linux/arch/m68k
Mathieu Desnoyers 8690bbcf3b Introduce cpu_dcache_is_aliasing() across all architectures
Introduce a generic way to query whether the data cache is virtually
aliased on all architectures. Its purpose is to ensure that subsystems
which are incompatible with virtually aliased data caches (e.g. FS_DAX)
can reliably query this.

For data cache aliasing, there are three scenarios dependending on the
architecture. Here is a breakdown based on my understanding:

A) The data cache is always aliasing:

* arc
* csky
* m68k (note: shared memory mappings are incoherent ? SHMLBA is missing there.)
* sh
* parisc

B) The data cache aliasing is statically known or depends on querying CPU
   state at runtime:

* arm (cache_is_vivt() || cache_is_vipt_aliasing())
* mips (cpu_has_dc_aliases)
* nios2 (NIOS2_DCACHE_SIZE > PAGE_SIZE)
* sparc32 (vac_cache_size > PAGE_SIZE)
* sparc64 (L1DCACHE_SIZE > PAGE_SIZE)
* xtensa (DCACHE_WAY_SIZE > PAGE_SIZE)

C) The data cache is never aliasing:

* alpha
* arm64 (aarch64)
* hexagon
* loongarch (but with incoherent write buffers, which are disabled since
             commit d23b7795 ("LoongArch: Change SHMLBA from SZ_64K to PAGE_SIZE"))
* microblaze
* openrisc
* powerpc
* riscv
* s390
* um
* x86

Require architectures in A) and B) to select ARCH_HAS_CPU_CACHE_ALIASING and
implement "cpu_dcache_is_aliasing()".

Architectures in C) don't select ARCH_HAS_CPU_CACHE_ALIASING, and thus
cpu_dcache_is_aliasing() simply evaluates to "false".

Note that this leaves "cpu_icache_is_aliasing()" to be implemented as future
work. This would be useful to gate features like XIP on architectures
which have aliasing CPU dcache-icache but not CPU dcache-dcache.

Use "cpu_dcache" and "cpu_cache" rather than just "dcache" and "cache"
to clarify that we really mean "CPU data cache" and "CPU cache" to
eliminate any possible confusion with VFS "dentry cache" and "page
cache".

Link: https://lore.kernel.org/lkml/20030910210416.GA24258@mail.jlokier.co.uk/
Link: https://lkml.kernel.org/r/20240215144633.96437-9-mathieu.desnoyers@efficios.com
Fixes: d92576f116 ("dax: does not work correctly with virtual aliasing caches")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michael Sclafani <dm-devel@lists.linux.dev>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 15:27:19 -08:00
..
68000 m68knommu: updates and fixes for v6.7 2023-11-02 15:31:01 -10:00
amiga m68k: amiga: Add and use "amiga.h" 2023-10-06 10:03:02 +02:00
apollo m68k: apollo: Add and use "apollo.h" 2023-10-06 10:03:02 +02:00
atari m68k: atari: Add and use "atari.h" 2023-10-06 10:03:02 +02:00
bvme6000 m68k: Replace GPL 2.0+ README.legal boilerplate with SPDX 2023-10-06 10:03:04 +02:00
coldfire arch: include linux/cpu.h for trap_init() prototype 2023-11-23 11:32:31 +01:00
configs m68k: defconfig: Update defconfigs for v6.7-rc1 2024-01-03 13:34:08 +01:00
emu tty: m68k: nfcon: convert to u8 and size_t 2023-12-08 12:02:37 +01:00
fpsp040 m68k: fpsp040: Fix indentation by 5 spaces 2023-10-16 14:30:40 +02:00
hp300 m68k: hp300: Include "time.h" for hp300_sched_init() 2023-10-06 10:03:03 +02:00
ifpsp060 m68k: Replace GPL 2.0+ README.legal boilerplate with SPDX 2023-10-06 10:03:04 +02:00
include Introduce cpu_dcache_is_aliasing() across all architectures 2024-02-22 15:27:19 -08:00
kernel lsm/stable-6.8 PR 20240105 2024-01-09 12:57:46 -08:00
lib m68k: lib: Include <linux/libgcc.h> for __muldi3() 2023-10-16 14:30:40 +02:00
mac m68k: mac: Add and use "mac.h" 2023-10-06 10:03:03 +02:00
math-emu m68k: math-emu: Add missing prototypes 2023-10-06 10:03:01 +02:00
mm m68knommu: updates and fixes for v6.7 2023-11-02 15:31:01 -10:00
mvme16x m68k: Replace GPL 2.0+ README.legal boilerplate with SPDX 2023-10-06 10:03:04 +02:00
mvme147 m68k: Replace GPL 2.0+ README.legal boilerplate with SPDX 2023-10-06 10:03:04 +02:00
q40 m68k: Replace GPL 2.0+ README.legal boilerplate with SPDX 2023-10-06 10:03:04 +02:00
sun3 m68k: sun3: Fix indentation by 5 or 7 spaces 2023-10-16 14:30:39 +02:00
sun3x m68k: sun3/3x: Add and use "sun3.h" 2023-10-06 10:03:04 +02:00
tools/amiga
virt
install.sh
Kbuild
Kconfig Introduce cpu_dcache_is_aliasing() across all architectures 2024-02-22 15:27:19 -08:00
Kconfig.bus
Kconfig.cpu mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
Kconfig.debug m68k: Remove obsolete config NO_KERNEL_MSG 2023-03-20 15:39:14 +01:00
Kconfig.devices
Kconfig.machine m68knommu: improve config ROM setting defaults 2023-10-23 08:22:22 +10:00
Makefile kbuild: use 4-space indentation when followed by conditionals 2024-02-15 06:05:44 +09:00