arm64: add helper functions to read I-cache attributes
This adds helper functions and #defines to <asm/cachetype.h> to read the
line size and the number of sets from the level 1 instruction cache.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/include/asm/cachetype.h b/arch/arm64/include/asm/cachetype.h
index 7a2e076..4c631a0 100644
--- a/arch/arm64/include/asm/cachetype.h
+++ b/arch/arm64/include/asm/cachetype.h
@@ -39,6 +39,26 @@
extern unsigned long __icache_flags;
+#define CCSIDR_EL1_LINESIZE_MASK 0x7
+#define CCSIDR_EL1_LINESIZE(x) ((x) & CCSIDR_EL1_LINESIZE_MASK)
+
+#define CCSIDR_EL1_NUMSETS_SHIFT 13
+#define CCSIDR_EL1_NUMSETS_MASK (0x7fff << CCSIDR_EL1_NUMSETS_SHIFT)
+#define CCSIDR_EL1_NUMSETS(x) \
+ (((x) & CCSIDR_EL1_NUMSETS_MASK) >> CCSIDR_EL1_NUMSETS_SHIFT)
+
+extern u64 __attribute_const__ icache_get_ccsidr(void);
+
+static inline int icache_get_linesize(void)
+{
+ return 16 << CCSIDR_EL1_LINESIZE(icache_get_ccsidr());
+}
+
+static inline int icache_get_numsets(void)
+{
+ return 1 + CCSIDR_EL1_NUMSETS(icache_get_ccsidr());
+}
+
/*
* Whilst the D-side always behaves as PIPT on AArch64, aliasing is
* permitted in the I-cache.
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 1771696..d8c5a59 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -20,8 +20,10 @@
#include <asm/cputype.h>
#include <linux/bitops.h>
+#include <linux/bug.h>
#include <linux/init.h>
#include <linux/kernel.h>
+#include <linux/preempt.h>
#include <linux/printk.h>
#include <linux/smp.h>
@@ -190,3 +192,15 @@
boot_cpu_data = *info;
}
+
+u64 __attribute_const__ icache_get_ccsidr(void)
+{
+ u64 ccsidr;
+
+ WARN_ON(preemptible());
+
+ /* Select L1 I-cache and read its size ID register */
+ asm("msr csselr_el1, %1; isb; mrs %0, ccsidr_el1"
+ : "=r"(ccsidr) : "r"(1L));
+ return ccsidr;
+}