The patch titled
Subject: hexagon/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
has been added to the -mm mm-unstable branch. Its filename is
hexagon-mm-support-__have_arch_pte_swp_exclusive.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hexagon-mm-support-__have_arch_pte_swp_exclusive.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: hexagon/mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE
Date: Fri, 13 Jan 2023 18:10:06 +0100
Let's support __HAVE_ARCH_PTE_SWP_EXCLUSIVE by stealing one bit from the
offset. This reduces the maximum swap space per file to 16 GiB (was 32
GiB).
While at it, mask the type in __swp_entry().
Link: https://lkml.kernel.org/r/20230113171026.582290-7-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Brian Cain <bcain@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/hexagon/include/asm/pgtable.h~hexagon-mm-support-__have_arch_pte_swp_exclusive
+++ a/arch/hexagon/include/asm/pgtable.h
@@ -61,6 +61,9 @@ extern unsigned long empty_zero_page;
* So we'll put up with a bit of inefficiency for now...
*/
+/* We borrow bit 6 to store the exclusive marker in swap PTEs. */
+#define _PAGE_SWP_EXCLUSIVE (1<<6)
+
/*
* Top "FOURTH" level (pgd), which for the Hexagon VM is really
* only the second from the bottom, pgd and pud both being collapsed.
@@ -359,9 +362,12 @@ static inline unsigned long pmd_page_vad
#define ZERO_PAGE(vaddr) (virt_to_page(&empty_zero_page))
/*
+ * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that
+ * are !pte_none() && !pte_present().
+ *
* Swap/file PTE definitions. If _PAGE_PRESENT is zero, the rest of the PTE is
* interpreted as swap information. The remaining free bits are interpreted as
- * swap type/offset tuple. Rather than have the TLB fill handler test
+ * listed below. Rather than have the TLB fill handler test
* _PAGE_PRESENT, we're going to reserve the permissions bits and set them to
* all zeros for swap entries, which speeds up the miss handler at the cost of
* 3 bits of offset. That trade-off can be revisited if necessary, but Hexagon
@@ -371,9 +377,10 @@ static inline unsigned long pmd_page_vad
* Format of swap PTE:
* bit 0: Present (zero)
* bits 1-5: swap type (arch independent layer uses 5 bits max)
- * bits 6-9: bits 3:0 of offset
+ * bit 6: exclusive marker
+ * bits 7-9: bits 2:0 of offset
* bits 10-12: effectively _PAGE_PROTNONE (all zero)
- * bits 13-31: bits 22:4 of swap offset
+ * bits 13-31: bits 21:3 of swap offset
*
* The split offset makes some of the following macros a little gnarly,
* but there's plenty of precedent for this sort of thing.
@@ -383,11 +390,29 @@ static inline unsigned long pmd_page_vad
#define __swp_type(swp_pte) (((swp_pte).val >> 1) & 0x1f)
#define __swp_offset(swp_pte) \
- ((((swp_pte).val >> 6) & 0xf) | (((swp_pte).val >> 9) & 0x7ffff0))
+ ((((swp_pte).val >> 7) & 0x7) | (((swp_pte).val >> 10) & 0x3ffff8))
#define __swp_entry(type, offset) \
((swp_entry_t) { \
- ((type << 1) | \
- ((offset & 0x7ffff0) << 9) | ((offset & 0xf) << 6)) })
+ (((type & 0x1f) << 1) | \
+ ((offset & 0x3ffff8) << 10) | ((offset & 0x7) << 7)) })
+
+#define __HAVE_ARCH_PTE_SWP_EXCLUSIVE
+static inline int pte_swp_exclusive(pte_t pte)
+{
+ return pte_val(pte) & _PAGE_SWP_EXCLUSIVE;
+}
+
+static inline pte_t pte_swp_mkexclusive(pte_t pte)
+{
+ pte_val(pte) |= _PAGE_SWP_EXCLUSIVE;
+ return pte;
+}
+
+static inline pte_t pte_swp_clear_exclusive(pte_t pte)
+{
+ pte_val(pte) &= ~_PAGE_SWP_EXCLUSIVE;
+ return pte;
+}
#endif
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range.patch
mm-userfaultfd-rely-on-vma-vm_page_prot-in-uffd_wp_range-fix.patch
mm-mprotect-drop-pgprot_t-parameter-from-change_protection.patch
mm-mprotect-drop-pgprot_t-parameter-from-change_protection-fix.patch
selftests-vm-cow-add-cow-tests-for-collapsing-of-pte-mapped-anon-thp.patch
mm-nommu-factor-out-check-for-nommu-shared-mappings-into-is_nommu_shared_mapping.patch
mm-nommu-dont-use-vm_mayshare-for-map_private-mappings.patch
drivers-misc-open-dice-dont-touch-vm_mayshare.patch
selftests-mm-define-madv_pageout-to-fix-compilation-issues.patch
mm-debug_vm_pgtable-more-pte_swp_exclusive-sanity-checks.patch
alpha-mm-support-__have_arch_pte_swp_exclusive.patch
arc-mm-support-__have_arch_pte_swp_exclusive.patch
arm-mm-support-__have_arch_pte_swp_exclusive.patch
csky-mm-support-__have_arch_pte_swp_exclusive.patch
hexagon-mm-support-__have_arch_pte_swp_exclusive.patch
ia64-mm-support-__have_arch_pte_swp_exclusive.patch
loongarch-mm-support-__have_arch_pte_swp_exclusive.patch
m68k-mm-remove-dummy-__swp-definitions-for-nommu.patch
m68k-mm-support-__have_arch_pte_swp_exclusive.patch
microblaze-mm-support-__have_arch_pte_swp_exclusive.patch
mips-mm-support-__have_arch_pte_swp_exclusive.patch
nios2-mm-refactor-swap-pte-layout.patch
nios2-mm-support-__have_arch_pte_swp_exclusive.patch
openrisc-mm-support-__have_arch_pte_swp_exclusive.patch
parisc-mm-support-__have_arch_pte_swp_exclusive.patch
powerpc-mm-support-__have_arch_pte_swp_exclusive-on-32bit-book3s.patch
powerpc-nohash-mm-support-__have_arch_pte_swp_exclusive.patch
riscv-mm-support-__have_arch_pte_swp_exclusive.patch
sh-mm-support-__have_arch_pte_swp_exclusive.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-32bit.patch
sparc-mm-support-__have_arch_pte_swp_exclusive-on-64bit.patch
um-mm-support-__have_arch_pte_swp_exclusive.patch
x86-mm-support-__have_arch_pte_swp_exclusive-also-on-32bit.patch
xtensa-mm-support-__have_arch_pte_swp_exclusive.patch
mm-remove-__have_arch_pte_swp_exclusive.patch
