Re: [PATCH v3 19/25] powerpc/ftrace: Minimise number of #ifdefs

[Naveen N. Rao]

Christophe Leroy wrote:
> Le 18/05/2022 à 14:03, Michael Ellerman a écrit :
> > Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes:
> > > "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxxxxxxx> writes:
> > > > Christophe Leroy wrote:
> > > > > A lot of #ifdefs can be replaced by IS_ENABLED()
> > > > >
> > > > > Do so.
> > > > >
> > > > > This requires to have kernel_toc_addr() defined at all time
> > > > > as well as PPC_INST_LD_TOC and PPC_INST_STD_LR.
> > > > >
> > > > > Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> > > > > ---
> > > > > v2: Moved the setup of pop outside of the big if()/else() in __ftrace_make_nop()
> > > > > ---
> > > > >   arch/powerpc/include/asm/code-patching.h |   2 -
> > > > >   arch/powerpc/include/asm/module.h        |   2 -
> > > > >   arch/powerpc/include/asm/sections.h      |  24 +--
> > > > >   arch/powerpc/kernel/trace/ftrace.c       | 182 +++++++++++------------
> > > > >   4 files changed, 103 insertions(+), 107 deletions(-)
> > > >
> > > > <snip>
> > > >
> > > > > @@ -710,6 +707,9 @@ void arch_ftrace_update_code(int command)
> > > > >
> > > > >   #ifdef CONFIG_PPC64
> > > > >   #define PACATOC offsetof(struct paca_struct, kernel_toc)
> > > > > +#else
> > > > > +#define PACATOC 0
> > > > > +#endif
> > > >
> > > > This conflicts with my fix for the ftrace init tramp:
> > > > https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220516071422.463738-1-naveen.n.rao@xxxxxxxxxxxxxxxxxx/
> > > >
> > > > It probably makes sense to retain #ifdef CONFIG_PPC64, so that we can
> > > > get rid of the PACATOC. Here is an incremental diff:
> > >
> > > Where is the incremental diff meant to apply?
> > >
> > > It doesn't apply on top of patch 19, or at the end of the series.

Ugh, sorry. I had an additional patch that converts those 
ftrace_[regs_]_caller uses to FTRACE_REGS_ADDR, which prevented one of 
the hunks from applying.

> > I think I worked out what you meant.
> >
> > Can you check what's in next-test:
> >
> >    https://github.com/linuxppc/linux/commits/next-test
>
> Yes that looks fine.

+1

> As Naveen mentioned we can also get rid of PACATOC completely and use 
> offsetof(struct paca_struct, kernel_toc) directly at the only place 
> PACATOC is used.

Yes, or we can send it out as a separate cleanup.


Thanks,
Naveen