Commit b401efc1 authored Apr 01, 2020 by Josh Poimboeuf Committed by Borislav Petkov Apr 14, 2020

objtool: Fix switch table detection in .text.unlikely



If a switch jump table's indirect branch is in a ".cold" subfunction in
.text.unlikely, objtool doesn't detect it, and instead prints a false
warning:

  drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame
  drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame
  drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame

Fix it by comparing the function, instead of the section and offset.

Fixes: 13810435 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com

parent e81e0724

tools/objtool/check.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -1050,10 +1050,7 @@ static struct rela find_jump_table(struct objtool_file file,
		* it.
		*/
		for (;
		&insn->list != &file->insn_list &&
		insn->sec == func->sec &&
		insn->offset >= func->offset;

		&insn->list != &file->insn_list && insn->func && insn->func->pfunc == func;
		insn = insn->first_jump_src ?: list_prev_entry(insn, list)) {

		if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)

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