Re: [PATCH v1 2/4] powerpc/ftrace: Refactor ftrace_{regs_}caller

[Naveen N. Rao]

Christophe Leroy wrote:
> Le 03/03/2022 à 17:59, Naveen N. Rao a écrit :
> > Christophe Leroy wrote:
> >
> > The ability to disable ftrace in certain code paths through 
> > paca_struct->ftrace_enabled will also be relevant on ppc32 - it will be 
> > nice if it can be introduced there.
>
> Ah ? I understood from commit ea678ac627e0 ("powerpc64/ftrace: Add a 
> field in paca to disable ftrace in unsafe code paths") that it was for 
> when it runs in real mode. PPC32 doesn't run any C code in real mode.

It likely isn't necessary in that case.

> Are there any other situations that real_mode where we'd like to disable 
> it ? If so we could use the thread_struct as we don't have paca on PPC32.

For ppc64, we use this flag to disable certain paths in kvm, kexec, 
mce/hmi and idle/hotplug. If none of those are problematic on ppc32, 
then this isn't necessary.


Thanks,
- Naveen