linux-kernel - [PATCH 5.10 023/148] objtool: Correctly handle retpoline thunk calls

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Date:   Sat, 23 Jul 2022 11:53:55 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 5.10 023/148] objtool: Correctly handle retpoline thunk calls

From: Peter Zijlstra <peterz@...radead.org>

commit bcb1b6ff39da7e8a6a986eb08126fba2b5e13c32 upstream.

Just like JMP handling, convert a direct CALL to a retpoline thunk
into a retpoline safe indirect CALL.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Miroslav Benes <mbenes@...e.cz>
Link: https://lkml.kernel.org/r/20210326151259.567568238@infradead.org
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 tools/objtool/check.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -953,6 +953,18 @@ static int add_call_destinations(struct
 					  dest_off);
 				return -1;
 			}
+
+		} else if (!strncmp(reloc->sym->name, "__x86_indirect_thunk_", 21)) {
+			/*
+			 * Retpoline calls are really dynamic calls in
+			 * disguise, so convert them accordingly.
+			 */
+			insn->type = INSN_CALL_DYNAMIC;
+			insn->retpoline_safe = true;
+
+			remove_insn_ops(insn);
+			continue;
+
 		} else
 			insn->call_dest = reloc->sym;