1 files changed, 38 insertions, 2 deletions
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index a1bcde35db4c..61bc7d1800d7 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -2346,8 +2346,8 @@ bool kernel_page_present(struct page *page)
 
 #endif /* CONFIG_DEBUG_PAGEALLOC */
 
-int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
-			    unsigned numpages, unsigned long page_flags)
+int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
+				   unsigned numpages, unsigned long page_flags)
 {
 	int retval = -EINVAL;
 
@@ -2361,6 +2361,8 @@ int kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
 		.flags = 0,
 	};
 
+	WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");
+
 	if (!(__supported_pte_mask & _PAGE_NX))
 		goto out;
 
@@ -2383,6 +2385,40 @@ out:
 }
 
 /*
+ * __flush_tlb_all() flushes mappings only on current CPU and hence this
+ * function shouldn't be used in an SMP environment. Presently, it's used only
+ * during boot (way before smp_init()) by EFI subsystem and hence is ok.
+ */
+int __init kernel_unmap_pages_in_pgd(pgd_t *pgd, unsigned long address,
+				     unsigned long numpages)
+{
+	int retval;
+
+	/*
+	 * The typical sequence for unmapping is to find a pte through
+	 * lookup_address_in_pgd() (ideally, it should never return NULL because
+	 * the address is already mapped) and change it's protections. As pfn is
+	 * the *target* of a mapping, it's not useful while unmapping.
+	 */
+	struct cpa_data cpa = {
+		.vaddr		= &address,
+		.pfn		= 0,
+		.pgd		= pgd,
+		.numpages	= numpages,
+		.mask_set	= __pgprot(0),
+		.mask_clr	= __pgprot(_PAGE_PRESENT | _PAGE_RW),
+		.flags		= 0,
+	};
+
+	WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");
+
+	retval = __change_page_attr_set_clr(&cpa, 0);
+	__flush_tlb_all();
+
+	return retval;
+}
+
+/*
  * The testcases use internal knowledge of the implementation that shouldn't
  * be exposed to the rest of the kernel. Include these directly here.
  */