arm64/mm: fold check for KFENCE into can_set_direct_map()

KFENCE requires linear map to be mapped at page granularity, so that it is possible to protect/unprotect single pages, just like with rodata_full and DEBUG_PAGEALLOC. Instead of repating can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE) make can_set_direct_map() handle the KFENCE case. This also prevents potential false positives in kernel_page_present() that may return true for non-present page if CONFIG_KFENCE is enabled. Signed-off-by: Mike Rapoport <[email protected]> Reviewed-by: Anshuman Khandual <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Catalin Marinas <[email protected]>
fracktal · Sep 29, 2022 · b9dd04a · b9dd04a
1 parent 2305b80
commit b9dd04a
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Showing 2 changed files with 9 additions and 7 deletions.
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
@@ -535,7 +535,7 @@ static void __init map_mem(pgd_t *pgdp)
 	 */
 	BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end));
 
-	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
+	if (can_set_direct_map())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	/*
@@ -1542,11 +1542,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
 
 	VM_BUG_ON(!mhp_range_allowed(start, size, true));
 
-	/*
-	 * KFENCE requires linear map to be mapped at page granularity, so that
-	 * it is possible to protect/unprotect single pages in the KFENCE pool.
-	 */
-	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
+	if (can_set_direct_map())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),

diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
@@ -21,7 +21,13 @@ bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED
 
 bool can_set_direct_map(void)
 {
-	return rodata_full || debug_pagealloc_enabled();
+	/*
+	 * rodata_full, DEBUG_PAGEALLOC and KFENCE require linear map to be
+	 * mapped at page granularity, so that it is possible to
+	 * protect/unprotect single pages.
+	 */
+	return rodata_full || debug_pagealloc_enabled() ||
+		IS_ENABLED(CONFIG_KFENCE);
 }
 
 static int change_page_range(pte_t *ptep, unsigned long addr, void *data)