[PATCH v7 00/19] mm: ioremap: Convert architectures to take GENERIC_IOREMAP way

From: Baoquan He
Date: Tue Jun 20 2023 - 09:15:58 EST


Motivation and implementation:
==============================
Currently, many architecutres have't taken the standard GENERIC_IOREMAP
way to implement ioremap_prot(), iounmap(), and ioremap_xx(), but make
these functions specifically under each arch's folder. Those cause many
duplicated codes of ioremap() and iounmap().

In this patchset, firstly introduce generic_ioremap_prot() and
generic_iounmap() to extract the generic codes for GENERIC_IOREMAP.
By taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(),
generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap()
and iounmap() are all visible and available to arch. Arch needs to
provide wrapper functions to override the generic version if there's
arch specific handling in its corresponding ioremap_prot(), ioremap()
or iounmap(). With these changes, duplicated ioremap/iounmap() code uder
ARCH-es are removed, and the equivalent functioality is kept as before.

Background info:
================
1)
The converting more architectures to take GENERIC_IOREMAP way is
suggested by Christoph in below discussion:
https://lore.kernel.org/all/Yp7h0Jv6vpgt6xdZ@xxxxxxxxxxxxx/T/#u

2)
In the previous v1 to v3, it's basically further action after arm64
has converted to GENERIC_IOREMAP way in below patchset. It's done by
adding hook ioremap_allowed() and iounmap_allowed() in ARCH to add
ARCH specific handling the middle of ioremap_prot() and iounmap().

[PATCH v5 0/6] arm64: Cleanup ioremap() and support ioremap_prot()
https://lore.kernel.org/all/20220607125027.44946-1-wangkefeng.wang@xxxxxxxxxx/T/#u

Later, during v3 reviewing, Christophe Leroy suggested to introduce
generic_ioremap_prot() and generic_iounmap() to generic codes, and ARCH
can provide wrapper function ioremap_prot(), ioremap() or iounmap() if
needed. Christophe made a RFC patchset as below to specially demonstrate
his idea. This is what v4 and now v5 is doing.

[RFC PATCH 0/8] mm: ioremap: Convert architectures to take GENERIC_IOREMAP way
https://lore.kernel.org/all/cover.1665568707.git.christophe.leroy@xxxxxxxxxx/T/#u

Testing:
========
In v7, I only built and run on arm64 and s390, and pass the cross
compilig on hexagon following lkp's steps.

History:
=======
v6->v7:
- Fix the building error on s390 and hexagon reported by lkp test robot.
- Add Christoph, Mike, Catalin and Helge's ack.

v5->v6:
- Remove stale descriptions in log - Mike
- Remove the early unmapping handling from fixmap pool in iounmap() in
openrisc; Based on that, iounmap() in openrisc ARCH can be removed - Mike
- Add WARN_ON_ONCE to aid debugging in generic_ioremap_prot() - Christoph
- Split the inclusion of include/asm-generic/io.h and redefining of the
helpers from the old patch 11 into a prep patch; The following patch
can only contain code converting to GENERIC_IOREMAP for SuperH - Christoph
- Add header file linux/ioremap.h and move is_ioremap_addr() over
there - Christoph

v4->v5:
- Ard and Christophe suggested adding a preparation patch to remove
ARCH_HAS_IOREMAP_xx macros, this is done in newly added patch 1.
- In the current patch 13 ("parisc: mm: Convert to GENERIC_IOREMAP"),
so we don't need to add ARCH_HAS_IOREMAP_WC.

v3->v4:
- Change to contain arch specific handling in wrapper function
ioremap(), ioremap_prot() or iounmap() to replace the old hook
ioremap|iounmap_allowed() hook way for each arch.
- Add two patches to convert powerpc to GENERIC_IOREMAP. They are
picked from above Christophe's RFC patchset, I made some changes
to make them formal.

v2->v3:
- Rewrite log of all patches to add more details as Christoph suggested.

- Merge the old patch 1 and 2 which adjusts return values and
parameters of arch_ioremap() into one patch, namely the current
patch 3. Christoph suggested this.

- Change the return value of arch_iounmap() to bool type since we only
do arch specific address filtering or address checking, bool value
can reflect the checking better. This is pointed out by Niklas when
he reviewed the s390 patch.

- Put hexagon patch at the beginning of patchset since hexagon has the
same ioremap() and iounmap() as standard ones, no arch_ioremap() and
arch_iounmap() hooks need be introduced. So the later arch_ioremap
and arch_iounmap() adjustment are not related in hexagon. Christophe
suggested this.

- Remove the early ioremap code from openrisc ioremap() firstly since
openrisc doesn't have early ioremap handling in openrisc arch code.
This simplifies the later converting to GENERIC_IOREMAP method.
Christoph and Stafford suggersted this.

- Fix compiling erorrs reported by lkp in parisc and sh patches.
Adding macro defintions for those port|mem io functions in
<asm/io.h> to avoid repeated definition in <asm-generic/io.h>.

v1->v2:
- Rename io[re|un]map_allowed() to arch_io[re|un]map() and made
some minor changes in patch 1~2 as per Alexander and Kefeng's
suggestions. Accordingly, adjust patches~4~11 because of the renaming
arch_io[re|un]map().

Baoquan He (16):
asm-generic/iomap.h: remove ARCH_HAS_IOREMAP_xx macros
hexagon: mm: Convert to GENERIC_IOREMAP
openrisc: mm: remove unneeded early ioremap code
mm: ioremap: allow ARCH to have its own ioremap method definition
mm/ioremap: add slab availability checking in ioremap_prot
arc: mm: Convert to GENERIC_IOREMAP
ia64: mm: Convert to GENERIC_IOREMAP
openrisc: mm: Convert to GENERIC_IOREMAP
s390: mm: Convert to GENERIC_IOREMAP
sh: add <asm-generic/io.h> including
sh: mm: Convert to GENERIC_IOREMAP
xtensa: mm: Convert to GENERIC_IOREMAP
parisc: mm: Convert to GENERIC_IOREMAP
mm: move is_ioremap_addr() into new header file
arm64 : mm: add wrapper function ioremap_prot()
mm: ioremap: remove unneeded ioremap_allowed and iounmap_allowed

Christophe Leroy (3):
mm/ioremap: Define generic_ioremap_prot() and generic_iounmap()
mm/ioremap: Consider IOREMAP space in generic ioremap
powerpc: mm: Convert to GENERIC_IOREMAP

arch/arc/Kconfig | 1 +
arch/arc/include/asm/io.h | 7 ++-
arch/arc/mm/ioremap.c | 49 ++---------------
arch/arm64/include/asm/io.h | 3 +-
arch/arm64/mm/ioremap.c | 10 ++--
arch/hexagon/Kconfig | 1 +
arch/hexagon/include/asm/io.h | 11 ++--
arch/hexagon/mm/ioremap.c | 44 ----------------
arch/ia64/Kconfig | 1 +
arch/ia64/include/asm/io.h | 13 ++---
arch/ia64/mm/ioremap.c | 41 +++------------
arch/loongarch/include/asm/io.h | 2 -
arch/m68k/include/asm/io_mm.h | 2 -
arch/m68k/include/asm/kmap.h | 2 -
arch/mips/include/asm/io.h | 5 +-
arch/openrisc/Kconfig | 1 +
arch/openrisc/include/asm/io.h | 11 ++--
arch/openrisc/mm/ioremap.c | 82 -----------------------------
arch/parisc/Kconfig | 1 +
arch/parisc/include/asm/io.h | 15 ++++--
arch/parisc/mm/ioremap.c | 62 ++--------------------
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/io.h | 17 ++----
arch/powerpc/include/asm/pgtable.h | 8 ---
arch/powerpc/mm/ioremap.c | 26 +--------
arch/powerpc/mm/ioremap_32.c | 19 ++++---
arch/powerpc/mm/ioremap_64.c | 12 +----
arch/s390/Kconfig | 1 +
arch/s390/include/asm/io.h | 21 ++++----
arch/s390/kernel/perf_cpum_sf.c | 2 +-
arch/s390/pci/pci.c | 57 ++++----------------
arch/sh/Kconfig | 1 +
arch/sh/include/asm/io.h | 65 ++++++++++++-----------
arch/sh/include/asm/io_noioport.h | 7 +++
arch/sh/mm/ioremap.c | 65 ++++-------------------
arch/x86/include/asm/io.h | 5 --
arch/xtensa/Kconfig | 1 +
arch/xtensa/include/asm/io.h | 32 +++++------
arch/xtensa/mm/ioremap.c | 58 +++++---------------
drivers/net/ethernet/sfc/io.h | 2 +-
drivers/net/ethernet/sfc/siena/io.h | 2 +-
include/asm-generic/io.h | 31 +++--------
include/asm-generic/iomap.h | 6 +--
include/linux/ioremap.h | 30 +++++++++++
include/linux/mm.h | 5 --
kernel/iomem.c | 1 +
mm/ioremap.c | 41 ++++++++++-----
47 files changed, 248 insertions(+), 632 deletions(-)
delete mode 100644 arch/hexagon/mm/ioremap.c
create mode 100644 include/linux/ioremap.h

--
2.34.1