Patch "x86/entry/64: Fix paranoid_entry() frame pointer warning" has been added to the 4.15-stable tree

[<gregkh@linuxfoundation.org>]

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

    x86/entry/64: Fix paranoid_entry() frame pointer warning

to the 4.15-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:
     x86-entry-64-fix-paranoid_entry-frame-pointer-warning.patch
and it can be found in the queue-4.15 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 b3ccefaed922529e6a67de7b30af5aa38c76ace9 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Mon, 12 Feb 2018 11:45:03 -0600
Subject: x86/entry/64: Fix paranoid_entry() frame pointer warning

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit b3ccefaed922529e6a67de7b30af5aa38c76ace9 upstream.

With the following commit:

  f09d160992d1 ("x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros")

... one of my suggested improvements triggered a frame pointer warning:

  arch/x86/entry/entry_64.o: warning: objtool: paranoid_entry()+0x11: call without frame pointer save/setup

The warning is correct for the build-time code, but it's actually not
relevant at runtime because of paravirt patching.  The paravirt swapgs
call gets replaced with either a SWAPGS instruction or NOPs at runtime.

Go back to the previous behavior by removing the ELF function annotation
for paranoid_entry() and adding an unwind hint, which effectively
silences the warning.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Fixes: f09d160992d1 ("x86/entry/64: Get rid of the ALLOC_PT_GPREGS_ON_STACK and SAVE_AND_CLEAR_REGS macros")
Link: http://lkml.kernel.org/r/20180212174503.5acbymg5z6p32snu@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/entry/entry_64.S |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1128,6 +1128,7 @@ idtentry machine_check		do_mce			has_err
  * Return: ebx=0: need swapgs on exit, ebx=1: otherwise
  */
 ENTRY(paranoid_entry)
+	UNWIND_HINT_FUNC
 	cld
 	movl	$1, %ebx
 	movl	$MSR_GS_BASE, %ecx
@@ -1141,7 +1142,7 @@ ENTRY(paranoid_entry)
 	SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg=%rax save_reg=%r14
 
 	ret
-ENDPROC(paranoid_entry)
+END(paranoid_entry)
 
 /*
  * "Paranoid" exit path from exception stack.  This is invoked


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

queue-4.15/x86-entry-64-interleave-xor-register-clearing-with-push-instructions.patch
queue-4.15/x86-entry-64-merge-the-pop_c_regs-and-pop_extra_regs-macros-into-a-single-pop_regs-macro.patch
queue-4.15/x86-entry-64-remove-the-unused-icebp-macro.patch
queue-4.15/kvm-nvmx-set-the-cpu_based_use_msr_bitmaps-if-we-have-a-valid-l02-msr-bitmap.patch
queue-4.15/x86-nvmx-properly-set-spec_ctrl-and-pred_cmd-before-merging-msrs.patch
queue-4.15/x86-speculation-add-asm-msr-index.h-dependency.patch
queue-4.15/x86-entry-64-use-push_and_clean_regs-in-more-cases.patch
queue-4.15/x86-debug-use-ud2-for-warn.patch
queue-4.15/x86-entry-64-fix-paranoid_entry-frame-pointer-warning.patch
queue-4.15/x86-speculation-update-speculation-control-microcode-blacklist.patch
queue-4.15/x86-entry-64-clear-registers-for-exceptions-interrupts-to-reduce-speculation-attack-surface.patch
queue-4.15/x86-speculation-correct-speculation-control-microcode-blacklist-again.patch
queue-4.15/x86-entry-64-merge-save_c_regs-and-save_extra_regs-remove-unused-extensions.patch
queue-4.15/x86-debug-objtool-annotate-warn-related-ud2-as-reachable.patch
queue-4.15/objtool-fix-segfault-in-ignore_unreachable_insn.patch
queue-4.15/x86-entry-64-indent-push_and_clear_regs-and-pop_regs-properly.patch
queue-4.15/x86-entry-64-clear-extra-registers-beyond-syscall-arguments-to-reduce-speculation-attack-surface.patch
queue-4.15/kvm-x86-reduce-retpoline-performance-impact-in-slot_handle_level_range-by-always-inlining-iterator-helper-methods.patch
queue-4.15/x86-mm-pti-fix-pti-comment-in-entry_syscall_64.patch
queue-4.15/x86-entry-64-get-rid-of-the-alloc_pt_gpregs_on_stack-and-save_and_clear_regs-macros.patch
queue-4.15/x86-speculation-clean-up-various-spectre-related-details.patch
queue-4.15/x86-entry-64-introduce-the-push_and_clean_regs-macro.patch
queue-4.15/revert-x86-speculation-simplify-indirect_branch_prediction_barrier.patch
queue-4.15/x86-entry-64-compat-clear-registers-for-compat-syscalls-to-reduce-speculation-attack-surface.patch
queue-4.15/x86-mm-rename-flush_tlb_single-and-flush_tlb_one-to-__flush_tlb_one_.patch
queue-4.15/x86-entry-64-fix-cr3-restore-in-paranoid_exit.patch