x86/module: prepare module loading for ROX allocations of text

When module text memory will be allocated with ROX permissions, the
memory at the actual address where the module will live will contain
invalid instructions and there will be a writable copy that contains the
actual module code.

Update relocations and alternatives patching to deal with it.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Author: rppt

arch/um/kernel/um_arch.c

@@ -435,24 +435,25 @@ void __init arch_cpu_finalize_init(void)
 	os_check_bugs();
 }
 
-void apply_seal_endbr(s32 *start, s32 *end)
+void apply_seal_endbr(s32 *start, s32 *end, struct module *mod)
 {
 }
 
-void apply_retpolines(s32 *start, s32 *end)
+void apply_retpolines(s32 *start, s32 *end, struct module *mod)
 {
 }
 
-void apply_returns(s32 *start, s32 *end)
+void apply_returns(s32 *start, s32 *end, struct module *mod)
 {
 }
 
 void apply_fineibt(s32 *start_retpoline, s32 *end_retpoline,
-		   s32 *start_cfi, s32 *end_cfi)
+		   s32 *start_cfi, s32 *end_cfi, struct module *mod)
 {
 }
 
-void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
+void apply_alternatives(struct alt_instr *start, struct alt_instr *end,
+			struct module *mod)
 {
 }
 

arch/x86/entry/vdso/vma.c

@@ -54,7 +54,8 @@ int __init init_vdso_image(const struct vdso_image *image)
 
 	apply_alternatives((struct alt_instr *)(image->data + image->alt),
 			   (struct alt_instr *)(image->data + image->alt +
-						image->alt_len));
+						image->alt_len),
+			   NULL);
 
 	return 0;
 }

arch/x86/include/asm/alternative.h

@@ -96,16 +96,16 @@ extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
  * instructions were patched in already:
  */
 extern int alternatives_patched;
+struct module;
 
 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_seal_endbr(s32 *start, s32 *end);
+extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end,
+			       struct module *mod);
+extern void apply_retpolines(s32 *start, s32 *end, struct module *mod);
+extern void apply_returns(s32 *start, s32 *end, struct module *mod);
+extern void apply_seal_endbr(s32 *start, s32 *end, struct module *mod);
 extern void apply_fineibt(s32 *start_retpoline, s32 *end_retpoine,
-			  s32 *start_cfi, s32 *end_cfi);
-
-struct module;
+			  s32 *start_cfi, s32 *end_cfi, struct module *mod);
 
 struct callthunk_sites {
 	s32				*call_start, *call_end;