Re: [PATCH v3 11/19] unwind: Add deferred user space unwinding API
Josh Poimboeuf <[email protected]>
| Newsgroups | org.kernel.vger.linux-toolchains,org.kernel.vger.linux-kernel,org.kernel.vger.linux-perf-users |
|---|---|
| Message-ID | <[email protected]> |
On Tue, Oct 29, 2024 at 02:48:07PM +0100, Peter Zijlstra wrote:
> On Mon, Oct 28, 2024 at 02:47:38PM -0700, Josh Poimboeuf wrote:
>
> > +/*
> > + * The "context cookie" is a unique identifier which allows post-processing to
> > + * correlate kernel trace(s) with user unwinds. It has the CPU id the highest
> > + * 16 bits and a per-CPU entry counter in the lower 48 bits.
> > + */
> > +static u64 ctx_to_cookie(u64 cpu, u64 ctx)
> > +{
> > + BUILD_BUG_ON(NR_CPUS > 65535);
> > + return (ctx & ((1UL << 48) - 1)) | cpu;
> > +}
>
> Did you mean to: (cpu << 48) ?
Indeed... that was the victim of a late refactoring.
--
Josh