On Thu, Apr 18, 2019 at 10:41:47AM +0200, Thomas Gleixner wrote: > All architectures which support stacktrace carry duplicated code and > do the stack storage and filtering at the architecture side. > > Provide a consolidated interface with a callback function for consuming the > stack entries provided by the architecture specific stack walker. This > removes lots of duplicated code and allows to implement better filtering > than 'skip number of entries' in the future without touching any > architecture specific code. > > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: linux-arch@xxxxxxxxxxxxxxx This is a step in the right direction, especially if it allows us to get rid of the 'skip' stuff. But I'm not crazy about the callbacks. Another idea I had (but never got a chance to work on) was to extend the x86 unwind interface to all arches. So instead of the callbacks, each arch would implement something like this API: struct unwind_state state; void unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, unsigned long *first_frame); bool unwind_next_frame(struct unwind_state *state); inline bool unwind_done(struct unwind_state *state); Not only would it avoid the callbacks (which is a nice benefit already), it would also allow the interfaces to be used outside of the stack_trace_*() interfaces. That would come in handy in cases like the ftrace stack tracer code, which needs more than the stack_trace_*() API can give. Of course, this may be more work than what you thought you signed up for ;-) -- Josh
