arm64: cachetype: report weakest cache policy

In big.LITTLE systems, the I-cache policy may differ across CPUs, and
thus we must always meet the most stringent maintenance requirements of
any I-cache in the system when performing maintenance to ensure
correctness. Unfortunately this requirement is not met as we always look
at the current CPU's cache type register to determine the maintenance
requirements.

This patch causes the I-cache policy of all CPUs to be taken into
account for icache_is_aliasing and icache_is_aivivt. If any I-cache in
the system is aliasing or AIVIVT, the respective function will return
true. At boot each CPU may set flags to identify that at least one
I-cache in the system is aliasing and/or AIVIVT.

The now unused and potentially misleading icache_policy function is
removed.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/include/asm/cachetype.h b/arch/arm64/include/asm/cachetype.h
index 4b23e758d5e0e331b477ff2e07e6d22f7beea749..7a2e0762cb4048a880d8b53cb552175cb0f09cb2 100644 (file)
--- a/arch/arm64/include/asm/cachetype.h
+++ b/arch/arm64/include/asm/cachetype.h
@@ -30,10 +30,14 @@
 
 #ifndef __ASSEMBLY__
 
-static inline u32 icache_policy(void)
-{
-       return (read_cpuid_cachetype() >> CTR_L1IP_SHIFT) & CTR_L1IP_MASK;
-}
+#include <linux/bitops.h>
+
+#define CTR_L1IP(ctr)  (((ctr) >> CTR_L1IP_SHIFT) & CTR_L1IP_MASK)
+
+#define ICACHEF_ALIASING       BIT(0)
+#define ICACHEF_AIVIVT         BIT(1)
+
+extern unsigned long __icache_flags;
 
 /*
  * Whilst the D-side always behaves as PIPT on AArch64, aliasing is
@@ -41,12 +45,12 @@ static inline u32 icache_policy(void)
  */
 static inline int icache_is_aliasing(void)
 {
-       return icache_policy() != ICACHE_POLICY_PIPT;
+       return test_bit(ICACHEF_ALIASING, &__icache_flags);
 }
 
 static inline int icache_is_aivivt(void)
 {
-       return icache_policy() == ICACHE_POLICY_AIVIVT;
+       return test_bit(ICACHEF_AIVIVT, &__icache_flags);
 }
 
 static inline u32 cache_type_cwg(void)

diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 1f350fe5b318060fa68ef85e1b6b513a33285c61..3ce99fc1fde15be05ad85b5550add27649b446ec 100644 (file)
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -19,7 +19,9 @@
 #include <asm/cpu.h>
 #include <asm/cputype.h>
 
+#include <linux/bitops.h>
 #include <linux/init.h>
+#include <linux/printk.h>
 #include <linux/smp.h>
 
 /*
@@ -30,6 +32,28 @@
 DEFINE_PER_CPU(struct cpuinfo_arm64, cpu_data);
 static struct cpuinfo_arm64 boot_cpu_data;
 
+static char *icache_policy_str[] = {
+       [ICACHE_POLICY_RESERVED] = "RESERVED/UNKNOWN",
+       [ICACHE_POLICY_AIVIVT] = "AIVIVT",
+       [ICACHE_POLICY_VIPT] = "VIPT",
+       [ICACHE_POLICY_PIPT] = "PIPT",
+};
+
+unsigned long __icache_flags;
+
+static void cpuinfo_detect_icache_policy(struct cpuinfo_arm64 *info)
+{
+       unsigned int cpu = smp_processor_id();
+       u32 l1ip = CTR_L1IP(info->reg_ctr);
+
+       if (l1ip != ICACHE_POLICY_PIPT)
+               set_bit(ICACHEF_ALIASING, &__icache_flags);
+       if (l1ip == ICACHE_POLICY_AIVIVT);
+               set_bit(ICACHEF_AIVIVT, &__icache_flags);
+
+       pr_info("Detected %s I-cache on CPU%d", icache_policy_str[l1ip], cpu);
+}
+
 static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 {
        info->reg_cntfrq = arch_timer_get_cntfrq();
@@ -56,6 +80,8 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
        info->reg_id_mmfr3 = read_cpuid(ID_MMFR3_EL1);
        info->reg_id_pfr0 = read_cpuid(ID_PFR0_EL1);
        info->reg_id_pfr1 = read_cpuid(ID_PFR1_EL1);
+
+       cpuinfo_detect_icache_policy(info);
 }
 
 void cpuinfo_store_cpu(void)