Commit Graph

2398 Commits

Author SHA1 Message Date
Linus Torvalds
e022620b5d Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon:
 "A bumper crop of arm64 fixes for -rc3.

  The largest change is fixing our parsing of the 'rodata=full' command
  line option, which kstrtobool() started treating as 'rodata=false'.
  The fix actually makes the parsing of that option much less fragile
  and updates the documentation at the same time.

  We still have a boot issue pending when KASLR is disabled at compile
  time, but there's a fresh fix on the list which I'll send next week if
  it holds up to testing.

  Summary:

   - Fix workaround for Cortex-A76 erratum #1286807

   - Add workaround for AMU erratum #2457168 on Cortex-A510

   - Drop reference to removed CONFIG_ARCH_RANDOM #define

   - Fix parsing of the "rodata=full" cmdline option

   - Fix a bunch of issues in the SME register state switching and sigframe code

   - Fix incorrect extraction of the CTR_EL0.CWG register field

   - Fix ACPI cache topology probing when the PPTT is not present

   - Trivial comment and whitespace fixes"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/sme: Don't flush SVE register state when handling SME traps
  arm64/sme: Don't flush SVE register state when allocating SME storage
  arm64/signal: Flush FPSIMD register state when disabling streaming mode
  arm64/signal: Raise limit on stack frames
  arm64/cache: Fix cache_type_cwg() for register generation
  arm64/sysreg: Guard SYS_FIELD_ macros for asm
  arm64/sysreg: Directly include bitfield.h
  arm64: cacheinfo: Fix incorrect assignment of signed error value to unsigned fw_level
  arm64: errata: add detection for AMEVCNTR01 incrementing incorrectly
  arm64: fix rodata=full
  arm64: Fix comment typo
  docs/arm64: elf_hwcaps: unify newlines in HWCAP lists
  arm64: adjust KASLR relocation after ARCH_RANDOM removal
  arm64: Fix match_list for erratum 1286807 on Arm Cortex-A76
2022-08-26 11:32:53 -07:00
Mark Rutland
2e8cff0a0e arm64: fix rodata=full
On arm64, "rodata=full" has been suppored (but not documented) since
commit:

  c55191e96c ("arm64: mm: apply r/o permissions of VM areas to its linear alias as well")

As it's necessary to determine the rodata configuration early during
boot, arm64 has an early_param() handler for this, whereas init/main.c
has a __setup() handler which is run later.

Unfortunately, this split meant that since commit:

  f9a40b0890 ("init/main.c: return 1 from handled __setup() functions")

... passing "rodata=full" would result in a spurious warning from the
__setup() handler (though RO permissions would be configured
appropriately).

Further, "rodata=full" has been broken since commit:

  0d6ea3ac94 ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()")

... which caused strtobool() to parse "full" as false (in addition to
many other values not documented for the "rodata=" kernel parameter.

This patch fixes this breakage by:

* Moving the core parameter parser to an __early_param(), such that it
  is available early.

* Adding an (optional) arch hook which arm64 can use to parse "full".

* Updating the documentation to mention that "full" is valid for arm64.

* Having the core parameter parser handle "on" and "off" explicitly,
  such that any undocumented values (e.g. typos such as "ful") are
  reported as errors rather than being silently accepted.

Note that __setup() and early_param() have opposite conventions for
their return values, where __setup() uses 1 to indicate a parameter was
handled and early_param() uses 0 to indicate a parameter was handled.

Fixes: f9a40b0890 ("init/main.c: return 1 from handled __setup() functions")
Fixes: 0d6ea3ac94 ("lib/kstrtox.c: add "false"/"true" support to kstrtobool()")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Jagdish Gediya <jvgediya@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220817154022.3974645-1-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2022-08-23 11:02:02 +01:00
Nick Desaulniers
a0a12c3ed0 asm goto: eradicate CC_HAS_ASM_GOTO
GCC has supported asm goto since 4.5, and Clang has since version 9.0.0.
The minimum supported versions of these tools for the build according to
Documentation/process/changes.rst are 5.1 and 11.0.0 respectively.

Remove the feature detection script, Kconfig option, and clean up some
fallback code that is no longer supported.

The removed script was also testing for a GCC specific bug that was
fixed in the 4.7 release.

Also remove workarounds for bpftrace using clang older than 9.0.0, since
other BPF backend fixes are required at this point.

Link: https://lore.kernel.org/lkml/CAK7LNATSr=BXKfkdW8f-H5VT_w=xBpT2ZQcZ7rm6JfkdE+QnmA@mail.gmail.com/
Link: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48637
Acked-by: Borislav Petkov <bp@suse.de>
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-08-21 10:06:28 -07:00
Linus Torvalds
0af5cb349a Merge tag 'kbuild-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:

 - Remove the support for -O3 (CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3)

 - Fix error of rpm-pkg cross-builds

 - Support riscv for checkstack tool

 - Re-enable -Wformwat warnings for Clang

 - Clean up modpost, Makefiles, and misc scripts

* tag 'kbuild-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
  modpost: remove .symbol_white_list field entirely
  modpost: remove unneeded .symbol_white_list initializers
  modpost: add PATTERNS() helper macro
  modpost: shorten warning messages in report_sec_mismatch()
  Revert "Kbuild, lto, workaround: Don't warn for initcall_reference in modpost"
  modpost: use more reliable way to get fromsec in section_rel(a)()
  modpost: add array range check to sec_name()
  modpost: refactor get_secindex()
  kbuild: set EXIT trap before creating temporary directory
  modpost: remove unused Elf_Sword macro
  Makefile.extrawarn: re-enable -Wformat for clang
  kbuild: add dtbs_prepare target
  kconfig: Qt5: tell the user which packages are required
  modpost: use sym_get_data() to get module device_table data
  modpost: drop executable ELF support
  checkstack: add riscv support for scripts/checkstack.pl
  kconfig: shorten the temporary directory name for cc-option
  scripts: headers_install.sh: Update config leak ignore entries
  kbuild: error out if $(INSTALL_MOD_PATH) contains % or :
  kbuild: error out if $(KBUILD_EXTMOD) contains % or :
  ...
2022-08-10 10:40:41 -07:00
Linus Torvalds
e74acdf55d Merge tag 'modules-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux
Pull module updates from Luis Chamberlain:
 "For the 6.0 merge window the modules code shifts to cleanup and minor
  fixes effort. This becomes much easier to do and review now due to the
  code split to its own directory from effort on the last kernel
  release. I expect to see more of this with time and as we expand on
  test coverage in the future. The cleanups and fixes come from usual
  suspects such as Christophe Leroy and Aaron Tomlin but there are also
  some other contributors.

  One particular minor fix worth mentioning is from Helge Deller, where
  he spotted a *forever* incorrect natural alignment on both ELF section
  header tables:

    * .altinstructions
    * __bug_table sections

  A lot of back and forth went on in trying to determine the ill effects
  of this misalignment being present for years and it has been
  determined there should be no real ill effects unless you have a buggy
  exception handler. Helge actually hit one of these buggy exception
  handlers on parisc which is how he ended up spotting this issue. When
  implemented correctly these paths with incorrect misalignment would
  just mean a performance penalty, but given that we are dealing with
  alternatives on modules and with the __bug_table (where info regardign
  BUG()/WARN() file/line information associated with it is stored) this
  really shouldn't be a big deal.

  The only other change with mentioning is the kmap() with
  kmap_local_page() and my only concern with that was on what is done
  after preemption, but the virtual addresses are restored after
  preemption. This is only used on module decompression.

  This all has sit on linux-next for a while except the kmap stuff which
  has been there for 3 weeks"

* tag 'modules-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  module: Replace kmap() with kmap_local_page()
  module: Show the last unloaded module's taint flag(s)
  module: Use strscpy() for last_unloaded_module
  module: Modify module_flags() to accept show_state argument
  module: Move module's Kconfig items in kernel/module/
  MAINTAINERS: Update file list for module maintainers
  module: Use vzalloc() instead of vmalloc()/memset(0)
  modules: Ensure natural alignment for .altinstructions and __bug_table sections
  module: Increase readability of module_kallsyms_lookup_name()
  module: Fix ERRORs reported by checkpatch.pl
  module: Add support for default value for module async_probe
2022-08-08 14:12:19 -07:00
Linus Torvalds
eb5699ba31 Merge tag 'mm-nonmm-stable-2022-08-06-2' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc updates from Andrew Morton:
 "Updates to various subsystems which I help look after. lib, ocfs2,
  fatfs, autofs, squashfs, procfs, etc. A relatively small amount of
  material this time"

* tag 'mm-nonmm-stable-2022-08-06-2' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (72 commits)
  scripts/gdb: ensure the absolute path is generated on initial source
  MAINTAINERS: kunit: add David Gow as a maintainer of KUnit
  mailmap: add linux.dev alias for Brendan Higgins
  mailmap: update Kirill's email
  profile: setup_profiling_timer() is moslty not implemented
  ocfs2: fix a typo in a comment
  ocfs2: use the bitmap API to simplify code
  ocfs2: remove some useless functions
  lib/mpi: fix typo 'the the' in comment
  proc: add some (hopefully) insightful comments
  bdi: remove enum wb_congested_state
  kernel/hung_task: fix address space of proc_dohung_task_timeout_secs
  lib/lzo/lzo1x_compress.c: replace ternary operator with min() and min_t()
  squashfs: support reading fragments in readahead call
  squashfs: implement readahead
  squashfs: always build "file direct" version of page actor
  Revert "squashfs: provide backing_dev_info in order to disable read-ahead"
  fs/ocfs2: Fix spelling typo in comment
  ia64: old_rr4 added under CONFIG_HUGETLB_PAGE
  proc: fix test for "vsyscall=xonly" boot option
  ...
2022-08-07 10:03:24 -07:00
Linus Torvalds
b6bb70f9ab Merge tag 'cgroup-for-5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "Several core optimizations:

   - threadgroup_rwsem write locking is skipped when configuring
     controllers in empty subtrees.

     Combined with CLONE_INTO_CGROUP, this allows the common static
     usage pattern to not grab threadgroup_rwsem at all (glibc still
     doesn't seem ready for CLONE_INTO_CGROUP unfortunately).

   - threadgroup_rwsem used to be put into non-percpu mode by default
     due to latency concerns in specific use cases. There's no reason
     for everyone else to pay for it. Make the behavior optional.

   - psi no longer allocates memory when disabled.

  ... along with some code cleanups"

* tag 'cgroup-for-5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Skip subtree root in cgroup_update_dfl_csses()
  cgroup: remove "no" prefixed mount options
  cgroup: Make !percpu threadgroup_rwsem operations optional
  cgroup: Add "no" prefixed mount options
  cgroup: Elide write-locking threadgroup_rwsem when updating csses on an empty subtree
  cgroup.c: remove redundant check for mixable cgroup in cgroup_migrate_vet_dst
  cgroup.c: add helper __cset_cgroup_from_root to cleanup duplicated codes
  psi: dont alloc memory for psi by default
2022-08-03 09:45:08 -07:00
Linus Torvalds
aad26f55f4 Merge tag 'docs-6.0' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
 "This was a moderately busy cycle for documentation, but nothing
  all that earth-shaking:

   - More Chinese translations, and an update to the Italian
     translations.

     The Japanese, Korean, and traditional Chinese translations
     are more-or-less unmaintained at this point, instead.

   - Some build-system performance improvements.

   - The removal of the archaic submitting-drivers.rst document,
     with the movement of what useful material that remained into
     other docs.

   - Improvements to sphinx-pre-install to, hopefully, give more
     useful suggestions.

   - A number of build-warning fixes

  Plus the usual collection of typo fixes, updates, and more"

* tag 'docs-6.0' of git://git.lwn.net/linux: (92 commits)
  docs: efi-stub: Fix paths for x86 / arm stubs
  Docs/zh_CN: Update the translation of sched-stats to 5.19-rc8
  Docs/zh_CN: Update the translation of pci to 5.19-rc8
  Docs/zh_CN: Update the translation of pci-iov-howto to 5.19-rc8
  Docs/zh_CN: Update the translation of usage to 5.19-rc8
  Docs/zh_CN: Update the translation of testing-overview to 5.19-rc8
  Docs/zh_CN: Update the translation of sparse to 5.19-rc8
  Docs/zh_CN: Update the translation of kasan to 5.19-rc8
  Docs/zh_CN: Update the translation of iio_configfs to 5.19-rc8
  doc:it_IT: align Italian documentation
  docs: Remove spurious tag from admin-guide/mm/overcommit-accounting.rst
  Documentation: process: Update email client instructions for Thunderbird
  docs: ABI: correct QEMU fw_cfg spec path
  doc/zh_CN: remove submitting-driver reference from docs
  docs: zh_TW: align to submitting-drivers removal
  docs: zh_CN: align to submitting-drivers removal
  docs: ko_KR: howto: remove reference to removed submitting-drivers
  docs: ja_JP: howto: remove reference to removed submitting-drivers
  docs: it_IT: align to submitting-drivers removal
  docs: process: remove outdated submitting-drivers.rst
  ...
2022-08-02 19:24:24 -07:00
Linus Torvalds
7d9d077c78 Merge tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull RCU updates from Paul McKenney:

 - Documentation updates

 - Miscellaneous fixes

 - Callback-offload updates, perhaps most notably a new
   RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be
   offloaded at boot time, regardless of kernel boot parameters.

   This is useful to battery-powered systems such as ChromeOS and
   Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot
   parameter prevents offloaded callbacks from interfering with
   real-time workloads and with energy-efficiency mechanisms

 - Polled grace-period updates, perhaps most notably making these APIs
   account for both normal and expedited grace periods

 - Tasks RCU updates, perhaps most notably reducing the CPU overhead of
   RCU tasks trace grace periods by more than a factor of two on a
   system with 15,000 tasks.

   The reduction is expected to increase with the number of tasks, so it
   seems reasonable to hypothesize that a system with 150,000 tasks
   might see a 20-fold reduction in CPU overhead

 - Torture-test updates

 - Updates that merge RCU's dyntick-idle tracking into context tracking,
   thus reducing the overhead of transitioning to kernel mode from
   either idle or nohz_full userspace execution for kernels that track
   context independently of RCU.

   This is expected to be helpful primarily for kernels built with
   CONFIG_NO_HZ_FULL=y

* tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits)
  rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings
  rcu: Diagnose extended sync_rcu_do_polled_gp() loops
  rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings
  rcutorture: Test polled expedited grace-period primitives
  rcu: Add polled expedited grace-period primitives
  rcutorture: Verify that polled GP API sees synchronous grace periods
  rcu: Make Tiny RCU grace periods visible to polled APIs
  rcu: Make polled grace-period API account for expedited grace periods
  rcu: Switch polled grace-period APIs to ->gp_seq_polled
  rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty
  rcu/nocb: Add option to opt rcuo kthreads out of RT priority
  rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread()
  rcu/nocb: Add an option to offload all CPUs on boot
  rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call
  rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order
  rcu/nocb: Add/del rdp to iterate from rcuog itself
  rcu/tree: Add comment to describe GP-done condition in fqs loop
  rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs()
  rcu/kvfree: Remove useless monitor_todo flag
  rcu: Cleanup RCU urgency state for offline CPU
  ...
2022-08-02 19:12:45 -07:00
Linus Torvalds
c2a24a7a03 Merge tag 'v5.20-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto updates from Herbert Xu:
"API:

   - Make proc files report fips module name and version

  Algorithms:

   - Move generic SHA1 code into lib/crypto

   - Implement Chinese Remainder Theorem for RSA

   - Remove blake2s

   - Add XCTR with x86/arm64 acceleration

   - Add POLYVAL with x86/arm64 acceleration

   - Add HCTR2

   - Add ARIA

  Drivers:

   - Add support for new CCP/PSP device ID in ccp"

* tag 'v5.20-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (89 commits)
  crypto: tcrypt - Remove the static variable initialisations to NULL
  crypto: arm64/poly1305 - fix a read out-of-bound
  crypto: hisilicon/zip - Use the bitmap API to allocate bitmaps
  crypto: hisilicon/sec - fix auth key size error
  crypto: ccree - Remove a useless dma_supported() call
  crypto: ccp - Add support for new CCP/PSP device ID
  crypto: inside-secure - Add missing MODULE_DEVICE_TABLE for of
  crypto: hisilicon/hpre - don't use GFP_KERNEL to alloc mem during softirq
  crypto: testmgr - some more fixes to RSA test vectors
  cyrpto: powerpc/aes - delete the rebundant word "block" in comments
  hwrng: via - Fix comment typo
  crypto: twofish - Fix comment typo
  crypto: rmd160 - fix Kconfig "its" grammar
  crypto: keembay-ocs-ecc - Drop if with an always false condition
  Documentation: qat: rewrite description
  Documentation: qat: Use code block for qat sysfs example
  crypto: lib - add module license to libsha1
  crypto: lib - make the sha1 library optional
  crypto: lib - move lib/sha1.c into lib/crypto/
  crypto: fips - make proc files report fips module name and version
  ...
2022-08-02 17:45:14 -07:00
Baruch Siach
bdf0fe33a4 init/Kconfig: update KALLSYMS_ALL help text
CONFIG_KALLSYMS_ALL is required for kernel live patching which is a
common use case that is enabled in some major distros. Update the
Kconfig help text to reflect that.

While at it, s/e.g./i.e./ to match the text intention.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-07-27 21:17:59 +09:00
Nick Desaulniers
a6036a41bf kbuild: drop support for CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
The difference in most compilers between `-O3` and `-O2` is mostly down
to whether loops with statically determinable trip counts are fully
unrolled vs unrolled to a multiple of SIMD width.

This patch is effectively a revert of
commit 15f5db60a1 ("kbuild,arc: add
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC") without re-adding
ARCH_CFLAGS

Ever since
commit cfdbc2e16e ("ARC: Build system: Makefiles, Kconfig, Linker
script")
ARC has been built with -O3, though the reason for doing so was not
specified in inline comments or the commit message. This commit does not
re-add -O3 to arch/arc/Makefile.

Folks looking to experiment with `-O3` (or any compiler flag for that
matter) may pass them along to the command line invocation of make:

$ make KCFLAGS=-O3

Code that looks to re-add an explicit Kconfig option for `-O3` should
provide:
1. A rigorous and reproducible performance profile of a reasonable
   userspace workload that demonstrates a hot loop in the kernel that
   would benefit from `-O3` over `-O2`.
2. Disassembly of said loop body before and after.
3. Provides stats on terms of increase in file size.

Link: https://lore.kernel.org/linux-kbuild/CA+55aFz2sNBbZyg-_i8_Ldr2e8o9dfvdSfHHuRzVtP2VMAUWPg@mail.gmail.com/
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-07-27 21:17:59 +09:00
Tejun Heo
6a010a49b6 cgroup: Make !percpu threadgroup_rwsem operations optional
3942a9bd7b ("locking, rcu, cgroup: Avoid synchronize_sched() in
__cgroup_procs_write()") disabled percpu operations on threadgroup_rwsem
because the impiled synchronize_rcu() on write locking was pushing up the
latencies too much for android which constantly moves processes between
cgroups.

This makes the hotter paths - fork and exit - slower as they're always
forced into the slow path. There is no reason to force this on everyone
especially given that more common static usage pattern can now completely
avoid write-locking the rwsem. Write-locking is elided when turning on and
off controllers on empty sub-trees and CLONE_INTO_CGROUP enables seeding a
cgroup without grabbing the rwsem.

Restore the default percpu operations and introduce the mount option
"favordynmods" and config option CGROUP_FAVOR_DYNMODS for users who need
lower latencies for the dynamic operations.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Michal Koutn� <mkoutny@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
2022-07-23 04:29:02 -10:00
Paul E. McKenney
34bc7b454d Merge branch 'ctxt.2022.07.05a' into HEAD
ctxt.2022.07.05a: Linux-kernel memory model development branch.
2022-07-21 17:46:18 -07:00
Dan Moulding
5a704629f2 init: add "hostname" kernel parameter
The gethostname system call returns the hostname for the current machine. 
However, the kernel has no mechanism to initially set the current
machine's name in such a way as to guarantee that the first userspace
process to call gethostname will receive a meaningful result.  It relies
on some unspecified userspace process to first call sethostname before
gethostname can produce a meaningful name.

Traditionally the machine's hostname is set from userspace by the init
system.  The init system, in turn, often relies on a configuration file
(say, /etc/hostname) to provide the value that it will supply in the call
to sethostname.  Consequently, the file system containing /etc/hostname
usually must be available before the hostname will be set.  There may,
however, be earlier userspace processes that could call gethostname before
the file system containing /etc/hostname is mounted.  Such a process will
get some other, likely meaningless, name from gethostname (such as
"(none)", "localhost", or "darkstar").

A real-world example where this can happen, and lead to undesirable
results, is with mdadm.  When assembling arrays, mdadm distinguishes
between "local" arrays and "foreign" arrays.  A local array is one that
properly belongs to the current machine, and a foreign array is one that
is (possibly temporarily) attached to the current machine, but properly
belongs to some other machine.  To determine if an array is local or
foreign, mdadm may compare the "homehost" recorded on the array with the
current hostname.  If mdadm is run before the root file system is mounted,
perhaps because the root file system itself resides on an md-raid array,
then /etc/hostname isn't yet available and the init system will not yet
have called sethostname, causing mdadm to incorrectly conclude that all of
the local arrays are foreign.

Solving this problem *could* be delegated to the init system.  It could be
left up to the init system (including any init system that starts within
an initramfs, if one is in use) to ensure that sethostname is called
before any other userspace process could possibly call gethostname. 
However, it may not always be obvious which processes could call
gethostname (for example, udev itself might not call gethostname, but it
could via udev rules invoke processes that do).  Additionally, the init
system has to ensure that the hostname configuration value is stored in
some place where it will be readily accessible during early boot. 
Unfortunately, every init system will attempt to (or has already attempted
to) solve this problem in a different, possibly incorrect, way.  This
makes getting consistently working configurations harder for users.

I believe it is better for the kernel to provide the means by which the
hostname may be set early, rather than making this a problem for the init
system to solve.  The option to set the hostname during early startup, via
a kernel parameter, provides a simple, reliable way to solve this problem.
It also could make system configuration easier for some embedded systems.

[dmoulding@me.com: v2]
  Link: https://lkml.kernel.org/r/20220506060310.7495-2-dmoulding@me.com
Link: https://lkml.kernel.org/r/20220505180651.22849-2-dmoulding@me.com
Signed-off-by: Dan Moulding <dmoulding@me.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-07-17 17:31:37 -07:00
Eric Biggers
ec8f7f4821 crypto: lib - make the sha1 library optional
Since the Linux RNG no longer uses sha1_transform(), the SHA-1 library
is no longer needed unconditionally.  Make it possible to build the
Linux kernel without the SHA-1 library by putting it behind a kconfig
option, and selecting this new option from the kconfig options that gate
the remaining users: CRYPTO_SHA1 for crypto/sha1_generic.c, BPF for
kernel/bpf/core.c, and IPV6 for net/ipv6/addrconf.c.

Unfortunately, since BPF is selected by NET, for now this can only make
a difference for kernels built without networking support.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2022-07-15 16:43:59 +08:00
Christophe Leroy
73b4fc92f9 module: Move module's Kconfig items in kernel/module/
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>
2022-07-12 12:07:25 -07:00
Mauro Carvalho Chehab
c02b872a7c Documentation: update watch_queue.rst references
Changeset f5461124d5 ("Documentation: move watch_queue to core-api")
renamed: Documentation/watch_queue.rst
to: Documentation/core-api/watch_queue.rst.

Update the cross-references accordingly.

Fixes: f5461124d5 ("Documentation: move watch_queue to core-api")
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/1c220de9c58f35e815a3df9458ac2bea323c8bfb.1656234456.git.mchehab@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-07-07 13:09:59 -06:00
GONG, Ruiqi
375561bd61 stack: Declare {randomize_,}kstack_offset to fix Sparse warnings
Fix the following Sparse warnings that got noticed when the PPC-dev
patchwork was checking another patch (see the link below):

init/main.c:862:1: warning: symbol 'randomize_kstack_offset' was not declared. Should it be static?
init/main.c:864:1: warning: symbol 'kstack_offset' was not declared. Should it be static?

Which in fact are triggered on all architectures that have
HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET support (for instances x86, arm64
etc).

Link: https://lore.kernel.org/lkml/e7b0d68b-914d-7283-827c-101988923929@huawei.com/T/#m49b2d4490121445ce4bf7653500aba59eefcb67f
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: 39218ff4c6 ("stack: Optionally randomize kernel stack offset each syscall")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220629060423.2515693-1-gongruiqi1@huawei.com
2022-07-01 18:01:47 -07:00
Frederic Weisbecker
24a9c54182 context_tracking: Split user tracking Kconfig
Context tracking is going to be used not only to track user transitions
but also idle/IRQs/NMIs. The user tracking part will then become a
separate feature. Prepare Kconfig for that.

[ frederic: Apply Max Filippov feedback. ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
2022-06-29 17:04:09 -07:00
Paul E. McKenney
434c9eefb9 rcu-tasks: Add data structures for lightweight grace periods
This commit adds fields to task_struct and to rcu_tasks_percpu that will
be used to avoid the task-list scan for RCU Tasks Trace grace periods,
and also initializes these fields.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
2022-06-20 09:22:28 -07:00
Linus Torvalds
f0be87c42c gcc-12: disable '-Warray-bounds' universally for now
In commit 8b202ee218 ("s390: disable -Warray-bounds") the s390 people
disabled the '-Warray-bounds' warning for gcc-12, because the new logic
in gcc would cause warnings for their use of the S390_lowcore macro,
which accesses absolute pointers.

It turns out gcc-12 has many other issues in this area, so this takes
that s390 warning disable logic, and turns it into a kernel build config
entry instead.

Part of the intent is that we can make this all much more targeted, and
use this conflig flag to disable it in only particular configurations
that cause problems, with the s390 case as an example:

        select GCC12_NO_ARRAY_BOUNDS

and we could do that for other configuration cases that cause issues.

Or we could possibly use the CONFIG_CC_NO_ARRAY_BOUNDS thing in a more
targeted way, and disable the warning only for particular uses: again
the s390 case as an example:

  KBUILD_CFLAGS_DECOMPRESSOR += $(if $(CONFIG_CC_NO_ARRAY_BOUNDS),-Wno-array-bounds)

but this ends up just doing it globally in the top-level Makefile, since
the current issues are spread fairly widely all over:

  KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds

We'll try to limit this later, since the gcc-12 problems are rare enough
that *much* of the kernel can be built with it without disabling this
warning.

Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-09 10:11:12 -07:00
Linus Torvalds
1ec6574a3c Merge tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull kthread updates from Eric Biederman:
 "This updates init and user mode helper tasks to be ordinary user mode
  tasks.

  Commit 40966e316f ("kthread: Ensure struct kthread is present for
  all kthreads") caused init and the user mode helper threads that call
  kernel_execve to have struct kthread allocated for them. This struct
  kthread going away during execve in turned made a use after free of
  struct kthread possible.

  Here, commit 343f4c49f2 ("kthread: Don't allocate kthread_struct for
  init and umh") is enough to fix the use after free and is simple
  enough to be backportable.

  The rest of the changes pass struct kernel_clone_args to clean things
  up and cause the code to make sense.

  In making init and the user mode helpers tasks purely user mode tasks
  I ran into two complications. The function task_tick_numa was
  detecting tasks without an mm by testing for the presence of
  PF_KTHREAD. The initramfs code in populate_initrd_image was using
  flush_delayed_fput to ensuere the closing of all it's file descriptors
  was complete, and flush_delayed_fput does not work in a userspace
  thread.

  I have looked and looked and more complications and in my code review
  I have not found any, and neither has anyone else with the code
  sitting in linux-next"

* tag 'kthread-cleanups-for-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  sched: Update task_tick_numa to ignore tasks without an mm
  fork: Stop allowing kthreads to call execve
  fork: Explicitly set PF_KTHREAD
  init: Deal with the init process being a user mode process
  fork: Generalize PF_IO_WORKER handling
  fork: Explicity test for idle tasks in copy_thread
  fork: Pass struct kernel_clone_args into copy_thread
  kthread: Don't allocate kthread_struct for init and umh
2022-06-03 16:03:05 -07:00
Linus Torvalds
35b51afd23 Merge tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:

 - Support for the Svpbmt extension, which allows memory attributes to
   be encoded in pages

 - Support for the Allwinner D1's implementation of page-based memory
   attributes

 - Support for running rv32 binaries on rv64 systems, via the compat
   subsystem

 - Support for kexec_file()

 - Support for the new generic ticket-based spinlocks, which allows us
   to also move to qrwlock. These should have already gone in through
   the asm-geneic tree as well

 - A handful of cleanups and fixes, include some larger ones around
   atomics and XIP

* tag 'riscv-for-linus-5.19-mw0' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
  RISC-V: Prepare dropping week attribute from arch_kexec_apply_relocations[_add]
  riscv: compat: Using seperated vdso_maps for compat_vdso_info
  RISC-V: Fix the XIP build
  RISC-V: Split out the XIP fixups into their own file
  RISC-V: ignore xipImage
  RISC-V: Avoid empty create_*_mapping definitions
  riscv: Don't output a bogus mmu-type on a no MMU kernel
  riscv: atomic: Add custom conditional atomic operation implementation
  riscv: atomic: Optimize dec_if_positive functions
  riscv: atomic: Cleanup unnecessary definition
  RISC-V: Load purgatory in kexec_file
  RISC-V: Add purgatory
  RISC-V: Support for kexec_file on panic
  RISC-V: Add kexec_file support
  RISC-V: use memcpy for kexec_file mode
  kexec_file: Fix kexec_file.c build error for riscv platform
  riscv: compat: Add COMPAT Kbuild skeletal support
  riscv: compat: ptrace: Add compat_arch_ptrace implement
  riscv: compat: signal: Add rt_frame implementation
  riscv: add memory-type errata for T-Head
  ...
2022-05-31 14:10:54 -07:00
Linus Torvalds
76bfd3de34 Merge tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
 "The majority of the changes are for fixes and clean ups.

  Notable changes:

   - Rework trace event triggers code to be easier to interact with.

   - Support for embedding bootconfig with the kernel (as suppose to
     having it embedded in initram). This is useful for embedded boards
     without initram disks.

   - Speed up boot by parallelizing the creation of tracefs files.

   - Allow absolute ring buffer timestamps handle timestamps that use
     more than 59 bits.

   - Added new tracing clock "TAI" (International Atomic Time)

   - Have weak functions show up in available_filter_function list as:
     __ftrace_invalid_address___<invalid-offset> instead of using the
     name of the function before it"

* tag 'trace-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (52 commits)
  ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to avoid adding weak function
  tracing: Fix comments for event_trigger_separate_filter()
  x86/traceponit: Fix comment about irq vector tracepoints
  x86,tracing: Remove unused headers
  ftrace: Clean up hash direct_functions on register failures
  tracing: Fix comments of create_filter()
  tracing: Disable kcov on trace_preemptirq.c
  tracing: Initialize integer variable to prevent garbage return value
  ftrace: Fix typo in comment
  ftrace: Remove return value of ftrace_arch_modify_*()
  tracing: Cleanup code by removing init "char *name"
  tracing: Change "char *" string form to "char []"
  tracing/timerlat: Do not wakeup the thread if the trace stops at the IRQ
  tracing/timerlat: Print stacktrace in the IRQ handler if needed
  tracing/timerlat: Notify IRQ new max latency only if stop tracing is set
  kprobes: Fix build errors with CONFIG_KRETPROBES=n
  tracing: Fix return value of trace_pid_write()
  tracing: Fix potential double free in create_var_ref()
  tracing: Use strim() to remove whitespace instead of doing it manually
  ftrace: Deal with error return code of the ftrace_process_locs() function
  ...
2022-05-29 10:31:36 -07:00