The patch titled
Subject: mm: define default MAX_PTRS_PER_* in include/pgtable.h
has been added to the -mm tree. Its filename is
mm-define-default-max_ptrs_per_-in-include-pgtableh.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-define-default-max_ptrs_per_-in-include-pgtableh.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-define-default-max_ptrs_per_-in-include-pgtableh.patch
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------------------------------------------------------
From: Daniel Axtens <dja@xxxxxxxxxx>
Subject: mm: define default MAX_PTRS_PER_* in include/pgtable.h
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.
Link: https://lkml.kernel.org/r/20210624034050.511391-4-dja@xxxxxxxxxx
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
Acked-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
--- a/arch/s390/include/asm/pgtable.h~mm-define-default-max_ptrs_per_-in-include-pgtableh
+++ a/arch/s390/include/asm/pgtable.h
@@ -344,8 +344,6 @@ static inline int is_module_addr(void *a
#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):
--- a/include/asm-generic/pgtable-nop4d.h~mm-define-default-max_ptrs_per_-in-include-pgtableh
+++ a/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))
--- a/include/linux/pgtable.h~mm-define-default-max_ptrs_per_-in-include-pgtableh
+++ a/include/linux/pgtable.h
@@ -1592,4 +1592,26 @@ 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 */
_
Patches currently in -mm which might be from dja@xxxxxxxxxx are
mm-vmalloc-unbreak-kasan-vmalloc-support.patch
kasan-allow-an-architecture-to-disable-inline-instrumentation.patch
kasan-allow-architectures-to-provide-an-outline-readiness-check.patch
mm-define-default-max_ptrs_per_-in-include-pgtableh.patch
kasan-use-max_ptrs_per_-for-early-shadow-tables.patch
