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3 years agos390/qdio: get rid of register asm
Heiko Carstens [Tue, 22 Jun 2021 13:26:16 +0000 (15:26 +0200)]
s390/qdio: get rid of register asm

Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ioasm: use symbolic names for asm operands
Heiko Carstens [Tue, 22 Jun 2021 12:50:27 +0000 (14:50 +0200)]
s390/ioasm: use symbolic names for asm operands

Change remaining inline assemblies to also use symbolic names for
operands, use "Q" constraint when possible, and use "+" modifier so
that an operand needs to be specified only once.

Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ioasm: get rid of register asm
Heiko Carstens [Tue, 22 Jun 2021 12:43:07 +0000 (14:43 +0200)]
s390/ioasm: get rid of register asm

Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cmf: get rid of register asm
Heiko Carstens [Tue, 22 Jun 2021 12:07:23 +0000 (14:07 +0200)]
s390/cmf: get rid of register asm

Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/lib,string: get rid of register asm
Heiko Carstens [Mon, 21 Jun 2021 12:56:46 +0000 (14:56 +0200)]
s390/lib,string: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/lib,uaccess: get rid of register asm
Heiko Carstens [Mon, 21 Jun 2021 11:38:45 +0000 (13:38 +0200)]
s390/lib,uaccess: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/string: get rid of register asm
Heiko Carstens [Mon, 21 Jun 2021 09:30:30 +0000 (11:30 +0200)]
s390/string: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cmpxchg: use register pair instead of register asm
Heiko Carstens [Thu, 17 Jun 2021 19:18:14 +0000 (21:18 +0200)]
s390/cmpxchg: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mm,pages-states: get rid of register asm
Heiko Carstens [Thu, 17 Jun 2021 18:30:15 +0000 (20:30 +0200)]
s390/mm,pages-states: get rid of register asm

There is no reason to use fixed registers for the essa
instruction. Therefore remove the register asm construct.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/lib,xor: get rid of register asm
Heiko Carstens [Thu, 17 Jun 2021 18:11:40 +0000 (20:11 +0200)]
s390/lib,xor: get rid of register asm

Looking at the generate code this was just a micro-optimization.
However given that as many register asm constructs as possible
will be removed from s390 code, remove this one as well.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/timex: get rid of register asm
Heiko Carstens [Thu, 17 Jun 2021 09:32:53 +0000 (11:32 +0200)]
s390/timex: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/hypfs: use register pair instead of register asm
Heiko Carstens [Thu, 17 Jun 2021 08:26:57 +0000 (10:26 +0200)]
s390/hypfs: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/zcrypt: Switch to flexible array member
Kees Cook [Wed, 16 Jun 2021 20:19:02 +0000 (13:19 -0700)]
s390/zcrypt: Switch to flexible array member

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
intentionally reading/writing across neighboring array fields.

Switch from zero-element arrays to flexible arrays so the compiler will
perform appropriate bounds checking, avoiding these future warnings:

In function '__fortify_memcpy',
    inlined from 'cca_sec2protkey' at drivers/s390/crypto/zcrypt_ccamisc.c:645:2:
./include/linux/fortify-string.h:244:4: error: call to '__write_overflow_field' declared with attribute error: detected write beyond size of field (1st parameter)

In function '__fortify_memcpy',
    inlined from 'cca_clr2seckey' at drivers/s390/crypto/zcrypt_ccamisc.c:568:3:
./include/linux/fortify-string.h:246:4: error: call to '__read_overflow2_field' declared with attribute error: detected read beyond size of field (2nd parameter)

In function '__fortify_memcpy',
    inlined from 'cca_genseckey' at drivers/s390/crypto/zcrypt_ccamisc.c:429:2:
./include/linux/fortify-string.h:246:4: error: call to '__read_overflow2_field' declared with attribute error: detected read beyond size of field (2nd parameter)

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210616201903.1245949-1-keescook@chromium.org
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/speculation: Use statically initialized const for instructions
Kees Cook [Wed, 16 Jun 2021 20:18:23 +0000 (13:18 -0700)]
s390/speculation: Use statically initialized const for instructions

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memcpy(), memmove(), and memset(), avoid
confusing the checks when using a static const source.

Move the static const array into a variable so the compiler can perform
appropriate bounds checking.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210616201823.1245603-1-keescook@chromium.org
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agovirtio/s390: get rid of open-coded kvm hypercall
Heiko Carstens [Mon, 21 Jun 2021 14:45:22 +0000 (16:45 +0200)]
virtio/s390: get rid of open-coded kvm hypercall

do_kvm_notify() and __do_kvm_notify() are an (exact) open-coded variant
of kvm_hypercall3(). Therefore simply make use of kvm_hypercall3(),
and get rid of duplicated code.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Link: https://lore.kernel.org/r/20210621144522.1304273-1-hca@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/pci: add zpci_set_irq()/zpci_clear_irq()
Niklas Schnelle [Thu, 10 Dec 2020 14:28:05 +0000 (15:28 +0100)]
s390/pci: add zpci_set_irq()/zpci_clear_irq()

Pull the directed vs floating IRQ check into common
zpci_set_irq()/zpci_clear_irq() functions and expose them for the rest
of the zPCI subsystem. Furthermore we add a zdev flag bit to easily
check if IRQs are registered. This is needed for use in resetting a zPCI
function.

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agoscripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390
Nathan Chancellor [Thu, 17 Jun 2021 19:31:40 +0000 (12:31 -0700)]
scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390

clang versions prior to the current development version of 13.0.0 cannot
compile s390 after commit 3abbdfde5a65 ("s390/bitops: use register pair
instead of register asm") and the s390 maintainers do not intend to work
around this in the kernel. Codify this in scripts/min-tool-version.sh
similar to arm64 with GCC 5.1.0 so that there are no reports of broken
builds.

[hca@linux.ibm.com: breaking compatibility with older clang compilers
 is intended to finally make use of a feature which allows the
 compiler to allocate even/odd register pairs. This is possible since
 a very long time with gcc, but only since llvm-project commit
 d058262b1471 ("[SystemZ] Support i128 inline asm operands.") with
 clang. Using that feature allows to get rid of error prone register
 asm statements, of which the above named kernel commit is only the
 first of a larger not yet complete series.]

Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20210617193139.856957-1-nathan@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ipl: use register pair instead of register asm
Heiko Carstens [Mon, 14 Jun 2021 20:32:21 +0000 (22:32 +0200)]
s390/ipl: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mem_detect: fix tprot() program check new psw handling
Heiko Carstens [Mon, 14 Jun 2021 20:09:20 +0000 (22:09 +0200)]
s390/mem_detect: fix tprot() program check new psw handling

The tprot() inline asm temporarily changes the program check new psw
to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mem_detect: use register pair instead of register asm
Heiko Carstens [Mon, 14 Jun 2021 19:57:58 +0000 (21:57 +0200)]
s390/mem_detect: use register pair instead of register asm

...and slightly cleanup the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mem_detect: fix diag260() program check new psw handling
Heiko Carstens [Mon, 14 Jun 2021 19:40:43 +0000 (21:40 +0200)]
s390/mem_detect: fix diag260() program check new psw handling

The __diag260() inline asm temporarily changes the program check new
psw to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/facility: get rid of register asm
Heiko Carstens [Mon, 14 Jun 2021 19:30:44 +0000 (21:30 +0200)]
s390/facility: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/uaccess: get rid of register asm
Heiko Carstens [Mon, 14 Jun 2021 19:07:37 +0000 (21:07 +0200)]
s390/uaccess: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sysinfo: get rid of register asm
Heiko Carstens [Mon, 14 Jun 2021 17:54:42 +0000 (19:54 +0200)]
s390/sysinfo: get rid of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/pgtable: use register pair instead of register asm
Heiko Carstens [Mon, 14 Jun 2021 17:38:07 +0000 (19:38 +0200)]
s390/pgtable: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ipl_parm: use register pair instead of register asm
Heiko Carstens [Mon, 14 Jun 2021 16:55:07 +0000 (18:55 +0200)]
s390/ipl_parm: use register pair instead of register asm

...and slightly cleanup the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ipl_parm: fix program check new psw handling
Heiko Carstens [Mon, 14 Jun 2021 12:49:31 +0000 (14:49 +0200)]
s390/ipl_parm: fix program check new psw handling

The __diag308() inline asm temporarily changes the program check new
psw to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/pci: use register pair instead of register asm
Niklas Schnelle [Tue, 15 Jun 2021 15:08:23 +0000 (17:08 +0200)]
s390/pci: use register pair instead of register asm

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/hvc_iucv: Remove power management support
Julian Wiedmann [Mon, 14 Jun 2021 07:14:27 +0000 (09:14 +0200)]
s390/hvc_iucv: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove the hvc_iucv_driver, but keep the device struct around so that
it can continue to provide the hvc_iucv_dev_attr_groups attributes.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/boot: add zstd support
Dimitri John Ledkov [Tue, 15 Jun 2021 11:41:50 +0000 (12:41 +0100)]
s390/boot: add zstd support

Enable ztsd support in s390/boot, to enable booting with zstd
compressed kernel when configured with CONFIG_KERNEL_ZSTD=y.

BOOT_HEAP_SIZE is defined to 0x30000 in this case. Actual decompressor
memory usage with allyesconfig is currently 0x26150.

BugLink: https://bugs.launchpad.net/bugs/1931725
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
cc: Heiko Carstens <hca@linux.ibm.com>
cc: Vasily Gorbik <gor@linux.ibm.com>
cc: Christian Borntraeger <borntraeger@de.ibm.com>
cc: linux-s390@vger.kernel.org
Link: https://lore.kernel.org/r/20210615114150.325080-1-dimitri.ledkov@canonical.com
[gor: added BOOT_HEAP_SIZE for zstd]
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/decompressor: correct BOOT_HEAP_SIZE condition
Vasily Gorbik [Tue, 15 Jun 2021 22:36:41 +0000 (00:36 +0200)]
s390/decompressor: correct BOOT_HEAP_SIZE condition

Currently BOOT_HEAP_SIZE is always defined as 0x400000 due to
bogus condition. Use CONFIG_KERNEL_BZIP2 instead of
CONFIG_HAVE_KERNEL_BZIP2 to correct that.

BOOT_HEAP_SIZE of 0x10000 is still good enough for every decompressor
algorithm but bzip2. Actual decompressor memory usage with allyesconfig
is the following:
gzip  0xbc28
bzip2 0x379518
xz    0x7410
lzma  0x3e6c
lzo   0
lz4   0

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: convert list_for_each to entry variant
Zou Wei [Tue, 15 Jun 2021 06:57:00 +0000 (14:57 +0800)]
s390/sclp: convert list_for_each to entry variant

convert list_for_each() to list_for_each_entry() where
applicable.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zou Wei <zou_wei@huawei.com>
Link: https://lore.kernel.org/r/1623740220-15846-1-git-send-email-zou_wei@huawei.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cpcmd: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/cpcmd: use register pair instead of register asm

Remove register asm usage from diag8_noresponse() since it wasn't
needed at all. There is no requirement for even/odd register pairs for
diag 0x8.

For diag_response() use register pairs to fulfill the rx+1 and ry+1
requirements as required if a response buffer is specified. Also
change the inline asm to return the condition code of the diagnose
instruction and do the conditional handling of response length
calculation in C.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sigp: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/sigp: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sthyi: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/sthyi: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/maccess: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/maccess: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/checksum: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/checksum: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/diag: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/diag: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/page: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/page: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/smp: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/smp: use register pair instead of register asm

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/bitops: use register pair instead of register asm
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390/bitops: use register pair instead of register asm

Get rid of register asm statement and use a register pair.
This allows the compiler to allocate registers on its own.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: introduce register pair union
Heiko Carstens [Wed, 9 Jun 2021 20:59:13 +0000 (22:59 +0200)]
s390: introduce register pair union

Introduce a register pair union, which is supposed to be used for
inline assemblies where instructions require parameters in even/odd
numbered register pairs.

This is more or less the same register pair construct which was
available for 31 bit builds which was removed with commit 1796ea228d5f
("s390: remove 31 bit support").

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/vmlogrdr: Remove power management support
Peter Oberparleiter [Fri, 11 Jun 2021 11:28:13 +0000 (13:28 +0200)]
s390/vmlogrdr: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover vmlogrdr-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: Remove sclp base power management support
Peter Oberparleiter [Fri, 11 Jun 2021 11:03:53 +0000 (13:03 +0200)]
s390/sclp: Remove sclp base power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover sclp base-related power management code. Note that we
keep the registration of the sclp platform driver since it is used to
externalize non-PM related attributes in sysfs.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: Remove quiesce power management support
Peter Oberparleiter [Fri, 11 Jun 2021 09:13:40 +0000 (11:13 +0200)]
s390/sclp: Remove quiesce power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover sclp quiesce-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: Remove memory hotplug power management support
Peter Oberparleiter [Fri, 11 Jun 2021 09:11:36 +0000 (11:11 +0200)]
s390/sclp: Remove memory hotplug power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover sclp memory hotplug-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: Remove vt220 power management support
Peter Oberparleiter [Fri, 11 Jun 2021 09:07:15 +0000 (11:07 +0200)]
s390/sclp: Remove vt220 power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover sclp vt220-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp: Remove console power management support
Peter Oberparleiter [Fri, 11 Jun 2021 09:05:40 +0000 (11:05 +0200)]
s390/sclp: Remove console power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover sclp console-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/monwriter: Remove power management support
Peter Oberparleiter [Wed, 9 Jun 2021 15:17:23 +0000 (17:17 +0200)]
s390/monwriter: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover monwriter-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/monreader: Remove power management support
Peter Oberparleiter [Wed, 9 Jun 2021 14:59:29 +0000 (16:59 +0200)]
s390/monreader: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover monreader-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/xpram: Remove power management support
Peter Oberparleiter [Wed, 9 Jun 2021 14:18:58 +0000 (16:18 +0200)]
s390/xpram: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover xpram-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/dcssblk: Remove power management support
Peter Oberparleiter [Wed, 9 Jun 2021 13:46:17 +0000 (15:46 +0200)]
s390/dcssblk: Remove power management support

Power management support was removed for s390 with
commit f5b114f6d22e ("s390: remove broken hibernate / power management
support").

Remove leftover dcssblk-related power management code.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cio: dont call css_wait_for_slow_path() inside a lock
Vineeth Vijayan [Wed, 9 Jun 2021 07:21:08 +0000 (09:21 +0200)]
s390/cio: dont call css_wait_for_slow_path() inside a lock

Currently css_wait_for_slow_path() gets called inside the chp->lock.
The path-verification-loop of slowpath inside this lock could lead to
deadlock as reported by the lockdep validator.

The ccw_device_get_chp_desc() during the instance of a device-set-online
would try to acquire the same 'chp->lock' to read the chp->desc.
The instance of this function can get called from multiple scenario,
like probing or setting-device online manually. This could, in some
corner-cases lead to the deadlock.

lockdep validator reported this as,

        CPU0                    CPU1
        ----                    ----
   lock(&chp->lock);
                                lock(kn->active#43);
                                lock(&chp->lock);
   lock((wq_completion)cio);

The chp->lock was introduced to serialize the access of struct
channel_path. This lock is not needed for the css_wait_for_slow_path()
function, so invoke the slow-path function outside this lock.

Fixes: 7f89d7de3293 ("[S390] cio: add lock to struct channel_path")
Cc: <stable@vger.kernel.org>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/irqflags: always inline arch irqflags functions
Heiko Carstens [Thu, 10 Jun 2021 15:58:00 +0000 (17:58 +0200)]
s390/irqflags: always inline arch irqflags functions

All s390 irqflags functions are very small and should be always inlined.
Therefore mark them __always_inline. This also allows to get rid of the
rather odd notrace attribute for these small functions, which was only
added to prevent tracing iff any of these functions would not be inlined.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/processor: always inline stap() and __load_psw_mask()
Heiko Carstens [Thu, 10 Jun 2021 15:50:25 +0000 (17:50 +0200)]
s390/processor: always inline stap() and __load_psw_mask()

s390 is the only architecture which makes use of the __no_kasan_or_inline
attribute for two functions. Given that both stap() and __load_psw_mask()
are very small functions they can and should be always inlined anyway.

Therefore get rid of __no_kasan_or_inline and always inline these
functions.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/debug: Remove pointer obfuscation
Peter Oberparleiter [Wed, 9 Jun 2021 12:05:56 +0000 (14:05 +0200)]
s390/debug: Remove pointer obfuscation

When read via debugfs, s390dbf debug-views print the kernel address of
the call-site that created a trace entry. The kernel's %p pointer
hashing feature obfuscates this address, and commit 35e102ee443d
("s390/debug: use pK for kernel pointers") made this obfuscation
configurable via the kptr_restrict sysctl.

Obfuscation of kernel address data printed via s390dbf debug-views does
not add any additional protection since the associated debugfs files are
only accessible to the root user that typically has enough other means
to obtain kernel address data.

Also trace payload data may contain binary representations of kernel
addresses as part of logged data structues. Requiring such payload data
to be obfuscated as well would be impractical and greatly diminish the
use of s390dbf.

Therefore completely remove pointer obfuscation from s390dbf
debug-views.

Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/setup: cleanup reserve/remove_oldmem
Vasily Gorbik [Thu, 8 Oct 2020 13:07:27 +0000 (15:07 +0200)]
s390/setup: cleanup reserve/remove_oldmem

Since OLDMEM_BASE/OLDMEM_SIZE is already taken into consideration and is
reflected in ident_map_size. reserve/remove_oldmem() is no longer needed
and could be removed.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: setup kernel memory layout early
Vasily Gorbik [Tue, 6 Oct 2020 20:12:39 +0000 (22:12 +0200)]
s390: setup kernel memory layout early

Currently there are two separate places where kernel memory layout has
to be known and adjusted:
1. early kasan setup.
2. paging setup later.

Those 2 places had to be kept in sync and adjusted to reflect peculiar
technical details of one another. With additional factors which influence
kernel memory layout like ultravisor secure storage limit, complexity
of keeping two things in sync grew up even more.

Besides that if we look forward towards creating identity mapping and
enabling DAT before jumping into uncompressed kernel - that would also
require full knowledge of and control over kernel memory layout.

So, de-duplicate and move kernel memory layout setup logic into
the decompressor.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/entry.S: factor out OUTSIDE macro
Alexander Gordeev [Mon, 7 Jun 2021 10:01:49 +0000 (12:01 +0200)]
s390/entry.S: factor out OUTSIDE macro

Introduce OUTSIDE macro that checks whether an instruction
address is inside or outside of a block of instructions.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ap/zcrypt: notify userspace with online, config and mode info
Harald Freudenberger [Tue, 13 Apr 2021 16:11:09 +0000 (18:11 +0200)]
s390/ap/zcrypt: notify userspace with online, config and mode info

This patch brings 3 reworked/new uevent changes:
* All AP uevents caused by an ap card or queue device now carry an
  additional uevent env value MODE=<accel|cca|ep11>. Here is an
  example:
    KERNEL[1267.301292] add  /devices/ap/card0a (ap)
    ACTION=add
    DEVPATH=/devices/ap/card0a
    SUBSYSTEM=ap
    DEVTYPE=ap_card
    DEV_TYPE=000D
    MODALIAS=ap:t0D
    MODE=ep11  <- this is new
    SEQNUM=1095
  This is true for bind, unbind, add, remove, and change uevents
  related to ap card or ap queue devices.
* On a change of the soft online attribute on a zcrypt queue or card
  device a new CHANGE uevent is sent with an env value ONLINE=<0|1>.
  Example uevent:
    KERNEL[613.067531] change /devices/ap/card09/09.0011 (ap)
    ACTION=change
    DEVPATH=/devices/ap/card09/09.0011
    SUBSYSTEM=ap
    ONLINE=0 <- this is new
    DEVTYPE=ap_queue
    DRIVER=cex4queue
    MODE=cca
    SEQNUM=1070
- On a change of the config state of an zcrypt card device a new
  CHANGE uevent is sent with an env value CONFIG=<0|1>.
  Example uevent:
    KERNEL[876.258680] change /devices/ap/card09 (ap)
    ACTION=change
    DEVPATH=/devices/ap/card09
    SUBSYSTEM=ap
    CONFIG=0 <- this is new
    DEVTYPE=ap_card
    DRIVER=cex4card
    DEV_TYPE=000D
    MODALIAS=ap:t0D
    MODE=cca
    SEQNUM=1073
  Setting a card config on/off causes the dependent queue devices to
  follow the config state change and thus uevents informing about the
  config state change for the queue devices are also emitted.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/decompressor: replace use of perl with simple sed/tr
Rob Landley [Tue, 18 May 2021 04:46:44 +0000 (23:46 -0500)]
s390/decompressor: replace use of perl with simple sed/tr

Use simple sed/tr instead of perl to generate decompressor symbols
file with the same result.

Signed-off-by: Rob Landley <rob@landley.net>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
[gor: changed commit message]
Link: https://lore.kernel.org/r/a48c51f8-5fe4-87e7-284e-c96e2381801a@landley.net
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mcck: cleanup use of cleanup_sie_mcck
Alexander Gordeev [Mon, 17 May 2021 06:18:13 +0000 (08:18 +0200)]
s390/mcck: cleanup use of cleanup_sie_mcck

cleanup_sie_mcck label is called from a single location only
and thus does not need to be a subroutine. Move the labelled
code to the caller - by doing that the SIE critical section
checks appear next to each other and the SIE cleanup becomes
bit more readable.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agoMerge branch 's390/fixes' into features
Vasily Gorbik [Mon, 7 Jun 2021 15:11:10 +0000 (17:11 +0200)]
Merge branch 's390/fixes' into features

This helps to avoid merge conflicts later.

* fixes:
  s390/mcck: fix invalid KVM guest condition check
  s390/mcck: fix calculation of SIE critical section size

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/lowcore: remove superfluous __packed annotations
Heiko Carstens [Tue, 1 Jun 2021 08:59:09 +0000 (10:59 +0200)]
s390/lowcore: remove superfluous __packed annotations

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: use struct tpi_info in lowcore.h
Sven Schnelle [Mon, 10 May 2021 19:10:18 +0000 (21:10 +0200)]
s390: use struct tpi_info in lowcore.h

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: add struct tpi_info to struct pt_regs
Sven Schnelle [Mon, 10 May 2021 19:10:16 +0000 (21:10 +0200)]
s390: add struct tpi_info to struct pt_regs

To avoid casting ptrace members, add a union containing
both struct tpi_info and explicit int_code/int_parm members.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cio: add tpi.h header file
Sven Schnelle [Mon, 10 May 2021 19:10:15 +0000 (21:10 +0200)]
s390/cio: add tpi.h header file

For future work we need the struct tpi_info declaration in asm/ptrace.h.
Due to circular dependencies it cannot stay in asm/lowcore.h or asm/cio.h,
which would be the preferred location. Therefore add it in its own header
file.

Also fix a typo in the length of a reserved field that did not have a
functional effect beyond an incorrect field value in the s390_cio_tpi
tracepoint.

Fixes: 42ace32b5b77 ("s390/cio: Consolidate inline assemblies and related data definitions")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: appldata depends on PROC_SYSCTL
Randy Dunlap [Fri, 28 May 2021 00:24:20 +0000 (17:24 -0700)]
s390: appldata depends on PROC_SYSCTL

APPLDATA_BASE should depend on PROC_SYSCTL instead of PROC_FS.
Building with PROC_FS but not PROC_SYSCTL causes a build error,
since appldata_base.c uses data and APIs from fs/proc/proc_sysctl.c.

arch/s390/appldata/appldata_base.o: in function `appldata_generic_handler':
appldata_base.c:(.text+0x192): undefined reference to `sysctl_vals'

Fixes: b5824b96d565 ("[S390] Remove config options.")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20210528002420.17634-1-rdunlap@infradead.org
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: disable SSP when needed
Fabrice Fontaine [Mon, 10 May 2021 05:31:33 +0000 (07:31 +0200)]
s390: disable SSP when needed

Though -nostdlib is passed in PURGATORY_LDFLAGS and -ffreestanding in
KBUILD_CFLAGS_DECOMPRESSOR, -fno-stack-protector must also be passed to
avoid linking errors related to undefined references to
'__stack_chk_guard' and '__stack_chk_fail' if toolchain enforces
-fstack-protector.

Fixes
 - https://gitlab.com/kubu93/buildroot/-/jobs/1247043361

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Link: https://lore.kernel.org/r/20210510053133.1220167-1-fontaine.fabrice@gmail.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ccwgroup: use BUS_NOTIFY_UNBOUND_DRIVER to trigger ungrouping
Julian Wiedmann [Wed, 5 May 2021 08:28:21 +0000 (10:28 +0200)]
s390/ccwgroup: use BUS_NOTIFY_UNBOUND_DRIVER to trigger ungrouping

ccwgroup_notifier() currently listens for BUS_NOTIFY_UNBIND_DRIVER
events, and triggers an ungrouping for the affected device.

Looking at __device_release_driver(), we can wait for a little longer
until the driver has been fully unbound and eg. bus->remove() has been
called. So listen for BUS_NOTIFY_UNBOUND_DRIVER instead. Due to locking
the current code should work just fine, but this clarifies our intent.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ccwgroup: simplify ungrouping when driver deregisters
Julian Wiedmann [Wed, 5 May 2021 08:25:14 +0000 (10:25 +0200)]
s390/ccwgroup: simplify ungrouping when driver deregisters

driver_unregister() ends up calling __device_release_driver() for
each device that is bound to the driver. Thus ccwgroup_notifier() will
see a BUS_NOTIFY_UNBIND_DRIVER event for these ccwgroup devices, and
trigger the ungrouping.

So there's no need to also trigger the ungrouping from within
ccwgroup_driver_unregister(), remove it.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/vfio-ap: clean up vfio_ap_drv's definition
Julian Wiedmann [Fri, 14 May 2021 08:31:07 +0000 (10:31 +0200)]
s390/vfio-ap: clean up vfio_ap_drv's definition

Define & initialize the driver struct in one go, so that everything
is in one place.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ap: extend AP change bindings-complete uevent with counter
Harald Freudenberger [Tue, 11 May 2021 13:01:18 +0000 (15:01 +0200)]
s390/ap: extend AP change bindings-complete uevent with counter

Userspace udev rules need an indication about the very first AP change
BINDINGS=complete uevent.

So now this uevent is extend with an additional key-value entry
COMPLETECOUNT=<counter>. The very first uevent will show counter=1 and
the following BINDINGS=complete uevents increase this counter by 1.

Here is an example how the very first BINDINGS=complete uevent
looks like:

  KERNEL[106.079510] change   /devices/ap (ap)
  ACTION=change
  DEVPATH=/devices/ap
  SUBSYSTEM=ap
  BINDINGS=complete
  COMPLETECOUNT=1
  SEQNUM=10686

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/smp: remove redundant pcpu::lowcore member
Alexander Gordeev [Thu, 6 May 2021 14:26:54 +0000 (16:26 +0200)]
s390/smp: remove redundant pcpu::lowcore member

Per-CPU pointer to lowcore is stored in global lowcore_ptr[]
array and duplicated in struct pcpu::lowcore member. This
update removes the redundancy.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/smp: do not preserve boot CPU lowcore on hotplug
Alexander Gordeev [Thu, 6 May 2021 14:26:53 +0000 (16:26 +0200)]
s390/smp: do not preserve boot CPU lowcore on hotplug

Once the kernel is running the boot CPU lowcore becomes
freeable and does not differ from the secondary CPU ones
in any way. Make use of it and do not preserve the boot
CPU lowcore on unplugging. That allows returning unused
memory when the boot CPU is offline and makes the code
more clear.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/smp: reallocate IPL CPU lowcore
Alexander Gordeev [Thu, 6 May 2021 14:26:52 +0000 (16:26 +0200)]
s390/smp: reallocate IPL CPU lowcore

The lowcore for IPL CPU is special. It is allocated early
in the boot process using memblock and never freed since.
The reason is pcpu_alloc_lowcore() and pcpu_free_lowcore()
routines use page allocator which is not available when
the IPL CPU is getting initialized.

Similar problem is already addressed for stacks - once the
virtual memory is available the early boot stacks get re-
allocated. Doing the same for lowcore will allow freeing
the IPL CPU lowcore and make no difference between the
boot and secondary CPUs.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mm: ensure switch_mm() is executed with interrupts disabled
Alexander Gordeev [Thu, 6 May 2021 18:06:00 +0000 (20:06 +0200)]
s390/mm: ensure switch_mm() is executed with interrupts disabled

Architecture callback switch_mm() is allowed to be called with
enabled interrupts. However, our implementation of switch_mm()
does not expect that. Let's follow other architectures and make
sure switch_mm() is always executed with interrupts disabled,
regardless of what happens with the generic kernel code in the
future.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/boot: access kernel command line via parmarea
Heiko Carstens [Fri, 7 May 2021 17:12:54 +0000 (19:12 +0200)]
s390/boot: access kernel command line via parmarea

Access the kernel command line via parmarea instead of using the
COMMAND_LINE define.
With this the following gcc11 warning is removed:

arch/s390/boot/ipl_parm.c: In function ‘setup_boot_command_line’:
arch/s390/boot/ipl_parm.c:168:50: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ipl: make parameter area accessible via struct parmarea
Heiko Carstens [Fri, 7 May 2021 17:12:39 +0000 (19:12 +0200)]
s390/ipl: make parameter area accessible via struct parmarea

Since commit 9a965ea95135 ("s390/kexec_file: Simplify parmarea
access") we have struct parmarea which describes the layout of the
kernel parameter area.

Make the kernel parameter area available as global variable parmarea
of type struct parmarea, which allows to easily access its members.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/sclp_vt220: fix console name to match device
Valentin Vidic [Tue, 27 Apr 2021 19:40:10 +0000 (21:40 +0200)]
s390/sclp_vt220: fix console name to match device

Console name reported in /proc/consoles:

  ttyS1                -W- (EC p  )    4:65

does not match the char device name:

  crw--w----    1 root     root        4,  65 May 17 12:18 /dev/ttysclp0

so debian-installer inside a QEMU s390x instance gets confused and fails
to start with the following error:

  steal-ctty: No such file or directory

Signed-off-by: Valentin Vidic <vvidic@valentin-vidic.from.hr>
Link: https://lore.kernel.org/r/20210427194010.9330-1-vvidic@valentin-vidic.from.hr
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ccwgroup: release the cdevs from within dev->release()
Julian Wiedmann [Sat, 24 Apr 2021 10:12:38 +0000 (12:12 +0200)]
s390/ccwgroup: release the cdevs from within dev->release()

Wiring up the cdevs is an essential part of the gdev creation. So
release them during the gdev destruction, ie. on the last put_device().
This could cause us to hold on to the cdevs a tiny bit longer, but
that's not a real concern.

As we have much less certainty of what context this put_device() is
executed from, switch to irqsave locking.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/ap: wire up bus->probe and bus->remove
Julian Wiedmann [Fri, 16 Apr 2021 10:46:27 +0000 (12:46 +0200)]
s390/ap: wire up bus->probe and bus->remove

Hijacking the device_driver's probe/remove callbacks for purely
bus-internal logic is a very unconvential construct. Instead just set
up our callbacks in the AP bus struct, and really_probe() will call them
in the same way as before.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/zcrypt: remove zcrypt_device_count
Julian Wiedmann [Fri, 16 Apr 2021 09:58:41 +0000 (11:58 +0200)]
s390/zcrypt: remove zcrypt_device_count

It's evidently unused.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/crypto: fix function/prototype mismatches
Sven Schnelle [Tue, 4 May 2021 15:07:02 +0000 (17:07 +0200)]
s390/crypto: fix function/prototype mismatches

gcc-11 warns:

drivers/s390/crypto/zcrypt_ccamisc.c:298:38: warning: argument 4 of type u8[64] {aka unsigned char[64]} with mismatched bound [-Warray-parameter=]
  298 |                   u32 keybitsize, u8 seckey[SECKEYBLOBSIZE])
      |                                   ~~~^~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/s390/crypto/zcrypt_ccamisc.c:24:
drivers/s390/crypto/zcrypt_ccamisc.h:162:63: note: previously declared as u8 * {aka unsigned char *}
  162 | int cca_genseckey(u16 cardnr, u16 domain, u32 keybitsize, u8 *seckey);
      |                                                           ~~~~^~~~~~
drivers/s390/crypto/zcrypt_ccamisc.c:441:41: warning: argument 5 of type u8[64] {aka unsigned char[64]} with mismatched bound [-Warray-parameter=]
  441 |                    const u8 *clrkey, u8 seckey[SECKEYBLOBSIZE])
      |                                      ~~~^~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/s390/crypto/zcrypt_ccamisc.c:24:
drivers/s390/crypto/zcrypt_ccamisc.h:168:42: note: previously declared as u8 * {aka unsigned char *}
  168 |                    const u8 *clrkey, u8 *seckey);
      |                                      ~~~~^~~~~~

Fix this by making the prototypes match the functions.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/traps: add struct to access transactional diagnostic block
Sven Schnelle [Wed, 5 May 2021 20:01:16 +0000 (22:01 +0200)]
s390/traps: add struct to access transactional diagnostic block

gcc-11 warns:

arch/s390/kernel/traps.c: In function __do_pgm_check:
arch/s390/kernel/traps.c:319:17: warning: memcpy reading 256 bytes from a region of size 0 [-Wstringop-overread]
  319 |                 memcpy(&current->thread.trap_tdb, &S390_lowcore.pgm_tdb, 256);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by adding a struct pgm_tdb to struct lowcore and copy that.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/irq: add union/struct to access external interrupt parameters
Sven Schnelle [Wed, 5 May 2021 20:01:11 +0000 (22:01 +0200)]
s390/irq: add union/struct to access external interrupt parameters

gcc-11 warns:

arch/s390/kernel/irq.c: In function do_ext_irq:
arch/s390/kernel/irq.c:175:9: warning: memcpy reading 4 bytes from a region of size 0 [-Wstringop-overread]
  175 |         memcpy(&regs->int_code, &S390_lowcore.ext_cpu_addr, 4);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by adding a struct for int_code to struct lowcore.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/facilities: move stfl information from lowcore to global data
Sven Schnelle [Wed, 5 May 2021 20:01:10 +0000 (22:01 +0200)]
s390/facilities: move stfl information from lowcore to global data

With gcc-11, there are a lot of warnings because the facility functions
are accessing lowcore through a null pointer. Fix this by moving the
facility arrays away from lowcore.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/entry: use assignment to read intcode / asm to copy gprs
Sven Schnelle [Wed, 5 May 2021 20:01:09 +0000 (22:01 +0200)]
s390/entry: use assignment to read intcode / asm to copy gprs

arch/s390/kernel/syscall.c: In function __do_syscall:
arch/s390/kernel/syscall.c:147:9: warning: memcpy reading 64 bytes from a region of size 0 [-Wstringop-overread]
  147 |         memcpy(&regs->gprs[8], S390_lowcore.save_area_sync, 8 * sizeof(unsigned long));
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/s390/kernel/syscall.c:148:9: warning: memcpy reading 4 bytes from a region of size 0 [-Wstringop-overread]
  148 |         memcpy(&regs->int_code, &S390_lowcore.svc_ilc, sizeof(regs->int_code));
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by moving the gprs restore from C to assembly, and use a assignment
for int_code instead of memcpy.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390: enable HAVE_IOREMAP_PROT
Niklas Schnelle [Fri, 19 Feb 2021 11:00:52 +0000 (12:00 +0100)]
s390: enable HAVE_IOREMAP_PROT

In commit 1381a0c67671 ("s390/pci: Implement ioremap_wc/prot() with
MIO") we implemented both ioremap_wc() and ioremap_prot() however until
now we had not set HAVE_IOREMAP_PROT in Kconfig, do so now.

This also requires implementing pte_pgprot() as this is used in the
generic_access_phys() code enabled by CONFIG_HAVE_IOREMAP_PROT. As with
ioremap_wc() we need to take the MMIO Write Back bit index into account.

Moreover since the pgprot value returned from pte_pgprot() is to be used
for mappings into kernel address space we must make sure that it uses
appropriate kernel page table protection bits. In particular a pgprot
value originally coming from userspace could have the _PAGE_PROTECT
bit set to enable fault based dirty bit accounting which would then make
the mapping inaccessible when used in kernel address space.

Fixes: 1381a0c67671 ("s390/pci: Implement ioremap_wc/prot() with MIO")
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cpumf: remove WARN_ON_ONCE in counter start handler
Thomas Richter [Thu, 29 Apr 2021 13:04:30 +0000 (15:04 +0200)]
s390/cpumf: remove WARN_ON_ONCE in counter start handler

Remove some WARN_ON_ONCE() warnings when a counter is started. Each
counter is installed function calls
event_sched_in() --> cpumf_pmu_add(..., PERF_EF_START).

This is done after the event has been created using
perf_pmu_event_init() which verifies the counter is valid.
Member hwc->config must be valid at this point.

Function cpumf_pmu_start(..., PERF_EF_RELOAD) is called from
function cpumf_pmu_add() for counter events. All other invocations of
cpumf_pmu_start(..., PERF_EF_RELOAD) are from the performance subsystem
for sampling events.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/cpumf: remove counter transaction call backs
Thomas Richter [Wed, 28 Apr 2021 11:30:56 +0000 (13:30 +0200)]
s390/cpumf: remove counter transaction call backs

The command 'perf stat -e cycles ...' triggers the following function
sequence in the CPU Measurement Facility counter device driver:

perf_pmu_event_init()
  __hw_perf_event_init()
    validate_ctr_auth()
    validate_ctr_version()

During event creation, the counter number is checked in functions
validate_ctr_auth() and validate_ctr_version() to verify it is a valid
counter and supported by the hardware. If this is not the case, both
functions return an error and the event is not created. System call
perf_event_open() returns an error in this case.

Later on the event is installed in the kernel event subsystem and the
driver functions cpumf_pmu_add() and cpumf_pmu_commit_txn() are called
to install the counter event by the hardware.

Since both events have been verified at event creation, there is no need
to re-evaluate the authorization state. This can not change since on
 * LPARs the authorization change requires a restart of the LPAR (and
   thus a reboot of the kernel)
 * DPMs can not take resources away, just add them.

Also the sequence of CPU Measurement facility counter device driver
calls is
  cpumf_pmu_start_txn
  cpumf_pmu_add
  cpumf_pmu_start
  cpumf_pmu_commit_txn
for every single event. Which means the condition in cpumf_pmu_add()
is never met and validate_ctr_auth() is never called.

This leaves the counter device driver transaction functions with
just one task:
start_txn: Verify a transaction is not in flight and call
perf_pmu_disable()
cancel_txn, commit_txn: Verify a transaction is in flight and call
perf_pmu_enable()

The same functionality is provided by the default transaction handling
functions in kernel/events/core.c. Use those by removing the
counter device driver private call back functions.

Suggested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mcck: fix invalid KVM guest condition check
Alexander Gordeev [Mon, 17 May 2021 06:18:12 +0000 (08:18 +0200)]
s390/mcck: fix invalid KVM guest condition check

Wrong condition check is used to decide if a machine check hit
while in KVM guest. As result of this check the instruction
following the SIE critical section might be considered as still
in KVM guest and _CIF_MCCK_GUEST CPU flag mistakenly set as
result.

Fixes: 4ab708ccde4b ("s390/nmi: s390: New low level handling for machine check happening in guest")
Cc: <stable@vger.kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agos390/mcck: fix calculation of SIE critical section size
Alexander Gordeev [Mon, 17 May 2021 06:18:11 +0000 (08:18 +0200)]
s390/mcck: fix calculation of SIE critical section size

The size of SIE critical section is calculated wrongly
as result of a missed subtraction in commit 02ea41696b8d
("s390: remove critical section cleanup from entry.S")

Fixes: 02ea41696b8d ("s390: remove critical section cleanup from entry.S")
Cc: <stable@vger.kernel.org>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
3 years agoLinux 5.13-rc5
Linus Torvalds [Sun, 6 Jun 2021 22:47:27 +0000 (15:47 -0700)]
Linux 5.13-rc5

3 years agoMerge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Linus Torvalds [Sun, 6 Jun 2021 22:39:56 +0000 (15:39 -0700)]
Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "Five small and fairly minor fixes, all in drivers"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: scsi_devinfo: Add blacklist entry for HPE OPEN-V
  scsi: ufs: ufs-mediatek: Fix HCI version in some platforms
  scsi: qedf: Do not put host in qedf_vport_create() unconditionally
  scsi: lpfc: Fix failure to transmit ABTS on FC link
  scsi: target: core: Fix warning on realtime kernels

3 years agoMerge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git...
Linus Torvalds [Sun, 6 Jun 2021 21:24:13 +0000 (14:24 -0700)]
Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Miscellaneous ext4 bug fixes"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: Only advertise encrypted_casefold when encryption and unicode are enabled
  ext4: fix no-key deletion for encrypt+casefold
  ext4: fix memory leak in ext4_fill_super
  ext4: fix fast commit alignment issues
  ext4: fix bug on in ext4_es_cache_extent as ext4_split_extent_at failed
  ext4: fix accessing uninit percpu counter variable with fast_commit
  ext4: fix memory leak in ext4_mb_init_backend on error path.

3 years agoMerge tag 'arm-soc-fixes-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git...
Linus Torvalds [Sun, 6 Jun 2021 20:00:36 +0000 (13:00 -0700)]
Merge tag 'arm-soc-fixes-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc

Pull ARM SoC fixes from Olof Johansson:
 "A set of fixes that have been coming in over the last few weeks, the
  usual mix of fixes:

   - DT fixups for TI K3

   - SATA drive detection fix for TI DRA7

   - Power management fixes and a few build warning removals for OMAP

   - OP-TEE fix to use standard API for UUID exporting

   - DT fixes for a handful of i.MX boards

  And a few other smaller items"

* tag 'arm-soc-fixes-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (29 commits)
  arm64: meson: select COMMON_CLK
  soc: amlogic: meson-clk-measure: remove redundant dev_err call in meson_msr_probe()
  ARM: OMAP1: ams-delta: remove unused function ams_delta_camera_power
  bus: ti-sysc: Fix flakey idling of uarts and stop using swsup_sidle_act
  ARM: dts: imx: emcon-avari: Fix nxp,pca8574 #gpio-cells
  ARM: dts: imx7d-pico: Fix the 'tuning-step' property
  ARM: dts: imx7d-meerkat96: Fix the 'tuning-step' property
  arm64: dts: freescale: sl28: var1: fix RGMII clock and voltage
  arm64: dts: freescale: sl28: var4: fix RGMII clock and voltage
  ARM: imx: pm-imx27: Include "common.h"
  arm64: dts: zii-ultra: fix 12V_MAIN voltage
  arm64: dts: zii-ultra: remove second GEN_3V3 regulator instance
  arm64: dts: ls1028a: fix memory node
  bus: ti-sysc: Fix am335x resume hang for usb otg module
  ARM: OMAP2+: Fix build warning when mmc_omap is not built
  ARM: OMAP1: isp1301-omap: Add missing gpiod_add_lookup_table function
  ARM: OMAP1: Fix use of possibly uninitialized irq variable
  optee: use export_uuid() to copy client UUID
  arm64: dts: ti: k3*: Introduce reg definition for interrupt routers
  arm64: dts: ti: k3-am65|j721e|am64: Map the dma / navigator subsystem via explicit ranges
  ...

3 years agoMerge tag 'powerpc-5.13-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...
Linus Torvalds [Sun, 6 Jun 2021 19:39:36 +0000 (12:39 -0700)]
Merge tag 'powerpc-5.13-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "Fix our KVM reverse map real-mode handling since we enabled huge
  vmalloc (in some configurations).

  Revert a recent change to our IOMMU code which broke some devices.

  Fix KVM handling of FSCR on P7/P8, which could have possibly let a
  guest crash it's Qemu.

  Fix kprobes validation of prefixed instructions across page boundary.

  Thanks to Alexey Kardashevskiy, Christophe Leroy, Fabiano Rosas,
  Frederic Barrat, Naveen N. Rao, and Nicholas Piggin"

* tag 'powerpc-5.13-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  Revert "powerpc/kernel/iommu: Align size for IOMMU_PAGE_SIZE() to save TCEs"
  KVM: PPC: Book3S HV: Save host FSCR in the P7/8 path
  powerpc: Fix reverse map real-mode address lookup with huge vmalloc
  powerpc/kprobes: Fix validation of prefixed instructions across page boundary

3 years agoMerge tag 'x86_urgent_for_v5.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel...
Linus Torvalds [Sun, 6 Jun 2021 19:25:43 +0000 (12:25 -0700)]
Merge tag 'x86_urgent_for_v5.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Borislav Petkov:
 "A bunch of x86/urgent stuff accumulated for the last two weeks so
  lemme unload it to you.

  It should be all totally risk-free, of course. :-)

   - Fix out-of-spec hardware (1st gen Hygon) which does not implement
     MSR_AMD64_SEV even though the spec clearly states so, and check
     CPUID bits first.

   - Send only one signal to a task when it is a SEGV_PKUERR si_code
     type.

   - Do away with all the wankery of reserving X amount of memory in the
     first megabyte to prevent BIOS corrupting it and simply and
     unconditionally reserve the whole first megabyte.

   - Make alternatives NOP optimization work at an arbitrary position
     within the patched sequence because the compiler can put
     single-byte NOPs for alignment anywhere in the sequence (32-bit
     retpoline), vs our previous assumption that the NOPs are only
     appended.

   - Force-disable ENQCMD[S] instructions support and remove
     update_pasid() because of insufficient protection against FPU state
     modification in an interrupt context, among other xstate horrors
     which are being addressed at the moment. This one limits the
     fallout until proper enablement.

   - Use cpu_feature_enabled() in the idxd driver so that it can be
     build-time disabled through the defines in disabled-features.h.

   - Fix LVT thermal setup for SMI delivery mode by making sure the APIC
     LVT value is read before APIC initialization so that softlockups
     during boot do not happen at least on one machine.

   - Mark all legacy interrupts as legacy vectors when the IO-APIC is
     disabled and when all legacy interrupts are routed through the PIC"

* tag 'x86_urgent_for_v5.13-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Check SME/SEV support in CPUID first
  x86/fault: Don't send SIGSEGV twice on SEGV_PKUERR
  x86/setup: Always reserve the first 1M of RAM
  x86/alternative: Optimize single-byte NOPs at an arbitrary position
  x86/cpufeatures: Force disable X86_FEATURE_ENQCMD and remove update_pasid()
  dmaengine: idxd: Use cpu_feature_enabled()
  x86/thermal: Fix LVT thermal setup for SMI delivery mode
  x86/apic: Mark _all_ legacy interrupts when IO/APIC is missing

3 years agoext4: Only advertise encrypted_casefold when encryption and unicode are enabled
Daniel Rosenberg [Thu, 3 Jun 2021 09:48:49 +0000 (09:48 +0000)]
ext4: Only advertise encrypted_casefold when encryption and unicode are enabled

Encrypted casefolding is only supported when both encryption and
casefolding are both enabled in the config.

Fixes: 6014b5b6422e ("ext4: handle casefolding with encryption")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Link: https://lore.kernel.org/r/20210603094849.314342-1-drosen@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>