linux/kernel/gcov/Kconfig
Johannes Berg 55b6f763d8 init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov
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.I1358f584b76f1898373adfed77f4462c8705b736@changeid
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>
2021-02-05 11:03:47 -08:00

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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.
endmenu