Re: Filling in struct mips64_watch_regs from a 32 bit process

[David Daney <ddaney@caviumnetworks.com>]

On 01/31/2011 05:12 PM, Earl Chew wrote:
> > > I notice that a 32 bit process running on a 64 bit kernel is expected to
> > > know that it should fill in mips64_watch_regs --- even though it is running
> > > against a 32 bit ABI.
> > >
> > > Is this an oversight, or am I missing something ?
> > It is intentional.
> Oh I see ... I have to call PTRACE_SET_WATCH_REGS first in order to figure
> out whether the kernel is expecting me to use pt_watch_style_mips32 or
> pt_watch_style_mips64.
That would be PTRACE_GET_WATCH_REGS.  It will tell you the width of the 
registers as well as how many are available (in the num_valid field) and 
the properties of each (in the watch_masks[] fields).
Fill in watchlo[] and watchhi[], write them back with 
PTRACE_SET_WATCH_REGS, then sit back and wait for SIGTRAP.
David Daney