From: Johannes Berg <johannes.berg@xxxxxxxxx> 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 splitting CONFIG_CONSTRUCTORS into CONFIG_CONSTRUCTORS_KERNEL and CONFIG_CONSTRUCTORS_MODULE, both of which are enabled by default if CONFIG_CONSTRUCTORS is turned on, but CONFIG_CONSTRUCTORS_KERNEL depends on !UML so that it's not used on ARCH=um. Also remove the "if !UML" from GCOV selecting CONSTRUCTORS now, since we really do want CONSTRUCTORS, just not kernel binary ones. Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> --- Tested with a kernel configured with CONFIG_GCOV_KERNEL, without the patch nothing ever appears in /sys/kernel/debug/gcov/ (apart from the reset file), and with it we get the files and they work. I have no idea which tree this might go through, any suggestions? --- include/asm-generic/vmlinux.lds.h | 6 +++--- include/linux/module.h | 2 +- init/Kconfig | 9 ++++++++- init/main.c | 2 +- kernel/gcov/Kconfig | 2 +- kernel/module.c | 4 ++-- 6 files changed, 16 insertions(+), 9 deletions(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index b2b3d81b1535..87b300471c54 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -698,7 +698,7 @@ INIT_TASK_DATA(align) \ } -#ifdef CONFIG_CONSTRUCTORS +#ifdef CONFIG_CONSTRUCTORS_KERNEL #define KERNEL_CTORS() . = ALIGN(8); \ __ctors_start = .; \ KEEP(*(SORT(.ctors.*))) \ @@ -990,11 +990,11 @@ /* * Clang's -fsanitize=kernel-address and -fsanitize=thread produce * unwanted sections (.eh_frame and .init_array.*), but - * CONFIG_CONSTRUCTORS wants to keep any .init_array.* sections. + * CONFIG_CONSTRUCTORS_KERNEL wants to keep any .init_array.* sections. * https://bugs.llvm.org/show_bug.cgi?id=46478 */ #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN) -# ifdef CONFIG_CONSTRUCTORS +# ifdef CONFIG_CONSTRUCTORS_KERNEL # define SANITIZER_DISCARDS \ *(.eh_frame) # else diff --git a/include/linux/module.h b/include/linux/module.h index 7a0bcb5b1ffc..027cfdbd84bd 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -528,7 +528,7 @@ struct module { atomic_t refcnt; #endif -#ifdef CONFIG_CONSTRUCTORS +#ifdef CONFIG_CONSTRUCTORS_MODULE /* Constructor functions. */ ctor_fn_t *ctors; unsigned int num_ctors; diff --git a/init/Kconfig b/init/Kconfig index b77c60f8b963..e409de8d6c17 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -76,7 +76,14 @@ config CC_HAS_ASM_INLINE config CONSTRUCTORS bool - depends on !UML + +config CONSTRUCTORS_KERNEL + def_bool y + depends on CONSTRUCTORS && !UML + +config CONSTRUCTORS_MODULE + def_bool y + depends on CONSTRUCTORS config IRQ_WORK bool diff --git a/init/main.c b/init/main.c index c68d784376ca..51eb4802511c 100644 --- a/init/main.c +++ b/init/main.c @@ -1066,7 +1066,7 @@ 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 +#ifdef CONFIG_CONSTRUCTORS_KERNEL 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 3110c77230c7..f62de2dea8a3 100644 --- a/kernel/gcov/Kconfig +++ b/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 diff --git a/kernel/module.c b/kernel/module.c index 4bf30e4b3eaa..c161a360d929 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3257,7 +3257,7 @@ static int find_module_sections(struct module *mod, struct load_info *info) &mod->num_unused_gpl_syms); mod->unused_gpl_crcs = section_addr(info, "__kcrctab_unused_gpl"); #endif -#ifdef CONFIG_CONSTRUCTORS +#ifdef CONFIG_CONSTRUCTORS_MODULE mod->ctors = section_objs(info, ".ctors", sizeof(*mod->ctors), &mod->num_ctors); if (!mod->ctors) @@ -3612,7 +3612,7 @@ static bool finished_loading(const char *name) /* Call module constructors. */ static void do_mod_ctors(struct module *mod) { -#ifdef CONFIG_CONSTRUCTORS +#ifdef CONFIG_CONSTRUCTORS_MODULE unsigned long i; for (i = 0; i < mod->num_ctors; i++) -- 2.26.2
