arch/tile: fix single-stepping over swint1 instructions on tilegx

If we are single-stepping and make a syscall, we call ptrace_notify()
explicitly on the return path back to user space, since we are returning
to a pc value set artificially to the next instruction, and otherwise
we won't register that we stepped over the syscall instruction (swint1).

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/arch/tile/kernel/intvec_64.S b/arch/tile/kernel/intvec_64.S
index 005535d108c1..fdff17c70cc8 100644
--- a/arch/tile/kernel/intvec_64.S
+++ b/arch/tile/kernel/intvec_64.S
@@ -22,6 +22,7 @@
 #include <asm/irqflags.h>
 #include <asm/asm-offsets.h>
 #include <asm/types.h>
+#include <asm/signal.h>
 #include <hv/hypervisor.h>
 #include <arch/abi.h>
 #include <arch/interrupts.h>
@@ -1039,11 +1040,25 @@ handle_syscall:
 
         /* Do syscall trace again, if requested. */
         ld      r30, r31
-        andi    r30, r30, _TIF_SYSCALL_TRACE
-        beqzt   r30, 1f
+        andi    r0, r30, _TIF_SYSCALL_TRACE
+        {
+         andi    r0, r30, _TIF_SINGLESTEP
+         beqzt   r0, 1f
+        }
         jal     do_syscall_trace
         FEEDBACK_REENTER(handle_syscall)
-1:      j       .Lresume_userspace   /* jump into middle of interrupt_return */
+        andi    r0, r30, _TIF_SINGLESTEP
+
+1:      beqzt   r0, 2f
+
+        /* Single stepping -- notify ptrace. */
+        {
+         movei   r0, SIGTRAP
+         jal     ptrace_notify
+        }
+        FEEDBACK_REENTER(handle_syscall)
+
+2:      j       .Lresume_userspace   /* jump into middle of interrupt_return */
 
 .Lcompat_syscall:
         /*