Patch "objtool, modules: Discard objtool annotation sections for modules" has been added to the 4.9-stable tree

Patch "objtool, modules: Discard objtool annotation sections for modules" has been added to the 4.9-stable tree

[gregkh]

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

    objtool, modules: Discard objtool annotation sections for modules

to the 4.9-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-modules-discard-objtool-annotation-sections-for-modules.patch
and it can be found in the queue-4.9 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 e390f9a9689a42f477a6073e2e7df530a4c1b740 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Wed, 1 Mar 2017 12:04:44 -0600
Subject: objtool, modules: Discard objtool annotation sections for modules

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit e390f9a9689a42f477a6073e2e7df530a4c1b740 upstream.

The '__unreachable' and '__func_stack_frame_non_standard' sections are
only used at compile time.  They're discarded for vmlinux but they
should also be discarded for modules.

Since this is a recurring pattern, prefix the section names with
".discard.".  It's a nice convention and vmlinux.lds.h already discards
such sections.

Also remove the 'a' (allocatable) flag from the __unreachable section
since it doesn't make sense for a discarded section.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends")
Link: http://lkml.kernel.org/r/20170301180444.lhd53c5tibc4ns77@treble
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[dwmw2: Remove the unreachable part in backporting since it's not here yet]
Signed-off-by: David Woodhouse <dwmw@amazon.co.ku>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/frame.h         |    2 +-
 scripts/mod/modpost.c         |    1 +
 scripts/module-common.lds     |    5 ++++-
 tools/objtool/builtin-check.c |    2 +-
 4 files changed, 7 insertions(+), 3 deletions(-)

--- a/include/linux/frame.h
+++ b/include/linux/frame.h
@@ -11,7 +11,7 @@
  * For more information, see tools/objtool/Documentation/stack-validation.txt.
  */
 #define STACK_FRAME_NON_STANDARD(func) \
-	static void __used __section(__func_stack_frame_non_standard) \
+	static void __used __section(.discard.func_stack_frame_non_standard) \
 		*__func_stack_frame_non_standard_##func = func
 
 #else /* !CONFIG_STACK_VALIDATION */
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -838,6 +838,7 @@ static const char *const section_white_l
 	".cmem*",			/* EZchip */
 	".fmt_slot*",			/* EZchip */
 	".gnu.lto*",
+	".discard.*",
 	NULL
 };
 
--- a/scripts/module-common.lds
+++ b/scripts/module-common.lds
@@ -4,7 +4,10 @@
  * combine them automatically.
  */
 SECTIONS {
-	/DISCARD/ : { *(.discard) }
+	/DISCARD/ : {
+		*(.discard)
+		*(.discard.*)
+	}
 
 	__ksymtab		0 : { *(SORT(___ksymtab+*)) }
 	__ksymtab_gpl		0 : { *(SORT(___ksymtab_gpl+*)) }
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -1229,7 +1229,7 @@ int cmd_check(int argc, const char **arg
 
 	INIT_LIST_HEAD(&file.insn_list);
 	hash_init(file.insn_hash);
-	file.whitelist = find_section_by_name(file.elf, "__func_stack_frame_non_standard");
+	file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
 	file.rodata = find_section_by_name(file.elf, ".rodata");
 	file.ignore_unreachables = false;
 	file.c_file = find_section_by_name(file.elf, ".comment");


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

queue-4.9/x86-spectre-add-boot-time-option-to-select-spectre-v2-mitigation.patch
queue-4.9/x86-retpoline-irq32-convert-assembler-indirect-jumps.patch
queue-4.9/objtool-detect-jumps-to-retpoline-thunks.patch
queue-4.9/x86-retpoline-hyperv-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-entry-convert-entry-assembler-indirect-jumps.patch
queue-4.9/x86-asm-use-register-variable-to-get-stack-pointer-value.patch
queue-4.9/x86-cpufeatures-add-x86_bug_cpu_insecure.patch
queue-4.9/objtool-modules-discard-objtool-annotation-sections-for-modules.patch
queue-4.9/x86-cpufeatures-make-cpu-bugs-sticky.patch
queue-4.9/x86-retpoline-ftrace-convert-ftrace-assembler-indirect-jumps.patch
queue-4.9/objtool-allow-alternatives-to-be-ignored.patch
queue-4.9/x86-retpoline-crypto-convert-crypto-assembler-indirect-jumps.patch
queue-4.9/selftests-x86-add-test_vsyscall.patch
queue-4.9/x86-retpoline-xen-convert-xen-hypercall-indirect-jumps.patch
queue-4.9/x86-cpu-merge-bugs.c-and-bugs_64.c.patch
queue-4.9/x86-retpoline-checksum32-convert-assembler-indirect-jumps.patch
queue-4.9/x86-retpoline-fill-return-stack-buffer-on-vmexit.patch
queue-4.9/x86-retpoline-remove-compile-time-warning.patch
queue-4.9/x86-retpoline-add-initial-retpoline-support.patch