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%3Ba=su...

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.u... 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