[v2,09/14] mm/powerpc: Redefine pXd_huge() with pXd_leaf()

Commit Message

Peter Xu March 18, 2024, 8:03 p.m. UTC

From: Peter Xu <[e-mail]>

PowerPC book3s 4K mostly has the same definition on both, except pXd_huge()
constantly returns 0 for hash MMUs.  As Michael Ellerman pointed out [1],
it is safe to check _PAGE_PTE on hash MMUs, as the bit will never be set so
it will keep returning false.

As a reference, __p[mu]d_mkhuge() will trigger a BUG_ON trying to create
such huge mappings for 4K hash MMUs.  Meanwhile, the major powerpc hugetlb
pgtable walker __find_linux_pte() already used pXd_leaf() to check leaf
hugetlb mappings.

The goal should be that we will have one API pXd_leaf() to detect all kinds
of huge mappings (hugepd is still special in this case, though).  AFAICT we
need to use the pXd_leaf() impl (rather than pXd_huge()'s) to make sure
ie. THPs on hash MMU will also return true.

This helps to simplify a follow up patch to drop pXd_huge() treewide.

NOTE: *_leaf() definition need to be moved before the inclusion of
asm/book3s/64/pgtable-4k.h, which defines pXd_huge() with it.

[1] https://lore.kernel.org/r/[e-mail]

Cc: Michael Ellerman <[e-mail]>
Cc: Nicholas Piggin <[e-mail]>
Cc: Christophe Leroy <[e-mail]>
Cc: "Aneesh Kumar K.V" <[e-mail]>
Cc: "Naveen N. Rao" <[e-mail]>
Cc: [e-mail]
Signed-off-by: Peter Xu <[e-mail]>
---
 .../include/asm/book3s/64/pgtable-4k.h        | 14 ++--------
 arch/powerpc/include/asm/book3s/64/pgtable.h  | 27 +++++++++----------
 2 files changed, 14 insertions(+), 27 deletions(-)

Patch

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable-4k.h b/arch/powerpc/include/asm/book3s/64/pgtable-4k.h
index 48f21820afe2..92545981bb49 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable-4k.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable-4k.h
@@ -8,22 +8,12 @@ 
 #ifdef CONFIG_HUGETLB_PAGE
 static inline int pmd_huge(pmd_t pmd)
 {
-	/*
-	 * leaf pte for huge page
-	 */
-	if (radix_enabled())
-		return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-	return 0;
+	return pmd_leaf(pmd);
 }
 
 static inline int pud_huge(pud_t pud)
 {
-	/*
-	 * leaf pte for huge page
-	 */
-	if (radix_enabled())
-		return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
-	return 0;
+	return pud_leaf(pud);
 }
 
 /*
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index df66dce8306f..fd7180fded75 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -262,6 +262,18 @@  extern unsigned long __kernel_io_end;
 
 extern struct page *vmemmap;
 extern unsigned long pci_io_base;
+
+#define pmd_leaf pmd_leaf
+static inline bool pmd_leaf(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
+#define pud_leaf pud_leaf
+static inline bool pud_leaf(pud_t pud)
+{
+	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}
 #endif /* __ASSEMBLY__ */
 
 #include <asm/book3s/64/hash.h>
@@ -1436,20 +1448,5 @@  static inline bool is_pte_rw_upgrade(unsigned long old_val, unsigned long new_va
 	return false;
 }
 
-/*
- * Like pmd_huge(), but works regardless of config options
- */
-#define pmd_leaf pmd_leaf
-static inline bool pmd_leaf(pmd_t pmd)
-{
-	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
-#define pud_leaf pud_leaf
-static inline bool pud_leaf(pud_t pud)
-{
-	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
-}
-
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */