Messages in this thread | | | Subject | Re: [PATCH] fix vsyscall unwind information | From | Mark Kettenis <> | Date | 06 May 2003 01:10:37 +0200 |
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Richard Henderson <rth@twiddle.net> writes:
> On Mon, May 05, 2003 at 08:05:58AM -0700, David Mosberger-Tang wrote: > > Richard> Why? Certainly it isn't needed for x86. > > > > Certain applications (such as debuggers) want to know. Sure, you can > > do symbol matching (if you have the symbol table) or code-reading > > (assuming you know the exact sigreturn sequence), but having a marker > > would be more reliable and faster. > > Eh. The whole point was to *eliminate* the special cases. > > If the debugger does nothing special now, it'll see the symbol > from the VDSO in the backtrace and print __kernel_sigreturn. > Isn't this sufficient for the user to recognize what's going on? > Does it really need to print <signal frame>?
Unfortunately, GDB needs to be able to recognize signal trampolines in order to be able to single step correctly when a signal arrives. At least on some platforms. Could be that the code-path in question isn't used for Linux/i386, but I vaguely remember it does.
Anyway, signal trampolines could be marked with a special augmentation in their CIE.
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