On Wednesday 21 September 2011 18:50:09, Linas Vepstas (Code Aurora) wrote: > On Wed, Sep 21, 2011 at 05:15:20PM +0100, Pedro Alves wrote: > > > On Sat, Sep 10, 2011 at 12:29:57PM +0100, Pedro Alves wrote: > > > > Yes, the x86/x86-64 ports or gdb and gdbserver are already > > > > using GET/SETREGSET even. > > Thanks; after a bit of initial confusion, I've gotten gdb to > work with this, so I'm happy. > > > I wish there was an equivalent of PTRACE_GETREGSET for siginfo... > > How? Why? One of the the cool features of PTRACE_GETREGSET is that it returns the regset in the natural layout of the tracee. So when debugging a 32-bit process on a 64-bit kernel, PTRACE_GETREGSET returns the regset in 32-bit layout. Recent enough GDBs can print the siginfo of a caught signal (before its delivered with (PTRACE_CONT, sig). Try "(gdb) p $_siginfo" on x86. Trouble is 32-bit processes on 64-bit kernels or other biarch setups. PTRACE_GETSIGINFO returns the siginfo in 64-bit layout, so GDB gets to try to immitate what the kernel's 32-bit compat layer does. Both for reading and writting siginfo. See compat_siginfo_from_siginfo and siginfo_from_compat_siginfo at [1]. The kernel already knows to convert siginfo to the native layout of the process -- needed to pass to the user space signal handler at least. But AFAIK, there's no way for the debugger to get at it before the signal is actually delivered. [1] http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/amd64-linux-nat.c?rev=1.35&content-type=text/x-cvsweb-markup&cvsroot=src -- Pedro Alves -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
