Re: [PATCH V4 6/7] riscv: ftrace: Add DYNAMIC_FTRACE_WITH_DIRECT_CALLS support

[Palmer Dabbelt]

On Thu, 01 Dec 2022 12:02:56 PST (-0800), Conor Dooley wrote:
> On Mon, Nov 28, 2022 at 10:32:29PM -0500, guoren@xxxxxxxxxx wrote:
> > From: Song Shuai <suagrfillet@xxxxxxxxx>
> >
> > This patch adds DYNAMIC_FTRACE_WITH_DIRECT_CALLS support for RISC-V.
> >
> > select the DYNAMIC_FTRACE_WITH_DIRECT_CALLS to provide the
> > register_ftrace_direct[_multi] interfaces allowing users to register
> > the customed trampoline (direct_caller) as the mcount for one or
> > more target functions. And modify_ftrace_direct[_multi] are also
> > provided for modifying direct_caller.
> >
> > To make the direct_caller and the other ftrace hooks (eg. function/fgraph
> > tracer, k[ret]probes) co-exist, a temporary register is nominated to
> > store the address of direct_caller in ftrace_regs_caller. After the
> > setting of the address direct_caller by direct_ops->func and the
> > RESTORE_REGS in ftrace_regs_caller, direct_caller will be jumped to
> > by the `jr` inst.
> >
> > Signed-off-by: Song Shuai <suagrfillet@xxxxxxxxx>
> > Tested-by: Guo Ren <guoren@xxxxxxxxxx>
> > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx>
> > ---
> >  arch/riscv/Kconfig              | 1 +
> >  arch/riscv/include/asm/ftrace.h | 6 ++++++
> >  arch/riscv/kernel/mcount-dyn.S  | 4 ++++
> >  3 files changed, 11 insertions(+)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 1d0e5838b11b..2828537abfcd 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -278,6 +278,7 @@ config ARCH_RV64I
> >  	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
> >  	select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && $(cc-option,-fpatchable-function-entry=8)
> >  	select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> > +	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
> >  	select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL
> >  	select HAVE_FUNCTION_GRAPH_TRACER
> >  	select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION
>
> Please sort new entries here in alphabetical order, so move the new
> entry up by one line :)

IIRC whomever sorted these entrties orignially posted a script that does 
that.  Maybe that should be integrated into either checkpatch or one of 
the patchwork robots so we don't have to manually remember the alphabet?