ICS: implement rollback mechanics

rollback the EIP on return to user space if TIF_ROLLBACK_RCS is set

4 files changed, 17 insertions, 3 deletions

diff --git a/arch/i386/kernel/signal.c b/arch/i386/kernel/signal.c
index 65d7620eaa..e4ab40862b 100644
--- a/arch/i386/kernel/signal.c
+++ b/arch/i386/kernel/signal.c
@@ -27,6 +27,8 @@
 #include <asm/i387.h>
 #include "sigframe.h"
 
+#include <linux/ics.h>
+
 #define DEBUG_SIG 0
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
@@ -653,5 +655,12 @@ void do_notify_resume(struct pt_regs *regs, void *_unused,
         if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
                 do_signal(regs);
         
+        if (thread_info_flags & _TIF_ROLLBACK_RCS) {
+                long addr = (long) get_rollback_addr();
+                if (addr)
+                        regs->eip = addr;
+                clear_thread_flag(TIF_ROLLBACK_RCS);            
+        }
+
         clear_thread_flag(TIF_IRET);
 }
diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h
index 4b187bb377..fd9dd60afe 100644
--- a/include/asm-i386/thread_info.h
+++ b/include/asm-i386/thread_info.h
@@ -131,6 +131,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 #define TIF_SECCOMP             8       /* secure computing */
 #define TIF_RESTORE_SIGMASK     9       /* restore signal mask in do_signal() */
+#define TIF_ROLLBACK_RCS        10      /* set EIP to rollback addr */
 #define TIF_MEMDIE              16
 #define TIF_DEBUG               17      /* uses debug registers */
 #define TIF_IO_BITMAP           18      /* uses I/O bitmap */
@@ -146,6 +147,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_ROLLBACK_RCS       (1<<TIF_ROLLBACK_RCS)
 #define _TIF_DEBUG              (1<<TIF_DEBUG)
 #define _TIF_IO_BITMAP          (1<<TIF_IO_BITMAP)
 #define _TIF_FREEZE             (1<<TIF_FREEZE)
diff --git a/include/linux/ics.h b/include/linux/ics.h
index 61dabe9693..f22654fb45 100644
--- a/include/linux/ics.h
+++ b/include/linux/ics.h
@@ -14,4 +14,7 @@ struct ics_cb {
         int             ics_stack[MAX_ICS_NESTING];
 };
 
+/* get rollback addr for current task */
+void* get_rollback_addr(void);
+
 #endif
diff --git a/kernel/ics.c b/kernel/ics.c
index e32693b880..7af33c3692 100644
--- a/kernel/ics.c
+++ b/kernel/ics.c
@@ -66,7 +66,7 @@ struct fdso_ops ics_ops = {
 };
 
 
-static void* get_rollback(void)
+void* get_rollback_addr(void)
 {
         int err;
         void* addr;
@@ -114,7 +114,7 @@ static void abort_local_ics_reader(struct ics* ics)
         if (!t->ics_cb)
                 return;
 
-        rollback_addr = get_rollback();
+        rollback_addr = get_rollback_addr();
 
         if (!rollback_addr)
                 return;
@@ -129,7 +129,7 @@ static void abort_local_ics_reader(struct ics* ics)
                         /* garbage on stack */
                         return;
                 if (ics == stacked) {
-                        arch_do_rollback(rollback_addr);
+                        set_tsk_thread_flag(t, TIF_ROLLBACK_RCS);
                         atomic_inc(&ics->aborted_ctr);
                         return;
                 }