Le 17/06/2021 à 08:39, Daniel Axtens a écrit :
Commit c65e774fb3f6 ("x86/mm: Make PGDIR_SHIFT and PTRS_PER_P4D variable")
made PTRS_PER_P4D variable on x86 and introduced MAX_PTRS_PER_P4D as a
constant for cases which need a compile-time constant (e.g. fixed-size
arrays).
powerpc likewise has boot-time selectable MMU features which can cause
other mm "constants" to vary. For KASAN, we have some static
PTE/PMD/PUD/P4D arrays so we need compile-time maximums for all these
constants. Extend the MAX_PTRS_PER_ idiom, and place default definitions
in include/pgtable.h. These define MAX_PTRS_PER_x to be PTRS_PER_x unless
an architecture has defined MAX_PTRS_PER_x in its arch headers.
Clean up pgtable-nop4d.h and s390's MAX_PTRS_PER_P4D definitions while
we're at it: both can just pick up the default now.
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
s390 was compile tested only.
---
arch/s390/include/asm/pgtable.h | 2 --
include/asm-generic/pgtable-nop4d.h | 1 -
include/linux/pgtable.h | 22 ++++++++++++++++++++++
3 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 7c66ae5d7e32..cf05954ce013 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -342,8 +342,6 @@ static inline int is_module_addr(void *addr)
#define PTRS_PER_P4D _CRST_ENTRIES
#define PTRS_PER_PGD _CRST_ENTRIES
-#define MAX_PTRS_PER_P4D PTRS_PER_P4D
-
/*
* Segment table and region3 table entry encoding
* (R = read-only, I = invalid, y = young bit):
diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h
index ce2cbb3c380f..2f6b1befb129 100644
--- a/include/asm-generic/pgtable-nop4d.h
+++ b/include/asm-generic/pgtable-nop4d.h
@@ -9,7 +9,6 @@
typedef struct { pgd_t pgd; } p4d_t;
#define P4D_SHIFT PGDIR_SHIFT
-#define MAX_PTRS_PER_P4D 1
#define PTRS_PER_P4D 1
#define P4D_SIZE (1UL << P4D_SHIFT)
#define P4D_MASK (~(P4D_SIZE-1))
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 9e6f71265f72..69700e3e615f 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1625,4 +1625,26 @@ typedef unsigned int pgtbl_mod_mask;
#define pte_leaf_size(x) PAGE_SIZE
#endif
+/*
+ * Some architectures have MMUs that are configurable or selectable at boot
+ * time. These lead to variable PTRS_PER_x. For statically allocated arrays it
+ * helps to have a static maximum value.
+ */
+
+#ifndef MAX_PTRS_PER_PTE
+#define MAX_PTRS_PER_PTE PTRS_PER_PTE
+#endif
+
+#ifndef MAX_PTRS_PER_PMD
+#define MAX_PTRS_PER_PMD PTRS_PER_PMD
+#endif
+
+#ifndef MAX_PTRS_PER_PUD
+#define MAX_PTRS_PER_PUD PTRS_PER_PUD
+#endif
+
+#ifndef MAX_PTRS_PER_P4D
+#define MAX_PTRS_PER_P4D PTRS_PER_P4D
+#endif
+
#endif /* _LINUX_PGTABLE_H */
