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.
