The kernel test robot reported that clang no longer compiles the 32-bit
x86 kernel in some configurations due to commit 95ece48165c1
("locking/atomic/x86: Rewrite x86_32 arch_atomic64_{,fetch}_{and,or,xor}()
functions").

The build fails with

  arch/x86/include/asm/cmpxchg_32.h:149:9: error: inline assembly requires more registers than available

and the reason seems to be that not only does the cmpxchg8b instruction
need four fixed registers (EDX:EAX and ECX:EBX), with the emulation
fallback the inline asm also wants a fifth fixed register for the
address (it uses %esi for that, but that's just a software convention
with cmpxchg8b_emu).

Avoiding using another pointer input to the asm (and just forcing it to
use the "0(%esi)" addressing that we end up requiring for the sw
fallback) seems to fix the issue.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202406230912.F6XFIyA6-lkp@intel.com/
Fixes: 95ece48165c1 ("locking/atomic/x86: Rewrite x86_32 arch_atomic64_{,fetch}_{and,or,xor}() functions")
Link: https://lore.kernel.org/all/202406230912.F6XFIyA6-lkp@intel.com/
Suggested-by: Uros Bizjak <ubizjak@gmail.com>
Reviewed-and-Tested-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull hardening fixes from Kees Cook:

 - Remove invalid tty __counted_by annotation (Nathan Chancellor)

 - Add missing MODULE_DESCRIPTION()s for KUnit string tests (Jeff
   Johnson)

 - Remove non-functional per-arch kstack entropy filtering

* tag 'hardening-v6.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  tty: mxser: Remove __counted_by from mxser_board.ports[]
  randomize_kstack: Remove non-functional per-arch entropy filtering
  string: kunit: add missing MODULE_DESCRIPTION() macros

An unintended consequence of commit 9c573cd31343 ("randomize_kstack:
Improve entropy diffusion") was that the per-architecture entropy size
filtering reduced how many bits were being added to the mix, rather than
how many bits were being used during the offsetting. All architectures
fell back to the existing default of 0x3FF (10 bits), which will consume
at most 1KiB of stack space. It seems that this is working just fine,
so let's avoid the confusion and update everything to use the default.

The prior intent of the per-architecture limits were:

  arm64: capped at 0x1FF (9 bits), 5 bits effective
  powerpc: uncapped (10 bits), 6 or 7 bits effective
  riscv: uncapped (10 bits), 6 bits effective
  x86: capped at 0xFF (8 bits), 5 (x86_64) or 6 (ia32) bits effective
  s390: capped at 0xFF (8 bits), undocumented effective entropy

Current discussion has led to just dropping the original per-architecture
filters. The additional entropy appears to be safe for arm64, x86,
and s390. Quoting Arnd, "There is no point pretending that 15.75KB is
somehow safe to use while 15.00KB is not."

Co-developed-by: Yuntao Liu <liuyuntao12@huawei.com>
Signed-off-by: Yuntao Liu <liuyuntao12@huawei.com>
Fixes: 9c573cd31343 ("randomize_kstack: Improve entropy diffusion")
Link: https://lore.kernel.org/r/20240617133721.377540-1-liuyuntao12@huawei.com
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com> # s390
Link: https://lore.kernel.org/r/20240619214711.work.953-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>

Pull EFI fixes from Ard Biesheuvel:
 "Another small set of EFI fixes. Only the x86 one is likely to affect
  any actual users (and has a cc:stable), but the issue it fixes was
  only observed in an unusual context (kexec in a confidential VM).

   - Ensure that EFI runtime services are not unmapped by PAN on ARM

   - Avoid freeing the memory holding the EFI memory map inadvertently
     on x86

   - Avoid a false positive kmemleak warning on arm64"

* tag 'efi-fixes-for-v6.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi/arm64: Fix kmemleak false positive in arm64_efi_rt_init()
  efi/x86: Free EFI memory map only when installing a new one.
  efi/arm: Disable LPAE PAN when calling EFI runtime services

Pull x86 fixes from Ingo Molnar:

 - Fix the 8 bytes get_user() logic on x86-32

 - Fix build bug that creates weird & mistaken target directory under
   arch/x86/

* tag 'x86-urgent-2024-06-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Don't add the EFI stub to targets, again
  x86/uaccess: Fix missed zeroing of ia32 u64 get_user() range checking

The logic in __efi_memmap_init() is shared between two different
execution flows:
- mapping the EFI memory map early or late into the kernel VA space, so
  that its entries can be accessed;
- the x86 specific cloning of the EFI memory map in order to insert new
  entries that are created as a result of making a memory reservation
  via a call to efi_mem_reserve().

In the former case, the underlying memory containing the kernel's view
of the EFI memory map (which may be heavily modified by the kernel
itself on x86) is not modified at all, and the only thing that changes
is the virtual mapping of this memory, which is different between early
and late boot.

In the latter case, an entirely new allocation is created that carries a
new, updated version of the kernel's view of the EFI memory map. When
installing this new version, the old version will no longer be
referenced, and if the memory was allocated by the kernel, it will leak
unless it gets freed.

The logic that implements this freeing currently lives on the code path
that is shared between these two use cases, but it should only apply to
the latter. So move it to the correct spot.

While at it, drop the dummy definition for non-x86 architectures, as
that is no longer needed.

Cc: <stable@vger.kernel.org>
Fixes: f0ef6523475f ("efi: Fix efi_memmap_alloc() leaks")
Tested-by: Ashish Kalra <Ashish.Kalra@amd.com>
Link: https://lore.kernel.org/all/36ad5079-4326-45ed-85f6-928ff76483d3@amd.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

When reworking the range checking for get_user(), the get_user_8() case
on 32-bit wasn't zeroing the high register. (The jump to bad_get_user_8
was accidentally dropped.) Restore the correct error handling
destination (and rename the jump to using the expected ".L" prefix).

While here, switch to using a named argument ("size") for the call
template ("%c4" to "%c[size]") as already used in the other call
templates in this file.

Found after moving the usercopy selftests to KUnit:

      # usercopy_test_invalid: EXPECTATION FAILED at
      lib/usercopy_kunit.c:278
      Expected val_u64 == 0, but
          val_u64 == -60129542144 (0xfffffff200000000)

Closes: https://lore.kernel.org/all/CABVgOSn=tb=Lj9SxHuT4_9MTjjKVxsq-ikdXC4kGHO4CfKVmGQ@mail.gmail.com
Fixes: b19b74bc99b1 ("x86/mm: Rework address range check in get_user() and put_user()")
Reported-by: David Gow <davidgow@google.com>
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Tested-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/all/20240610210213.work.143-kees%40kernel.org

* Fixes and debugging help for the #VE sanity check.  Also disable
  it by default, even for CONFIG_DEBUG_KERNEL, because it was found
  to trigger spuriously (most likely a processor erratum as the
  exact symptoms vary by generation).

* Avoid WARN() when two NMIs arrive simultaneously during an NMI-disabled
  situation (GIF=0 or interrupt shadow) when the processor supports
  virtual NMI.  While generally KVM will not request an NMI window
  when virtual NMIs are supported, in this case it *does* have to
  single-step over the interrupt shadow or enable the STGI intercept,
  in order to deliver the latched second NMI.

* Drop support for hand tuning APIC timer advancement from userspace.
  Since we have adaptive tuning, and it has proved to work well,
  drop the module parameter for manual configuration and with it a
  few stupid bugs that it had.

Pull x86 fixes from Ingo Molnar:

 - Fix regressions of the new x86 CPU VFM (vendor/family/model)
   enumeration/matching code

 - Fix crash kernel detection on buggy firmware with
   non-compliant ACPI MADT tables

 - Address Kconfig warning

* tag 'x86-urgent-2024-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Fix x86_match_cpu() to match just X86_VENDOR_INTEL
  crypto: x86/aes-xts - switch to new Intel CPU model defines
  x86/topology: Handle bogus ACPI tables correctly
  x86/kconfig: Select ARCH_WANT_FRAME_POINTERS again when UNWINDER_FRAME_POINTER=y

Don't suppress printing EPT_VIOLATION_VE in /proc/cpuinfo, knowing whether
or not KVM_INTEL_PROVE_VE actually does anything is extremely valuable.
A privileged user can get at the information by reading the raw MSR, but
the whole point of the VMX flags is to avoid needing to glean information
from raw MSR reads.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20240518000430.1118488-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>