[IA64] MCA recovery improvements

Jack Steiner uncovered some opportunities for improvement in
the MCA recovery code.

  1) Set bsp to save registers on the kernel stack.
  2) Disable interrupts while in the MCA recovery code.
  3) Change the way the user process is killed, to avoid 
     a panic in schedule.

Testing shows that these changes make the recovery code much 
more reliable with the 2.6.12 kernel.

Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 17 insertions, 5 deletions

diff --git a/arch/ia64/kernel/mca_drv.c b/arch/ia64/kernel/mca_drv.c
index ab478172c349..abc0113a821d 100644
--- a/arch/ia64/kernel/mca_drv.c
+++ b/arch/ia64/kernel/mca_drv.c
@@ -132,8 +132,7 @@ mca_handler_bh(unsigned long paddr)
         spin_unlock(&mca_bh_lock);
 
         /* This process is about to be killed itself */
-        force_sig(SIGKILL, current);
-        schedule();
+        do_exit(SIGKILL);
 }
 
 /**
@@ -439,6 +438,7 @@ recover_from_read_error(slidx_table_t *slidx, peidx_table_t *peidx, pal_bus_chec
                         psr2 = (struct ia64_psr *)&pmsa->pmsa_ipsr;
                         psr2->cpl = 0;
                         psr2->ri  = 0;
+                        psr2->i  = 0;
 
                         return 1;
                 }
diff --git a/arch/ia64/kernel/mca_drv_asm.S b/arch/ia64/kernel/mca_drv_asm.S
index bcfa05acc561..2d7e0217638d 100644
--- a/arch/ia64/kernel/mca_drv_asm.S
+++ b/arch/ia64/kernel/mca_drv_asm.S
@@ -10,6 +10,7 @@
 
 #include <asm/asmmacro.h>
 #include <asm/processor.h>
+#include <asm/ptrace.h>
 
 GLOBAL_ENTRY(mca_handler_bhhook)
         invala                                          // clear RSE ?
@@ -20,12 +21,21 @@ GLOBAL_ENTRY(mca_handler_bhhook)
         ;;                                              
         alloc           r16=ar.pfs,0,2,1,0              // make a new frame
         ;;
+        mov             ar.rsc=0
+        ;;
         mov             r13=IA64_KR(CURRENT)            // current task pointer
         ;;
-        adds            r12=IA64_TASK_THREAD_KSP_OFFSET,r13
+        mov             r2=r13
+        ;;
+        addl            r22=IA64_RBS_OFFSET,r2
+        ;;
+        mov             ar.bspstore=r22
         ;;
-        ld8             r12=[r12]                       // stack pointer
+        addl            sp=IA64_STK_OFFSET-IA64_PT_REGS_SIZE,r2
         ;;
+        adds            r2=IA64_TASK_THREAD_ON_USTACK_OFFSET,r13
+        ;;
+        st1             [r2]=r0                         // clear current->thread.on_ustack flag
         mov             loc0=r16
         movl            loc1=mca_handler_bh             // recovery C function
         ;;
@@ -34,7 +44,9 @@ GLOBAL_ENTRY(mca_handler_bhhook)
         ;;
         mov             loc1=rp
         ;;
-        br.call.sptk.many    rp=b6                      // not return ...
+        ssm             psr.i
+        ;;
+        br.call.sptk.many    rp=b6                      // does not return ...
         ;;
         mov             ar.pfs=loc0
         mov             rp=loc1