Patch "objtool: Detect jumps to retpoline thunks" has been added to the 4.14-stable tree

Patch "objtool: Detect jumps to retpoline thunks" has been added to the 4.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    objtool: Detect jumps to retpoline thunks

to the 4.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     objtool-detect-jumps-to-retpoline-thunks.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 39b735332cb8b33a27c28592d969e4016c86c3ea Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Thu, 11 Jan 2018 21:46:23 +0000
Subject: objtool: Detect jumps to retpoline thunks

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit 39b735332cb8b33a27c28592d969e4016c86c3ea upstream.

A direct jump to a retpoline thunk is really an indirect jump in
disguise.  Change the objtool instruction type accordingly.

Objtool needs to know where indirect branches are so it can detect
switch statement jump tables.

This fixes a bunch of warnings with CONFIG_RETPOLINE like:

  arch/x86/events/intel/uncore_nhmex.o: warning: objtool: nhmex_rbox_msr_enable_event()+0x44: sibling call from callable instruction with modified stack frame
  kernel/signal.o: warning: objtool: copy_siginfo_to_user()+0x91: sibling call from callable instruction with modified stack frame
  ...

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: thomas.lendacky@amd.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: https://lkml.kernel.org/r/1515707194-20531-2-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 tools/objtool/check.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -456,6 +456,13 @@ static int add_jump_destinations(struct
 		} else if (rela->sym->sec->idx) {
 			dest_sec = rela->sym->sec;
 			dest_off = rela->sym->sym.st_value + rela->addend + 4;
+		} else if (strstr(rela->sym->name, "_indirect_thunk_")) {
+			/*
+			 * Retpoline jumps are really dynamic jumps in
+			 * disguise, so convert them accordingly.
+			 */
+			insn->type = INSN_JUMP_DYNAMIC;
+			continue;
 		} else {
 			/* sibling call */
 			insn->jump_dest = 0;


Patches currently in stable-queue which might be from jpoimboe@redhat.com are

queue-4.14/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.14/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.14/objtool-allow-alternatives-to-be-ignored.patch
queue-4.14/x86-retpoline-add-initial-retpoline-support.patch