On Thu, Jun 17, 2021 at 12:26 PM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > On Thu, Jun 17, 2021 at 11:31:03AM -0700, Andrii Nakryiko wrote: > > On Thu, Jun 17, 2021 at 11:22 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote: > > > > > > On Thu, Jun 17, 2021 at 10:45:41AM -0700, Andrii Nakryiko wrote: > > > > > > > > I know I suggested this patch, but I believe it would only be useful in > > > > > > > > combination with the use of UNWIND_HINT_REGS in SAVE_REGS_STRING. But I > > > > > > > > think that would be tricky to pull off correctly. Instead, we have > > > > > > > > UNWIND_HINT_FUNC, which is working fine. > > > > > > > > > > > > > > > > So I'd suggest dropping this patch, as the unwinder isn't actually > > > > > > > > reading regs->ip after all. > > > > > > > > > > > > > > ... and I guess this means patches 6-8 are no longer necessary. > > > > > > > > > > > > OK, I also confirmed that dropping those patche does not make any change > > > > > > on the stacktrace. > > > > > > Let me update the series without those. > > > > > > > > > > Oops, Andrii, can you also test the kernel without this patch? > > > > > (you don't need to drop patch 6-8) > > > > > > > > Hi Masami, > > > > > > > > Dropping this patch and leaving all the other in place breaks stack > > > > traces from kretprobes for BPF. I double checked with and without this > > > > patch. Without this patch we are back to having broken stack traces. I > > > > see either > > > > > > > > kretprobe_trampoline+0x0 > > > > > > > > or > > > > > > > > ftrace_trampoline+0xc8 > > > > kretprobe_trampoline+0x0 > > Do the stack traces end there? Or do they continue normally after that? That's the entire stack trace. > > -- > Josh >
