Introduce and EXPORT a read-only counterpart to apply_to_page_range().
It only exposes the PTE value, not a pointer to the pagetables itself
and is thus quite a bit safer to export. A number of
apply_to_page_range() users can be converted to this primitive.
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
include/linux/mm.h | 4 ++++
mm/memory.c | 24 ++++++++++++++++++++++++
2 files changed, 28 insertions(+)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2876,6 +2876,10 @@ extern int apply_to_page_range(struct mm
extern int apply_to_existing_page_range(struct mm_struct *mm,
unsigned long address, unsigned long size,
pte_fn_t fn, void *data);
+extern int verify_page_range(struct mm_struct *mm,
+ unsigned long addr, unsigned long size,
+ int (*fn)(pte_t pte, unsigned long addr, void
*data),
+ void *data);
extern void init_mem_debugging_and_hardening(void);
#ifdef CONFIG_PAGE_POISONING
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2559,6 +2559,30 @@ int apply_to_existing_page_range(struct
return __apply_to_page_range(mm, addr, size, fn, data, false);
}
+struct vpr_data {
+ int (*fn)(pte_t pte, unsigned long addr, void *data);
+ void *data;
+};
+
+static int vpr_fn(pte_t *pte, unsigned long addr, void *data)
+{
+ struct vpr_data *vpr = data;
+ return vpr->fn(*pte, addr, vpr->data);
+}
+
+int verify_page_range(struct mm_struct *mm,
+ unsigned long addr, unsigned long size,
+ int (*fn)(pte_t pte, unsigned long addr, void *data),
+ void *data)
+{
+ struct vpr_data vpr = {
+ .fn = fn,
+ .data = data,
+ };
+ return apply_to_page_range(mm, addr, size, vpr_fn, &vpr);
+}
+EXPORT_SYMBOL_GPL(verify_page_range);
+
/*
* handle_pte_fault chooses page fault handler according to an entry which was
* read non-atomically. Before making any commitment, on those architectures
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