RE: [patch] ia64: fix potential NaT bit error for sys_pipe().

Chen, Kenneth W
2005-01-21T18:48:46Z

David Mosberger wrote on Thursday, January 20, 2005 9:53 AM:
> Please disregard the patch named in $SUBJECT. It appears to be
> breaking light-weight syscalls. That's rather odd, but since Rohit
> has some better ideas on how to fix this issue, I'd rather drop this
> patch for the time being (the root problem is still there and IMHO,
> needs to be fixed urgently).
>

Seth, Rohit wrote on Thursday, January 20, 2005 11:01 AM
> I will send out the first rev of patch today to address the
> functionality issue. This patch will not worry about exporting the NAT
> bits in r8-r11 to user. So, the ld.fills will be replaced by simple ld.
>
> Though, as per the disussions with David, there is scope of further
> optimization in the way we are saving/restoring r8-r11 in this code.
> This will probably need little more analysis to ensure best
> placement/scheduling of new code. Will send that later...

Here is the first part of the patch that Rohit mentioned earlier.

--- 1.1/arch/ia64/kernel/entry.S Mon Oct 18 14:53:44 2004
+++ edited/arch/ia64/kernel/entry.S Thu Jan 20 15:21:50 2005
@@ -614,8 +614,8 @@
adds r2=PT(R8)+16,sp // r2 = &pt_regs.r8
adds r3=PT(R10)+16,sp // r3 = &pt_regs.r10
;;
-.mem.offset 0,0; (p6) st8.spill [r2]=r8 // store return value in slot for r8 and set unat bit
-.mem.offset 8,0; (p6) st8.spill [r3]=r0 // clear error indication in slot for r10 and set unat bit
+.mem.offset 0,0; (p6) st8 [r2]=r8 // store return value in slot for r8
+.mem.offset 8,0; (p6) st8 [r3]=r0 // clear error indication in slot for r10
(p7) br.cond.spnt handle_syscall_error // handle potential syscall failure
END(ia64_ret_from_syscall)
// fall through
@@ -708,12 +708,12 @@
(p6) br.cond.spnt .work_pending
;;
// start restoring the state saved on the kernel stack (struct pt_regs):
- ld8.fill r8=[r16],16
- ld8.fill r9=[r17],16
+ ld8 r8=[r16],16
+ ld8 r9=[r17],16
mov f6ð // clear f6
;;
- ld8.fill r10=[r16],16
- ld8.fill r11=[r17],16
+ ld8 r10=[r16],16
+ ld8 r11=[r17],16
mov f7ð // clear f7
;;
ld8 r29=[r16],16 // load cr.ipsr

Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
Signed-off-by: Rohit Seth <rohit.seth@intel.com>