Re: [bug report][stable] perf probe: failed to add events

[Greg KH]

On Tue, Feb 26, 2019 at 03:31:14PM +0800, Joseph Qi wrote:
> Hi,
> 
> I'm using kernel v4.19.24 and have found that there is an issue when
> using perf probe to define a new dynamic tracepoint.
> 
> $ perf probe -a handle_mm_fault
> Failed to write event: Numerical result out of range
>   Error: Failed to add events.
> 
> I've also tried kernel v4.20, and it can pass.

Ick, has this ever worked on the 4.19 stable tree?  If so, any chance
you can run 'git bisect' to find the offending commit?

> So I've bisected and finally found the first good commit is:
> bf904d2762ee x86/pti/64: Remove the SYSCALL64 entry trampoline
> which is based on another commit:
> 98f05b5138f0 Use the TSS sp2 slot for SYSCALL/SYSRET scratch space
> 
> Once I've backpoted these two commits into 4.19.24, the above case can
> pass, though I'm not sure how it is fixed.
> So is there any plan to let them go into stable as well?

If they are needed, I'll gladly queue them up, but this feels like
something might have broken, so it should be easier to just revert the
offending commit instead.

Andy, any ideas?

thanks,

greg k-h