On Tue, 15 Oct 2024 20:39:06 +0200 Heiko Carstens <hca@xxxxxxxxxxxxx> wrote: > On Tue, Oct 15, 2024 at 10:29:17AM +0900, Masami Hiramatsu (Google) wrote: > > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > > > > Use ftrace_regs instead of fgraph_ret_regs for tracing return value > > on function_graph tracer because of simplifying the callback interface. > > > > The CONFIG_HAVE_FUNCTION_GRAPH_RETVAL is also replaced by > > CONFIG_HAVE_FUNCTION_GRAPH_FREGS. > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > > ... > > > diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S > > index 7e267ef63a7f..a9ca56ea0858 100644 > > --- a/arch/s390/kernel/mcount.S > > +++ b/arch/s390/kernel/mcount.S > > @@ -134,14 +134,15 @@ SYM_CODE_END(ftrace_common) > > SYM_FUNC_START(return_to_handler) > > stmg %r2,%r5,32(%r15) > > lgr %r1,%r15 > > - aghi %r15,-(STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE) > > + aghi %r15,-(STACK_FRAME_OVERHEAD+STACK_FRAME_SIZE_FREGS) > > stg %r1,__SF_BACKCHAIN(%r15) > > - la %r3,STACK_FRAME_OVERHEAD(%r15) > > - stg %r1,__FGRAPH_RET_FP(%r3) > > - stg %r2,__FGRAPH_RET_GPR2(%r3) > > - lgr %r2,%r3 > > + la %r4,STACK_FRAME_OVERHEAD(%r15) > > + stg %r2,__PT_R2(%r4) > > + stg %r3,__PT_R3(%r4) > > + stg %r1,__PT_R15(%r4) > > + lgr %r2,%r4 > > brasl %r14,ftrace_return_to_handler > > - aghi %r15,STACK_FRAME_OVERHEAD+__FGRAPH_RET_SIZE > > + aghi %r15,STACK_FRAME_SIZE_FREGS > > lgr %r14,%r2 > > lmg %r2,%r5,32(%r15) > > BR_EX %r14 > > Why didn't you simply merge the addon patch which I provided, and > which I tested? > https://lore.kernel.org/all/20240916121656.20933-B-hca@xxxxxxxxxxxxx > > That would make things much simpler... e.g. your new patch is also > writing r3 to fregs, why? The stackframe allocation is also wrong. > I didn't try, but I guess the above code would crash instantly. I thought it is better to focus on replacing fgraph_ret_regs with ftrace_regs in this patch, but if it is wrong and I should remove stack_frame, let me fix that. Thank you, -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
