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-rw-r--r--arch/x86/mm/pti.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
index d58bcee470fc..59290356f19f 100644
--- a/arch/x86/mm/pti.c
+++ b/arch/x86/mm/pti.c
@@ -265,6 +265,29 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
}
/*
+ * Clone a single p4d (i.e. a top-level entry on 4-level systems and a
+ * next-level entry on 5-level systems.
+ */
+static void __init pti_clone_p4d(unsigned long addr)
+{
+ p4d_t *kernel_p4d, *user_p4d;
+ pgd_t *kernel_pgd;
+
+ user_p4d = pti_user_pagetable_walk_p4d(addr);
+ kernel_pgd = pgd_offset_k(addr);
+ kernel_p4d = p4d_offset(kernel_pgd, addr);
+ *user_p4d = *kernel_p4d;
+}
+
+/*
+ * Clone the CPU_ENTRY_AREA into the user space visible page table.
+ */
+static void __init pti_clone_user_shared(void)
+{
+ pti_clone_p4d(CPU_ENTRY_AREA_BASE);
+}
+
+/*
* Initialize kernel page table isolation
*/
void __init pti_init(void)
@@ -273,4 +296,6 @@ void __init pti_init(void)
return;
pr_info("enabled\n");
+
+ pti_clone_user_shared();
}