Add a clean-to-point-of-persistence cache maintenance helper, and wire
up the basic architectural support for the pmem driver based on it.
Signed-off-by: Robin Murphy <***@arm.com>
---
arch/arm64/Kconfig | 11 +++++++++++
arch/arm64/include/asm/assembler.h | 6 ++++++
arch/arm64/include/asm/cacheflush.h | 1 +
arch/arm64/include/asm/cpucaps.h | 3 ++-
arch/arm64/kernel/cpufeature.c | 11 +++++++++++
arch/arm64/mm/cache.S | 14 ++++++++++++++
arch/arm64/mm/pageattr.c | 18 ++++++++++++++++++
7 files changed, 63 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index dfd908630631..0b0576a54724 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -960,6 +960,17 @@ config ARM64_UAO
regular load/store instructions if the cpu does not implement the
feature.
+config ARM64_PMEM
+ bool "Enable support for persistent memory"
+ select ARCH_HAS_PMEM_API
+ help
+ Say Y to enable support for the persistent memory API based on the
+ ARMv8.2 DCPoP feature.
+
+ The feature is detected at runtime, and the kernel will use DC CVAC
+ operations if DC CVAP is not supported (following the behaviour of
+ DC CVAP itself if the system does not define a point of persistence).
+
endmenu
config ARM64_MODULE_CMODEL_LARGE
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 1b67c3782d00..5d8903c45031 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -353,6 +353,12 @@ alternative_if_not ARM64_WORKAROUND_CLEAN_CACHE
alternative_else
dc civac, \kaddr
alternative_endif
+ .elseif (\op == cvap)
+alternative_if ARM64_HAS_DCPOP
+ sys 3, c7, c12, 1, \kaddr // dc cvap
+alternative_else
+ dc cvac, \kaddr
+alternative_endif
.else
dc \op, \kaddr
.endif
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index b4b43a94dffd..76d1cc85d5b1 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -69,6 +69,7 @@ extern void flush_icache_range(unsigned long start, unsigned long end);
extern void __flush_dcache_area(void *addr, size_t len);
extern void __inval_dcache_area(void *addr, size_t len);
extern void __clean_dcache_area_poc(void *addr, size_t len);
+extern void __clean_dcache_area_pop(void *addr, size_t len);
extern void __clean_dcache_area_pou(void *addr, size_t len);
extern long __flush_cache_user_range(unsigned long start, unsigned long end);
extern void sync_icache_aliases(void *kaddr, unsigned long len);
diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h
index 8d2272c6822c..8da621627d7c 100644
--- a/arch/arm64/include/asm/cpucaps.h
+++ b/arch/arm64/include/asm/cpucaps.h
@@ -39,7 +39,8 @@
#define ARM64_WORKAROUND_QCOM_FALKOR_E1003 18
#define ARM64_WORKAROUND_858921 19
#define ARM64_WORKAROUND_CAVIUM_30115 20
+#define ARM64_HAS_DCPOP 21
-#define ARM64_NCAPS 21
+#define ARM64_NCAPS 22
#endif /* __ASM_CPUCAPS_H */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index a2542ef3ff25..cd52d365d1f0 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -889,6 +889,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.min_field_value = 0,
.matches = has_no_fpsimd,
},
+#ifdef CONFIG_ARM64_PMEM
+ {
+ .desc = "Data cache clean to Point of Persistence",
+ .capability = ARM64_HAS_DCPOP,
+ .def_scope = SCOPE_SYSTEM,
+ .matches = has_cpuid_feature,
+ .sys_reg = SYS_ID_AA64ISAR1_EL1,
+ .field_pos = ID_AA64ISAR1_DPB_SHIFT,
+ .min_field_value = 1,
+ },
+#endif
{},
};
diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S
index ed47fbbb4b05..7f1dbe962cf5 100644
--- a/arch/arm64/mm/cache.S
+++ b/arch/arm64/mm/cache.S
@@ -172,6 +172,20 @@ ENDPIPROC(__clean_dcache_area_poc)
ENDPROC(__dma_clean_area)
/*
+ * __clean_dcache_area_pop(kaddr, size)
+ *
+ * Ensure that any D-cache lines for the interval [kaddr, kaddr+size)
+ * are cleaned to the PoP.
+ *
+ * - kaddr - kernel address
+ * - size - size in question
+ */
+ENTRY(__clean_dcache_area_pop)
+ dcache_by_line_op cvap, sy, x0, x1, x2, x3
+ ret
+ENDPIPROC(__clean_dcache_area_pop)
+
+/*
* __dma_flush_area(start, size)
*
* clean & invalidate D / U line
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index a682a0a2a0fa..a461a00ceb3e 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -183,3 +183,21 @@ bool kernel_page_present(struct page *page)
}
#endif /* CONFIG_HIBERNATION */
#endif /* CONFIG_DEBUG_PAGEALLOC */
+
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+#include <asm/cacheflush.h>
+
+static inline void arch_wb_cache_pmem(void *addr, size_t size)
+{
+ /* Ensure order against any prior non-cacheable writes */
+ dmb(sy);
+ __clean_dcache_area_pop(addr, size);
+}
+EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
+
+static inline void arch_invalidate_pmem(void *addr, size_t size)
+{
+ __inval_dcache_area(addr, size);
+}
+EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
+#endif
--
2.12.2.dirty