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4e9903b086
There are some issues in the test_fortify Makefile code.
Problem 1: cc-disable-warning invokes compiler dozens of times
To see how many times the cc-disable-warning is evaluated, change
this code:
$(call cc-disable-warning,fortify-source)
to:
$(call cc-disable-warning,$(shell touch /tmp/fortify-$$$$)fortify-source)
Then, build the kernel with CONFIG_FORTIFY_SOURCE=y. You will see a
large number of '/tmp/fortify-<PID>' files created:
$ ls -1 /tmp/fortify-* | wc
80 80 1600
This means the compiler was invoked 80 times just for checking the
-Wno-fortify-source flag support.
$(call cc-disable-warning,fortify-source) should be added to a simple
variable instead of a recursive variable.
Problem 2: do not recompile string.o when the test code is updated
The test cases are independent of the kernel. However, when the test
code is updated, $(obj)/string.o is rebuilt and vmlinux is relinked
due to this dependency:
$(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)
always-y is suitable for building the log files.
Problem 3: redundant code
clean-files += $(addsuffix .o, $(TEST_FORTIFY_LOGS))
... is unneeded because the top Makefile globally cleans *.o files.
This commit fixes these issues and makes the code readable.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20240727150302.1823750-2-masahiroy@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.