On 09/12/2019 11:08, Michael Ellerman wrote:

Steven Price [off-list ref] writes:

quoted

walk_page_range() is going to be allowed to walk page tables other than
those of user space. For this it needs to know when it has reached a
'leaf' entry in the page tables. This information is provided by the
p?d_leaf() functions/macros.

For powerpc pmd_large() already exists and does what we want, so hoist
it out of the CONFIG_TRANSPARENT_HUGEPAGE condition and implement the
other levels. Macros are used to provide the generic p?d_leaf() names.

CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <redacted>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: linuxppc-dev@lists.ozlabs.org
CC: kvm-ppc@vger.kernel.org
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index b01624e5c467..3dd7b6f5edd0 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -923,6 +923,12 @@ static inline int pud_present(pud_t pud)
 	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pud_leaf	pud_large
+static inline int pud_large(pud_t pud)
+{
+	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}

We already have:

#define pud_is_leaf pud_is_leaf
static inline bool pud_is_leaf(pud_t pud)
{
	return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
}

And so on.

These went in relatively recently in:

  d6eacedd1f0e ("powerpc/book3s: Use config independent helpers for page table walk")


Assuming those all work for you, maybe your patch in this series should
just do:

#define pud_leaf pud_is_leaf

And so on. And then we can do a patch later to change the arch/powerpc
code to use pud_leaf() etc. directly and drop the "is" versions.

Thanks for pointing this out - these didn't exist when I started this
patch series, but yes it would be a good idea to make use of them now.
Followed by cleaning up to use the shorter p?d_leaf() versions in a
later patch.

Thanks,

Steve

cheers

quoted

@@ -966,6 +972,12 @@ static inline int pgd_present(pgd_t pgd)
 	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
 }
 
+#define pgd_leaf	pgd_large
+static inline int pgd_large(pgd_t pgd)
+{
+	return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PTE));
+}
+
 static inline pte_t pgd_pte(pgd_t pgd)
 {
 	return __pte_raw(pgd_raw(pgd));

@@ -1133,6 +1145,15 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
 	return pte_access_permitted(pmd_pte(pmd), write);
 }
 
+#define pmd_leaf	pmd_large
+/*
+ * returns true for pmd migration entries, THP, devmap, hugetlb
+ */
+static inline int pmd_large(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
 extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);

@@ -1159,15 +1180,6 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
 	return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
 }
 
-/*
- * returns true for pmd migration entries, THP, devmap, hugetlb
- * But compile time dependent on THP config
- */
-static inline int pmd_large(pmd_t pmd)
-{
-	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
 static inline pmd_t pmd_mknotpresent(pmd_t pmd)
 {
 	return __pmd(pmd_val(pmd) & ~_PAGE_PRESENT);

-- 
2.20.1

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