[IA64] do not sync RBS when changing PT_AR_BSP or PT_CFM

Syncing is no longer needed, because user RBS is already
up-to-date.  Actually, if a debugger modified the contents
of the original RBS prior to changing PT_AR_BSP, the
modifications would get overwritten.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c
index 9d2591423eb7dd0ae987aa5a3529e66ece4549e5..54b7ea5515591c7331bc4a625b2b818c1f165566 100644 (file)
--- a/arch/ia64/kernel/ptrace.c
+++ b/arch/ia64/kernel/ptrace.c
@@ -1011,14 +1011,9 @@ access_uarea (struct task_struct *child, unsigned long addr,
                         * the kernel was entered.
                         *
                         * Furthermore, when changing the contents of
-                        * PT_AR_BSP (or PT_CFM) we MUST copy any
-                        * users-level stacked registers that are
-                        * stored on the kernel stack back to
-                        * user-space because otherwise, we might end
-                        * up clobbering kernel stacked registers.
-                        * Also, if this happens while the task is
-                        * blocked in a system call, which convert the
-                        * state such that the non-system-call exit
+                        * PT_AR_BSP (or PT_CFM) while the task is
+                        * blocked in a system call, convert the state
+                        * so that the non-system-call exit
                         * path is used.  This ensures that the proper
                         * state will be picked up when resuming
                         * execution.  However, it *also* means that
@@ -1035,10 +1030,6 @@ access_uarea (struct task_struct *child, unsigned long addr,
                        urbs_end = ia64_get_user_rbs_end(child, pt, &cfm);
                        if (write_access) {
                                if (*data != urbs_end) {
-                                       if (ia64_sync_user_rbs(child, sw,
-                                                              pt->ar_bspstore,
-                                                              urbs_end) < 0)
-                                               return -1;
                                        if (in_syscall(pt))
                                                convert_to_non_syscall(child,
                                                                       pt,
@@ -1058,10 +1049,6 @@ access_uarea (struct task_struct *child, unsigned long addr,
                        urbs_end = ia64_get_user_rbs_end(child, pt, &cfm);
                        if (write_access) {
                                if (((cfm ^ *data) & PFM_MASK) != 0) {
-                                       if (ia64_sync_user_rbs(child, sw,
-                                                              pt->ar_bspstore,
-                                                              urbs_end) < 0)
-                                               return -1;
                                        if (in_syscall(pt))
                                                convert_to_non_syscall(child,
                                                                       pt,