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Commit 35aee626 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
Browse files

objtool, modules: Discard objtool annotation sections for modules 



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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarJosh 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: default avatarIngo Molnar <mingo@kernel.org>
[dwmw2: Remove the unreachable part in backporting since it's not here yet]
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.ku>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 00bcb5ad

include/linux/frame.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */

scripts/mod/modpost.c

+1 −0
Original line number Diff line number Diff line
@@ -838,6 +838,7 @@ static const char *const section_white_list[] = 
	".cmem*",			/* EZchip */

	".fmt_slot*",			/* EZchip */

	".gnu.lto*",

	".discard.*",

	NULL

};

scripts/module-common.lds

+4 −1
Original line number Diff line number Diff line
@@ -4,7 +4,10 @@ 
 * combine them automatically.

 */

SECTIONS {

	/DISCARD/ : { *(.discard) }

	/DISCARD/ : {

		*(.discard)

		*(.discard.*)

	}



	__ksymtab		0 : { *(SORT(___ksymtab+*)) }

	__ksymtab_gpl		0 : { *(SORT(___ksymtab_gpl+*)) }

tools/objtool/builtin-check.c

+1 −1
Original line number Diff line number Diff line
@@ -1229,7 +1229,7 @@ int cmd_check(int argc, const char **argv) 


	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");