livepatch: Free klp_{object,func}_ext data after initialization

The klp_object_ext and klp_func_ext data, which are stored in the
__klp_objects and __klp_funcs sections, respectively, are not needed
after they are used to create the actual klp_object and klp_func
instances. This operation is implemented by the init function in
scripts/livepatch/init.c.

Prefix the two sections with ".init" so they are freed after the module
is initializated.

Signed-off-by: Petr Pavlu <[email protected]>
Acked-by: Joe Lawrence <[email protected]>
Acked-by: Miroslav Benes <[email protected]>
Reviewed-by: Aaron Tomlin <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Josh Poimboeuf <[email protected]>

Author: petrpavlu

scripts/livepatch/init.c

@@ -19,7 +19,7 @@ static int __init livepatch_mod_init(void)
 	unsigned int nr_objs;
 	int ret;
 
-	obj_exts = klp_find_section_by_name(THIS_MODULE, "__klp_objects",
+	obj_exts = klp_find_section_by_name(THIS_MODULE, ".init.klp_objects",
 					    &obj_exts_sec_size);
 	nr_objs = obj_exts_sec_size / sizeof(*obj_exts);
 	if (!nr_objs) {

scripts/module.lds.S

@@ -34,8 +34,8 @@ SECTIONS {
 
 	__patchable_function_entries : { *(__patchable_function_entries) }
 
-	__klp_funcs		0: ALIGN(8) { KEEP(*(__klp_funcs)) }
-	__klp_objects		0: ALIGN(8) { KEEP(*(__klp_objects)) }
+	.init.klp_funcs		0 : ALIGN(8) { KEEP(*(.init.klp_funcs)) }
+	.init.klp_objects	0 : ALIGN(8) { KEEP(*(.init.klp_objects)) }
 
 #ifdef CONFIG_ARCH_USES_CFI_TRAPS
 	__kcfi_traps		: { KEEP(*(.kcfi_traps)) }

tools/objtool/check.c

@@ -4761,7 +4761,7 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, "__bug_table")			||
 		    !strcmp(sec->name, "__ex_table")			||
 		    !strcmp(sec->name, "__jump_table")			||
-		    !strcmp(sec->name, "__klp_funcs")			||
+		    !strcmp(sec->name, ".init.klp_funcs")		||
 		    !strcmp(sec->name, "__mcount_loc")			||
 		    !strcmp(sec->name, ".llvm.call-graph-profile")	||
 		    !strcmp(sec->name, ".llvm_bb_addr_map")		||

tools/objtool/include/objtool/klp.h

@@ -6,12 +6,12 @@
 #define SHN_LIVEPATCH		0xff20
 
 /*
- * __klp_objects and __klp_funcs are created by klp diff and used by the patch
- * module init code to build the klp_patch, klp_object and klp_func structs
- * needed by the livepatch API.
+ * .init.klp_objects and .init.klp_funcs are created by klp diff and used by the
+ * patch module init code to build the klp_patch, klp_object and klp_func
+ * structs needed by the livepatch API.
  */
-#define KLP_OBJECTS_SEC	"__klp_objects"
-#define KLP_FUNCS_SEC	"__klp_funcs"
+#define KLP_OBJECTS_SEC	".init.klp_objects"
+#define KLP_FUNCS_SEC	".init.klp_funcs"
 
 /*
  * __klp_relocs is an intermediate section which are created by klp diff and

tools/objtool/klp-diff.c

@@ -1436,7 +1436,7 @@ static int clone_special_sections(struct elfs *e)
 }
 
 /*
- * Create __klp_objects and __klp_funcs sections which are intermediate
+ * Create .init.klp_objects and .init.klp_funcs sections which are intermediate
  * sections provided as input to the patch module's init code for building the
  * klp_patch, klp_object and klp_func structs for the livepatch API.
  */