cvs commit: src/sys/ia64/ia64 machdep.c syscall.S vm_machdep.c

[Marcel Moolenaar]

marcel      2003/10/02 20:50:29 PDT

  FreeBSD src repository

  Modified files:
    sys/ia64/ia64        machdep.c syscall.S vm_machdep.c 
  Log:
  Swap the syscall caller frame info (i.e. the return pointer and
  frame marker) and the syscall stub frame info in the trap frame.
  Previously we stored the stub frame info in (rp,pfs) and the
  caller frame info in (iip,cfm). This ends up being suboptimal
  for the following reasons:
  1. When we create a new context, such as for an execve(2), we had
     to set the (rp,pfs) pair for the entry point when using the
     syscall path out of the kernel but we need to set the (iip,cfm)
     pair when we take the interrupt way out. This is mostly just
     an inconsistency from the kernel's point of view, but an ugly
     irregularity from gdb(1)'s point of view.
  2. The getcontext(2) and setcontext(2) syscalls had to swap the
     (rp,pfs) and (iip,cfm) pairs to make the context compatible
     with one created purely in userland.
  
  Swapping the (rp,pfs) and (iip,cfm) pairs is visible to signal
  handlers that actually peek at the mcontext_t and to gdb(1).
  Since this change is made for gdb(1) and we don't care about
  signal handlers that peek at the mcontext_t because we're still
  a tier 2 platform, this ABI breakage is academic at this moment
  in time.
  
  Note that there was no real reason to save the caller frame info
  in (iip,cfm) and the stub frame info in (rp,pfs).
  
  Revision  Changes    Path
  1.157     +5 -11     src/sys/ia64/ia64/machdep.c
  1.8       +30 -26    src/sys/ia64/ia64/syscall.S
  1.72      +2 -3      src/sys/ia64/ia64/vm_machdep.c