[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, 7 insertions, 0 deletions

diff --git a/include/asm-ia64/ptrace.h b/include/asm-ia64/ptrace.h
index f4ef87a36236..13435f778b0c 100644
--- a/include/asm-ia64/ptrace.h
+++ b/include/asm-ia64/ptrace.h
@@ -292,6 +292,7 @@ struct switch_stack {
                          unsigned long, long);
   extern void ia64_flush_fph (struct task_struct *);
   extern void ia64_sync_fph (struct task_struct *);
+  extern void ia64_sync_krbs(void);
   extern long ia64_sync_user_rbs (struct task_struct *, struct switch_stack *,
                                   unsigned long, unsigned long);
 
@@ -303,6 +304,12 @@ struct switch_stack {
   extern void ia64_increment_ip (struct pt_regs *pt);
   extern void ia64_decrement_ip (struct pt_regs *pt);
 
+  extern void ia64_ptrace_stop(void);
+  #define arch_ptrace_stop(code, info) \
+        ia64_ptrace_stop()
+  #define arch_ptrace_stop_needed(code, info) \
+        (!test_thread_flag(TIF_RESTORE_RSE))
+
 #endif /* !__KERNEL__ */
 
 /* pt_all_user_regs is used for PTRACE_GETREGS PTRACE_SETREGS */