[PATCH RESEND v2 00/23] proc: convert the arch and platform entries (Part 3/7)

[Christian Brauner <brauner@kernel.org>]

Part 3/7 of "proc: move procfs to what kernfs does", on top of part 2
and independent of parts 4 to 6:

  https://patch.msgid.link/20261104-work-procfs-v2-0-b45cd5789ac5@brauner

This converts the proc entries under arch/ and the ones of ACPI, the
platform drivers, via-pmu and PNP to what "proc: let procfs own the data
path" set up. Afterwards the entries' code only runs with the entry
pinned and never touches userspace memory. One patch per subsystem and
method.

- procfs copies in the writes of alpha's srm_env, the ARM and sh
  alignment files, the rtas, pseries, mconsole and exitcode files,
  sparc's led, /proc/mtrr, simdisk, /proc/acpi/wakeup, via-pmu's
  options, thinkpad_acpi, toshiba_acpi and pnpbios. Most of them just
  stop copying in themselves or switch from kstrto*_from_user() to
  kstrto*(). Where a write larger than anything the entry parses now
  fails with -EINVAL from procfs the commit says so.
- procfs copies out the reads of /proc/atags, /proc/bootinfo, the rtas
  error log and flash files, /proc/powerpc/systemcfg, simdisk and
  /proc/bus/isapnp, mostly simple_read_from_buffer() turned into
  memory_read_from_buffer().
- procfs owns the seq_file of /proc/mtrr and copies its ioctl arguments
  in and out. The ioctls are table driven now, the native and the 32-bit
  commands share one table.
- the rtas flash files take their image in 4k pieces and keep doing that
  with PROC_ENTRY_SHORT_WRITES.
- the rtas error log is a stream, it hands out a record before procfs
  copies it out, so a reader that passes a bad buffer loses it. Its
  pollers sleep on the wait queue procfs owns for the entry now and
  rtasd wakes them with proc_poll_notify().

Build tested per commit on x86_64 and with W=1 on the touched objects on
alpha, arm, m68k, powerpc, sh, sparc, um, x86 and xtensa. The entries I
could get at in an x86 VM behave the same with and without the series.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
Changes in v2:
- rtasd lets procfs own the wait queue of the rtas error log
- rebased onto v7.4-rc1, the thinkpad_acpi write merged with its
  cleanup.h restyle upstream
- Link to v1: https://patch.msgid.link/20261102-work-procfs-arch-v1-0-c9492ab08480@kernel.org

---
Christian Brauner (23):
      alpha: srm_env: let procfs copy in writes
      ARM: alignment: let procfs copy in writes
      ARM: atags: let procfs copy out reads of /proc/atags
      m68k/bootinfo: let procfs copy out reads of /proc/bootinfo
      powerpc/rtas: let procfs copy in writes
      powerpc/rtas: let procfs copy out reads
      powerpc/rtasd: let procfs own the wait queue of the rtas error log
      powerpc/pseries: let procfs copy in writes
      powerpc/procfs: let procfs copy out reads of /proc/powerpc/systemcfg
      sh: alignment: let procfs copy in writes
      sparc: led: let procfs copy in writes
      um: let procfs copy in writes
      x86/mtrr: let procfs own the seq_file of /proc/mtrr
      x86/mtrr: let procfs copy in writes to /proc/mtrr
      x86/mtrr: let procfs copy the ioctl arguments of /proc/mtrr
      xtensa: simdisk: let procfs copy in writes
      xtensa: simdisk: let procfs copy out reads
      ACPI: proc: let procfs copy in writes to /proc/acpi/wakeup
      macintosh/via-pmu: let procfs copy in writes to the options file
      platform/x86: thinkpad_acpi: let procfs copy in writes
      platform/x86: toshiba_acpi: let procfs copy in writes
      PNP: pnpbios: let procfs copy in writes
      PNP: isapnp: let procfs copy out reads

 arch/alpha/kernel/srm_env.c                 | 12 +---
 arch/arm/kernel/atags_proc.c                |  6 +-
 arch/arm/mm/alignment.c                     |  7 +--
 arch/m68k/kernel/bootinfo_proc.c            |  6 +-
 arch/powerpc/kernel/proc_powerpc.c          |  6 +-
 arch/powerpc/kernel/rtas-proc.c             | 40 ++++++------
 arch/powerpc/kernel/rtas_flash.c            | 62 +++++++++----------
 arch/powerpc/kernel/rtasd.c                 | 30 +++------
 arch/powerpc/platforms/pseries/lpar.c       | 14 ++---
 arch/powerpc/platforms/pseries/lparcfg.c    |  7 +--
 arch/powerpc/platforms/pseries/reconfig.c   | 22 +++----
 arch/sh/mm/alignment.c                      |  7 +--
 arch/sparc/kernel/led.c                     | 12 +---
 arch/um/drivers/mconsole_kern.c             | 11 +---
 arch/um/kernel/exitcode.c                   | 14 ++---
 arch/x86/kernel/cpu/mtrr/if.c               | 95 ++++++++++++++++-------------
 arch/xtensa/platforms/iss/simdisk.c         | 32 ++++------
 drivers/acpi/proc.c                         |  7 +--
 drivers/macintosh/via-pmu.c                 |  7 +--
 drivers/platform/x86/lenovo/thinkpad_acpi.c | 12 +---
 drivers/platform/x86/toshiba_acpi.c         | 36 ++++-------
 drivers/pnp/isapnp/proc.c                   | 20 +++---
 drivers/pnp/pnpbios/proc.c                  |  9 +--
 23 files changed, 198 insertions(+), 276 deletions(-)
---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261101-work-procfs-arch-8d4ade48be31
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