Messages in this thread | | | Subject | Re: [RFC PATCH 0/3]perf/core: extend perf_reg and perf_sample_regs_intr | From | Michael Ellerman <> | Date | Fri, 06 Nov 2015 20:39:59 +1100 |
| |
On Fri, 2015-11-06 at 13:17 +0530, Madhavan Srinivasan wrote: > On Friday 06 November 2015 08:28 AM, Sukadev Bhattiprolu wrote: > > Peter Zijlstra [peterz@infradead.org] wrote: > > > On Thu, Nov 05, 2015 at 02:16:15AM +0530, Madhavan Srinivasan wrote: > > > > Second patch updates struct arch_misc_reg for arch/powerpc with pmu registers > > > > and adds offsetof macro for the same. It extends perf_reg_value() > > > > to use reg idx to decide on struct to return value from. > > > > > > Why; what's in those regs? > > > > Those are PMU control registers/counters (in Patch 2) that are of > > interest only in the context of a PMU interrupt and not relevant > > to ptrace itself. > > Yes. Thats right.
> > Could we add those registers to 'struct pt_regs' anyway? > > I would prefer not to. Since as you mentioned, these are > not relevant to ptrace. Currently patch 2, adds only few > pmu registers, but would like to include more.
You can't just add them to pt_regs, it's part of the userspace ABI.
We could define a kernel internal version of pt_regs, but I don't think we want to for this.
If we did that would bloat pt_regs for all users in the kernel, when we really only want these regs for perf.
cheers
| |