On Tue, Nov 03, 2009 at 12:12:17PM -0800, Jason Thorpe wrote: > > On Nov 2, 2009, at 9:08 PM, David Young wrote: > > > Module Name: src > > Committed By: dyoung > > Date: Tue Nov 3 05:08:19 UTC 2009 > > > > Modified Files: > > src/sys/arch/i386/i386: copy.S > > Added Files: > > src/share/man/man9/man9.i386: return_address.9 > > src/sys/arch/i386/include: return.h > > > > Log Message: > > Add return_address(9) for reading the Nth return address from the call > > stack. > > What's the intended usage? How is __builtin_return_address() not sufficient?
'options SPLDEBUG' uses it to log the call stack when splraise(IPL_HIGH) is raised. Now that we have it, I will probably use it all over. :-) I used to use __builtin_return_address(n), but for n > 0 it can probe arbitrary addresses, leading to supervisor page faults. It happens in software interrupts, especially. Dave -- David Young OJC Technologies dyo...@ojctech.com Urbana, IL * (217) 278-3933
