With CONFIG_GENDWARFKSYMS, __gendwarfksyms_ptr variables are
added to the kernel in EXPORT_SYMBOL() to ensure DWARF type
information is available for exported symbols in the TUs where
they're actually exported. These symbols are dropped when linking
vmlinux, but dangling references to them remain in DWARF.
With CONFIG_DEBUG_INFO_BTF enabled on X86, pahole versions after
commit 47dcb534e253 ("btf_encoder: Stop indexing symbols for
VARs") and before commit 9810758003ce ("btf_encoder: Verify 0
address DWARF variables are in ELF section") place these symbols
in the .data..percpu section, which results in an "Invalid
offset" error in btf_datasec_check_meta() during boot, as all
the variables are at zero offset and have non-zero size. If
CONFIG_DEBUG_INFO_BTF_MODULES is enabled, this also results in a
failure to load modules with:
failed to validate module [$module] BTF: -22
As the issue occurs in pahole v1.28 and the fix was merged
after v1.29 was released, require pahole <v1.28 or >v1.29 when
GENDWARFKSYMS is enabled with DEBUG_INFO_BTF on X86.
Reported-by: Paolo Pisati <paolo.pisati@canonical.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
- Support multiple hook locations for maint scripts of Debian package
- Remove 'cpio' from the build tool requirement
- Introduce gendwarfksyms tool, which computes CRCs for export symbols
based on the DWARF information
- Support CONFIG_MODVERSIONS for Rust
- Resolve all conflicts in the genksyms parser
- Fix several syntax errors in genksyms
-----BEGIN PGP SIGNATURE-----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=D553
-----END PGP SIGNATURE-----
Merge tag 'kbuild-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Support multiple hook locations for maint scripts of Debian package
- Remove 'cpio' from the build tool requirement
- Introduce gendwarfksyms tool, which computes CRCs for export symbols
based on the DWARF information
- Support CONFIG_MODVERSIONS for Rust
- Resolve all conflicts in the genksyms parser
- Fix several syntax errors in genksyms
* tag 'kbuild-v6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (64 commits)
kbuild: fix Clang LTO with CONFIG_OBJTOOL=n
kbuild: Strip runtime const RELA sections correctly
kconfig: fix memory leak in sym_warn_unmet_dep()
kconfig: fix file name in warnings when loading KCONFIG_DEFCONFIG_LIST
genksyms: fix syntax error for attribute before init-declarator
genksyms: fix syntax error for builtin (u)int*x*_t types
genksyms: fix syntax error for attribute after 'union'
genksyms: fix syntax error for attribute after 'struct'
genksyms: fix syntax error for attribute after abstact_declarator
genksyms: fix syntax error for attribute before nested_declarator
genksyms: fix syntax error for attribute before abstract_declarator
genksyms: decouple ATTRIBUTE_PHRASE from type-qualifier
genksyms: record attributes consistently for init-declarator
genksyms: restrict direct-declarator to take one parameter-type-list
genksyms: restrict direct-abstract-declarator to take one parameter-type-list
genksyms: remove Makefile hack
genksyms: fix last 3 shift/reduce conflicts
genksyms: fix 6 shift/reduce conflicts and 5 reduce/reduce conflicts
genksyms: reduce type_qualifier directly to decl_specifier
genksyms: rename cvar_qualifier to type_qualifier
...
Switch away from using sha1 for module signing by default and use the
more modern sha512 instead, which is what among others Arch, Fedora,
RHEL, and Ubuntu are currently using for their kernels.
Sha1 has not been considered secure against well-funded opponents since
2005[1]; since 2011 the NIST and other organizations furthermore
recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora
Linux 41+[3], and likely some other current and future distributions
reject the creation of sha1 signatures, which leads to a build error of
allmodconfig configurations:
80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342:
make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1
make[4]: *** Deleting file 'certs/signing_key.pem'
make[4]: *** Waiting for unfinished jobs....
make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2
make[2]: *** [.../Makefile:1936: .] Error 2
make[1]: *** [.../Makefile:224: __sub-make] Error 2
make[1]: Leaving directory '...'
make: *** [Makefile:224: __sub-make] Error 2
This change makes allmodconfig work again and sets a default that is
more appropriate for current and future users, too.
Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1]
Link: https://csrc.nist.gov/projects/hash-functions [2]
Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3]
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: kdevops <kdevops@lists.linux.dev> [0]
Link: https://github.com/linux-kdevops/linux-modules-kpd/actions/runs/11420092929/job/31775404330 [0]
Link: https://lore.kernel.org/r/52ee32c0c92afc4d3263cea1f8a1cdc809728aff.1729088288.git.linux@leemhuis.info
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
If you know that your kernel modules will only ever be loaded by a newer
kernel, you can disable BASIC_MODVERSIONS to save space. This also
allows easy creation of test modules to see how tooling will respond to
modules that only have the new format.
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Generate both the existing modversions format and the new extended one
when running modpost. Presence of this metadata in the final .ko is
guarded by CONFIG_EXTENDED_MODVERSIONS.
We no longer generate an error on long symbols in modpost if
CONFIG_EXTENDED_MODVERSIONS is set, as they can now be appropriately
encoded in the extended section. These symbols will be skipped in the
previous encoding. An error will still be generated if
CONFIG_EXTENDED_MODVERSIONS is not set.
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
When MODVERSIONS is enabled, allow selecting gendwarfksyms as the
implementation, but default to genksyms.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Add a basic DWARF parser, which uses libdw to traverse the debugging
information in an object file and looks for functions and variables.
In follow-up patches, this will be expanded to produce symbol versions
for CONFIG_MODVERSIONS from DWARF.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
There are a few fixes / cleanups from Vincent, Chunhui, and Petr, but the
most important part of this pull request is the Rust community stepping
up to help maintain both C / Rust code for future Rust module support. We
grow the set of modules maintainers by 3 now, and with this hope to scale to
help address what's needed to properly support future Rust module support.
A lot of exciting stuff coming in future kernel releases.
This has been on linux-next for ~ 3 weeks now with no issues.
-----BEGIN PGP SIGNATURE-----
iQJGBAABCgAwFiEENnNq2KuOejlQLZofziMdCjCSiKcFAmb3InQSHG1jZ3JvZkBr
ZXJuZWwub3JnAAoJEM4jHQowkoinA/IP/RP3O3Cwtyjd51lMNzEmJR0WE0J7/C3z
v4L3teqoiH4vWF0vDd8jVE1SL9RZ0TnrSUUF/Kbf7YolXELPO+WSvPepGqlzeUTd
KH+PZX+AmaGXhwAGmB53AMhcP8HmGci+IZZgyZUnYxZawcFYU24WYO84JAKltNsy
/wqepYXObc0HiNXk+VS3h8Z+1y9nhJ55xluvTf5guQbrtjl1xWXSdVdF1/V5wnjp
qShNSNn1bktFO0lK7IW/UmM0kEoFHHyUslwNcP/rJLIb99lDV3M+Vd3i41dBkuYw
iSCD+a/0fOmUj909Q4VfZQkK4vKEi04XIz1EHb2uYOGKcr75gnWmCRyUL1TJSFO/
oXNd2SlvwMYXxMczsaLppAPERRgSMWnsBEZWZ7nk2uBpuFay43LfEdZcPwknGNkz
7Ns+3PHr6W3phUo1izrgxBk6xTyEDR6etxThSGvq/dhG3VuivV6hRyxFZX9NaTSD
a/uFhIj2f8FuV9TLYUzPO/NwwLklPFe9dCvtWEHgSvtyaeX1pSvyjz8fLbXDGyu/
qVXMp2fegLJ2bq9A0ABtd7nuVNCAN24pl+Nwws+GMRmCg9b1Sfego16WoLUDbbHX
mjVAFTtKgqEg0ePnbjqGm7I7siY/9x8I39aA9WbNoXKNFu3hwMDHLAavATmj+1dV
UlrMxvfv20WQ
=4P89
-----END PGP SIGNATURE-----
Merge tag 'modules-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull module updates from Luis Chamberlain:
"There are a few fixes / cleanups from Vincent, Chunhui, and Petr, but
the most important part of this pull request is the Rust community
stepping up to help maintain both C / Rust code for future Rust module
support. We grow the set of modules maintainers by three now, and with
this hope to scale to help address what's needed to properly support
future Rust module support.
A lot of exciting stuff coming in future kernel releases.
This has been on linux-next for ~ 3 weeks now with no issues"
* tag 'modules-6.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
module: Refine kmemleak scanned areas
module: abort module loading when sysfs setup suffer errors
MAINTAINERS: scale modules with more reviewers
module: Clean up the description of MODULE_SIG_<type>
module: Split modules_install compression and in-kernel decompression
Currently the Rust support is gated on not having MODVERSIONS enabled,
and as a result an "allmodconfig" build will disable Rust build tests.
While MODVERSIONS configurations are worth build testing, the feature is
not actually meaningful unless you run the result, and I'd rather get
build coverage of Rust than MODVERSIONS. So let's disable MODVERSIONS
for build testing until the Rust side clears up.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The MODULE_SIG_<type> config choice has an inconsistent prompt styled as
a question and lengthy option names.
Simplify the prompt and option names to be consistent with other module
options.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
The kernel configuration allows specifying a module compression mode. If
one is selected then each module gets compressed during
'make modules_install' and additionally one can also enable support for
a respective direct in-kernel decompression support. This means that the
decompression support cannot be enabled without the automatic compression.
Some distributions, such as the (open)SUSE family, use a signer service for
modules. A build runs on a worker machine but signing is done by a separate
locked-down server that is in possession of the signing key. The build
invokes 'make modules_install' to create a modules tree, collects
information about the modules, asks the signer service for their signature,
appends each signature to the respective module and compresses all modules.
When using this arrangment, the 'make modules_install' step produces
unsigned+uncompressed modules and the distribution's own build recipe takes
care of signing and compression later.
The signing support can be currently enabled without automatically signing
modules during 'make modules_install'. However, the in-kernel decompression
support can be selected only after first enabling automatic compression
during this step.
To allow only enabling the in-kernel decompression support without the
automatic compression during 'make modules_install', separate the
compression options similarly to the signing options, as follows:
> Enable loadable module support
[*] Module compression
Module compression type (GZIP) --->
[*] Automatically compress all modules
[ ] Support in-kernel module decompression
* "Module compression" (MODULE_COMPRESS) is a new main switch for the
compression/decompression support. It replaces MODULE_COMPRESS_NONE.
* "Module compression type" (MODULE_COMPRESS_<type>) chooses the
compression type, one of GZ, XZ, ZSTD.
* "Automatically compress all modules" (MODULE_COMPRESS_ALL) is a new
option to enable module compression during 'make modules_install'. It
defaults to Y.
* "Support in-kernel module decompression" (MODULE_DECOMPRESS) enables
in-kernel decompression.
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
module_alloc() is used everywhere as a mean to allocate memory for code.
Beside being semantically wrong, this unnecessarily ties all subsystems
that need to allocate code, such as ftrace, kprobes and BPF to modules and
puts the burden of code allocation to the modules code.
Several architectures override module_alloc() because of various
constraints where the executable memory can be located and this causes
additional obstacles for improvements of code allocation.
Start splitting code allocation from modules by introducing execmem_alloc()
and execmem_free() APIs.
Initially, execmem_alloc() is a wrapper for module_alloc() and
execmem_free() is a replacement of module_memfree() to allow updating all
call sites to use the new APIs.
Since architectures define different restrictions on placement,
permissions, alignment and other parameters for memory that can be used by
different subsystems that allocate executable memory, execmem_alloc() takes
a type argument, that will be used to identify the calling subsystem and to
allow architectures define parameters for ranges suitable for that
subsystem.
No functional changes.
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
If UNUSED_KSYMS_WHITELIST is a file generated
before Kbuild runs, and the source tree is in
a read-only filesystem, the developer must put
the file somewhere and specify an absolute
path to UNUSED_KSYMS_WHITELIST. This worked,
but if IKCONFIG=y, an absolute path is embedded
into .config and eventually into vmlinux, causing
the build to be less reproducible when building
on a different machine.
This patch makes the handling of
UNUSED_KSYMS_WHITELIST to be similar to
MODULE_SIG_KEY.
First, check if UNUSED_KSYMS_WHITELIST is an
absolute path, just as before this patch. If so,
use the path as is.
If it is a relative path, use wildcard to check
the existence of the file below objtree first.
If it does not exist, fall back to the original
behavior of adding $(srctree)/ before the value.
After this patch, the developer can put the generated
file in objtree, then use a relative path against
objtree in .config, eradicating any absolute paths
that may be evaluated differently on different machines.
Signed-off-by: Yifan Hong <elsk@google.com>
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
zero in iaa.
-----BEGIN PGP SIGNATURE-----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=Mau0
-----END PGP SIGNATURE-----
Merge tag 'v6.9-p2' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto fixes from Herbert Xu:
"This fixes a regression that broke iwd as well as a divide by zero in
iaa"
* tag 'v6.9-p2' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
crypto: iaa - Fix nr_cpus < nr_iaa case
Revert "crypto: pkcs7 - remove sha1 support"
This reverts commit 16ab7cb582 because it
broke iwd. iwd uses the KEYCTL_PKEY_* UAPIs via its dependency libell,
and apparently it is relying on SHA-1 signature support. These UAPIs
are fairly obscure, and their documentation does not mention which
algorithms they support. iwd really should be using a properly
supported userspace crypto library instead. Regardless, since something
broke we have to revert the change.
It may be possible that some parts of this commit can be reinstated
without breaking iwd (e.g. probably the removal of MODULE_SIG_SHA1), but
for now this just does a full revert to get things working again.
Reported-by: Karel Balej <balejk@matfyz.cz>
Closes: https://lore.kernel.org/r/CZSHRUIJ4RKL.34T4EASV5DNJM@matfyz.cz
Cc: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Tested-by: Karel Balej <balejk@matfyz.cz>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This reverts the following two commits:
- a555bdd0c5 ("Kbuild: enable TRIM_UNUSED_KSYMS again, with some guarding")
- 5cf0fd591f ("Kbuild: disable TRIM_UNUSED_KSYMS option")
Commit 5e9e95cc91 ("kbuild: implement CONFIG_TRIM_UNUSED_KSYMS without
recursion") solved the build time issue.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Add Kconfig options to use SHA-3 for kernel module signing. 256 size
for RSA only, and higher sizes for RSA and NIST P-384.
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
sha224 does not provide enough security against collision attacks
relative to the default keys used for signing (RSA 4k & P-384). Also
sha224 never became popular, as sha256 got widely adopter ahead of
sha224 being introduced.
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Removes support for sha1 signed kernel modules, importing sha1 signed
x.509 certificates.
rsa-pkcs1pad keeps sha1 padding support, which seems to be used by
virtio driver.
sha1 remains available as there are many drivers and subsystems using
it. Note only hmac(sha1) with secret keys remains cryptographically
secure.
In the kernel there are filesystems, IMA, tpm/pcr that appear to be
using sha1. Maybe they can all start to be slowly upgraded to
something else i.e. blake3, ParallelHash, SHAKE256 as needed.
Signed-off-by: Dimitri John Ledkov <dimitri.ledkov@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The finit_module() system call can in the worst case use up to more than
twice of a module's size in virtual memory. Duplicate finit_module()
system calls are non fatal, however they unnecessarily strain virtual
memory during bootup and in the worst case can cause a system to fail
to boot. This is only known to currently be an issue on systems with
larger number of CPUs.
To help debug this situation we need to consider the different sources for
finit_module(). Requests from the kernel that rely on module auto-loading,
ie, the kernel's *request_module() API, are one source of calls. Although
modprobe checks to see if a module is already loaded prior to calling
finit_module() there is a small race possible allowing userspace to
trigger multiple modprobe calls racing against modprobe and this not
seeing the module yet loaded.
This adds debugging support to the kernel module auto-loader (*request_module()
calls) to easily detect duplicate module requests. To aid with possible bootup
failure issues incurred by this, it will converge duplicates requests to a
single request. This avoids any possible strain on virtual memory during
bootup which could be incurred by duplicate module autoloading requests.
Folks debugging virtual memory abuse on bootup can and should enable
this to see what pr_warn()s come on, to see if module auto-loading is to
blame for their wores. If they see duplicates they can further debug this
by enabling the module.enable_dups_trace kernel parameter or by enabling
CONFIG_MODULE_DEBUG_AUTOLOAD_DUPS_TRACE.
Current evidence seems to point to only a few duplicates for module
auto-loading. And so the source for other duplicates creating heavy
virtual memory pressure due to larger number of CPUs should becoming
from another place (likely udev).
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Loading modules with finit_module() can end up using vmalloc(), vmap()
and vmalloc() again, for a total of up to 3 separate allocations in the
worst case for a single module. We always kernel_read*() the module,
that's a vmalloc(). Then vmap() is used for the module decompression,
and if so the last read buffer is freed as we use the now decompressed
module buffer to stuff data into our copy module. The last allocation is
specific to each architectures but pretty much that's generally a series
of vmalloc() calls or a variation of vmalloc to handle ELF sections with
special permissions.
Evaluation with new stress-ng module support [1] with just 100 ops
is proving that you can end up using GiBs of data easily even with all
care we have in the kernel and userspace today in trying to not load modules
which are already loaded. 100 ops seems to resemble the sort of pressure a
system with about 400 CPUs can create on module loading. Although issues
relating to duplicate module requests due to each CPU inucurring a new
module reuest is silly and some of these are being fixed, we currently lack
proper tooling to help diagnose easily what happened, when it happened
and who likely is to blame -- userspace or kernel module autoloading.
Provide an initial set of stats which use debugfs to let us easily scrape
post-boot information about failed loads. This sort of information can
be used on production worklaods to try to optimize *avoiding* redundant
memory pressure using finit_module().
There's a few examples that can be provided:
A 255 vCPU system without the next patch in this series applied:
Startup finished in 19.143s (kernel) + 7.078s (userspace) = 26.221s
graphical.target reached after 6.988s in userspace
And 13.58 GiB of virtual memory space lost due to failed module loading:
root@big ~ # cat /sys/kernel/debug/modules/stats
Mods ever loaded 67
Mods failed on kread 0
Mods failed on decompress 0
Mods failed on becoming 0
Mods failed on load 1411
Total module size 11464704
Total mod text size 4194304
Failed kread bytes 0
Failed decompress bytes 0
Failed becoming bytes 0
Failed kmod bytes 14588526272
Virtual mem wasted bytes 14588526272
Average mod size 171115
Average mod text size 62602
Average fail load bytes 10339140
Duplicate failed modules:
module-name How-many-times Reason
kvm_intel 249 Load
kvm 249 Load
irqbypass 8 Load
crct10dif_pclmul 128 Load
ghash_clmulni_intel 27 Load
sha512_ssse3 50 Load
sha512_generic 200 Load
aesni_intel 249 Load
crypto_simd 41 Load
cryptd 131 Load
evdev 2 Load
serio_raw 1 Load
virtio_pci 3 Load
nvme 3 Load
nvme_core 3 Load
virtio_pci_legacy_dev 3 Load
virtio_pci_modern_dev 3 Load
t10_pi 3 Load
virtio 3 Load
crc32_pclmul 6 Load
crc64_rocksoft 3 Load
crc32c_intel 40 Load
virtio_ring 3 Load
crc64 3 Load
The following screen shot, of a simple 8vcpu 8 GiB KVM guest with the
next patch in this series applied, shows 226.53 MiB are wasted in virtual
memory allocations which due to duplicate module requests during boot.
It also shows an average module memory size of 167.10 KiB and an an
average module .text + .init.text size of 61.13 KiB. The end shows all
modules which were detected as duplicate requests and whether or not
they failed early after just the first kernel_read*() call or late after
we've already allocated the private space for the module in
layout_and_allocate(). A system with module decompression would reveal
more wasted virtual memory space.
We should put effort now into identifying the source of these duplicate
module requests and trimming these down as much possible. Larger systems
will obviously show much more wasted virtual memory allocations.
root@kmod ~ # cat /sys/kernel/debug/modules/stats
Mods ever loaded 67
Mods failed on kread 0
Mods failed on decompress 0
Mods failed on becoming 83
Mods failed on load 16
Total module size 11464704
Total mod text size 4194304
Failed kread bytes 0
Failed decompress bytes 0
Failed becoming bytes 228959096
Failed kmod bytes 8578080
Virtual mem wasted bytes 237537176
Average mod size 171115
Average mod text size 62602
Avg fail becoming bytes 2758544
Average fail load bytes 536130
Duplicate failed modules:
module-name How-many-times Reason
kvm_intel 7 Becoming
kvm 7 Becoming
irqbypass 6 Becoming & Load
crct10dif_pclmul 7 Becoming & Load
ghash_clmulni_intel 7 Becoming & Load
sha512_ssse3 6 Becoming & Load
sha512_generic 7 Becoming & Load
aesni_intel 7 Becoming
crypto_simd 7 Becoming & Load
cryptd 3 Becoming & Load
evdev 1 Becoming
serio_raw 1 Becoming
nvme 3 Becoming
nvme_core 3 Becoming
t10_pi 3 Becoming
virtio_pci 3 Becoming
crc32_pclmul 6 Becoming & Load
crc64_rocksoft 3 Becoming
crc32c_intel 3 Becoming
virtio_pci_modern_dev 2 Becoming
virtio_pci_legacy_dev 1 Becoming
crc64 2 Becoming
virtio 2 Becoming
virtio_ring 2 Becoming
[0] https://github.com/ColinIanKing/stress-ng.git
[1] echo 0 > /proc/sys/vm/oom_dump_tasks
./stress-ng --module 100 --module-name xfs
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Add support for zstd compressed modules to the in-kernel decompression
code. This allows zstd compressed modules to be decompressed by the
kernel, similar to the existing support for gzip and xz compressed
modules.
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Piotr Gorski <lucjan.lucjanov@gmail.com>
Cc: Nick Terrell <terrelln@fb.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
In init/Kconfig, the part dedicated to modules is quite large.
Move it into a dedicated Kconfig in kernel/module/
MODULES_TREE_LOOKUP was outside of the 'if MODULES', but as it is
only used when MODULES are set, move it in with everything else to
avoid confusion.
MODULE_SIG_FORMAT is left in init/Kconfig because this configuration
item is not used in kernel/modules/ but in kernel/ and can be
selected independently from CONFIG_MODULES. It is for instance
selected from security/integrity/ima/Kconfig.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
