From: Johannes Berg johannes.berg@intel.com
[ Upstream commit 55b6f763d8bcb5546997933105d66d3e6b080e6a ]
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.I1358f584b76f1898373ad... Signed-off-by: Johannes Berg johannes.berg@intel.com Reviewed-by: Peter Oberparleiter oberpar@linux.ibm.com Cc: Arnd Bergmann arnd@arndb.de Cc: Jessica Yu jeyu@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- init/Kconfig | 1 - init/main.c | 8 +++++++- kernel/gcov/Kconfig | 2 +- 3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig index 5eb91dde4018c..15543270fec79 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -28,7 +28,6 @@ config CC_HAS_ASM_GOTO
config CONSTRUCTORS bool - depends on !UML
config IRQ_WORK bool diff --git a/init/main.c b/init/main.c index fdfef08da0c4b..3a74255641578 100644 --- a/init/main.c +++ b/init/main.c @@ -741,7 +741,13 @@ asmlinkage __visible void __init 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++) diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig index 1e3823fa799b2..db5856bf8b514 100644 --- a/kernel/gcov/Kconfig +++ b/kernel/gcov/Kconfig @@ -3,7 +3,7 @@ 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