linux-stable/include/linux/cacheinfo.h
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

147 lines
4.4 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_CACHEINFO_H
#define _LINUX_CACHEINFO_H
#include <linux/bitops.h>
#include <linux/cpumask.h>
#include <linux/smp.h>
struct device_node;
struct attribute;
enum cache_type {
CACHE_TYPE_NOCACHE = 0,
CACHE_TYPE_INST = BIT(0),
CACHE_TYPE_DATA = BIT(1),
CACHE_TYPE_SEPARATE = CACHE_TYPE_INST | CACHE_TYPE_DATA,
CACHE_TYPE_UNIFIED = BIT(2),
};
extern unsigned int coherency_max_size;
/**
* struct cacheinfo - represent a cache leaf node
* @id: This cache's id. It is unique among caches with the same (type, level).
* @type: type of the cache - data, inst or unified
* @level: represents the hierarchy in the multi-level cache
* @coherency_line_size: size of each cache line usually representing
* the minimum amount of data that gets transferred from memory
* @number_of_sets: total number of sets, a set is a collection of cache
* lines sharing the same index
* @ways_of_associativity: number of ways in which a particular memory
* block can be placed in the cache
* @physical_line_partition: number of physical cache lines sharing the
* same cachetag
* @size: Total size of the cache
* @shared_cpu_map: logical cpumask representing all the cpus sharing
* this cache node
* @attributes: bitfield representing various cache attributes
* @fw_token: Unique value used to determine if different cacheinfo
* structures represent a single hardware cache instance.
* @disable_sysfs: indicates whether this node is visible to the user via
* sysfs or not
* @priv: pointer to any private data structure specific to particular
* cache design
*
* While @of_node, @disable_sysfs and @priv are used for internal book
* keeping, the remaining members form the core properties of the cache
*/
struct cacheinfo {
unsigned int id;
enum cache_type type;
unsigned int level;
unsigned int coherency_line_size;
unsigned int number_of_sets;
unsigned int ways_of_associativity;
unsigned int physical_line_partition;
unsigned int size;
cpumask_t shared_cpu_map;
unsigned int attributes;
#define CACHE_WRITE_THROUGH BIT(0)
#define CACHE_WRITE_BACK BIT(1)
#define CACHE_WRITE_POLICY_MASK \
(CACHE_WRITE_THROUGH | CACHE_WRITE_BACK)
#define CACHE_READ_ALLOCATE BIT(2)
#define CACHE_WRITE_ALLOCATE BIT(3)
#define CACHE_ALLOCATE_POLICY_MASK \
(CACHE_READ_ALLOCATE | CACHE_WRITE_ALLOCATE)
#define CACHE_ID BIT(4)
void *fw_token;
bool disable_sysfs;
void *priv;
};
struct cpu_cacheinfo {
struct cacheinfo *info_list;
unsigned int per_cpu_data_slice_size;
unsigned int num_levels;
unsigned int num_leaves;
bool cpu_map_populated;
bool early_ci_levels;
};
struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu);
int early_cache_level(unsigned int cpu);
int init_cache_level(unsigned int cpu);
int init_of_cache_level(unsigned int cpu);
int populate_cache_leaves(unsigned int cpu);
int cache_setup_acpi(unsigned int cpu);
bool last_level_cache_is_valid(unsigned int cpu);
bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y);
int fetch_cache_info(unsigned int cpu);
int detect_cache_attributes(unsigned int cpu);
#ifndef CONFIG_ACPI_PPTT
/*
* acpi_get_cache_info() is only called on ACPI enabled
* platforms using the PPTT for topology. This means that if
* the platform supports other firmware configuration methods
* we need to stub out the call when ACPI is disabled.
* ACPI enabled platforms not using PPTT won't be making calls
* to this function so we need not worry about them.
*/
static inline
int acpi_get_cache_info(unsigned int cpu,
unsigned int *levels, unsigned int *split_levels)
{
return -ENOENT;
}
#else
int acpi_get_cache_info(unsigned int cpu,
unsigned int *levels, unsigned int *split_levels);
#endif
const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
/*
* Get the id of the cache associated with @cpu at level @level.
* cpuhp lock must be held.
*/
static inline int get_cpu_cacheinfo_id(int cpu, int level)
{
struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
int i;
for (i = 0; i < ci->num_leaves; i++) {
if (ci->info_list[i].level == level) {
if (ci->info_list[i].attributes & CACHE_ID)
return ci->info_list[i].id;
return -1;
}
}
return -1;
}
#ifdef CONFIG_ARM64
#define use_arch_cache_info() (true)
#else
#define use_arch_cache_info() (false)
#endif
#ifndef CONFIG_ARCH_HAS_CPU_CACHE_ALIASING
#define cpu_dcache_is_aliasing() false
#else
#include <asm/cachetype.h>
#endif
#endif /* _LINUX_CACHEINFO_H */