Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1423207

Re: [PATCH] kcov: reject open when kernel not instrumented

Show all headers | View raw

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

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH] kcov: reject open when kernel not instrumented Mark Rutland <mark.rutland@arm.com> - 2016-06-15 17:50 +0200
  Re: [PATCH] kcov: reject open when kernel not instrumented Dmitry Vyukov <dvyukov@google.com> - 2016-06-15 18:00 +0200
  Re: [PATCH] kcov: reject open when kernel not instrumented Michal Marek <mmarek@suse.com> - 2016-06-15 18:30 +0200
    Re: [PATCH] kcov: reject open when kernel not instrumented Mark Rutland <mark.rutland@arm.com> - 2016-06-15 18:40 +0200
      Re: [PATCH] kcov: reject open when kernel not instrumented Dmitry Vyukov <dvyukov@google.com> - 2016-06-15 18:40 +0200

csiph-web