Pull locking updates from Ingo Molnar:

 - Introduce local{,64}_try_cmpxchg() - a slightly more optimal
   primitive, which will be used in perf events ring-buffer code

 - Simplify/modify rwsems on PREEMPT_RT, to address writer starvation

 - Misc cleanups/fixes

* tag 'locking-core-2023-05-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/atomic: Correct (cmp)xchg() instrumentation
  locking/x86: Define arch_try_cmpxchg_local()
  locking/arch: Wire up local_try_cmpxchg()
  locking/generic: Wire up local{,64}_try_cmpxchg()
  locking/atomic: Add generic try_cmpxchg{,64}_local() support
  locking/rwbase: Mitigate indefinite writer starvation
  locking/arch: Rename all internal __xchg() names to __arch_xchg()

Decrease the probability of this internal facility to be used by
driver code.

Signed-off-by: Andrzej Hajda <andrzej.hajda@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Palmer Dabbelt <palmer@rivosinc.com> [riscv]
Link: https://lore.kernel.org/r/20230118154450.73842-1-andrzej.hajda@intel.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>

Pull objtool updates from Ingo Molnar:

 - Mark arch_cpu_idle_dead() __noreturn, make all architectures &
   drivers that did this inconsistently follow this new, common
   convention, and fix all the fallout that objtool can now detect
   statically

 - Fix/improve the ORC unwinder becoming unreliable due to
   UNWIND_HINT_EMPTY ambiguity, split it into UNWIND_HINT_END_OF_STACK
   and UNWIND_HINT_UNDEFINED to resolve it

 - Fix noinstr violations in the KCSAN code and the lkdtm/stackleak code

 - Generate ORC data for __pfx code

 - Add more __noreturn annotations to various kernel startup/shutdown
   and panic functions

 - Misc improvements & fixes

* tag 'objtool-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
  x86/hyperv: Mark hv_ghcb_terminate() as noreturn
  scsi: message: fusion: Mark mpt_halt_firmware() __noreturn
  x86/cpu: Mark {hlt,resume}_play_dead() __noreturn
  btrfs: Mark btrfs_assertfail() __noreturn
  objtool: Include weak functions in global_noreturns check
  cpu: Mark nmi_panic_self_stop() __noreturn
  cpu: Mark panic_smp_self_stop() __noreturn
  arm64/cpu: Mark cpu_park_loop() and friends __noreturn
  x86/head: Mark *_start_kernel() __noreturn
  init: Mark start_kernel() __noreturn
  init: Mark [arch_call_]rest_init() __noreturn
  objtool: Generate ORC data for __pfx code
  x86/linkage: Fix padding for typed functions
  objtool: Separate prefix code from stack validation code
  objtool: Remove superfluous dead_end_function() check
  objtool: Add symbol iteration helpers
  objtool: Add WARN_INSN()
  scripts/objdump-func: Support multiple functions
  context_tracking: Fix KCSAN noinstr violation
  objtool: Add stackleak instrumentation to uaccess safe list
  ...

Pull x86 LAM (Linear Address Masking) support from Dave Hansen:
 "Add support for the new Linear Address Masking CPU feature.

  This is similar to ARM's Top Byte Ignore and allows userspace to store
  metadata in some bits of pointers without masking it out before use"

* tag 'x86_mm_for_6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mm/iommu/sva: Do not allow to set FORCE_TAGGED_SVA bit from outside
  x86/mm/iommu/sva: Fix error code for LAM enabling failure due to SVA
  selftests/x86/lam: Add test cases for LAM vs thread creation
  selftests/x86/lam: Add ARCH_FORCE_TAGGED_SVA test cases for linear-address masking
  selftests/x86/lam: Add inherit test cases for linear-address masking
  selftests/x86/lam: Add io_uring test cases for linear-address masking
  selftests/x86/lam: Add mmap and SYSCALL test cases for linear-address masking
  selftests/x86/lam: Add malloc and tag-bits test cases for linear-address masking
  x86/mm/iommu/sva: Make LAM and SVA mutually exclusive
  iommu/sva: Replace pasid_valid() helper with mm_valid_pasid()
  mm: Expose untagging mask in /proc/$PID/status
  x86/mm: Provide arch_prctl() interface for LAM
  x86/mm: Reduce untagged_addr() overhead for systems without LAM
  x86/uaccess: Provide untagged_addr() and remove tags before address check
  mm: Introduce untagged_addr_remote()
  x86/mm: Handle LAM on context switch
  x86: CPUID and CR3/CR4 flags for Linear Address Masking
  x86: Allow atomic MM_CONTEXT flags setting
  x86/mm: Rework address range check in get_user() and put_user()

Pull MM updates from Andrew Morton:

 - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of
   switching from a user process to a kernel thread.

 - More folio conversions from Kefeng Wang, Zhang Peng and Pankaj
   Raghav.

 - zsmalloc performance improvements from Sergey Senozhatsky.

 - Yue Zhao has found and fixed some data race issues around the
   alteration of memcg userspace tunables.

 - VFS rationalizations from Christoph Hellwig:
     - removal of most of the callers of write_one_page()
     - make __filemap_get_folio()'s return value more useful

 - Luis Chamberlain has changed tmpfs so it no longer requires swap
   backing. Use `mount -o noswap'.

 - Qi Zheng has made the slab shrinkers operate locklessly, providing
   some scalability benefits.

 - Keith Busch has improved dmapool's performance, making part of its
   operations O(1) rather than O(n).

 - Peter Xu adds the UFFD_FEATURE_WP_UNPOPULATED feature to userfaultd,
   permitting userspace to wr-protect anon memory unpopulated ptes.

 - Kirill Shutemov has changed MAX_ORDER's meaning to be inclusive
   rather than exclusive, and has fixed a bunch of errors which were
   caused by its unintuitive meaning.

 - Axel Rasmussen give userfaultfd the UFFDIO_CONTINUE_MODE_WP feature,
   which causes minor faults to install a write-protected pte.

 - Vlastimil Babka has done some maintenance work on vma_merge():
   cleanups to the kernel code and improvements to our userspace test
   harness.

 - Cleanups to do_fault_around() by Lorenzo Stoakes.

 - Mike Rapoport has moved a lot of initialization code out of various
   mm/ files and into mm/mm_init.c.

 - Lorenzo Stoakes removd vmf_insert_mixed_prot(), which was added for
   DRM, but DRM doesn't use it any more.

 - Lorenzo has also coverted read_kcore() and vread() to use iterators
   and has thereby removed the use of bounce buffers in some cases.

 - Lorenzo has also contributed further cleanups of vma_merge().

 - Chaitanya Prakash provides some fixes to the mmap selftesting code.

 - Matthew Wilcox changes xfs and afs so they no longer take sleeping
   locks in ->map_page(), a step towards RCUification of pagefaults.

 - Suren Baghdasaryan has improved mmap_lock scalability by switching to
   per-VMA locking.

 - Frederic Weisbecker has reworked the percpu cache draining so that it
   no longer causes latency glitches on cpu isolated workloads.

 - Mike Rapoport cleans up and corrects the ARCH_FORCE_MAX_ORDER Kconfig
   logic.

 - Liu Shixin has changed zswap's initialization so we no longer waste a
   chunk of memory if zswap is not being used.

 - Yosry Ahmed has improved the performance of memcg statistics
   flushing.

 - David Stevens has fixed several issues involving khugepaged,
   userfaultfd and shmem.

 - Christoph Hellwig has provided some cleanup work to zram's IO-related
   code paths.

 - David Hildenbrand has fixed up some issues in the selftest code's
   testing of our pte state changing.

 - Pankaj Raghav has made page_endio() unneeded and has removed it.

 - Peter Xu contributed some rationalizations of the userfaultfd
   selftests.

 - Yosry Ahmed has fixed an issue around memcg's page recalim
   accounting.

 - Chaitanya Prakash has fixed some arm-related issues in the
   selftests/mm code.

 - Longlong Xia has improved the way in which KSM handles hwpoisoned
   pages.

 - Peter Xu fixes a few issues with uffd-wp at fork() time.

 - Stefan Roesch has changed KSM so that it may now be used on a
   per-process and per-cgroup basis.

* tag 'mm-stable-2023-04-27-15-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm,unmap: avoid flushing TLB in batch if PTE is inaccessible
  shmem: restrict noswap option to initial user namespace
  mm/khugepaged: fix conflicting mods to collapse_file()
  sparse: remove unnecessary 0 values from rc
  mm: move 'mmap_min_addr' logic from callers into vm_unmapped_area()
  hugetlb: pte_alloc_huge() to replace huge pte_alloc_map()
  maple_tree: fix allocation in mas_sparse_area()
  mm: do not increment pgfault stats when page fault handler retries
  zsmalloc: allow only one active pool compaction context
  selftests/mm: add new selftests for KSM
  mm: add new KSM process and sysfs knobs
  mm: add new api to enable ksm per process
  mm: shrinkers: fix debugfs file permissions
  mm: don't check VMA write permissions if the PTE/PMD indicates write permissions
  migrate_pages_batch: fix statistics for longterm pin retry
  userfaultfd: use helper function range_in_vma()
  lib/show_mem.c: use for_each_populated_zone() simplify code
  mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list()
  fs/buffer: convert create_page_buffers to folio_create_buffers
  fs/buffer: add folio_create_empty_buffers helper
  ...

On sparc64, there is no HW modified bit, therefore, SW tracks via a SW bit
if the PTE is dirty via pte_mkdirty().  However, pte_mkdirty() currently
also unconditionally sets the HW writable bit, which is wrong.

pte_mkdirty() is not supposed to make a PTE actually writable, unless the
SW writable bit -- pte_write() -- indicates that the PTE is not
write-protected.  Fortunately, sparc64 also defines a SW writable bit.

For example, this already turned into a problem in the context of THP
splitting as documented in commit 624a2c94f5b7 ("Partly revert "mm/thp:
carry over dirty bit when thp splits on pmd""), and for page migration, as
documented in commit 96a9c287e25d ("mm/migrate: fix wrongly apply write
bit after mkdirty on sparc64").

Also, we might want to use the dirty PTE bit in the context of KSM with
shared zeropage [1], whereby setting the page writable would be
problematic.

But more general, any code that might end up setting a PTE/PMD dirty
inside a VM without write permissions is possibly broken,

Before this commit (sun4u in QEMU):
	root@debian:~/linux/tools/testing/selftests/mm# ./mkdirty
	# [INFO] detected THP size: 8192 KiB
	TAP version 13
	1..6
	# [INFO] PTRACE write access
	not ok 1 SIGSEGV generated, page not modified
	# [INFO] PTRACE write access to THP
	not ok 2 SIGSEGV generated, page not modified
	# [INFO] Page migration
	ok 3 SIGSEGV generated, page not modified
	# [INFO] Page migration of THP
	ok 4 SIGSEGV generated, page not modified
	# [INFO] PTE-mapping a THP
	ok 5 SIGSEGV generated, page not modified
	# [INFO] UFFDIO_COPY
	not ok 6 SIGSEGV generated, page not modified
	Bail out! 3 out of 6 tests failed
	# Totals: pass:3 fail:3 xfail:0 xpass:0 skip:0 error:0

Test #3,#4,#5 pass ever since we added some MM workarounds, the
underlying issue remains.

Let's fix the remaining issues and prepare for reverting the workarounds
by setting the HW writable bit only if both, the SW dirty bit and the SW
writable bit are set.

We have to move pte_dirty() and pte_write() up. The code patching
mechanism and handling constants > 22bit is a bit special on sparc64.

The ASM logic in pte_mkdirty() and pte_mkwrite() match the logic in
pte_mkold() to create the mask depending on the machine type. The ASM
logic in __pte_mkhwwrite() matches the logic in pte_present(), just
using an "or" instead of an "and" instruction.

With this commit (sun4u in QEMU):
	root@debian:~/linux/tools/testing/selftests/mm# ./mkdirty
	# [INFO] detected THP size: 8192 KiB
	TAP version 13
	1..6
	# [INFO] PTRACE write access
	ok 1 SIGSEGV generated, page not modified
	# [INFO] PTRACE write access to THP
	ok 2 SIGSEGV generated, page not modified
	# [INFO] Page migration
	ok 3 SIGSEGV generated, page not modified
	# [INFO] Page migration of THP
	ok 4 SIGSEGV generated, page not modified
	# [INFO] PTE-mapping a THP
	ok 5 SIGSEGV generated, page not modified
	# [INFO] UFFDIO_COPY
	ok 6 SIGSEGV generated, page not modified
	# Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0

This handling seems to have been in place forever.

[1] https://lkml.kernel.org/r/533a7c3d-3a48-b16b-b421-6e8386e0b142@redhat.com

Link: https://lkml.kernel.org/r/20230411142512.438404-4-david@redhat.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Sparc is the only place devtree_lock is used outside of drivers/of/.
Move the devtree_lock declaration into of_private.h and Sparc's prom.h
so pulling in spinlock.h to of.h can be avoided for everything besides
Sparc.

Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-1-581e2605fe47@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>

Add a line in /proc/$PID/status to report untag_mask. It can be
used to find out LAM status of the process from the outside. It is
useful for debuggers.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/all/20230312112612.31869-10-kirill.shutemov%40linux.intel.com

untagged_addr() removes tags/metadata from the address and brings it to
the canonical form. The helper is implemented on arm64 and sparc. Both of
them do untagging based on global rules.

However, Linear Address Masking (LAM) on x86 introduces per-process
settings for untagging. As a result, untagged_addr() is now only
suitable for untagging addresses for the current proccess.

The new helper untagged_addr_remote() has to be used when the address
targets remote process. It requires the mmap lock for target mm to be
taken.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/all/20230312112612.31869-6-kirill.shutemov%40linux.intel.com

cpu_play_dead() doesn't return.  Annotate it as such.  By extension this
also makes arch_cpu_idle_dead() noreturn.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Link: https://lore.kernel.org/r/847fdb53cc7124bb7c94e3e104e443a29be85184.1676358308.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>