On 01/19, Sergio Durigan Junior wrote: > > On Friday, January 10 2014, Oleg Nesterov wrote: > > > So suppose that gdb does ptrace(PTRACE_SINGLESTEP) and the tracee > > executes the "syscall" insn. What it should report? > [...] > > But what should syscall-exit do? Should it still report SIGSEGV as > > it currently does, or should it report _SYSCALL_EXIT instead (if > > PTRACE_O_SYSCALL_EXIT of course), or should it report both? > > Both only if _SYSCALL_EXIT is set. Otherwise, stick to the current > behavior, I guess.
OK, both. In which order? Probably _EXIT first. But this looks a bit strange. Suppose that the tracee reports _EXIT, then debugger does ptrace(PTRACE_CONT), should the tracee report SIGTRAP? SIGTRAP before _EXIT looks a bit strange too... Single-step trap should be reported after insn, but we are still in syscall. So perhaps _EXIT should win and do not report the step? > Isn't it what my current patch does, by the way? I forgot how this patch looks so I can be easily wrong, but iirc no. Note that tracehook_report_syscall_exit() doesn't even call ptrace_report_syscall() if step == T. Btw, if you send v2, please CC Michael Kerrisk <[email protected]>. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
