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
..
abiv1	mm: Introduce flush_cache_vmap_early()	2023-12-14 00:23:17 -08:00
abiv2	mm: Introduce flush_cache_vmap_early()	2023-12-14 00:23:17 -08:00
boot	csky: Remove unused $(dtb-y) from boot/Makefile	2022-05-13 14:45:09 +08:00
configs	netfs, fscache: Combine fscache with netfs	2023-12-24 15:08:46 +00:00
include	Introduce cpu_dcache_is_aliasing() across all architectures	2024-02-22 15:27:19 -08:00
kernel	arch: vdso: consolidate gettime prototypes	2023-11-23 11:32:32 +01:00
lib	csky: delay: Add function alignment	2022-12-29 23:47:52 -05:00
mm	csky: fix up lock_mm_and_find_vma() conversion	2023-06-29 23:34:29 -07:00
Kbuild	csky: Move $(core-y) into arch/csky/Kbuild	2022-05-13 15:09:28 +08:00
Kconfig	Introduce cpu_dcache_is_aliasing() across all architectures	2024-02-22 15:27:19 -08:00
Kconfig.debug	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
Kconfig.platforms	csky/Kconfig: Add Kconfig.platforms to support some drivers	2020-02-21 15:43:24 +08:00
Makefile	kbuild: remove head-y syntax	2022-10-02 18:06:03 +09:00