Thread (16 messages) 16 messages, 1 author, 2023-06-23
STALE1079d

[PATCH v3 11/15] objtool: Remove too strict constraint in jump table search

From: Christophe Leroy <hidden>
Date: 2023-06-23 17:06:58
Also in: lkml
Subsystem: objtool, the rest · Maintainers: Josh Poimboeuf, Peter Zijlstra, Linus Torvalds

In code there is often a pattern like:

	load jump table address
	do some test
	conditional jump to label1:
	do something
	unconditional jump to label2:
label1:
	do something else
	read jump table
	dynamic jump
label2:
	do other job here ....

find_jump_table() contains a constraint that stops the backsearch
of the table address loading when a jump is found in-between.

Remove that constraint.

Signed-off-by: Christophe Leroy <redacted>
---
 tools/objtool/check.c | 7 -------
 1 file changed, 7 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 05d789e6d3b6..c9f0fd31d146 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2067,13 +2067,6 @@ static struct reloc *find_jump_table(struct objtool_file *file,
 		if (insn != orig_insn && insn->type == INSN_JUMP_DYNAMIC)
 			break;
 
-		/* allow small jumps within the range */
-		if (insn->type == INSN_JUMP_UNCONDITIONAL &&
-		    insn->jump_dest &&
-		    (insn->jump_dest->offset <= insn->offset ||
-		     insn->jump_dest->offset > orig_insn->offset))
-		    break;
-
 		table_reloc = arch_find_switch_table(file, insn);
 		if (!table_reloc)
 			continue;
-- 
2.40.1
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