Commit 41a506ef71eb ("powerpc/ftrace: Create a dummy stackframe to fix
stack unwind") added use of a new stack frame on ftrace entry to fix
stack unwind. However, the commit missed updating the offset used while
tearing down the ftrace stack when ftrace is disabled. Fix the same.

In addition, the commit missed saving the correct stack pointer in
pt_regs. Update the same.

Fixes: 41a506ef71eb ("powerpc/ftrace: Create a dummy stackframe to fix stack unwind")
Cc: stable@vger.kernel.org # v6.5+
Signed-off-by: Naveen N Rao <naveen@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231130065947.2188860-1-naveen@kernel.org

Before running a guest, the host process (e.g., QEMU) FP/VEC registers
are saved if they were being used, similarly to when the kernel uses FP
registers. The guest values are then loaded into regs, and the host
process registers will be restored lazily when it uses FP/VEC.

KVM HV has a bug here: the host process registers do get saved, but the
user MSR bits remain enabled, which indicates the registers are valid
for the process. After they are clobbered by running the guest, this
valid indication causes the host process to take on the FP/VEC register
values of the guest.

Fixes: 34e119c96b2b ("KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs")
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231122025811.2973-1-npiggin@gmail.com

During floating point and vector save to thread data f0/vs0 are
clobbered by the FPSCR/VSCR store routine. This has been obvserved to
lead to userspace register corruption and application data corruption
with io-uring.

Fix it by restoring f0/vs0 after FPSCR/VSCR store has completed for
all the FP, altivec, VMX register save paths.

Tested under QEMU in kvm mode, running on a Talos II workstation with
dual POWER9 DD2.2 CPUs.

Additional detail (mpe):

Typically save_fpu() is called from __giveup_fpu() which saves the FP
regs and also *turns off FP* in the tasks MSR, meaning the kernel will
reload the FP regs from the thread struct before letting the task use FP
again. So in that case save_fpu() is free to clobber f0 because the FP
regs no longer hold live values for the task.

There is another case though, which is the path via:
  sys_clone()
    ...
    copy_process()
      dup_task_struct()
        arch_dup_task_struct()
          flush_all_to_thread()
            save_all()

That path saves the FP regs but leaves them live. That's meant as an
optimisation for a process that's using FP/VSX and then calls fork(),
leaving the regs live means the parent process doesn't have to take a
fault after the fork to get its FP regs back. The optimisation was added
in commit 8792468da5e1 ("powerpc: Add the ability to save FPU without
giving it up").

That path does clobber f0, but f0 is volatile across function calls,
and typically programs reach copy_process() from userspace via a syscall
wrapper function. So in normal usage f0 being clobbered across a
syscall doesn't cause visible data corruption.

But there is now a new path, because io-uring can call copy_process()
via create_io_thread() from the signal handling path. That's OK if the
signal is handled as part of syscall return, but it's not OK if the
signal is handled due to some other interrupt.

That path is:

interrupt_return_srr_user()
  interrupt_exit_user_prepare()
    interrupt_exit_user_prepare_main()
      do_notify_resume()
        get_signal()
          task_work_run()
            create_worker_cb()
              create_io_worker()
                copy_process()
                  dup_task_struct()
                    arch_dup_task_struct()
                      flush_all_to_thread()
                        save_all()
                          if (tsk->thread.regs->msr & MSR_FP)
                            save_fpu()
                            # f0 is clobbered and potentially live in userspace

Note the above discussion applies equally to save_altivec().

Fixes: 8792468da5e1 ("powerpc: Add the ability to save FPU without giving it up")
Cc: stable@vger.kernel.org # v4.6+
Closes: https://lore.kernel.org/all/480932026.45576726.1699374859845.JavaMail.zimbra@raptorengineeringinc.com/
Closes: https://lore.kernel.org/linuxppc-dev/480221078.47953493.1700206777956.JavaMail.zimbra@raptorengineeringinc.com/
Tested-by: Timothy Pearson <tpearson@raptorengineering.com>
Tested-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
[mpe: Reword change log to describe exact path of corruption & other minor tweaks]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/1921539696.48534988.1700407082933.JavaMail.zimbra@raptorengineeringinc.com

Pull powerpc fixes from Michael Ellerman:

 - Finish a refactor of pgprot_framebuffer() which dependend
   on some changes that were merged via the drm tree

 - Fix some kernel-doc warnings to quieten the bots

Thanks to Nathan Lynch and Thomas Zimmermann.

* tag 'powerpc-6.7-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/rtas: Fix ppc_rtas_rmo_buf_show() kernel-doc
  powerpc/pseries/rtas-work-area: Fix rtas_work_area_reserve_arena() kernel-doc
  powerpc/fb: Call internal __phys_mem_access_prot() in fbdev code
  powerpc: Remove file parameter from phys_mem_access_prot()
  powerpc/machdep: Remove trailing whitespaces

Pull iommu updates from Joerg Roedel:
 "Core changes:
   - Make default-domains mandatory for all IOMMU drivers
   - Remove group refcounting
   - Add generic_single_device_group() helper and consolidate drivers
   - Cleanup map/unmap ops
   - Scaling improvements for the IOVA rcache depot
   - Convert dart & iommufd to the new domain_alloc_paging()

  ARM-SMMU:
   - Device-tree binding update:
       - Add qcom,sm7150-smmu-v2 for Adreno on SM7150 SoC
   - SMMUv2:
       - Support for Qualcomm SDM670 (MDSS) and SM7150 SoCs
   - SMMUv3:
       - Large refactoring of the context descriptor code to move the CD
         table into the master, paving the way for '->set_dev_pasid()'
         support on non-SVA domains
   - Minor cleanups to the SVA code

  Intel VT-d:
   - Enable debugfs to dump domain attached to a pasid
   - Remove an unnecessary inline function

  AMD IOMMU:
   - Initial patches for SVA support (not complete yet)

  S390 IOMMU:
   - DMA-API conversion and optimized IOTLB flushing

  And some smaller fixes and improvements"

* tag 'iommu-updates-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (102 commits)
  iommu/dart: Remove the force_bypass variable
  iommu/dart: Call apple_dart_finalize_domain() as part of alloc_paging()
  iommu/dart: Convert to domain_alloc_paging()
  iommu/dart: Move the blocked domain support to a global static
  iommu/dart: Use static global identity domains
  iommufd: Convert to alloc_domain_paging()
  iommu/vt-d: Use ops->blocked_domain
  iommu/vt-d: Update the definition of the blocking domain
  iommu: Move IOMMU_DOMAIN_BLOCKED global statics to ops->blocked_domain
  Revert "iommu/vt-d: Remove unused function"
  iommu/amd: Remove DMA_FQ type from domain allocation path
  iommu: change iommu_map_sgtable to return signed values
  iommu/virtio: Add __counted_by for struct viommu_request and use struct_size()
  iommu/vt-d: debugfs: Support dumping a specified page table
  iommu/vt-d: debugfs: Create/remove debugfs file per {device, pasid}
  iommu/vt-d: debugfs: Dump entry pointing to huge page
  iommu/vt-d: Remove unused function
  iommu/arm-smmu-v3-sva: Remove bond refcount
  iommu/arm-smmu-v3-sva: Remove unused iommu_sva handle
  iommu/arm-smmu-v3: Rename cdcfg to cd_table
  ...

>From a W=1 build:

>> arch/powerpc/kernel/rtas-proc.c:771: warning: Function parameter or member 'm' not described in
>> 'ppc_rtas_rmo_buf_show'
>> arch/powerpc/kernel/rtas-proc.c:771: warning: Function parameter or member 'v' not described in
>> 'ppc_rtas_rmo_buf_show'

Add the missing parameter descriptions.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202309211645.1Lvwmbv4-lkp@intel.com/
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231106-rtas-trivial-v1-2-61847655c51f@linux.ibm.com

Remove 'file' parameter from struct machdep_calls.phys_mem_access_prot
and its implementation in pci_phys_mem_access_prot(). The file is not
used on PowerPC. By removing it, a later patch can simplify fbdev's
mmap code, which uses phys_mem_access_prot() on PowerPC.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
[mpe: Rebase on unrelated changes to phys_mem_access_prot()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230922080636.26762-5-tzimmermann@suse.de

Pull tty and serial updates from Greg KH:
 "Here is the big set of tty/serial driver changes for 6.7-rc1. Included
  in here are:

   - console/vgacon cleanups and removals from Arnd

   - tty core and n_tty cleanups from Jiri

   - lots of 8250 driver updates and cleanups

   - sc16is7xx serial driver updates

   - dt binding updates

   - first set of port lock wrapers from Thomas for the printk fixes
     coming in future releases

   - other small serial and tty core cleanups and updates

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (193 commits)
  serdev: Replace custom code with device_match_acpi_handle()
  serdev: Simplify devm_serdev_device_open() function
  serdev: Make use of device_set_node()
  tty: n_gsm: add copyright Siemens Mobility GmbH
  tty: n_gsm: fix race condition in status line change on dead connections
  serial: core: Fix runtime PM handling for pending tx
  vgacon: fix mips/sibyte build regression
  dt-bindings: serial: drop unsupported samsung bindings
  tty: serial: samsung: drop earlycon support for unsupported platforms
  tty: 8250: Add note for PX-835
  tty: 8250: Fix IS-200 PCI ID comment
  tty: 8250: Add Brainboxes Oxford Semiconductor-based quirks
  tty: 8250: Add support for Intashield IX cards
  tty: 8250: Add support for additional Brainboxes PX cards
  tty: 8250: Fix up PX-803/PX-857
  tty: 8250: Fix port count of PX-257
  tty: 8250: Add support for Intashield IS-100
  tty: 8250: Add support for Brainboxes UP cards
  tty: 8250: Add support for additional Brainboxes UC cards
  tty: 8250: Remove UC-257 and UC-431
  ...

Pull powerpc updates from Michael Ellerman:

 - Add support for KVM running as a nested hypervisor under development
   versions of PowerVM, using the new PAPR nested virtualisation API

 - Add support for the BPF prog pack allocator

 - A rework of the non-server MMU handling to support execute-only on
   all platforms

 - Some optimisations & cleanups for the powerpc qspinlock code

 - Various other small features and fixes

Thanks to Aboorva Devarajan, Aditya Gupta, Amit Machhiwal, Benjamin
Gray, Christophe Leroy, Dr. David Alan Gilbert, Gaurav Batra, Gautam
Menghani, Geert Uytterhoeven, Haren Myneni, Hari Bathini, Joel Stanley,
Jordan Niethe, Julia Lawall, Kautuk Consul, Kuan-Wei Chiu, Michael
Neuling, Minjie Du, Muhammad Muzammil, Naveen N Rao, Nicholas Piggin,
Nick Child, Nysal Jan K.A, Peter Lafreniere, Rob Herring, Sachin Sant,
Sebastian Andrzej Siewior, Shrikanth Hegde, Srikar Dronamraju, Stanislav
Kinsburskii, Vaibhav Jain, Wang Yufen, Yang Yingliang, and Yuan Tan.

* tag 'powerpc-6.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (100 commits)
  powerpc/vmcore: Add MMU information to vmcoreinfo
  Revert "powerpc: add `cur_cpu_spec` symbol to vmcoreinfo"
  powerpc/bpf: use bpf_jit_binary_pack_[alloc|finalize|free]
  powerpc/bpf: rename powerpc64_jit_data to powerpc_jit_data
  powerpc/bpf: implement bpf_arch_text_invalidate for bpf_prog_pack
  powerpc/bpf: implement bpf_arch_text_copy
  powerpc/code-patching: introduce patch_instructions()
  powerpc/32s: Implement local_flush_tlb_page_psize()
  powerpc/pseries: use kfree_sensitive() in plpks_gen_password()
  powerpc/code-patching: Perform hwsync in __patch_instruction() in case of failure
  powerpc/fsl_msi: Use device_get_match_data()
  powerpc: Remove cpm_dp...() macros
  powerpc/qspinlock: Rename yield_propagate_owner tunable
  powerpc/qspinlock: Propagate sleepy if previous waiter is preempted
  powerpc/qspinlock: don't propagate the not-sleepy state
  powerpc/qspinlock: propagate owner preemptedness rather than CPU number
  powerpc/qspinlock: stop queued waiters trying to set lock sleepy
  powerpc/perf: Fix disabling BHRB and instruction sampling
  powerpc/trace: Add support for HAVE_FUNCTION_ARG_ACCESS_API
  powerpc/tools: Pass -mabi=elfv2 to gcc-check-mprofile-kernel.sh
  ...

Pull tracing updates from Steven Rostedt:

 - Remove eventfs_file descriptor

   This is the biggest change, and the second part of making eventfs
   create its files dynamically.

   In 6.6 the first part was added, and that maintained a one to one
   mapping between eventfs meta descriptors and the directories and file
   inodes and dentries that were dynamically created. The directories
   were represented by a eventfs_inode and the files were represented by
   a eventfs_file.

   In v6.7 the eventfs_file is removed. As all events have the same
   directory make up (sched_switch has an "enable", "id", "format", etc
   files), the handing of what files are underneath each leaf eventfs
   directory is moved back to the tracing subsystem via a callback.

   When an event is added to the eventfs, it registers an array of
   evenfs_entry's. These hold the names of the files and the callbacks
   to call when the file is referenced. The callback gets the name so
   that the same callback may be used by multiple files. The callback
   then supplies the filesystem_operations structure needed to create
   this file.

   This has brought the memory footprint of creating multiple eventfs
   instances down by 2 megs each!

 - User events now has persistent events that are not associated to a
   single processes. These are privileged events that hang around even
   if no process is attached to them

 - Clean up of seq_buf

   There's talk about using seq_buf more to replace strscpy() and
   friends. But this also requires some minor modifications of seq_buf
   to be able to do this

 - Expand instance ring buffers individually

   Currently if boot up creates an instance, and a trace event is
   enabled on that instance, the ring buffer for that instance and the
   top level ring buffer are expanded (1.4 MB per CPU). This wastes
   memory as this happens when nothing is using the top level instance

 - Other minor clean ups and fixes

* tag 'trace-v6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits)
  seq_buf: Export seq_buf_puts()
  seq_buf: Export seq_buf_putc()
  eventfs: Use simple_recursive_removal() to clean up dentries
  eventfs: Remove special processing of dput() of events directory
  eventfs: Delete eventfs_inode when the last dentry is freed
  eventfs: Hold eventfs_mutex when calling callback functions
  eventfs: Save ownership and mode
  eventfs: Test for ei->is_freed when accessing ei->dentry
  eventfs: Have a free_ei() that just frees the eventfs_inode
  eventfs: Remove "is_freed" union with rcu head
  eventfs: Fix kerneldoc of eventfs_remove_rec()
  tracing: Have the user copy of synthetic event address use correct context
  eventfs: Remove extra dget() in eventfs_create_events_dir()
  tracing: Have trace_event_file have ref counters
  seq_buf: Introduce DECLARE_SEQ_BUF and seq_buf_str()
  eventfs: Fix typo in eventfs_inode union comment
  eventfs: Fix WARN_ON() in create_file_dentry()
  powerpc: Remove initialisation of readpos
  tracing/histograms: Simplify last_cmd_set()
  seq_buf: fix a misleading comment
  ...