Hi Menglong, I remember why I haven't implement this.
On Fri, 10 Oct 2025 11:38:46 +0800 Menglong Dong <[email protected]> wrote: > + > +static struct ftrace_ops fprobe_ftrace_ops = { > + .func = fprobe_ftrace_entry, > + .flags = FTRACE_OPS_FL_SAVE_REGS, Actually, this flag is the problem. This can fail fprobe on architecture which does not support CONFIG_DYNAMIC_FTRACE_WITH_REGS (e.g. arm64, riscv) * SAVE_REGS - The ftrace_ops wants regs saved at each function called * and passed to the callback. If this flag is set, but the * architecture does not support passing regs * (CONFIG_DYNAMIC_FTRACE_WITH_REGS is not defined), then the * ftrace_ops will fail to register, unless the next flag * is set. fgraph has a special entry code for saving ftrace_regs. So at least we need to fail back to fgraph if arch does not support CONFIG_DYNAMIC_FTRACE_WITH_REGS. Thank you, -- Masami Hiramatsu (Google) <[email protected]>
