[IA64] Synchronize kernel RSE to user-space and back

This is base kernel patch for ptrace RSE bug. It's basically a backport
from the utrace RSE patch I sent out several weeks ago. please review.

when a thread is stopped (ptraced), debugger might change thread's user
stack (change memory directly), and we must avoid the RSE stored in
kernel to override user stack (user space's RSE is newer than kernel's
in the case). To workaround the issue, we copy kernel RSE to user RSE
before the task is stopped, so user RSE has updated data.  we then copy
user RSE to kernel after the task is resummed from traced stop and
kernel will use the newer RSE to return to user.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
CC: Roland McGrath <roland@redhat.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
index 5a2c47957069..93d83cbe0c8c 100644
--- a/include/asm-ia64/thread_info.h
+++ b/include/asm-ia64/thread_info.h
@@ -94,6 +94,7 @@ extern void tsk_clear_notify_resume(struct task_struct *tsk);
 #define TIF_MCA_INIT            18      /* this task is processing MCA or INIT */
 #define TIF_DB_DISABLED         19      /* debug trap disabled for fsyscall */
 #define TIF_FREEZE              20      /* is freezing for suspend */
+#define TIF_RESTORE_RSE         21      /* user RBS is newer than kernel RBS */
 
 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
@@ -107,6 +108,7 @@ extern void tsk_clear_notify_resume(struct task_struct *tsk);
 #define _TIF_MCA_INIT           (1 << TIF_MCA_INIT)
 #define _TIF_DB_DISABLED        (1 << TIF_DB_DISABLED)
 #define _TIF_FREEZE             (1 << TIF_FREEZE)
+#define _TIF_RESTORE_RSE        (1 << TIF_RESTORE_RSE)
 
 /* "work to do on user-return" bits */
 #define TIF_ALLWORK_MASK        (_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SYSCALL_AUDIT|\