Subject: [PATCH 9/9] powerpc: A new cache geometry aux vectors

From: Benjamin Herrenschmidt <[email-masked]>
Date: Sun, 8 Jan 2017 17:31:50 -0600

This adds AUX vectors for the L1I,D, L2 and L3 cache levels
providing for each cache level the size of the cache in bytes
and the geometry (line size and number of ways).

We chose to not use the existing alpha/sh definition which
packs all the information in a single entry per cache level as
it is too restricted to represent some of the geometries used
on POWER.

Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
---
 arch/powerpc/include/asm/cache.h       |  1 +
 arch/powerpc/include/asm/elf.h         | 17 ++++++++++++++++-
 arch/powerpc/include/uapi/asm/auxvec.h | 33 ++++++++++++++++++++++++++++++++-
 arch/powerpc/kernel/setup-common.c     |  5 ++++-
 arch/powerpc/kernel/setup_64.c         |  4 ++++
 5 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/cache.h b/arch/powerpc/include/asm/cache.h
index 3987bd9..1557d26 100644
--- a/arch/powerpc/include/asm/cache.h
+++ b/arch/powerpc/include/asm/cache.h
@@ -35,6 +35,7 @@ struct ppc_cache_info {
 	u32 log_block_size;
 	u32 blocks_per_page;
 	u32 sets;
+	u32 assoc;
 };
 
 struct ppc64_caches {
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index 730c27e..a128836 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -108,13 +108,17 @@ do {								\
  */
 # define elf_read_implies_exec(ex, exec_stk) (is_32bit_task() ? \
 		(exec_stk == EXSTACK_DEFAULT) : 0)
-#else 
+#else
 # define elf_read_implies_exec(ex, exec_stk) (exec_stk == EXSTACK_DEFAULT)
 #endif /* __powerpc64__ */
 
 extern int dcache_bsize;
 extern int icache_bsize;
 extern int ucache_bsize;
+extern long il1cache_shape;
+extern long dl1cache_shape;
+extern long l2cache_shape;
+extern long l3cache_shape;
 
 /* vDSO has arch_setup_additional_pages */
 #define ARCH_HAS_SETUP_ADDITIONAL_PAGES
@@ -136,6 +140,9 @@ extern int arch_setup_additional_pages(struct linux_binprm *bprm,
 
 #endif /* CONFIG_SPU_BASE */
 
+#define get_cache_shape(level) \
+	(ppc64_caches.level.assoc << 16 | ppc64_caches.level.line_size)
+
 /*
  * The requirements here are:
  * - keep the final alignment of sp (sp & 0xf)
@@ -156,6 +163,14 @@ do {									\
 	NEW_AUX_ENT(AT_ICACHEBSIZE, icache_bsize);			\
 	NEW_AUX_ENT(AT_UCACHEBSIZE, ucache_bsize);			\
 	VDSO_AUX_ENT(AT_SYSINFO_EHDR, current->mm->context.vdso_base);	\
+	NEW_AUX_ENT(AT_L1I_CACHESIZE, ppc64_caches.l1i.size);		\
+	NEW_AUX_ENT(AT_L1I_CACHEGEOMETRY, get_cache_shape(l1i));	\
+	NEW_AUX_ENT(AT_L1D_CACHESIZE, ppc64_caches.l1i.size);		\
+	NEW_AUX_ENT(AT_L1D_CACHEGEOMETRY, get_cache_shape(l1i));	\
+	NEW_AUX_ENT(AT_L2_CACHESIZE, ppc64_caches.l2.size);		\
+	NEW_AUX_ENT(AT_L2_CACHEGEOMETRY, get_cache_shape(l2));		\
+	NEW_AUX_ENT(AT_L3_CACHESIZE, ppc64_caches.l3.size);		\
+	NEW_AUX_ENT(AT_L3_CACHEGEOMETRY, get_cache_shape(l3));		\
 } while (0)
 
 #endif /* _ASM_POWERPC_ELF_H */
diff --git a/arch/powerpc/include/uapi/asm/auxvec.h b/arch/powerpc/include/uapi/asm/auxvec.h
index ce17d2c..be6e94e 100644
--- a/arch/powerpc/include/uapi/asm/auxvec.h
+++ b/arch/powerpc/include/uapi/asm/auxvec.h
@@ -16,6 +16,37 @@
  */
 #define AT_SYSINFO_EHDR		33
 
-#define AT_VECTOR_SIZE_ARCH 6 /* entries in ARCH_DLINFO */
+/*
+ * AT_*CACHEBSIZE above represent the cache *block* size which is
+ * the size that is affected by the cache management instructions.
+ *
+ * It doesn't nececssarily matches the cache *line* size which is
+ * more of a performance tuning hint. Additionally the latter can
+ * be different for the different cache levels.
+ *
+ * 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
+#define AT_L3_CACHESIZE		46
+#define AT_L3_CACHEGEOMETRY	47
+
+#define AT_VECTOR_SIZE_ARCH	14 /* entries in ARCH_DLINFO */
 
 #endif
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index e0eeed4..cfa2a06 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -94,7 +94,10 @@ EXPORT_SYMBOL_GPL(boot_cpuid);
 int dcache_bsize;
 int icache_bsize;
 int ucache_bsize;
-
+long il1cache_shape = -1;
+long dl1cache_shape = -1;
+long l2cache_shape = -1;
+long l3cache_shape = -1;
 
 unsigned long klimit = (unsigned long) _end;
 
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index b3c93d8..16cb0b7 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -451,6 +451,10 @@ static bool __init parse_cache_info(struct device_node *np,
 	info->block_size = bsize;
 	info->log_block_size = __ilog2(bsize);
 	info->blocks_per_page = PAGE_SIZE / bsize;
+	if (sets == 0)
+		info->assoc = 0xffff;
+	else
+		info->assoc = size / (sets * lsize);
 
 	return success;
 }
-- 
2.9.3