On Thu, 31 Oct 2024 15:53:24 -0400 Steven Rostedt <[email protected]> wrote:
> On Sat, 26 Oct 2024 13:35:30 +0900 > "Masami Hiramatsu (Google)" <[email protected]> wrote: > > > From: Masami Hiramatsu (Google) <[email protected]> > > > > 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?? Ah, good catch! It should put the flag only when HAVE_DYNAMIC_FTRACE_WITH_ARGS is enabled. static struct ftrace_ops graph_ops = { .func = ftrace_graph_func, #ifdef CONFIG_DYNAMIC_FTRACE_WITH_ARGS .flags = FTRACE_OPS_GRAPH_STUB | FTRACE_OPS_FL_SAVE_ARGS, #elif defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) .flags = FTRACE_OPS_GRAPH_STUB | FTRACE_OPS_FL_SAVE_REGS, #else .flags = FTRACE_OPS_GRAPH_STUB, #endif This will save fregs or regs or NULL according to the configuration. > > -- 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) { -- Masami Hiramatsu (Google) <[email protected]>
