x86/alternative: Rename apply_ibt_endbr()

The current name doesn't reflect what it does very well.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lkml.kernel.org/r/20230622144321.427441595%40infradead.org

Author: Peter Zijlstra

arch/um/kernel/um_arch.c

@@ -437,7 +437,7 @@ void __init arch_cpu_finalize_init(void)
 	os_check_bugs();
 }
 
-void apply_ibt_endbr(s32 *start, s32 *end)
+void apply_seal_endbr(s32 *start, s32 *end)
 {
 }
 

arch/x86/include/asm/alternative.h

@@ -96,7 +96,7 @@ extern void alternative_instructions(void);
 extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
 extern void apply_retpolines(s32 *start, s32 *end);
 extern void apply_returns(s32 *start, s32 *end);
-extern void apply_ibt_endbr(s32 *start, s32 *end);
+extern void apply_seal_endbr(s32 *start, s32 *end);
 extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
 			  s32 *start_cfi, s32 *end_cfi);
 

arch/x86/include/asm/ibt.h

@@ -34,7 +34,7 @@
 /*
  * Create a dummy function pointer reference to prevent objtool from marking
  * the function as needing to be "sealed" (i.e. ENDBR converted to NOP by
- * apply_ibt_endbr()).
+ * apply_seal_endbr()).
  */
 #define IBT_NOSEAL(fname)				\
 	".pushsection .discard.ibt_endbr_noseal\n\t"	\

arch/x86/kernel/alternative.c

@@ -803,7 +803,7 @@ static void __init_or_module poison_endbr(void *addr, bool warn)
 /*
  * Generated by: objtool --ibt
  */
-void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end)
+void __init_or_module noinline apply_seal_endbr(s32 *start, s32 *end)
 {
 	s32 *s;
 
@@ -818,7 +818,7 @@ void __init_or_module noinline apply_ibt_endbr(s32 *start, s32 *end)
 
 #else
 
-void __init_or_module apply_ibt_endbr(s32 *start, s32 *end) { }
+void __init_or_module apply_seal_endbr(s32 *start, s32 *end) { }
 
 #endif /* CONFIG_X86_KERNEL_IBT */
 
@@ -1565,7 +1565,10 @@ void __init alternative_instructions(void)
 	 */
 	callthunks_patch_builtin_calls();
 
-	apply_ibt_endbr(__ibt_endbr_seal, __ibt_endbr_seal_end);
+	/*
+	 * Seal all functions that do not have their address taken.
+	 */
+	apply_seal_endbr(__ibt_endbr_seal, __ibt_endbr_seal_end);
 
 #ifdef CONFIG_SMP
 	/* Patch to UP if other cpus not imminent. */

arch/x86/kernel/module.c

@@ -358,7 +358,7 @@ int module_finalize(const Elf_Ehdr *hdr,
 	}
 	if (ibt_endbr) {
 		void *iseg = (void *)ibt_endbr->sh_addr;
-		apply_ibt_endbr(iseg, iseg + ibt_endbr->sh_size);
+		apply_seal_endbr(iseg, iseg + ibt_endbr->sh_size);
 	}
 	if (locks) {
 		void *lseg = (void *)locks->sh_addr;