linux/kernel/gcov/Kconfig
Johannes Berg 786b2384bf um: Enable CONFIG_CONSTRUCTORS
We do need to call the constructors for *modules*, and
at least for KASAN in the future, we must call even the
kernel constructors only later when the kernel has been
initialized.

Instead of relying on libc to call them, emit an empty
section for libc and let the kernel's CONSTRUCTORS code
do the rest of the job.

Tested that it indeed doesn't work in modules, and does
work after the fixes in both, with a few functions with
__attribute__((constructor)) in both dynamic and static
builds.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
2019-09-15 21:37:13 +02:00

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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
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