Re: questions on struct sigcontext

["Chris Friesen" <cfriesen@nortel.com>]

Daniel Jacobowitz wrote:

> There used to be slots for badvaddr and cause.  You'll have to ask
> Ralf why he decided to clobber them for DSP state, I don't remember
> :-)  I suspect they may never have held useful information for you;
> we don't context switch them for userspace, so an intervening fault
> in kernel space or in another thread could change them.

I'm a bit confused as to how they would never have held useful 
information--did you mean the registers themselves, or the entries in 
struct sigcontext?

If the cause/badvaddr entries in struct sigcontext were filled in by the 
exception handler in the kernel, wouldn't the values in that struct be 
completely valid even if the registers themselves were changed before 
userspace could handle the signal?

If this is not the case then it seems like si_addr/si_code wouldn't be 
trustworthy either.

Chris