On Thu, Dec 6, 2018 at 10:22 AM Dave Hansen <dave.han...@intel.com> wrote: > > On 12/5/18 3:20 PM, Sean Christopherson wrote: > > @@ -223,6 +224,10 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, > > const char *str, > > tsk->thread.error_code = error_code; > > tsk->thread.trap_nr = trapnr; > > > > + if (user_mode(regs) && > > + fixup_vdso_exception(regs, trapnr, error_code, 0)) > > + return 0; > > + > > return -1; > > } > > > > @@ -563,6 +568,9 @@ do_general_protection(struct pt_regs *regs, long > > error_code) > > tsk->thread.error_code = error_code; > > tsk->thread.trap_nr = X86_TRAP_GP; > > > > + if (fixup_vdso_exception(regs, X86_TRAP_GP, error_code, 0)) > > + return; > > + > > show_signal(tsk, SIGSEGV, "", desc, regs, error_code); > > > > force_sig(SIGSEGV, tsk); > > @@ -854,6 +862,9 @@ static void math_error(struct pt_regs *regs, int > > error_code, int trapnr) > > if (!si_code) > > return; > > > > + if (fixup_vdso_exception(regs, trapnr, error_code, 0)) > > + return; > > + > > force_sig_fault(SIGFPE, si_code, > > (void __user *)uprobe_get_trap_addr(regs), task); > > } > > -- > > Needs commenting, please. > > But, also, this seems really ad-hoc. Probably, that's a result of our > signal generation being really ad-hoc itself. But, if this claims > "Attempt to fixup exceptions in vDSO before signaling", how do we assure > ourselves that we hit all the ad-hoc signal generation cases? How do we > know we didn't miss one or ten? > > I want to hear more of the story of how you picked these sites and also > decided that this is a comprehensive-enough set of sites to patch.
With my maintainer hat on, it would be awesome if we could inspire Sean to do a nice cleanup and unify the code such that there is a single "send a signal to user code to report an exception that wasn't fixed up" path. But that's also quite a big request for an otherwise not-terribly-huge patch... But, in the absence of a cleanup like that, we should at least enumerate all the signals that are indented to get fixed up somewhere in the comments or the changelog. I'm a big suspicious that the correct answer is "all of them", with the possible exception of MCE.
