Commit 55b6f763 authored by Johannes Berg's avatar Johannes Berg Committed by Linus Torvalds
Browse files

init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov 

On ARCH=um, loading a module doesn't result in its constructors getting
called, which breaks module gcov since the debugfs files are never
registered.  On the other hand, in-kernel constructors have already been
called by the dynamic linker, so we can't call them again.

Get out of this conundrum by allowing CONFIG_CONSTRUCTORS to be
selected, but avoiding the in-kernel constructor calls.

Also remove the "if !UML" from GCOV selecting CONSTRUCTORS now, since we
really do want CONSTRUCTORS, just not kernel binary ones.

Link: https://lkml.kernel.org/r/20210120172041.c246a2cac2fb.I1358f584b76f1898373adfed77f4462c8705b736@changeid


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
Reviewed-by: default avatarPeter Oberparleiter <oberpar@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jessica Yu <jeyu@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 4f6ec860

init/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -76,7 +76,6 @@ config CC_HAS_ASM_INLINE 


config CONSTRUCTORS

	bool

	depends on !UML



config IRQ_WORK

	bool

init/main.c

+7 −1
Original line number Diff line number Diff line
@@ -1066,7 +1066,13 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) 
/* Call all constructor functions linked into the kernel. */

static void __init do_ctors(void)

{

#ifdef CONFIG_CONSTRUCTORS

/*

 * For UML, the constructors have already been called by the

 * normal setup code as it's just a normal ELF binary, so we

 * cannot do it again - but we do need CONFIG_CONSTRUCTORS

 * even on UML for modules.

 */

#if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML)

	ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;



	for (; fn < (ctor_fn_t *) __ctors_end; fn++)

kernel/gcov/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -4,7 +4,7 @@ menu "GCOV-based kernel profiling" 
config GCOV_KERNEL

	bool "Enable gcov-based kernel profiling"

	depends on DEBUG_FS

	select CONSTRUCTORS if !UML

	select CONSTRUCTORS

	default n

	help

	This option enables gcov-based code profiling (e.g. for code coverage