[IA64] prevent accidental modification of args in jprobe handler

When jprobe is hit, the function parameters of the original function
should be saved before jprobe handler is executed, and restored it after
jprobe handler is executed, because jprobe handler might change the
register values due to tail call optimization by the gcc.

Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/arch/ia64/kernel/jprobes.S b/arch/ia64/kernel/jprobes.S
index 2323377e3695..5cd6226f44f2 100644
--- a/arch/ia64/kernel/jprobes.S
+++ b/arch/ia64/kernel/jprobes.S
@@ -60,3 +60,30 @@ END(jprobe_break)
 GLOBAL_ENTRY(jprobe_inst_return)
         br.call.sptk.many b0=jprobe_break
 END(jprobe_inst_return)
+
+GLOBAL_ENTRY(invalidate_stacked_regs)
+        movl r16=invalidate_restore_cfm
+        ;;
+        mov b6=r16
+        ;;
+        br.ret.sptk.many b6
+        ;;
+invalidate_restore_cfm:
+        mov r16=ar.rsc
+        ;;
+        mov ar.rsc=r0
+        ;;
+        loadrs
+        ;;
+        mov ar.rsc=r16
+        ;;
+        br.cond.sptk.many rp
+END(invalidate_stacked_regs)
+
+GLOBAL_ENTRY(flush_register_stack)
+        // flush dirty regs to backing store (must be first in insn group)
+        flushrs
+        ;;
+        br.ret.sptk.many rp
+END(flush_register_stack)
+