[PATCH 2/2] arm64: remove page granularity limitation from KFENCE

@@ -18,6 +18,7 @@
 #include <linux/screen_info.h>
 #include <linux/init.h>
 #include <linux/kexec.h>
+#include <linux/kfence.h>
 #include <linux/root_dev.h>
 #include <linux/cpu.h>
 #include <linux/interrupt.h>

@@ -345,6 +346,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
 
 	arm64_memblock_init();
 
+	kfence_alloc_pool();
+
 	paging_init();
 
 	acpi_table_upgrade();

@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/ioport.h>
 #include <linux/kexec.h>
+#include <linux/kfence.h>
 #include <linux/libfdt.h>
 #include <linux/mman.h>
 #include <linux/nodemask.h>

@@ -515,10 +516,16 @@ static void __init map_mem(pgd_t *pgdp)
 	 */
 	BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end));
 
-	if (rodata_full || crash_mem_map || debug_pagealloc_enabled() ||
-	    IS_ENABLED(CONFIG_KFENCE))
+	if (rodata_full || crash_mem_map || debug_pagealloc_enabled())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
+	/*
+	 * KFENCE requires linear map to be mapped at page granularity, so
+	 * temporarily skip mapping for __kfence_pool in the following
+	 * for-loop
+	 */
+	memblock_mark_nomap(__pa(__kfence_pool), KFENCE_POOL_SIZE);
+
 	/*
 	 * Take care not to create a writable alias for the
 	 * read-only text and rodata sections of the kernel image.

@@ -553,6 +560,15 @@ static void __init map_mem(pgd_t *pgdp)
 	__map_memblock(pgdp, kernel_start, kernel_end,
 		       PAGE_KERNEL, NO_CONT_MAPPINGS);
 	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
+
+	/*
+	 * Map the __kfence_pool at page granularity now.
+	 */
+	__map_memblock(pgdp, __pa(__kfence_pool),
+		       __pa(__kfence_pool + KFENCE_POOL_SIZE),
+		       pgprot_tagged(PAGE_KERNEL),
+		       NO_EXEC_MAPPINGS | NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
+	memblock_clear_nomap(__pa(__kfence_pool), KFENCE_POOL_SIZE);
 }
 
 void mark_rodata_ro(void)

@@ -1480,12 +1496,7 @@ 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 (rodata_full || debug_pagealloc_enabled() ||
-	    IS_ENABLED(CONFIG_KFENCE))
+	if (rodata_full || debug_pagealloc_enabled())
 		flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
 
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),