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commit89604523a7upstream. When using plugins, GCC requires that the -fplugin= options precedes any of its plugin arguments appearing on the command line as well. This is usually not a concern, but as it turns out, this requirement is causing some issues with ARM's per-task stack protector plugin and Kbuild's implementation of $(cc-option). When the per-task stack protector plugin is enabled, and we tweak the implementation of cc-option not to pipe the stderr output of GCC to /dev/null, the following output is generated when GCC is executed in the context of cc-option: cc1: error: plugin arm_ssp_per_task_plugin should be specified before \ -fplugin-arg-arm_ssp_per_task_plugin-tso=1 in the command line cc1: error: plugin arm_ssp_per_task_plugin should be specified before \ -fplugin-arg-arm_ssp_per_task_plugin-offset=24 in the command line These errors will cause any option passed to cc-option to be treated as unsupported, which is obviously incorrect. The cause of this issue is the fact that the -fplugin= argument is added to GCC_PLUGINS_CFLAGS, whereas the arguments above are added to KBUILD_CFLAGS, and the contents of the former get filtered out of the latter before being passed to the GCC running the cc-option test, and so the -fplugin= option does not appear at all on the GCC command line. Adding the arguments to GCC_PLUGINS_CFLAGS instead of KBUILD_CFLAGS would be the correct approach here, if it weren't for the fact that we are using $(eval) to defer the moment that they are added until after asm-offsets.h is generated, which is after the point where the contents of GCC_PLUGINS_CFLAGS are added to KBUILD_CFLAGS. So instead, we have to add our plugin arguments to both. For similar reasons, we cannot append DISABLE_ARM_SSP_PER_TASK_PLUGIN to KBUILD_CFLAGS, as it will be passed to GCC when executing in the context of cc-option, whereas the other plugin arguments will have been filtered out, resulting in a similar error and false negative result as above. So add it to ccflags-y instead. Fixes:189af46571("ARM: smp: add support for per-task stack canaries") Reported-by: Merlijn Wajer <merlijn@wizzup.org> Tested-by: Tony Lindgren <tony@atomide.com> Acked-by: Kees Cook <keescook@chromium.org> Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 Restructured Text 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.