Hi Dave, Are these issues only for crash tools? or it occurs in kernel func-backtrace too? And how would you fix it? Thank you, Dave Anderson wrote: > > ----- "Dave Anderson" <anderson@xxxxxxxxxx> wrote: > >> I've got a fix for x86_64 -- which have always depended on the existence of >> the "thread_return" label. But I note that x86 backtraces also are not working, >> which I'll take a look at today. > > As it turns out, the x86 backtrace failures in 2.6.33/34 are caused by a different > kprobes-related commit, which moved the system_call assembly function to the > .kprobes.text section: > > commit a00e817f42663941ea0aa5f85a9d1c4f8b212839 > Author: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > Date: Tue Sep 8 12:47:55 2009 -0400 > > kprobes/x86-32: Move irq-exit functions to kprobes section > > Move irq-exit functions to .kprobes.text section to protect against > kprobes recursion. > > When I ran kprobe stress test on x86-32, I found below symbols > cause unrecoverable recursive probing: > > ret_from_exception > ret_from_intr > check_userspace > restore_all > restore_all_notrace > restore_nocheck > irq_return > > And also, I found some interrupt/exception entry points that > cause similar problems. > > This patch moves those symbols (including their container functions) > to .kprobes.text section to prevent any kprobes probing. > > Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx> > Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> > Cc: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx> > Cc: Jim Keniston <jkenisto@xxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > LKML-Reference: <20090908164755.24050.81182.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> > > ... [ snip ] ... > > @@ -513,6 +521,10 @@ sysexit_audit: > PTGS_TO_GS_EX > ENDPROC(ia32_sysenter_target) > > +/* > + * syscall stub including irq exit should be protected against kprobes > + */ > + .pushsection .kprobes.text, "ax" > # system call handler stub > ENTRY(system_call) > RING0_INT_FRAME # can't unwind into user space anyway > @@ -705,6 +717,10 @@ syscall_badsys: > jmp resume_userspace > END(syscall_badsys) > CFI_ENDPROC > +/* > + * End of kprobes section > + */ > + .popsection > > I should have a fix tomorrow (if that's the only issue)... > > Dave -- Masami Hiramatsu e-mail: mhiramat@xxxxxxxxxx -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
