2 files changed, 84 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)
+
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 346fedf9ea47..50ae8c7d453d 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -766,11 +766,56 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
         return ret;
 }
 
+struct param_bsp_cfm {
+        unsigned long ip;
+        unsigned long *bsp;
+        unsigned long cfm;
+};
+
+static void ia64_get_bsp_cfm(struct unw_frame_info *info, void *arg)
+{
+        unsigned long ip;
+        struct param_bsp_cfm *lp = arg;
+
+        do {
+                unw_get_ip(info, &ip);
+                if (ip == 0)
+                        break;
+                if (ip == lp->ip) {
+                        unw_get_bsp(info, (unsigned long*)&lp->bsp);
+                        unw_get_cfm(info, (unsigned long*)&lp->cfm);
+                        return;
+                }
+        } while (unw_unwind(info) >= 0);
+        lp->bsp = 0;
+        lp->cfm = 0;
+        return;
+}
+
 int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct jprobe *jp = container_of(p, struct jprobe, kp);
         unsigned long addr = ((struct fnptr *)(jp->entry))->ip;
         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        struct param_bsp_cfm pa;
+        int bytes;
+
+        /*
+         * Callee owns the argument space and could overwrite it, eg
+         * tail call optimization. So to be absolutely safe
+         * we save the argument space before transfering the control
+         * to instrumented jprobe function which runs in
+         * the process context
+         */
+        pa.ip = regs->cr_iip;
+        unw_init_running(ia64_get_bsp_cfm, &pa);
+        bytes = (char *)ia64_rse_skip_regs(pa.bsp, pa.cfm & 0x3f)
+                                - (char *)pa.bsp;
+        memcpy( kcb->jprobes_saved_stacked_regs,
+                pa.bsp,
+                bytes );
+        kcb->bsp = pa.bsp;
+        kcb->cfm = pa.cfm;
 
         /* save architectural state */
         kcb->jprobe_saved_regs = *regs;
@@ -792,8 +837,20 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
 int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 {
         struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+        int bytes;
 
+        /* restoring architectural state */
         *regs = kcb->jprobe_saved_regs;
+
+        /* restoring the original argument space */
+        flush_register_stack();
+        bytes = (char *)ia64_rse_skip_regs(kcb->bsp, kcb->cfm & 0x3f)
+                                - (char *)kcb->bsp;
+        memcpy( kcb->bsp,
+                kcb->jprobes_saved_stacked_regs,
+                bytes );
+        invalidate_stacked_regs();
+
         preempt_enable_no_resched();
         return 1;
 }