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arm64: cacheinfo: Remove CCSIDR-based cache information probing 

The CCSIDR_EL1.{NumSets,Associativity,LineSize} fields are only for use
in conjunction with set/way cache maintenance and are not guaranteed to
represent the actual microarchitectural features of a design.

The architecture explicitly states:

| You cannot make any inference about the actual sizes of caches based
| on these parameters.

Furthermore, CCSIDR_EL1.{WT,WB,RA,WA} have been removed retrospectively
from ARMv8 and are now considered to be UNKNOWN.

Since the kernel doesn't make use of set/way cache maintenance and it is
not possible for userspace to execute these instructions, we have no
need for the CCSIDR information in the kernel.

This patch removes the accessors, along with the related portions of the
cacheinfo support, which should instead be reintroduced when firmware has
a mechanism to provide us with reliable information.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Will Deacon 2017-03-10 20:32:21 +00:00 committed by Catalin Marinas
parent 3689c75af2
commit a8d4636f96
2 changed files with 0 additions and 62 deletions
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24
arch/arm64/include/asm/cachetype.h
View File

@ -39,30 +39,6 @@
extern unsigned long __icache_flags;
/*
* NumSets, bits[27:13] - (Number of sets in cache) - 1
* Associativity, bits[12:3] - (Associativity of cache) - 1
* LineSize, bits[2:0] - (Log2(Number of words in cache line)) - 2
*/
#define CCSIDR_EL1_WRITE_THROUGH BIT(31)
#define CCSIDR_EL1_WRITE_BACK BIT(30)
#define CCSIDR_EL1_READ_ALLOCATE BIT(29)
#define CCSIDR_EL1_WRITE_ALLOCATE BIT(28)
#define CCSIDR_EL1_LINESIZE_MASK 0x7
#define CCSIDR_EL1_LINESIZE(x) ((x) & CCSIDR_EL1_LINESIZE_MASK)
#define CCSIDR_EL1_ASSOCIATIVITY_SHIFT 3
#define CCSIDR_EL1_ASSOCIATIVITY_MASK 0x3ff
#define CCSIDR_EL1_ASSOCIATIVITY(x) \
(((x) >> CCSIDR_EL1_ASSOCIATIVITY_SHIFT) & CCSIDR_EL1_ASSOCIATIVITY_MASK)
#define CCSIDR_EL1_NUMSETS_SHIFT 13
#define CCSIDR_EL1_NUMSETS_MASK 0x7fff
#define CCSIDR_EL1_NUMSETS(x) \
(((x) >> CCSIDR_EL1_NUMSETS_SHIFT) & CCSIDR_EL1_NUMSETS_MASK)
#define CACHE_LINESIZE(x) (16 << CCSIDR_EL1_LINESIZE(x))
#define CACHE_NUMSETS(x) (CCSIDR_EL1_NUMSETS(x) + 1)
#define CACHE_ASSOCIATIVITY(x) (CCSIDR_EL1_ASSOCIATIVITY(x) + 1)
/*
* Whilst the D-side always behaves as PIPT on AArch64, aliasing is
* permitted in the I-cache.

38
arch/arm64/kernel/cacheinfo.c
View File

@ -17,15 +17,9 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/bitops.h>
#include <linux/cacheinfo.h>
#include <linux/cpu.h>
#include <linux/compiler.h>
#include <linux/of.h>
#include <asm/cachetype.h>
#include <asm/processor.h>
#define MAX_CACHE_LEVEL 7 /* Max 7 level supported */
/* Ctypen, bits[3(n - 1) + 2 : 3(n - 1)], for n = 1 to 7 */
#define CLIDR_CTYPE_SHIFT(level) (3 * (level - 1))
@ -43,43 +37,11 @@ static inline enum cache_type get_cache_type(int level)
return CLIDR_CTYPE(clidr, level);
}
/*
* Cache Size Selection Register(CSSELR) selects which Cache Size ID
* Register(CCSIDR) is accessible by specifying the required cache
* level and the cache type. We need to ensure that no one else changes
* CSSELR by calling this in non-preemtible context
*/
u64 __attribute_const__ cache_get_ccsidr(u64 csselr)
{
u64 ccsidr;
WARN_ON(preemptible());
write_sysreg(csselr, csselr_el1);
isb();
ccsidr = read_sysreg(ccsidr_el1);
return ccsidr;
}
static void ci_leaf_init(struct cacheinfo *this_leaf,
enum cache_type type, unsigned int level)
{
bool is_icache = type & CACHE_TYPE_INST;
u64 tmp = cache_get_ccsidr((level - 1) << 1 | is_icache);
this_leaf->level = level;
this_leaf->type = type;
this_leaf->coherency_line_size = CACHE_LINESIZE(tmp);
this_leaf->number_of_sets = CACHE_NUMSETS(tmp);
this_leaf->ways_of_associativity = CACHE_ASSOCIATIVITY(tmp);
this_leaf->size = this_leaf->number_of_sets *
this_leaf->coherency_line_size * this_leaf->ways_of_associativity;
this_leaf->attributes =
((tmp & CCSIDR_EL1_WRITE_THROUGH) ? CACHE_WRITE_THROUGH : 0) |
((tmp & CCSIDR_EL1_WRITE_BACK) ? CACHE_WRITE_BACK : 0) |
((tmp & CCSIDR_EL1_READ_ALLOCATE) ? CACHE_READ_ALLOCATE : 0) |
((tmp & CCSIDR_EL1_WRITE_ALLOCATE) ? CACHE_WRITE_ALLOCATE : 0);
}
static int __init_cache_level(unsigned int cpu)