Re: [PATCH 0/3] KCOV function entry/exit records

[Jann Horn]

On Wed, Mar 11, 2026 at 11:57 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> And I don't suppose KCOV will finally honour noinstr ?

I believe it should, as long as the compiler is new enough?

We have this in include/linux/compiler-clang.h, and I just checked
that, for example, the noinstr function fpu_idle_fpregs indeed doesn't
get instrumented with clang:
```
/*
 * Support for __has_feature(coverage_sanitizer) was added in Clang 13 together
 * with no_sanitize("coverage"). Prior versions of Clang support coverage
 * instrumentation, but cannot be queried for support by the preprocessor.
 */
#if __has_feature(coverage_sanitizer)
#define __no_sanitize_coverage __attribute__((no_sanitize("coverage")))
#else
#define __no_sanitize_coverage
#endif
```

And include/linux/compiler-gcc.h has this, which also seems to be
effective in a GCC build:
```
/*
 * Only supported since gcc >= 12
 */
#if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
#define __no_sanitize_coverage __attribute__((__no_sanitize_coverage__))
#else
#define __no_sanitize_coverage
#endif
```