android_kernel_xiaomi_sm8350/kernel/gcov/Kconfig
Johannes Berg dd350f3918 Revert "um: Enable CONFIG_CONSTRUCTORS"
commit 87c9366e17259040a9118e06b6dc8de986e5d3d1 upstream.

This reverts commit 786b2384bf ("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: 786b2384bf ("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>
2020-02-01 09:34:53 +00:00

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# SPDX-License-Identifier: GPL-2.0-only
menu "GCOV-based kernel profiling"
config GCOV_KERNEL
bool "Enable gcov-based kernel profiling"
depends on DEBUG_FS
select CONSTRUCTORS if !UML
default n
---help---
This option enables gcov-based code profiling (e.g. for code coverage
measurements).
If unsure, say N.
Additionally specify CONFIG_GCOV_PROFILE_ALL=y to get profiling data
for the entire kernel. To enable profiling for specific files or
directories, add a line similar to the following to the respective
Makefile:
For a single file (e.g. main.o):
GCOV_PROFILE_main.o := y
For all files in one directory:
GCOV_PROFILE := y
To exclude files from being profiled even when CONFIG_GCOV_PROFILE_ALL
is specified, use:
GCOV_PROFILE_main.o := n
and:
GCOV_PROFILE := n
Note that the debugfs filesystem has to be mounted to access
profiling data.
config ARCH_HAS_GCOV_PROFILE_ALL
def_bool n
config GCOV_PROFILE_ALL
bool "Profile entire Kernel"
depends on !COMPILE_TEST
depends on GCOV_KERNEL
depends on ARCH_HAS_GCOV_PROFILE_ALL
default n
---help---
This options activates profiling for the entire kernel.
If unsure, say N.
Note that a kernel compiled with profiling flags will be significantly
larger and run slower. Also be sure to exclude files from profiling
which are not linked to the kernel image to prevent linker errors.
choice
prompt "Specify GCOV format"
depends on GCOV_KERNEL
depends on CC_IS_GCC
---help---
The gcov format is usually determined by the GCC version, and the
default is chosen according to your GCC version. However, there are
exceptions where format changes are integrated in lower-version GCCs.
In such a case, change this option to adjust the format used in the
kernel accordingly.
config GCOV_FORMAT_3_4
bool "GCC 3.4 format"
depends on GCC_VERSION < 40700
---help---
Select this option to use the format defined by GCC 3.4.
config GCOV_FORMAT_4_7
bool "GCC 4.7 format"
---help---
Select this option to use the format defined by GCC 4.7.
endchoice
endmenu