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-rw-r--r--arch/x86/kernel/ldt.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index 69af9a0d57b7..733e6ace0fa4 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -126,6 +126,57 @@ static void do_sanity_check(struct mm_struct *mm,
}
}
+#ifdef CONFIG_X86_PAE
+
+static pmd_t *pgd_to_pmd_walk(pgd_t *pgd, unsigned long va)
+{
+ p4d_t *p4d;
+ pud_t *pud;
+
+ if (pgd->pgd == 0)
+ return NULL;
+
+ p4d = p4d_offset(pgd, va);
+ if (p4d_none(*p4d))
+ return NULL;
+
+ pud = pud_offset(p4d, va);
+ if (pud_none(*pud))
+ return NULL;
+
+ return pmd_offset(pud, va);
+}
+
+static void map_ldt_struct_to_user(struct mm_struct *mm)
+{
+ pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+ pmd_t *k_pmd, *u_pmd;
+
+ k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR);
+ u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR);
+
+ if (static_cpu_has(X86_FEATURE_PTI) && !mm->context.ldt)
+ set_pmd(u_pmd, *k_pmd);
+}
+
+static void sanity_check_ldt_mapping(struct mm_struct *mm)
+{
+ pgd_t *k_pgd = pgd_offset(mm, LDT_BASE_ADDR);
+ pgd_t *u_pgd = kernel_to_user_pgdp(k_pgd);
+ bool had_kernel, had_user;
+ pmd_t *k_pmd, *u_pmd;
+
+ k_pmd = pgd_to_pmd_walk(k_pgd, LDT_BASE_ADDR);
+ u_pmd = pgd_to_pmd_walk(u_pgd, LDT_BASE_ADDR);
+ had_kernel = (k_pmd->pmd != 0);
+ had_user = (u_pmd->pmd != 0);
+
+ do_sanity_check(mm, had_kernel, had_user);
+}
+
+#else /* !CONFIG_X86_PAE */
+
static void map_ldt_struct_to_user(struct mm_struct *mm)
{
pgd_t *pgd = pgd_offset(mm, LDT_BASE_ADDR);
@@ -143,6 +194,8 @@ static void sanity_check_ldt_mapping(struct mm_struct *mm)
do_sanity_check(mm, had_kernel, had_user);
}
+#endif /* CONFIG_X86_PAE */
+
/*
* If PTI is enabled, this maps the LDT into the kernelmode and
* usermode tables for the given mm.