Commit 43d5430a authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

objtool: Keep track of retpoline call sites 



Provide infrastructure for architectures to rewrite/augment compiler
generated retpoline calls. Similar to what we do for static_call()s,
keep track of the instructions that are retpoline calls.

Use the same list_head, since a retpoline call cannot also be a
static_call.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/20210326151300.130805730@infradead.org
parent 2f2f7e47

tools/objtool/check.c

+29 −5
Original line number Diff line number Diff line
@@ -451,7 +451,7 @@ static int create_static_call_sections(struct objtool_file *file) 
		return 0;



	idx = 0;

	list_for_each_entry(insn, &file->static_call_list, static_call_node)

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

		idx++;



	sec = elf_create_section(file->elf, ".static_call_sites", SHF_WRITE,
@@ -460,7 +460,7 @@ static int create_static_call_sections(struct objtool_file *file) 
		return -1;



	idx = 0;

	list_for_each_entry(insn, &file->static_call_list, static_call_node) {

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



		site = (struct static_call_site *)sec->data->d_buf + idx;

		memset(site, 0, sizeof(struct static_call_site));
@@ -829,13 +829,16 @@ static int add_jump_destinations(struct objtool_file *file) 
			else

				insn->type = INSN_JUMP_DYNAMIC_CONDITIONAL;



			list_add_tail(&insn->call_node,

				      &file->retpoline_call_list);



			insn->retpoline_safe = true;

			continue;

		} else if (insn->func) {

			/* internal or external sibling call (with reloc) */

			insn->call_dest = reloc->sym;

			if (insn->call_dest->static_call_tramp) {

				list_add_tail(&insn->static_call_node,

				list_add_tail(&insn->call_node,

					      &file->static_call_list);

			}

			continue;
@@ -897,7 +900,7 @@ static int add_jump_destinations(struct objtool_file *file) 
				/* internal sibling call (without reloc) */

				insn->call_dest = insn->jump_dest->func;

				if (insn->call_dest->static_call_tramp) {

					list_add_tail(&insn->static_call_node,

					list_add_tail(&insn->call_node,

						      &file->static_call_list);

				}

			}
@@ -981,6 +984,9 @@ static int add_call_destinations(struct objtool_file *file) 
			insn->type = INSN_CALL_DYNAMIC;

			insn->retpoline_safe = true;



			list_add_tail(&insn->call_node,

				      &file->retpoline_call_list);



			remove_insn_ops(insn);

			continue;
@@ -988,7 +994,7 @@ static int add_call_destinations(struct objtool_file *file) 
			insn->call_dest = reloc->sym;



		if (insn->call_dest && insn->call_dest->static_call_tramp) {

			list_add_tail(&insn->static_call_node,

			list_add_tail(&insn->call_node,

				      &file->static_call_list);

		}
@@ -1714,6 +1720,11 @@ static void mark_rodata(struct objtool_file *file) 
	file->rodata = found;

}



__weak int arch_rewrite_retpolines(struct objtool_file *file)

{

	return 0;

}



static int decode_sections(struct objtool_file *file)

{

	int ret;
@@ -1742,6 +1753,10 @@ static int decode_sections(struct objtool_file *file) 
	if (ret)

		return ret;



	/*

	 * Must be before add_special_section_alts() as that depends on

	 * jump_dest being set.

	 */

	ret = add_jump_destinations(file);

	if (ret)

		return ret;
@@ -1778,6 +1793,15 @@ static int decode_sections(struct objtool_file *file) 
	if (ret)

		return ret;



	/*

	 * Must be after add_special_section_alts(), since this will emit

	 * alternatives. Must be after add_{jump,call}_destination(), since

	 * those create the call insn lists.

	 */

	ret = arch_rewrite_retpolines(file);

	if (ret)

		return ret;



	return 0;

}

tools/objtool/include/objtool/arch.h

+2 −0
Original line number Diff line number Diff line
@@ -88,4 +88,6 @@ int arch_decode_hint_reg(struct instruction *insn, u8 sp_reg); 


bool arch_is_retpoline(struct symbol *sym);



int arch_rewrite_retpolines(struct objtool_file *file);



#endif /* _ARCH_H */

tools/objtool/include/objtool/check.h

+1 −1
Original line number Diff line number Diff line
@@ -39,7 +39,7 @@ struct alt_group { 
struct instruction {

	struct list_head list;

	struct hlist_node hash;

	struct list_head static_call_node;

	struct list_head call_node;

	struct list_head mcount_loc_node;

	struct section *sec;

	unsigned long offset;

tools/objtool/include/objtool/objtool.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ struct objtool_file { 
	struct elf *elf;

	struct list_head insn_list;

	DECLARE_HASHTABLE(insn_hash, 20);

	struct list_head retpoline_call_list;

	struct list_head static_call_list;

	struct list_head mcount_loc_list;

	bool ignore_unreachables, c_file, hints, rodata;

tools/objtool/objtool.c

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ struct objtool_file *objtool_open_read(const char *_objname) 


	INIT_LIST_HEAD(&file.insn_list);

	hash_init(file.insn_hash);

	INIT_LIST_HEAD(&file.retpoline_call_list);

	INIT_LIST_HEAD(&file.static_call_list);

	INIT_LIST_HEAD(&file.mcount_loc_list);

	file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");