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Message-ID: <20210506194158.091028792@infradead.org>
User-Agent: quilt/0.66
Date:   Thu, 06 May 2021 21:34:03 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     x86@kernel.org, jpoimboe@redhat.com, jbaron@akamai.com,
        rostedt@goodmis.org, ardb@kernel.org
Cc:     linux-kernel@vger.kernel.org, peterz@infradead.org
Subject: [PATCH 11/13] objtool: Rewrite jump_label instructions
References: <20210506193352.719596001@infradead.org>
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Precedence: bulk

When a jump_entry::key has bit1 set, rewrite the instruction to be a
NOP. This allows the compiler/assembler to emit JMP (and thus decide
on which encoding to use).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 tools/objtool/check.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1223,6 +1223,20 @@ static int handle_jump_alt(struct objtoo
 		return -1;
 	}
 
+	if (special_alt->key_addend & 2) {
+		struct reloc *reloc = insn_reloc(file, orig_insn);
+
+		if (reloc) {
+			reloc->type = R_NONE;
+			elf_write_reloc(file->elf, reloc);
+		}
+		elf_write_insn(file->elf, orig_insn->sec,
+			       orig_insn->offset, orig_insn->len,
+			       arch_nop_insn(orig_insn->len));
+		orig_insn->type = INSN_NOP;
+		return 0;
+	}
+
 	*new_insn = list_next_entry(orig_insn, list);
 	return 0;
 }