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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
..
boot sparc: Use $(kecho) to announce kernel images being ready 2023-12-04 13:28:06 +01:00
configs arch/*/configs/*defconfig: Replace AUTOFS4_FS by AUTOFS_FS 2023-07-29 14:08:22 -07:00
crypto crypto: sparc/crc32c - stop using the shash alignmask 2023-10-27 18:04:24 +08:00
include Introduce cpu_dcache_is_aliasing() across all architectures 2024-02-22 15:27:19 -08:00
kernel sparc: Use device_get_match_data() 2024-01-19 08:08:53 -06:00
lib arch: turn off -Werror for architectures with known warnings 2023-12-10 17:21:33 -08:00
math-emu treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
mm Quite a lot of kexec work this time around. Many singleton patches in 2024-01-09 11:46:20 -08:00
net net: remove skb->vlan_present 2022-11-11 18:18:05 -08:00
power
prom arch: turn off -Werror for architectures with known warnings 2023-12-10 17:21:33 -08:00
vdso sparc: vdso: use $(addprefix ) instead of $(foreach ) 2023-12-10 15:34:37 +09:00
video arch/sparc: Add module license and description for fbdev helpers 2023-06-29 13:30:02 +02:00
Kbuild kbuild: use more subdir- for visiting subdirectories while cleaning 2021-10-24 13:49:46 +09:00
Kconfig Introduce cpu_dcache_is_aliasing() across all architectures 2024-02-22 15:27:19 -08:00
Kconfig.debug watchdog/sparc64: define HARDLOCKUP_DETECTOR_SPARC64 2023-06-19 16:25:29 -07:00
Makefile kbuild: unify vdso_install rules 2023-10-28 21:09:02 +09:00