Pull Kbuild fixes from Masahiro Yamada:

 - fix -gz=zlib compiler option test for CONFIG_DEBUG_INFO_COMPRESSED

 - improve cc-option in scripts/Kbuild.include to clean up temp files

 - improve cc-option in scripts/Kconfig.include for more reliable
   compile option test

 - do not copy modules.builtin by 'make install' because it would break
   existing systems

 - use 'userprogs' syntax for watch_queue sample

* tag 'kbuild-fixes-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  samples: watch_queue: build sample program for target architecture
  Revert "Makefile: install modules.builtin even if CONFIG_MODULES=n"
  scripts: Fix typo in headers_install.sh
  kconfig: unify cc-option and as-option
  kbuild: improve cc-option to clean up all temporary files
  Makefile: Improve compressed debug info support detection

Pull libnvdimm updates from Dan Williams:
 "A feature (papr_scm health retrieval) and a fix (sysfs attribute
  visibility) for v5.8.

  Vaibhav explains in the merge commit below why missing v5.8 would be
  painful and I agreed to try a -rc2 pull because only cosmetics kept
  this out of -rc1 and his initial versions were posted in more than
  enough time for v5.8 consideration:

   'These patches are tied to specific features that were committed to
    customers in upcoming distros releases (RHEL and SLES) whose
    time-lines are tied to 5.8 kernel release.

    Being able to track the health of an nvdimm is critical for our
    customers that are running workloads leveraging papr-scm nvdimms.
    Missing the 5.8 kernel would mean missing the distro timelines and
    shifting forward the availability of this feature in distro kernels
    by at least 6 months'

  Summary:

   - Fix the visibility of the region 'align' attribute.

     The new unit tests for region alignment handling caught a corner
     case where the alignment cannot be specified if the region is
     converted from static to dynamic provisioning at runtime.

   - Add support for device health retrieval for the persistent memory
     supported by the papr_scm driver.

     This includes both the standard sysfs "health flags" that the nfit
     persistent memory driver publishes and a mechanism for the ndctl
     tool to retrieve a health-command payload"

* tag 'libnvdimm-for-5.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  nvdimm/region: always show the 'align' attribute
  powerpc/papr_scm: Implement support for PAPR_PDSM_HEALTH
  ndctl/papr_scm,uapi: Add support for PAPR nvdimm specific methods
  powerpc/papr_scm: Improve error logging and handling papr_scm_ndctl()
  powerpc/papr_scm: Fetch nvdimm health information from PHYP
  seq_buf: Export seq_buf_printf
  powerpc: Document details on H_SCM_HEALTH hcall

Merge non-faulting memory access cleanups from Christoph Hellwig:
 "Andrew and I decided to drop the patches implementing your suggested
  rename of the probe_kernel_* and probe_user_* helpers from -mm as
  there were way to many conflicts.

  After -rc1 might be a good time for this as all the conflicts are
  resolved now"

This also adds a type safety checking patch on top of the renaming
series to make the subtle behavioral difference between 'get_user()' and
'get_kernel_nofault()' less potentially dangerous and surprising.

* emailed patches from Christoph Hellwig <hch@lst.de>:
  maccess: make get_kernel_nofault() check for minimal type compatibility
  maccess: rename probe_kernel_address to get_kernel_nofault
  maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault
  maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.

Also switch the argument order around, so that it acts and looks
like get_user().

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

cc-option and as-option are almost the same; both pass the flag to
$(CC). The main difference is the cc-option stops before the assemble
stage (-S option) whereas as-option stops after (-c option).

I chose -S because it is slightly faster, but $(cc-option,-gz=zlib)
returns a wrong result (https://lkml.org/lkml/2020/6/9/1529).
It has been fixed by commit 7b16994437c7 ("Makefile: Improve compressed
debug info support detection"), but the assembler should always be
invoked for more reliable compiler option tests.

However, you cannot simply replace -S with -c because the following
code in lib/Kconfig.debug would break:

    depends on $(cc-option,-gsplit-dwarf)

The combination of -c and -gsplit-dwarf does not accept /dev/null as
output.

  $ cat /dev/null | gcc -gsplit-dwarf -S -x c - -o /dev/null
  $ echo $?
  0

  $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o /dev/null
  objcopy: Warning: '/dev/null' is not an ordinary file
  $ echo $?
  1

  $ cat /dev/null | gcc -gsplit-dwarf -c -x c - -o tmp.o
  $ echo $?
  0

There is another flag that creates an separate file based on the
object file path:

  $ cat /dev/null | gcc -ftest-coverage -c -x c - -o /dev/null
  <stdin>:1: error: cannot open /dev/null.gcno

So, we cannot use /dev/null to sink the output.

Align the cc-option implementation with scripts/Kbuild.include.

With -c option used in cc-option, as-option is unneeded.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Will Deacon <will@kernel.org>

'seq_buf' provides a very useful abstraction for writing to a string
buffer without needing to worry about it over-flowing. However even
though the API has been stable for couple of years now its still not
exported to kernel loadable modules limiting its usage.

Hence this patch proposes update to 'seq_buf.c' to mark
seq_buf_printf() which is part of the seq_buf API to be exported to
kernel loadable GPL modules. This symbol will be used in later parts
of this patch-set to simplify content creation for a sysfs attribute.

Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Piotr Maziarz <piotrx.maziarz@linux.intel.com>
Cc: Cezary Rojewski <cezary.rojewski@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lore.kernel.org/r/20200615124407.32596-3-vaibhav@linux.ibm.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

In case of failure of check_expect_hints_stats(), the resources
allocated by objagg_hints_get should be freed. The patch fixes
this issue.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

Commit
  10e68b02c861 ("Makefile: support compressed debug info")
added support for compressed debug sections.

Support is detected by checking
- does the compiler support -gz=zlib
- does the assembler support --compressed-debug-sections=zlib
- does the linker support --compressed-debug-sections=zlib

However, the gcc driver's support for this option is somewhat
convoluted. The driver's builtin specs are set based on the version of
binutils that it was configured with. It reports an error if the
configure-time linker/assembler (i.e., not necessarily the actual
assembler that will be run) do not support the option, but only if the
assembler (or linker) is actually invoked when -gz=zlib is passed.

The cc-option check in scripts/Kconfig.include does not invoke the
assembler, so the gcc driver reports success even if it does not support
the option being passed to the assembler.

Because the as-option check passes the option directly to the assembler
via -Wa,--compressed-debug-sections=zlib, the gcc driver does not see
this option and will never report an error.

Combined with an installed version of binutils that is more recent than
the one the compiler was built with, it is possible for all three tests
to succeed, yet an actual compilation with -gz=zlib to fail.

Moreover, it is unnecessary to explicitly pass
--compressed-debug-sections=zlib to the assembler via -Wa, since the
driver will do that automatically when it supports -gz=zlib.

Convert the as-option to just -gz=zlib, simplifying it as well as
performing a better test of the gcc driver's capabilities.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Pull more Kbuild updates from Masahiro Yamada:

 - fix build rules in binderfs sample

 - fix build errors when Kbuild recurses to the top Makefile

 - covert '---help---' in Kconfig to 'help'

* tag 'kbuild-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  treewide: replace '---help---' in Kconfig files with 'help'
  kbuild: fix broken builds because of GZIP,BZIP2,LZOP variables
  samples: binderfs: really compile this sample and fix build issues

Pull x86 entry updates from Thomas Gleixner:
 "The x86 entry, exception and interrupt code rework

  This all started about 6 month ago with the attempt to move the Posix
  CPU timer heavy lifting out of the timer interrupt code and just have
  lockless quick checks in that code path. Trivial 5 patches.

  This unearthed an inconsistency in the KVM handling of task work and
  the review requested to move all of this into generic code so other
  architectures can share.

  Valid request and solved with another 25 patches but those unearthed
  inconsistencies vs. RCU and instrumentation.

  Digging into this made it obvious that there are quite some
  inconsistencies vs. instrumentation in general. The int3 text poke
  handling in particular was completely unprotected and with the batched
  update of trace events even more likely to expose to endless int3
  recursion.

  In parallel the RCU implications of instrumenting fragile entry code
  came up in several discussions.

  The conclusion of the x86 maintainer team was to go all the way and
  make the protection against any form of instrumentation of fragile and
  dangerous code pathes enforcable and verifiable by tooling.

  A first batch of preparatory work hit mainline with commit
  d5f744f9a2ac ("Pull x86 entry code updates from Thomas Gleixner")

  That (almost) full solution introduced a new code section
  '.noinstr.text' into which all code which needs to be protected from
  instrumentation of all sorts goes into. Any call into instrumentable
  code out of this section has to be annotated. objtool has support to
  validate this.

  Kprobes now excludes this section fully which also prevents BPF from
  fiddling with it and all 'noinstr' annotated functions also keep
  ftrace off. The section, kprobes and objtool changes are already
  merged.

  The major changes coming with this are:

    - Preparatory cleanups

    - Annotating of relevant functions to move them into the
      noinstr.text section or enforcing inlining by marking them
      __always_inline so the compiler cannot misplace or instrument
      them.

    - Splitting and simplifying the idtentry macro maze so that it is
      now clearly separated into simple exception entries and the more
      interesting ones which use interrupt stacks and have the paranoid
      handling vs. CR3 and GS.

    - Move quite some of the low level ASM functionality into C code:

       - enter_from and exit to user space handling. The ASM code now
         calls into C after doing the really necessary ASM handling and
         the return path goes back out without bells and whistels in
         ASM.

       - exception entry/exit got the equivivalent treatment

       - move all IRQ tracepoints from ASM to C so they can be placed as
         appropriate which is especially important for the int3
         recursion issue.

    - Consolidate the declaration and definition of entry points between
      32 and 64 bit. They share a common header and macros now.

    - Remove the extra device interrupt entry maze and just use the
      regular exception entry code.

    - All ASM entry points except NMI are now generated from the shared
      header file and the corresponding macros in the 32 and 64 bit
      entry ASM.

    - The C code entry points are consolidated as well with the help of
      DEFINE_IDTENTRY*() macros. This allows to ensure at one central
      point that all corresponding entry points share the same
      semantics. The actual function body for most entry points is in an
      instrumentable and sane state.

      There are special macros for the more sensitive entry points, e.g.
      INT3 and of course the nasty paranoid #NMI, #MCE, #DB and #DF.
      They allow to put the whole entry instrumentation and RCU handling
      into safe places instead of the previous pray that it is correct
      approach.

    - The INT3 text poke handling is now completely isolated and the
      recursion issue banned. Aside of the entry rework this required
      other isolation work, e.g. the ability to force inline bsearch.

    - Prevent #DB on fragile entry code, entry relevant memory and
      disable it on NMI, #MC entry, which allowed to get rid of the
      nested #DB IST stack shifting hackery.

    - A few other cleanups and enhancements which have been made
      possible through this and already merged changes, e.g.
      consolidating and further restricting the IDT code so the IDT
      table becomes RO after init which removes yet another popular
      attack vector

    - About 680 lines of ASM maze are gone.

  There are a few open issues:

   - An escape out of the noinstr section in the MCE handler which needs
     some more thought but under the aspect that MCE is a complete
     trainwreck by design and the propability to survive it is low, this
     was not high on the priority list.

   - Paravirtualization

     When PV is enabled then objtool complains about a bunch of indirect
     calls out of the noinstr section. There are a few straight forward
     ways to fix this, but the other issues vs. general correctness were
     more pressing than parawitz.

   - KVM

     KVM is inconsistent as well. Patches have been posted, but they
     have not yet been commented on or picked up by the KVM folks.

   - IDLE

     Pretty much the same problems can be found in the low level idle
     code especially the parts where RCU stopped watching. This was
     beyond the scope of the more obvious and exposable problems and is
     on the todo list.

  The lesson learned from this brain melting exercise to morph the
  evolved code base into something which can be validated and understood
  is that once again the violation of the most important engineering
  principle "correctness first" has caused quite a few people to spend
  valuable time on problems which could have been avoided in the first
  place. The "features first" tinkering mindset really has to stop.

  With that I want to say thanks to everyone involved in contributing to
  this effort. Special thanks go to the following people (alphabetical
  order): Alexandre Chartre, Andy Lutomirski, Borislav Petkov, Brian
  Gerst, Frederic Weisbecker, Josh Poimboeuf, Juergen Gross, Lai
  Jiangshan, Macro Elver, Paolo Bonzin,i Paul McKenney, Peter Zijlstra,
  Vitaly Kuznetsov, and Will Deacon"

* tag 'x86-entry-2020-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (142 commits)
  x86/entry: Force rcu_irq_enter() when in idle task
  x86/entry: Make NMI use IDTENTRY_RAW
  x86/entry: Treat BUG/WARN as NMI-like entries
  x86/entry: Unbreak __irqentry_text_start/end magic
  x86/entry: __always_inline CR2 for noinstr
  lockdep: __always_inline more for noinstr
  x86/entry: Re-order #DB handler to avoid *SAN instrumentation
  x86/entry: __always_inline arch_atomic_* for noinstr
  x86/entry: __always_inline irqflags for noinstr
  x86/entry: __always_inline debugreg for noinstr
  x86/idt: Consolidate idt functionality
  x86/idt: Cleanup trap_init()
  x86/idt: Use proper constants for table size
  x86/idt: Add comments about early #PF handling
  x86/idt: Mark init only functions __init
  x86/entry: Rename trace_hardirqs_off_prepare()
  x86/entry: Clarify irq_{enter,exit}_rcu()
  x86/entry: Remove DBn stacks
  x86/entry: Remove debug IDT frobbing
  x86/entry: Optimize local_db_save() for virt
  ...