On Sat, 26 Oct 2024 13:35:30 +0900 "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote: > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > > Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not > available, it passes a NULL instead. User callback function can access > some registers (including return address) via this ftrace_regs. > > Note that the ftrace_regs can be NULL when the arch does NOT define: > HAVE_DYNAMIC_FTRACE_WITH_ARGS or HAVE_DYNAMIC_FTRACE_WITH_REGS. > More specifically, if HAVE_DYNAMIC_FTRACE_WITH_REGS is defined but > not the HAVE_DYNAMIC_FTRACE_WITH_ARGS, and the ftrace ops used to > register the function callback does not set FTRACE_OPS_FL_SAVE_REGS. > In this case, ftrace_regs can be NULL in user callback. If HAVE_DYNAMIC_FTRACE_WITH_REGS is defined but not HAVE_DYNAMIC_FTRACE_WITH_ARGS is not, then the callback will have regs defined. > @@ -977,7 +980,7 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, > > static struct ftrace_ops graph_ops = { > .func = ftrace_graph_func, > - .flags = FTRACE_OPS_GRAPH_STUB, > + .flags = FTRACE_OPS_GRAPH_STUB | FTRACE_OPS_FL_SAVE_ARGS, Enabling FTRACE_OPS_FL_SAVE_ARGS will pass full regs in that case. Are you just saying in the change log that this is what you did? As it currently reads, it sounds like a fgraph user needs to add FTRACE_OPS_FL_SAVE_REGS?? -- Steve > #ifdef FTRACE_GRAPH_TRAMP_ADDR > .trampoline = FTRACE_GRAPH_TRAMP_ADDR, > /* trampoline_size is only needed for dynamically allocated tramps */ > @@ -987,7 +990,8 @@ static struct ftrace_ops graph_ops = { > void fgraph_init_ops(struct ftrace_ops *dst_ops, > struct ftrace_ops *src_ops) > { > - dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB; > + dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB | > + FTRACE_OPS_FL_SAVE_ARGS; > > #ifdef CONFIG_DYNAMIC_FTRACE > if (src_ops) {