Hi,
This patch introduces code to traverse the kernel page tables, starting from
the highest level pgdir table in init_level4_pgt.
Signed-off-by: Ankita Garg <ankita@xxxxxxxxxx>
---
arch/x86/include/asm/pgtable_64.h | 1 +
drivers/misc/memref.c | 1 +
include/linux/memtrace.h | 1 +
lib/memtrace.c | 95 +++++++++++++++++++++++++++++++++++++
4 files changed, 98 insertions(+), 0 deletions(-)
diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 975f709..09c99e0 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -13,6 +13,7 @@
#include <asm/processor.h>
#include <linux/bitops.h>
#include <linux/threads.h>
+#include <linux/module.h>
extern pud_t level3_kernel_pgt[512];
extern pud_t level3_ident_pgt[512];
diff --git a/drivers/misc/memref.c b/drivers/misc/memref.c
index 4e8785f..abf8b23 100644
--- a/drivers/misc/memref.c
+++ b/drivers/misc/memref.c
@@ -152,6 +152,7 @@ static int memref_thread(void *data)
seq = inc_seq_number();
walk_tasks(task);
+ kernel_mapping_ref();
update_and_log_data();
msleep(interval);
}
diff --git a/include/linux/memtrace.h b/include/linux/memtrace.h
index 0fa15e0..b1fce57 100644
--- a/include/linux/memtrace.h
+++ b/include/linux/memtrace.h
@@ -24,6 +24,7 @@ unsigned int inc_seq_number(void);
void set_memtrace_block_sz(int sz);
void mark_memtrace_block_accessed(unsigned long paddr);
void init_memtrace_blocks(void);
+void kernel_mapping_ref(void);
void update_and_log_data(void);
#endif /* _LINUX_MEMTRACE_H */
diff --git a/lib/memtrace.c b/lib/memtrace.c
index 5ebd7c8..aec5b65 100644
--- a/lib/memtrace.c
+++ b/lib/memtrace.c
@@ -72,6 +72,101 @@ void set_memtrace_block_sz(int sz)
}
EXPORT_SYMBOL_GPL(set_memtrace_block_sz);
+#define PTE_LEVEL_MULT (PAGE_SIZE)
+#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
+#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
+#define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
+
+static void walk_k_pte_level(pmd_t pmd, unsigned long addr)
+ {
+ pte_t *pte;
+ int i, ret;
+ unsigned long pfn;
+ struct page *pg;
+
+ pte = (pte_t*) pmd_page_vaddr(pmd);
+
+ for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
+ if(!pte_present(*pte) && pte_none(*pte) && pte_huge(*pte))
+ continue;
+
+ pfn = pte_pfn(*pte);
+ if(pfn_valid(pfn) && pte_young(*pte)) {
+ ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
+ (unsigned long *) &pte->pte);
+ if (ret) {
+ pg = pfn_to_page(pfn);
+ ClearPageReferenced(pg);
+ mark_memtrace_block_accessed(pfn << PAGE_SHIFT);
+ }
+ }
+ }
+}
+
+#if PTRS_PER_PMD > 1
+
+static void walk_k_pmd_level(pud_t pud, unsigned long addr)
+ {
+ pmd_t *pmd;
+ int i;
+
+ pmd = (pmd_t *) pud_page_vaddr(pud);
+
+ for (i = 0; i < PTRS_PER_PMD; i++) {
+
+ if(!pmd_none(*pmd) && pmd_present(*pmd) && !pmd_large(*pmd))
+ walk_k_pte_level(*pmd, addr + i * PMD_LEVEL_MULT);
+
+ pmd++;
+ }
+ }
+
+#else
+#define walk_pmd_level(p,a) walk_pte_level(__pmd(pud_val(p)),a)
+#define pud_none(a) pmd_none(__pmd(pud_val(a)))
+#define pud_large(a) pmd_large(__pmd(pud_val(a)))
+#endif
+
+#if PTRS_PER_PUD > 1
+
+static void walk_k_pud_level(pgd_t pgd, unsigned long addr)
+ {
+ pud_t *pud;
+ int i;
+
+ pud = (pud_t *) pgd_page_vaddr(pgd);
+
+ for (i = 0; i < PTRS_PER_PUD; i++) {
+
+ if(!pud_none(*pud) && pud_present(*pud) && !pud_large(*pud))
+ walk_k_pmd_level(*pud, addr + i * PUD_LEVEL_MULT);
+ pud++;
+ }
+ }
+
+#else
+#define walk_pud_level(p,a) walk_pmd_level(__pud(pgd_val(p)),a)
+#define pgd_none(a) pud_none(__pud(pgd_val(a)))
+#define pgd_large(a) pud_large(__pud(pgd_val(a)))
+#endif
+
+void kernel_mapping_ref(void)
+{
+ pgd_t *pgd;
+ int i;
+
+ pgd = (pgd_t *) &init_level4_pgt;
+
+ for (i=0; i < PTRS_PER_PGD; i++) {
+
+ if(!pgd_none(*pgd) && pgd_present(*pgd) && !pgd_large(*pgd)) {
+ walk_k_pud_level(*pgd, i * PGD_LEVEL_MULT);
+ }
+ pgd++;
+ }
+}
+EXPORT_SYMBOL_GPL(kernel_mapping_ref);
+
void mark_memtrace_block_accessed(unsigned long paddr)
{
int memtrace_block;
--
1.7.4
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