On Wed, Jun 15, 2016 at 06:21:03PM +0200, Michal Marek wrote: > Dne 15.6.2016 v 17:49 Mark Rutland napsal(a): > > If the toolchain does not support -fsanitize-coverage=trace-pc, we blat > > this option from CFLAGS_KCOV, and build the kernel without > > instrumentation, even if CONFIG_KCOV was selected. However, we still > > build the rest of the kcov infrastructure, and expose a kcov file under > > debugfs. This can be confusing, as the kernel will appear to support > > kcov, yet will never manage to sample any trace PC values. While we do > > note this fact at build time, this may be missed, and a user may not > > have access to build logs. > > > > This patch adds an artificial CONFIG symbol, CONFIG_KCOV_CC, that is > > only set when the toolchain supports -fsanitize-coverage=trace-pc, and > > hence the kernel is built with instrumentation. When this is not the > > case, the kernel will return -ENOTSUPP if userspace attempts to open the > > kcov debugfs file, indicating that kcov functionality is unavailable. > > Hi Mark, > > please use a define outside the CONFIG_ namespace, because it is not a > config option that one can find in .config or a Kconfig file. We already > have CC_HAVE_ASM_GOTO, CC_USING_FENTRY and similar in the kernel.
Sure thing. I guess I should also not use IS_ENABLED, and will fall back to the usual ifdefferty. Dmitry, Alexander, any preference for the name? Is CC_HAVE_SANCOV_TRACE_PC ok? I guess we should also clean up arm64's current use of CONFIG_AS_LSE (which I guess should be something like AS_HAVE_LSE per the CC_HAVE_ASM_GOTO example). I can cook up a patch for that too. Thanks, Mark.
