Commit 00abd384 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

objtool: Add .call_sites section 



In preparation for call depth tracking provide a section which collects all
direct calls.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111146.016511961@infradead.org
parent 6644ee84

arch/x86/kernel/vmlinux.lds.S

+7 −0
Original line number Diff line number Diff line
@@ -291,6 +291,13 @@ SECTIONS 
		*(.return_sites)

		__return_sites_end = .;

	}



	. = ALIGN(8);

	.call_sites : AT(ADDR(.call_sites) - LOAD_OFFSET) {

		__call_sites = .;

		*(.call_sites)

		__call_sites_end = .;

	}

#endif



#ifdef CONFIG_X86_KERNEL_IBT

tools/objtool/check.c

+51 −0
Original line number Diff line number Diff line
@@ -902,6 +902,49 @@ static int create_mcount_loc_sections(struct objtool_file *file) 
	return 0;

}



static int create_direct_call_sections(struct objtool_file *file)

{

	struct instruction *insn;

	struct section *sec;

	unsigned int *loc;

	int idx;



	sec = find_section_by_name(file->elf, ".call_sites");

	if (sec) {

		INIT_LIST_HEAD(&file->call_list);

		WARN("file already has .call_sites section, skipping");

		return 0;

	}



	if (list_empty(&file->call_list))

		return 0;



	idx = 0;

	list_for_each_entry(insn, &file->call_list, call_node)

		idx++;



	sec = elf_create_section(file->elf, ".call_sites", 0, sizeof(unsigned int), idx);

	if (!sec)

		return -1;



	idx = 0;

	list_for_each_entry(insn, &file->call_list, call_node) {



		loc = (unsigned int *)sec->data->d_buf + idx;

		memset(loc, 0, sizeof(unsigned int));



		if (elf_add_reloc_to_insn(file->elf, sec,

					  idx * sizeof(unsigned int),

					  R_X86_64_PC32,

					  insn->sec, insn->offset))

			return -1;



		idx++;

	}



	return 0;

}



/*

 * Warnings shouldn't be reported for ignored functions.

 */
@@ -1279,6 +1322,9 @@ static void annotate_call_site(struct objtool_file *file, 
		return;

	}



	if (insn->type == INSN_CALL && !insn->sec->init)

		list_add_tail(&insn->call_node, &file->call_list);



	if (!sibling && dead_end_function(file, sym))

		insn->dead_end = true;

}
@@ -4305,6 +4351,11 @@ int check(struct objtool_file *file) 
		if (ret < 0)

			goto out;

		warnings += ret;



		ret = create_direct_call_sections(file);

		if (ret < 0)

			goto out;

		warnings += ret;

	}



	if (opts.mcount) {

tools/objtool/include/objtool/objtool.h

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ struct objtool_file { 
	struct list_head static_call_list;

	struct list_head mcount_loc_list;

	struct list_head endbr_list;

	struct list_head call_list;

	bool ignore_unreachables, hints, rodata;



	unsigned int nr_endbr;

tools/objtool/objtool.c

+1 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ struct objtool_file *objtool_open_read(const char *_objname) 
	INIT_LIST_HEAD(&file.static_call_list);

	INIT_LIST_HEAD(&file.mcount_loc_list);

	INIT_LIST_HEAD(&file.endbr_list);

	INIT_LIST_HEAD(&file.call_list);

	file.ignore_unreachables = opts.no_unreachable;

	file.hints = false;