Messages in this thread | | | Subject | Re: [PATCH] kcov: reject open when kernel not instrumented | From | Michal Marek <> | Date | Wed, 15 Jun 2016 18:21:03 +0200 |
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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.
Thanks, Michal
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