[PATCH v4 0/3] Get cache information from userland

[PATCH v4 0/3] Get cache information from userland

[Zong Li]

There are no standard CSR registers to provide cache information, the
way for RISC-V is to get this information from DT. Currently, AT_L1I_X,
AT_L1D_X and AT_L2_X are present in glibc header, and sysconf syscall
could use them to get information of cache through AUX vector. We
exploit 'struct cacheinfo' to obtain the information of cache, then we
don't need additional variable or data structure to record it.

We also need some works in glibc, but we have to support the function in
kernel first by rule of glibc, then post the patch to glibc site.

The result of 'getconf -a' as follows:

LEVEL1_ICACHE_SIZE                 32768
LEVEL1_ICACHE_ASSOC                8
LEVEL1_ICACHE_LINESIZE             64
LEVEL1_DCACHE_SIZE                 32768
LEVEL1_DCACHE_ASSOC                8
LEVEL1_DCACHE_LINESIZE             64
LEVEL2_CACHE_SIZE                  2097152
LEVEL2_CACHE_ASSOC                 32
LEVEL2_CACHE_LINESIZE              64

Changed in v4:
  - Check null pointer before use.
  - Re-write the code for readability.
  - Rebase source to v5.9-rc3.

Changed in v3:
  - Fix sparse warning: Use NULL instead of integer 0.

Changed in v2:
  - Add error checking for parsing cache properties.

Zong Li (3):
  riscv: Set more data to cacheinfo
  riscv: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
  riscv: Add cache information in AUX vector

 arch/riscv/include/asm/cacheinfo.h   |  5 ++
 arch/riscv/include/asm/elf.h         | 13 ++++
 arch/riscv/include/uapi/asm/auxvec.h | 24 +++++++
 arch/riscv/kernel/cacheinfo.c        | 98 +++++++++++++++++++++++-----
 4 files changed, 124 insertions(+), 16 deletions(-)

-- 
2.28.0

[PATCH v4 1/3] riscv: Set more data to cacheinfo

[Zong Li]

Set cacheinfo.{size,sets,line_size} for each cache node, then we can
get these information from userland through auxiliary vector.

Signed-off-by: Zong Li <zong.li@sifive.com>
---
 arch/riscv/kernel/cacheinfo.c | 66 +++++++++++++++++++++++++++--------
 1 file changed, 51 insertions(+), 15 deletions(-)

diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index bd0f122965c3..291d7d8f748b 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -25,12 +25,53 @@ cache_get_priv_group(struct cacheinfo *this_leaf)
 	return NULL;
 }
 
-static void ci_leaf_init(struct cacheinfo *this_leaf,
-			 struct device_node *node,
-			 enum cache_type type, unsigned int level)
+static void ci_leaf_init(struct cacheinfo *this_leaf, enum cache_type type,
+			 unsigned int level, unsigned int size,
+			 unsigned int sets, unsigned int line_size)
 {
 	this_leaf->level = level;
 	this_leaf->type = type;
+	this_leaf->size = size;
+	this_leaf->number_of_sets = sets;
+	this_leaf->coherency_line_size = line_size;
+
+	/*
+	 * If the cache is fully associative, there is no need to
+	 * check the other properties.
+	 */
+	if (sets == 1)
+		return;
+
+	/*
+	 * Set the ways number for n-ways associative, make sure
+	 * all properties are big than zero.
+	 */
+	if (sets > 0 && size > 0 && line_size > 0)
+		this_leaf->ways_of_associativity = (size / sets) / line_size;
+}
+
+static void fill_cacheinfo(struct cacheinfo **this_leaf,
+			   struct device_node *node, unsigned int level)
+{
+	unsigned int size, sets, line_size;
+
+	if (!of_property_read_u32(node, "cache-size", &size) &&
+	    !of_property_read_u32(node, "cache-block-size", &line_size) &&
+	    !of_property_read_u32(node, "cache-sets", &sets)) {
+		ci_leaf_init((*this_leaf)++, CACHE_TYPE_UNIFIED, level, size, sets, line_size);
+	}
+
+	if (!of_property_read_u32(node, "i-cache-size", &size) &&
+	    !of_property_read_u32(node, "i-cache-sets", &sets) &&
+	    !of_property_read_u32(node, "i-cache-block-size", &line_size)) {
+		ci_leaf_init((*this_leaf)++, CACHE_TYPE_INST, level, size, sets, line_size);
+	}
+
+	if (!of_property_read_u32(node, "d-cache-size", &size) &&
+	    !of_property_read_u32(node, "d-cache-sets", &sets) &&
+	    !of_property_read_u32(node, "d-cache-block-size", &line_size)) {
+		ci_leaf_init((*this_leaf)++, CACHE_TYPE_DATA, level, size, sets, line_size);
+	}
 }
 
 static int __init_cache_level(unsigned int cpu)
@@ -83,29 +124,24 @@ static int __populate_cache_leaves(unsigned int cpu)
 	struct device_node *prev = NULL;
 	int levels = 1, level = 1;
 
-	if (of_property_read_bool(np, "cache-size"))
-		ci_leaf_init(this_leaf++, np, CACHE_TYPE_UNIFIED, level);
-	if (of_property_read_bool(np, "i-cache-size"))
-		ci_leaf_init(this_leaf++, np, CACHE_TYPE_INST, level);
-	if (of_property_read_bool(np, "d-cache-size"))
-		ci_leaf_init(this_leaf++, np, CACHE_TYPE_DATA, level);
+	/* Level 1 caches in cpu node */
+	fill_cacheinfo(&this_leaf, np, level);
 
+	/* Next level caches in cache nodes */
 	prev = np;
 	while ((np = of_find_next_cache_node(np))) {
 		of_node_put(prev);
 		prev = np;
+
 		if (!of_device_is_compatible(np, "cache"))
 			break;
 		if (of_property_read_u32(np, "cache-level", &level))
 			break;
 		if (level <= levels)
 			break;
-		if (of_property_read_bool(np, "cache-size"))
-			ci_leaf_init(this_leaf++, np, CACHE_TYPE_UNIFIED, level);
-		if (of_property_read_bool(np, "i-cache-size"))
-			ci_leaf_init(this_leaf++, np, CACHE_TYPE_INST, level);
-		if (of_property_read_bool(np, "d-cache-size"))
-			ci_leaf_init(this_leaf++, np, CACHE_TYPE_DATA, level);
+
+		fill_cacheinfo(&this_leaf, np, level);
+
 		levels = level;
 	}
 	of_node_put(np);
-- 
2.28.0

[PATCH v4 2/3] riscv: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO

[Zong Li]

AT_VECTOR_SIZE_ARCH should be defined with the maximum number of
NEW_AUX_ENT entries that ARCH_DLINFO can contain, but it wasn't defined
for RISC-V at all even though ARCH_DLINFO will contain one NEW_AUX_ENT
for the VDSO address.

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/include/uapi/asm/auxvec.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/include/uapi/asm/auxvec.h b/arch/riscv/include/uapi/asm/auxvec.h
index d86cb17bbabe..22e0ae888406 100644
--- a/arch/riscv/include/uapi/asm/auxvec.h
+++ b/arch/riscv/include/uapi/asm/auxvec.h
@@ -10,4 +10,7 @@
 /* vDSO location */
 #define AT_SYSINFO_EHDR 33
 
+/* entries in ARCH_DLINFO */
+#define AT_VECTOR_SIZE_ARCH	1
+
 #endif /* _UAPI_ASM_RISCV_AUXVEC_H */
-- 
2.28.0

[PATCH v4 3/3] riscv: Add cache information in AUX vector

[Zong Li]

There are no standard CSR registers to provide cache information, the
way for RISC-V is to get this information from DT. Currently, AT_L1I_X,
AT_L1D_X and AT_L2_X are present in glibc header, and sysconf syscall
could use them to get information of cache through AUX vector.

The result of 'getconf -a' as follows:
LEVEL1_ICACHE_SIZE                 32768
LEVEL1_ICACHE_ASSOC                8
LEVEL1_ICACHE_LINESIZE             64
LEVEL1_DCACHE_SIZE                 32768
LEVEL1_DCACHE_ASSOC                8
LEVEL1_DCACHE_LINESIZE             64
LEVEL2_CACHE_SIZE                  2097152
LEVEL2_CACHE_ASSOC                 32
LEVEL2_CACHE_LINESIZE              64

Signed-off-by: Zong Li <zong.li@sifive.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/include/asm/cacheinfo.h   |  5 +++++
 arch/riscv/include/asm/elf.h         | 13 +++++++++++
 arch/riscv/include/uapi/asm/auxvec.h | 23 +++++++++++++++++++-
 arch/riscv/kernel/cacheinfo.c        | 32 +++++++++++++++++++++++++++-
 4 files changed, 71 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/cacheinfo.h b/arch/riscv/include/asm/cacheinfo.h
index 5d9662e9aba8..d1a365215ec0 100644
--- a/arch/riscv/include/asm/cacheinfo.h
+++ b/arch/riscv/include/asm/cacheinfo.h
@@ -1,4 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 SiFive
+ */
 
 #ifndef _ASM_RISCV_CACHEINFO_H
 #define _ASM_RISCV_CACHEINFO_H
@@ -11,5 +14,7 @@ struct riscv_cacheinfo_ops {
 };
 
 void riscv_set_cacheinfo_ops(struct riscv_cacheinfo_ops *ops);
+uintptr_t get_cache_size(u32 level, enum cache_type type);
+uintptr_t get_cache_geometry(u32 level, enum cache_type type);
 
 #endif /* _ASM_RISCV_CACHEINFO_H */
diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h
index d83a4efd052b..5c725e1df58b 100644
--- a/arch/riscv/include/asm/elf.h
+++ b/arch/riscv/include/asm/elf.h
@@ -11,6 +11,7 @@
 #include <uapi/asm/elf.h>
 #include <asm/auxvec.h>
 #include <asm/byteorder.h>
+#include <asm/cacheinfo.h>
 
 /*
  * These are used to set parameters in the core dumps.
@@ -61,6 +62,18 @@ extern unsigned long elf_hwcap;
 do {								\
 	NEW_AUX_ENT(AT_SYSINFO_EHDR,				\
 		(elf_addr_t)current->mm->context.vdso);		\
+	NEW_AUX_ENT(AT_L1I_CACHESIZE,				\
+		get_cache_size(1, CACHE_TYPE_INST));		\
+	NEW_AUX_ENT(AT_L1I_CACHEGEOMETRY,			\
+		get_cache_geometry(1, CACHE_TYPE_INST));	\
+	NEW_AUX_ENT(AT_L1D_CACHESIZE,				\
+		get_cache_size(1, CACHE_TYPE_DATA));		\
+	NEW_AUX_ENT(AT_L1D_CACHEGEOMETRY,			\
+		get_cache_geometry(1, CACHE_TYPE_DATA));	\
+	NEW_AUX_ENT(AT_L2_CACHESIZE,				\
+		get_cache_size(2, CACHE_TYPE_UNIFIED));		\
+	NEW_AUX_ENT(AT_L2_CACHEGEOMETRY,			\
+		get_cache_geometry(2, CACHE_TYPE_UNIFIED));	\
 } while (0)
 #define ARCH_HAS_SETUP_ADDITIONAL_PAGES
 struct linux_binprm;
diff --git a/arch/riscv/include/uapi/asm/auxvec.h b/arch/riscv/include/uapi/asm/auxvec.h
index 22e0ae888406..32c73ba1d531 100644
--- a/arch/riscv/include/uapi/asm/auxvec.h
+++ b/arch/riscv/include/uapi/asm/auxvec.h
@@ -10,7 +10,28 @@
 /* vDSO location */
 #define AT_SYSINFO_EHDR 33
 
+/*
+ * The set of entries below represent more extensive information
+ * about the caches, in the form of two entry per cache type,
+ * one entry containing the cache size in bytes, and the other
+ * containing the cache line size in bytes in the bottom 16 bits
+ * and the cache associativity in the next 16 bits.
+ *
+ * The associativity is such that if N is the 16-bit value, the
+ * cache is N way set associative. A value if 0xffff means fully
+ * associative, a value of 1 means directly mapped.
+ *
+ * For all these fields, a value of 0 means that the information
+ * is not known.
+ */
+#define AT_L1I_CACHESIZE	40
+#define AT_L1I_CACHEGEOMETRY	41
+#define AT_L1D_CACHESIZE	42
+#define AT_L1D_CACHEGEOMETRY	43
+#define AT_L2_CACHESIZE		44
+#define AT_L2_CACHEGEOMETRY	45
+
 /* entries in ARCH_DLINFO */
-#define AT_VECTOR_SIZE_ARCH	1
+#define AT_VECTOR_SIZE_ARCH	7
 
 #endif /* _UAPI_ASM_RISCV_AUXVEC_H */
diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index 291d7d8f748b..de59dd457b41 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -3,7 +3,6 @@
  * Copyright (C) 2017 SiFive
  */
 
-#include <linux/cacheinfo.h>
 #include <linux/cpu.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
@@ -25,6 +24,37 @@ cache_get_priv_group(struct cacheinfo *this_leaf)
 	return NULL;
 }
 
+static struct cacheinfo *get_cacheinfo(u32 level, enum cache_type type)
+{
+	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(smp_processor_id());
+	struct cacheinfo *this_leaf;
+	int index;
+
+	for (index = 0; index < this_cpu_ci->num_leaves; index++) {
+		this_leaf = this_cpu_ci->info_list + index;
+		if (this_leaf->level == level && this_leaf->type == type)
+			return this_leaf;
+	}
+
+	return NULL;
+}
+
+uintptr_t get_cache_size(u32 level, enum cache_type type)
+{
+	struct cacheinfo *this_leaf = get_cacheinfo(level, type);
+
+	return this_leaf ? this_leaf->size : 0;
+}
+
+uintptr_t get_cache_geometry(u32 level, enum cache_type type)
+{
+	struct cacheinfo *this_leaf = get_cacheinfo(level, type);
+
+	return this_leaf ? (this_leaf->ways_of_associativity << 16 |
+			    this_leaf->coherency_line_size) :
+			   0;
+}
+
 static void ci_leaf_init(struct cacheinfo *this_leaf, enum cache_type type,
 			 unsigned int level, unsigned int size,
 			 unsigned int sets, unsigned int line_size)
-- 
2.28.0

Re: [PATCH v4 0/3] Get cache information from userland

[Pekka Enberg]

For the series:

Reviewed-by: Pekka Enberg <penberg@kernel.org>

- Pekka

Re: [PATCH v4 0/3] Get cache information from userland

[Palmer Dabbelt]

On Mon, 31 Aug 2020 00:33:47 PDT (-0700), zong.li@sifive.com wrote:
> There are no standard CSR registers to provide cache information, the
> way for RISC-V is to get this information from DT. Currently, AT_L1I_X,
> AT_L1D_X and AT_L2_X are present in glibc header, and sysconf syscall
> could use them to get information of cache through AUX vector. We
> exploit 'struct cacheinfo' to obtain the information of cache, then we
> don't need additional variable or data structure to record it.
>
> We also need some works in glibc, but we have to support the function in
> kernel first by rule of glibc, then post the patch to glibc site.
>
> The result of 'getconf -a' as follows:
>
> LEVEL1_ICACHE_SIZE                 32768
> LEVEL1_ICACHE_ASSOC                8
> LEVEL1_ICACHE_LINESIZE             64
> LEVEL1_DCACHE_SIZE                 32768
> LEVEL1_DCACHE_ASSOC                8
> LEVEL1_DCACHE_LINESIZE             64
> LEVEL2_CACHE_SIZE                  2097152
> LEVEL2_CACHE_ASSOC                 32
> LEVEL2_CACHE_LINESIZE              64
>
> Changed in v4:
>   - Check null pointer before use.
>   - Re-write the code for readability.
>   - Rebase source to v5.9-rc3.
>
> Changed in v3:
>   - Fix sparse warning: Use NULL instead of integer 0.
>
> Changed in v2:
>   - Add error checking for parsing cache properties.
>
> Zong Li (3):
>   riscv: Set more data to cacheinfo
>   riscv: Define AT_VECTOR_SIZE_ARCH for ARCH_DLINFO
>   riscv: Add cache information in AUX vector
>
>  arch/riscv/include/asm/cacheinfo.h   |  5 ++
>  arch/riscv/include/asm/elf.h         | 13 ++++
>  arch/riscv/include/uapi/asm/auxvec.h | 24 +++++++
>  arch/riscv/kernel/cacheinfo.c        | 98 +++++++++++++++++++++++-----
>  4 files changed, 124 insertions(+), 16 deletions(-)

Ah, I just saw these so they're in instead of the v2.  Thanks!