The patch titled
Subject: init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov
has been added to the -mm tree. Its filename is
init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov.patch
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------------------------------------------------------
From: Johannes Berg <johannes.berg@xxxxxxxxx>
Subject: 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: Johannes Berg <johannes.berg@xxxxxxxxx>
Reviewed-by: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Jessica Yu <jeyu@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
init/Kconfig | 1 -
init/main.c | 8 +++++++-
kernel/gcov/Kconfig | 2 +-
3 files changed, 8 insertions(+), 3 deletions(-)
--- a/init/Kconfig~init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov
+++ a/init/Kconfig
@@ -76,7 +76,6 @@ config CC_HAS_ASM_INLINE
config CONSTRUCTORS
bool
- depends on !UML
config IRQ_WORK
bool
--- a/init/main.c~init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov
+++ a/init/main.c
@@ -1066,7 +1066,13 @@ asmlinkage __visible void __init __no_sa
/* 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++)
--- a/kernel/gcov/Kconfig~init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov
+++ a/kernel/gcov/Kconfig
@@ -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
_
Patches currently in -mm which might be from johannes.berg@xxxxxxxxx are
init-gcov-allow-config_constructors-on-uml-to-fix-module-gcov.patch
mm-slub-disable-user-tracing-for-kmemleak-caches-by-default.patch
