An mm_struct is needed to enable x86 to use of the generic
walk_page_range() function.
In the case of walking the user page tables (when
CONFIG_PAGE_TABLE_ISOLATION is enabled), it is necessary to create a
fake_mm structure because there isn't an mm_struct with a pointer
to the pgd of the user page tables. This fake_mm structure is
initialised with the minimum necessary for the generic page walk code.
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
arch/x86/mm/dump_pagetables.c | 36 ++++++++++++++++++++---------------
1 file changed, 21 insertions(+), 15 deletions(-)
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index 40b3f1da6e15..c0fbb9e5a790 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -111,8 +111,6 @@ static struct addr_marker address_markers[] = {
[END_OF_SPACE_NR] = { -1, NULL }
};
-#define INIT_PGD ((pgd_t *) &init_top_pgt)
-
#else /* CONFIG_X86_64 */
enum address_markers_idx {
@@ -147,8 +145,6 @@ static struct addr_marker address_markers[] = {
[END_OF_SPACE_NR] = { -1, NULL }
};
-#define INIT_PGD (swapper_pg_dir)
-
#endif /* !CONFIG_X86_64 */
/* Multipliers for offsets within the PTEs */
@@ -522,10 +518,10 @@ static inline bool is_hypervisor_range(int idx)
#endif
}
-static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
+static void ptdump_walk_pgd_level_core(struct seq_file *m, struct mm_struct *mm,
bool checkwx, bool dmesg)
{
- pgd_t *start = pgd;
+ pgd_t *start = mm->pgd;
pgprotval_t prot, eff;
int i;
struct pg_state st = {};
@@ -572,39 +568,49 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
{
- ptdump_walk_pgd_level_core(m, mm->pgd, false, true);
+ ptdump_walk_pgd_level_core(m, mm, false, true);
}
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+static void ptdump_walk_pgd_level_user_core(struct seq_file *m,
+ struct mm_struct *mm,
+ bool checkwx, bool dmesg)
+{
+ struct mm_struct fake_mm = {
+ .pgd = kernel_to_user_pgdp(mm->pgd)
+ };
+ init_rwsem(&fake_mm.mmap_sem);
+ ptdump_walk_pgd_level_core(m, &fake_mm, checkwx, dmesg);
+}
+#endif
+
void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
bool user)
{
- pgd_t *pgd = mm->pgd;
#ifdef CONFIG_PAGE_TABLE_ISOLATION
if (user && static_cpu_has(X86_FEATURE_PTI))
- pgd = kernel_to_user_pgdp(pgd);
+ ptdump_walk_pgd_level_user_core(m, mm, false, false);
+ else
#endif
- ptdump_walk_pgd_level_core(m, pgd, false, false);
+ ptdump_walk_pgd_level_core(m, mm, false, false);
}
EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
void ptdump_walk_user_pgd_level_checkwx(void)
{
#ifdef CONFIG_PAGE_TABLE_ISOLATION
- pgd_t *pgd = INIT_PGD;
-
if (!(__supported_pte_mask & _PAGE_NX) ||
!static_cpu_has(X86_FEATURE_PTI))
return;
pr_info("x86/mm: Checking user space page tables\n");
- pgd = kernel_to_user_pgdp(pgd);
- ptdump_walk_pgd_level_core(NULL, pgd, true, false);
+ ptdump_walk_pgd_level_user_core(NULL, &init_mm, true, false);
#endif
}
void ptdump_walk_pgd_level_checkwx(void)
{
- ptdump_walk_pgd_level_core(NULL, INIT_PGD, true, false);
+ ptdump_walk_pgd_level_core(NULL, &init_mm, true, false);
}
static int __init pt_dump_init(void)
--
2.20.1
