From: Johannes Berg johannes.berg@intel.com
commit 87c9366e17259040a9118e06b6dc8de986e5d3d1 upstream.
This reverts commit 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS").
There are two issues with this commit, uncovered by Anton in tests on some (Debian) systems:
1) I completely forgot to call any constructors if CONFIG_CONSTRUCTORS isn't set. Don't recall now if it just wasn't needed on my system, or if I never tested this case.
2) With that fixed, it works - with CONFIG_CONSTRUCTORS *unset*. If I set CONFIG_CONSTRUCTORS, it fails again, which isn't totally unexpected since whatever wanted to run is likely to have to run before the kernel init etc. that calls the constructors in this case.
Basically, some constructors that gcc emits (libc has?) need to run very early during init; the failure mode otherwise was that the ptrace fork test already failed:
---------------------- $ ./linux mem=512M Core dump limits : soft - 0 hard - NONE Checking that ptrace can change system call numbers...check_ptrace : child exited with exitcode 6, while expecting 0; status 0x67f Aborted ----------------------
Thinking more about this, it's clear that we simply cannot support CONFIG_CONSTRUCTORS in UML. All the cases we need now (gcov, kasan) involve not use of the __attribute__((constructor)), but instead some constructor code/entry generated by gcc. Therefore, we cannot distinguish between kernel constructors and system constructors.
Thus, revert this commit.
Cc: stable@vger.kernel.org [5.4+] Fixes: 786b2384bf1c ("um: Enable CONFIG_CONSTRUCTORS") Reported-by: Anton Ivanov anton.ivanov@cambridgegreys.com Signed-off-by: Johannes Berg johannes.berg@intel.com Acked-by: Anton Ivanov anton.ivanov@cambridgegreys.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Signed-off-by: Richard Weinberger richard@nod.at
--- arch/um/include/asm/common.lds.S | 2 +- arch/um/kernel/dyn.lds.S | 1 + init/Kconfig | 1 + kernel/gcov/Kconfig | 2 +- 4 files changed, 4 insertions(+), 2 deletions(-)
--- a/arch/um/include/asm/common.lds.S +++ b/arch/um/include/asm/common.lds.S @@ -82,8 +82,8 @@ __preinit_array_end = .; } .init_array : { - /* dummy - we call this ourselves */ __init_array_start = .; + *(.init_array) __init_array_end = .; } .fini_array : { --- a/arch/um/kernel/dyn.lds.S +++ b/arch/um/kernel/dyn.lds.S @@ -103,6 +103,7 @@ SECTIONS be empty, which isn't pretty. */ . = ALIGN(32 / 8); .preinit_array : { *(.preinit_array) } + .init_array : { *(.init_array) } .fini_array : { *(.fini_array) } .data : { INIT_TASK_DATA(KERNEL_STACK_SIZE) --- a/init/Kconfig +++ b/init/Kconfig @@ -54,6 +54,7 @@ config CC_DISABLE_WARN_MAYBE_UNINITIALIZ
config CONSTRUCTORS bool + depends on !UML
config IRQ_WORK bool --- 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 + select CONSTRUCTORS if !UML default n ---help--- This option enables gcov-based code profiling (e.g. for code coverage