book3s64/radix: Refactoring common kfence related functions

Both radix and hash on book3s requires to detect if kfence
early init is enabled or not. Hash needs to disable kfence
if early init is not enabled because with kfence the linear map is
mapped using PAGE_SIZE rather than 16M mapping.
We don't support multiple page sizes for slb entry used for kernel
linear map in book3s64.

This patch refactors out the common functions required to detect kfence
early init is enabled or not.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/f4a787224fbe5bb787158ace579780c0257f6602.1729271995.git.ritesh.list@gmail.com

arch/powerpc/include/asm/kfence.h

@@ -15,7 +15,7 @@
 #define ARCH_FUNC_PREFIX "."
 #endif
 
-#ifdef CONFIG_KFENCE
+extern bool kfence_early_init;
 extern bool kfence_disabled;
 
 static inline void disable_kfence(void)
@@ -27,7 +27,11 @@ static inline bool arch_kfence_init_pool(void)
 {
 	return !kfence_disabled;
 }
-#endif
+
+static inline bool kfence_early_init_enabled(void)
+{
+	return IS_ENABLED(CONFIG_KFENCE) && kfence_early_init;
+}
 
 #ifdef CONFIG_PPC64
 static inline bool kfence_protect_page(unsigned long addr, bool protect)

arch/powerpc/mm/book3s64/pgtable.c

@@ -37,6 +37,19 @@ EXPORT_SYMBOL(__pmd_frag_nr);
 unsigned long __pmd_frag_size_shift;
 EXPORT_SYMBOL(__pmd_frag_size_shift);
 
+#ifdef CONFIG_KFENCE
+extern bool kfence_early_init;
+static int __init parse_kfence_early_init(char *arg)
+{
+	int val;
+
+	if (get_option(&arg, &val))
+		kfence_early_init = !!val;
+	return 0;
+}
+early_param("kfence.sample_interval", parse_kfence_early_init);
+#endif
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 /*
  * This is called when relaxing access to a hugepage. It's also called in the page

arch/powerpc/mm/book3s64/radix_pgtable.c

@@ -363,18 +363,6 @@ static int __meminit create_physical_mapping(unsigned long start,
 }
 
 #ifdef CONFIG_KFENCE
-static bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
-
-static int __init parse_kfence_early_init(char *arg)
-{
-	int val;
-
-	if (get_option(&arg, &val))
-		kfence_early_init = !!val;
-	return 0;
-}
-early_param("kfence.sample_interval", parse_kfence_early_init);
-
 static inline phys_addr_t alloc_kfence_pool(void)
 {
 	phys_addr_t kfence_pool;

arch/powerpc/mm/init-common.c

@@ -33,6 +33,7 @@ bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
 bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
 #ifdef CONFIG_KFENCE
 bool __ro_after_init kfence_disabled;
+bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;
 #endif
 
 static int __init parse_nosmep(char *p)