-3-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
[heiko.carstens@de.ibm.com: compile fix for !CONFIG_COMPAT]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Patch series "s390: rework compat wrapper generation".
As promised, I gave this a go and changed the SYSCALL_DEFINEx()
infrastructure to always include the wrappers for doing the
31-bit argument conversion on s390 compat mode.
This does three main things:
- The UID16 rework saved a lot of duplicated code, and would
probably make sense by itself, but is also required as
we can no longer call sys_*() functions directly after the
last step.
- Removing the compat_wrapper.c file is of course the main
goal here, in order to remove the need to maintain the
compat_wrapper.c file when new system calls get added.
Unfortunately, this requires adding some complexity in
syscall_wrapper.h, and trades a small reduction in source
code lines for a small increase in binary size for
unused wrappers.
- As an added benefit, the use of syscall_wrapper.h now makes
it easy to change the syscall wrappers so they no longer
see all user space register contents, similar to changes
done in commits fa697140f9 ("syscalls/x86: Use 'struct pt_regs'
based syscall calling convention for 64-bit syscalls") and
4378a7d4be ("arm64: implement syscall wrappers").
I leave the actual implementation of this for you, if you
want to do it later.
I did not test the changes at runtime, but I looked at the
generated object code, which seems fine here and includes
the same conversions as before.
This patch(of 5):
The sys_personality function is not meant to be called from other system
calls. We could introduce an intermediate ksys_personality function,
but it does almost nothing, so this just moves the implementation into
the caller.
Link: https://lore.kernel.org/lkml/20190116131527.2071570-1-arnd@arndb.de
Link: https://lore.kernel.org/lkml/20190116131527.2071570-2-arnd@arndb.de
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This introduces a new generic SOL_SOCKET-level socket option called
SO_BINDTOIFINDEX. It behaves similar to SO_BINDTODEVICE, but takes a
network interface index as argument, rather than the network interface
name.
User-space often refers to network-interfaces via their index, but has
to temporarily resolve it to a name for a call into SO_BINDTODEVICE.
This might pose problems when the network-device is renamed
asynchronously by other parts of the system. When this happens, the
SO_BINDTODEVICE might either fail, or worse, it might bind to the wrong
device.
In most cases user-space only ever operates on devices which they
either manage themselves, or otherwise have a guarantee that the device
name will not change (e.g., devices that are UP cannot be renamed).
However, particularly in libraries this guarantee is non-obvious and it
would be nice if that race-condition would simply not exist. It would
make it easier for those libraries to operate even in situations where
the device-name might change under the hood.
A real use-case that we recently hit is trying to start the network
stack early in the initrd but make it survive into the real system.
Existing distributions rename network-interfaces during the transition
from initrd into the real system. This, obviously, cannot affect
devices that are up and running (unless you also consider moving them
between network-namespaces). However, the network manager now has to
make sure its management engine for dormant devices will not run in
parallel to these renames. Particularly, when you offload operations
like DHCP into separate processes, these might setup their sockets
early, and thus have to resolve the device-name possibly running into
this race-condition.
By avoiding a call to resolve the device-name, we no longer depend on
the name and can run network setup of dormant devices in parallel to
the transition off the initrd. The SO_BINDTOIFINDEX ioctl plugs this
race.
Reviewed-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When calling smp_call_ipl_cpu() from the IPL CPU, we will try to read
from pcpu_devices->lowcore. However, due to prefixing, that will result
in reading from absolute address 0 on that CPU. We have to go via the
actual lowcore instead.
This means that right now, we will read lc->nodat_stack == 0 and
therfore work on a very wrong stack.
This BUG essentially broke rebooting under QEMU TCG (which will report
a low address protection exception). And checking under KVM, it is
also broken under KVM. With 1 VCPU it can be easily triggered.
:/# echo 1 > /proc/sys/kernel/sysrq
:/# echo b > /proc/sysrq-trigger
[ 28.476745] sysrq: SysRq : Resetting
[ 28.476793] Kernel stack overflow.
[ 28.476817] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13
[ 28.476820] Hardware name: IBM 2964 NE1 716 (KVM/Linux)
[ 28.476826] Krnl PSW : 0400c00180000000 0000000000115c0c (pcpu_delegate+0x12c/0x140)
[ 28.476861] R:0 T:1 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
[ 28.476863] Krnl GPRS: ffffffffffffffff 0000000000000000 000000000010dff8 0000000000000000
[ 28.476864] 0000000000000000 0000000000000000 0000000000ab7090 000003e0006efbf0
[ 28.476864] 000000000010dff8 0000000000000000 0000000000000000 0000000000000000
[ 28.476865] 000000007fffc000 0000000000730408 000003e0006efc58 0000000000000000
[ 28.476887] Krnl Code: 0000000000115bfe: 4170f000 la %r7,0(%r15)
[ 28.476887] 0000000000115c02: 41f0a000 la %r15,0(%r10)
[ 28.476887] #0000000000115c06: e370f0980024 stg %r7,152(%r15)
[ 28.476887] >0000000000115c0c: c0e5fffff86e brasl %r14,114ce8
[ 28.476887] 0000000000115c12: 41f07000 la %r15,0(%r7)
[ 28.476887] 0000000000115c16: a7f4ffa8 brc 15,115b66
[ 28.476887] 0000000000115c1a: 0707 bcr 0,%r7
[ 28.476887] 0000000000115c1c: 0707 bcr 0,%r7
[ 28.476901] Call Trace:
[ 28.476902] Last Breaking-Event-Address:
[ 28.476920] [<0000000000a01c4a>] arch_call_rest_init+0x22/0x80
[ 28.476927] Kernel panic - not syncing: Corrupt kernel stack, can't continue.
[ 28.476930] CPU: 0 PID: 424 Comm: sh Not tainted 5.0.0-rc1+ #13
[ 28.476932] Hardware name: IBM 2964 NE1 716 (KVM/Linux)
[ 28.476932] Call Trace:
Fixes: 2f859d0dad ("s390/smp: reduce size of struct pcpu")
Cc: stable@vger.kernel.org # 4.0+
Reported-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
While "s390/vdso: avoid 64-bit vdso mapping for compat tasks" fixed
64-bit vdso mapping for compat tasks under gdb it introduced another
problem. "compat_mm" flag is not inherited during fork and when
31-bit process forks a child (but does not perform exec) it ends up
with 64-bit vdso. To address that, init_new_context (which is called
during fork and exec) now initialize compat_mm based on thread TIF_31BIT
flag. Later compat_mm is adjusted in arch_setup_additional_pages, which
is called during exec.
Fixes: d1befa6582 ("s390/vdso: avoid 64-bit vdso mapping for compat tasks")
Reported-by: Stefan Liebler <stli@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
smp_rescan_cpus() is called without the device_hotplug_lock, which can lead
to a dedlock when a new CPU is found and immediately set online by a udev
rule.
This was observed on an older kernel version, where the cpu_hotplug_begin()
loop was still present, and it resulted in hanging chcpu and systemd-udev
processes. This specific deadlock will not show on current kernels. However,
there may be other possible deadlocks, and since smp_rescan_cpus() can still
trigger a CPU hotplug operation, the device_hotplug_lock should be held.
For reference, this was the deadlock with the old cpu_hotplug_begin() loop:
chcpu (rescan) systemd-udevd
echo 1 > /sys/../rescan
-> smp_rescan_cpus()
-> (*) get_online_cpus()
(increases refcount)
-> smp_add_present_cpu()
(new CPU found)
-> register_cpu()
-> device_add()
-> udev "add" event triggered -----------> udev rule sets CPU online
-> echo 1 > /sys/.../online
-> lock_device_hotplug_sysfs()
(this is missing in rescan path)
-> device_online()
-> (**) device_lock(new CPU dev)
-> cpu_up()
-> cpu_hotplug_begin()
(loops until refcount == 0)
-> deadlock with (*)
-> bus_probe_device()
-> device_attach()
-> device_lock(new CPU dev)
-> deadlock with (**)
Fix this by taking the device_hotplug_lock in the CPU rescan path.
Cc: <stable@vger.kernel.org>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
The ASCE of an mm_struct can be modified after a task has been created,
e.g. via crst_table_downgrade for a compat process. The active_mm logic
to avoid the switch_mm call if the next task is a kernel thread can
lead to a situation where switch_mm is called where 'prev == next' is
true but 'prev->context.asce == next->context.asce' is not.
This can lead to a situation where a CPU uses the outdated ASCE to run
a task. The result can be a crash, endless loops and really subtle
problem due to TLBs being created with an invalid ASCE.
Cc: stable@kernel.org # v3.15+
Fixes: 53e857f308 ("s390/mm,tlb: race of lazy TLB flush vs. recreation")
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Right now the early machine detection code check stsi 3.2.2 for "KVM"
and set MACHINE_IS_VM if this is different. As the console detection
uses diagnose 8 if MACHINE_IS_VM returns true this will crash Linux
early for any non z/VM system that sets a different value than KVM.
So instead of assuming z/VM, do not set any of MACHINE_IS_LPAR,
MACHINE_IS_VM, or MACHINE_IS_KVM.
CC: stable@vger.kernel.org
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
