Re: gdb cannot cross doreti_ast ?
- In reply to: Konstantin Belousov : "Re: gdb cannot cross doreti_ast ?"
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Date: Tue, 02 Nov 2021 15:38:40 UTC
On 01/11/2021 11:39, Konstantin Belousov wrote: > On Mon, Nov 01, 2021 at 10:51:11AM +0200, Andriy Gapon wrote: >> >> I have a crash dump and kgdb (from gdb 10.2) cannot cross doreti_ast() when >> examining a stack trace: >> >> #0 sched_switch (td=0xfffff801291507c0, newtd=0xfffff80061bc97c0, >> flags=<optimized out>) at /usr/src/sys/kern/sched_ule.c:2146 >> #1 0xffffffff80748494 in mi_switch (flags=266, newtd=0x0) at >> /usr/src/sys/kern/kern_synch.c:452 >> #2 0xffffffff80751154 in thread_suspend_switch (td=0xfffff801291507c0, >> p=<optimized out>) at /usr/src/sys/kern/kern_thread.c:1118 >> #3 0xffffffff80750f74 in thread_single (p=0xfffff8011df70000, >> mode=<optimized out>) at /usr/src/sys/kern/kern_thread.c:862 >> #4 0xffffffff80702b86 in exit1 (td=0xfffff801291507c0, rval=0, signo=15) at >> /usr/src/sys/kern/kern_exit.c:240 >> #5 0xffffffff80740f3a in sigexit (td=0xfffff801291507c0, sig=15) at >> /usr/src/sys/kern/kern_sig.c:3194 >> #6 0xffffffff8074230f in postsig (sig=15) at /usr/src/sys/kern/kern_sig.c:3079 >> #7 0xffffffff80794b43 in ast (framep=0xfffffe0105a76c00) at >> /usr/src/sys/kern/subr_trap.c:331 >> #8 0xffffffff809b5449 in doreti_ast () at /usr/src/sys/amd64/amd64/exception.S:1150 >> #9 0x00000008020c7400 in ?? () >> #10 0x0000000000000011 in ?? () >> #11 0x0000000000000000 in ?? () >> >> It's only a minor annoyance, but I would like to get it fixed. >> Maybe some markers need to be added to doreti_ast? >> Or some smarts need to be added to gdb to recognize doreti_ast? > > What do you want to see above doreti_ast? Basically there is no kernel > frames, except the struct trapframe at the very top. doreti_ast is the > last point with interrupts enabled (again) before return to usermode. > > The only wrong thing in this trace is that gdb did not stopped the > unwinding. It might be that we could add some dwarf annotation to > indicate the 'no frame' place. Oh, oops. I think I got confused by a post-processed output from ddb and expected to see something that couldn't be there. It looks that ddb also does not know that doreti_ast is a "terminal" function. So, the post processing I have here joined stacks from the thread that I showed and a next thread in the process but I did not notice that. -- Andriy Gapon