[IA64] Handle debug traps in fsys mode

We need to handle debug traps in fsys mode non-fatally.  They can
happen now that we have fsyscalls which contain probe instructions.

Signed-off-by: Jason Uhlenkott <jasonuhl@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

diff --git a/arch/ia64/kernel/traps.c b/arch/ia64/kernel/traps.c
index d3e0ecb..5539190 100644 (file)
--- a/arch/ia64/kernel/traps.c
+++ b/arch/ia64/kernel/traps.c
@@ -530,12 +530,15 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
                if (fsys_mode(current, &regs)) {
                        extern char __kernel_syscall_via_break[];
                        /*
-                        * Got a trap in fsys-mode: Taken Branch Trap and Single Step trap
-                        * need special handling; Debug trap is not supposed to happen.
+                        * Got a trap in fsys-mode: Taken Branch Trap
+                        * and Single Step trap need special handling;
+                        * Debug trap is ignored (we disable it here
+                        * and re-enable it in the lower-privilege trap).
                         */
                        if (unlikely(vector == 29)) {
-                               die("Got debug trap in fsys-mode---not supposed to happen!",
-                                   &regs, 0);
+                               set_thread_flag(TIF_DB_DISABLED);
+                               ia64_psr(&regs)->db = 0;
+                               ia64_psr(&regs)->lp = 1;
                                return;
                        }
                        /* re-do the system call via break 0x100000: */
@@ -589,10 +592,19 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
              case 34:
                if (isr & 0x2) {
                        /* Lower-Privilege Transfer Trap */
+
+                       /* If we disabled debug traps during an fsyscall,
+                        * re-enable them here.
+                        */
+                       if (test_thread_flag(TIF_DB_DISABLED)) {
+                               clear_thread_flag(TIF_DB_DISABLED);
+                               ia64_psr(&regs)->db = 1;
+                       }
+
                        /*
-                        * Just clear PSR.lp and then return immediately: all the
-                        * interesting work (e.g., signal delivery is done in the kernel
-                        * exit path).
+                        * Just clear PSR.lp and then return immediately:
+                        * all the interesting work (e.g., signal delivery)
+                        * is done in the kernel exit path.
                         */
                        ia64_psr(&regs)->lp = 0;
                        return;

diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
index 653bb7f..1d6518f 100644 (file)
--- a/include/asm-ia64/thread_info.h
+++ b/include/asm-ia64/thread_info.h
@@ -93,6 +93,7 @@ struct thread_info {
 #define TIF_POLLING_NRFLAG     16      /* true if poll_idle() is polling TIF_NEED_RESCHED */
 #define TIF_MEMDIE             17
 #define TIF_MCA_INIT           18      /* this task is processing MCA or INIT */
+#define TIF_DB_DISABLED                19      /* debug trap disabled for fsyscall */
 
 #define _TIF_SYSCALL_TRACE     (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT     (1 << TIF_SYSCALL_AUDIT)
@@ -100,9 +101,10 @@ struct thread_info {
 #define _TIF_NOTIFY_RESUME     (1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
-#define _TIF_SIGDELAYED        (1 << TIF_SIGDELAYED)
+#define _TIF_SIGDELAYED                (1 << TIF_SIGDELAYED)
 #define _TIF_POLLING_NRFLAG    (1 << TIF_POLLING_NRFLAG)
 #define _TIF_MCA_INIT          (1 << TIF_MCA_INIT)
+#define _TIF_DB_DISABLED       (1 << TIF_DB_DISABLED)
 
 /* "work to do on user-return" bits */
 #define TIF_ALLWORK_MASK       (_TIF_NOTIFY_RESUME|_TIF_SIGPENDING|_TIF_NEED_RESCHED|_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SIGDELAYED)