Subject: Don't access 'current' registers in interrupt handler

From: Kevin Corry <kevcorry@us.ibm.com>
The pfm_cell_disable_counters() routine can be called during interrupt context,
and if we are using hardware-sampling, the "current" thread's registers may
not be available, and accessing them may cause a segfault. Since we don't
actually use the "ip" and "regs" arguments in the hardware-sampling handler, we
can just pass zeros and get rid of the reference to the "current" registers.

Signed-off-by: Kevin Corry <kevcorry@us.ibm.com>
Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd,bergmann@de.ibm.com>

Index: linux-2.6/arch/powerpc/perfmon/perfmon_cell.c
===================================================================
--- linux-2.6.orig/arch/powerpc/perfmon/perfmon_cell.c
+++ linux-2.6/arch/powerpc/perfmon/perfmon_cell.c
@@ -306,16 +306,14 @@ static void pfm_cell_disable_counters(st
 				      struct pfm_event_set *set)
 {
 	struct pfm_smpl_fmt *smpl_fmt = ctx->smpl_fmt;
-	struct pt_regs *regs;
 
 	cbe_disable_pm(smp_processor_id());
 
 	if (smpl_fmt && !strcmp(smpl_fmt->fmt_name, PFM_CELL_HW_SMPL_NAME)) {
 		ctx->ovfl_arg.ovfl_pmd = PFM_CELL_HW_SMPL_OVFL_PMD_PARTIAL;
 		ctx->ovfl_arg.active_set = ctx->active_set->id;
-		regs = current->thread.regs;
-		smpl_fmt->fmt_handler(ctx->smpl_addr, &ctx->ovfl_arg,
-				      instruction_pointer(regs), 0, regs);
+		smpl_fmt->fmt_handler(ctx->smpl_addr,
+				      &ctx->ovfl_arg, 0, 0, NULL);
 	}
 }