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Message-ID: <20250205151003.88959-16-ryan.roberts@arm.com>
Date: Wed, 5 Feb 2025 15:09:55 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Muchun Song <muchun.song@...ux.dev>,
Pasha Tatashin <pasha.tatashin@...een.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Uladzislau Rezki <urezki@...il.com>,
Christoph Hellwig <hch@...radead.org>,
Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ardb@...nel.org>,
Anshuman Khandual <anshuman.khandual@....com>,
Dev Jain <dev.jain@....com>,
Alexandre Ghiti <alexghiti@...osinc.com>,
Steve Capper <steve.capper@...aro.org>,
Kevin Brodsky <kevin.brodsky@....com>
Cc: Ryan Roberts <ryan.roberts@....com>,
linux-arm-kernel@...ts.infradead.org,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v1 15/16] mm: Generalize arch_sync_kernel_mappings()
arch_sync_kernel_mappings() is an optional hook for arches to allow them
to synchonize certain levels of the kernel pgtables after modification.
But arm64 could benefit from a hook similar to this, paired with a call
prior to starting the batch of modifications.
So let's introduce arch_update_kernel_mappings_begin() and
arch_update_kernel_mappings_end(). Both have a default implementation
which can be overridden by the arch code. The default for the former is
a nop, and the default for the latter is to call
arch_sync_kernel_mappings(), so the latter replaces previous
arch_sync_kernel_mappings() callsites. So by default, the resulting
behaviour is unchanged.
To avoid include hell, the pgtbl_mod_mask type and it's associated
macros are moved to their own header.
In a future patch, arm64 will opt-in to overriding both functions.
Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
include/linux/pgtable.h | 24 +----------------
include/linux/pgtable_modmask.h | 32 ++++++++++++++++++++++
include/linux/vmalloc.h | 47 +++++++++++++++++++++++++++++++++
mm/memory.c | 5 ++--
mm/vmalloc.c | 15 ++++++-----
5 files changed, 92 insertions(+), 31 deletions(-)
create mode 100644 include/linux/pgtable_modmask.h
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 94d267d02372..7f70786a73b3 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -4,6 +4,7 @@
#include <linux/pfn.h>
#include <asm/pgtable.h>
+#include <linux/pgtable_modmask.h>
#define PMD_ORDER (PMD_SHIFT - PAGE_SHIFT)
#define PUD_ORDER (PUD_SHIFT - PAGE_SHIFT)
@@ -1786,29 +1787,6 @@ static inline bool arch_has_pfn_modify_check(void)
# define PAGE_KERNEL_EXEC PAGE_KERNEL
#endif
-/*
- * Page Table Modification bits for pgtbl_mod_mask.
- *
- * These are used by the p?d_alloc_track*() set of functions an in the generic
- * vmalloc/ioremap code to track at which page-table levels entries have been
- * modified. Based on that the code can better decide when vmalloc and ioremap
- * mapping changes need to be synchronized to other page-tables in the system.
- */
-#define __PGTBL_PGD_MODIFIED 0
-#define __PGTBL_P4D_MODIFIED 1
-#define __PGTBL_PUD_MODIFIED 2
-#define __PGTBL_PMD_MODIFIED 3
-#define __PGTBL_PTE_MODIFIED 4
-
-#define PGTBL_PGD_MODIFIED BIT(__PGTBL_PGD_MODIFIED)
-#define PGTBL_P4D_MODIFIED BIT(__PGTBL_P4D_MODIFIED)
-#define PGTBL_PUD_MODIFIED BIT(__PGTBL_PUD_MODIFIED)
-#define PGTBL_PMD_MODIFIED BIT(__PGTBL_PMD_MODIFIED)
-#define PGTBL_PTE_MODIFIED BIT(__PGTBL_PTE_MODIFIED)
-
-/* Page-Table Modification Mask */
-typedef unsigned int pgtbl_mod_mask;
-
#endif /* !__ASSEMBLY__ */
#if !defined(MAX_POSSIBLE_PHYSMEM_BITS) && !defined(CONFIG_64BIT)
diff --git a/include/linux/pgtable_modmask.h b/include/linux/pgtable_modmask.h
new file mode 100644
index 000000000000..5a21b1bb8df3
--- /dev/null
+++ b/include/linux/pgtable_modmask.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_PGTABLE_MODMASK_H
+#define _LINUX_PGTABLE_MODMASK_H
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Page Table Modification bits for pgtbl_mod_mask.
+ *
+ * These are used by the p?d_alloc_track*() set of functions an in the generic
+ * vmalloc/ioremap code to track at which page-table levels entries have been
+ * modified. Based on that the code can better decide when vmalloc and ioremap
+ * mapping changes need to be synchronized to other page-tables in the system.
+ */
+#define __PGTBL_PGD_MODIFIED 0
+#define __PGTBL_P4D_MODIFIED 1
+#define __PGTBL_PUD_MODIFIED 2
+#define __PGTBL_PMD_MODIFIED 3
+#define __PGTBL_PTE_MODIFIED 4
+
+#define PGTBL_PGD_MODIFIED BIT(__PGTBL_PGD_MODIFIED)
+#define PGTBL_P4D_MODIFIED BIT(__PGTBL_P4D_MODIFIED)
+#define PGTBL_PUD_MODIFIED BIT(__PGTBL_PUD_MODIFIED)
+#define PGTBL_PMD_MODIFIED BIT(__PGTBL_PMD_MODIFIED)
+#define PGTBL_PTE_MODIFIED BIT(__PGTBL_PTE_MODIFIED)
+
+/* Page-Table Modification Mask */
+typedef unsigned int pgtbl_mod_mask;
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* _LINUX_PGTABLE_MODMASK_H */
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 16dd4cba64f2..cb5d8f1965a1 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -11,6 +11,7 @@
#include <asm/page.h> /* pgprot_t */
#include <linux/rbtree.h>
#include <linux/overflow.h>
+#include <linux/pgtable_modmask.h>
#include <asm/vmalloc.h>
@@ -213,6 +214,26 @@ extern int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
int vmap_pages_range(unsigned long addr, unsigned long end, pgprot_t prot,
struct page **pages, unsigned int page_shift);
+#ifndef arch_update_kernel_mappings_begin
+/**
+ * arch_update_kernel_mappings_begin - A batch of kernel pgtable mappings are
+ * about to be updated.
+ * @start: Virtual address of start of range to be updated.
+ * @end: Virtual address of end of range to be updated.
+ *
+ * An optional hook to allow architecture code to prepare for a batch of kernel
+ * pgtable mapping updates. An architecture may use this to enter a lazy mode
+ * where some operations can be deferred until the end of the batch.
+ *
+ * Context: Called in task context and may be preemptible.
+ */
+static inline void arch_update_kernel_mappings_begin(unsigned long start,
+ unsigned long end)
+{
+}
+#endif
+
+#ifndef arch_update_kernel_mappings_end
/*
* Architectures can set this mask to a combination of PGTBL_P?D_MODIFIED values
* and let generic vmalloc and ioremap code know when arch_sync_kernel_mappings()
@@ -229,6 +250,32 @@ int vmap_pages_range(unsigned long addr, unsigned long end, pgprot_t prot,
*/
void arch_sync_kernel_mappings(unsigned long start, unsigned long end);
+/**
+ * arch_update_kernel_mappings_end - A batch of kernel pgtable mappings have
+ * been updated.
+ * @start: Virtual address of start of range that was updated.
+ * @end: Virtual address of end of range that was updated.
+ *
+ * An optional hook to inform architecture code that a batch update is complete.
+ * This balances a previous call to arch_update_kernel_mappings_begin().
+ *
+ * An architecture may override this for any purpose, such as exiting a lazy
+ * mode previously entered with arch_update_kernel_mappings_begin() or syncing
+ * kernel mappings to a secondary pgtable. The default implementation calls an
+ * arch-provided arch_sync_kernel_mappings() if any arch-defined pgtable level
+ * was updated.
+ *
+ * Context: Called in task context and may be preemptible.
+ */
+static inline void arch_update_kernel_mappings_end(unsigned long start,
+ unsigned long end,
+ pgtbl_mod_mask mask)
+{
+ if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+ arch_sync_kernel_mappings(start, end);
+}
+#endif
+
/*
* Lowlevel-APIs (not for driver use!)
*/
diff --git a/mm/memory.c b/mm/memory.c
index a15f7dd500ea..f80930bc19f6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3035,6 +3035,8 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
if (WARN_ON(addr >= end))
return -EINVAL;
+ arch_update_kernel_mappings_begin(start, end);
+
pgd = pgd_offset(mm, addr);
do {
next = pgd_addr_end(addr, end);
@@ -3055,8 +3057,7 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
break;
} while (pgd++, addr = next, addr != end);
- if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
- arch_sync_kernel_mappings(start, start + size);
+ arch_update_kernel_mappings_end(start, end, mask);
return err;
}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 50fd44439875..c5c51d86ef78 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -312,10 +312,10 @@ int vmap_page_range(unsigned long addr, unsigned long end,
pgtbl_mod_mask mask = 0;
int err;
+ arch_update_kernel_mappings_begin(addr, end);
err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot),
ioremap_max_page_shift, &mask);
- if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
- arch_sync_kernel_mappings(addr, end);
+ arch_update_kernel_mappings_end(addr, end, mask);
flush_cache_vmap(addr, end);
if (!err)
@@ -463,6 +463,9 @@ void __vunmap_range_noflush(unsigned long start, unsigned long end)
pgtbl_mod_mask mask = 0;
BUG_ON(addr >= end);
+
+ arch_update_kernel_mappings_begin(start, end);
+
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
@@ -473,8 +476,7 @@ void __vunmap_range_noflush(unsigned long start, unsigned long end)
vunmap_p4d_range(pgd, addr, next, &mask);
} while (pgd++, addr = next, addr != end);
- if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
- arch_sync_kernel_mappings(start, end);
+ arch_update_kernel_mappings_end(start, end, mask);
}
void vunmap_range_noflush(unsigned long start, unsigned long end)
@@ -625,6 +627,8 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
WARN_ON(page_shift < PAGE_SHIFT);
+ arch_update_kernel_mappings_begin(start, end);
+
if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
page_shift == PAGE_SHIFT) {
err = vmap_small_pages_range_noflush(addr, end, prot, pages,
@@ -642,8 +646,7 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
}
}
- if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
- arch_sync_kernel_mappings(start, end);
+ arch_update_kernel_mappings_end(start, end, mask);
return err;
}
--
2.43.0
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