powerpc: Add PTRACE_SINGLEBLOCK support

Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK
request for ptrace.

The BookE implementation is tweaked to fire a single step after a
block step in order to mimmic the server behaviour.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 21 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 3635be61f899..9fa2c7dcd05a 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -704,15 +704,34 @@ void user_enable_single_step(struct task_struct *task)
 
         if (regs != NULL) {
 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
+                task->thread.dbcr0 &= ~DBCR0_BT;
                 task->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC;
                 regs->msr |= MSR_DE;
 #else
+                regs->msr &= ~MSR_BE;
                 regs->msr |= MSR_SE;
 #endif
         }
         set_tsk_thread_flag(task, TIF_SINGLESTEP);
 }
 
+void user_enable_block_step(struct task_struct *task)
+{
+        struct pt_regs *regs = task->thread.regs;
+
+        if (regs != NULL) {
+#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
+                task->thread.dbcr0 &= ~DBCR0_IC;
+                task->thread.dbcr0 = DBCR0_IDM | DBCR0_BT;
+                regs->msr |= MSR_DE;
+#else
+                regs->msr &= ~MSR_SE;
+                regs->msr |= MSR_BE;
+#endif
+        }
+        set_tsk_thread_flag(task, TIF_SINGLESTEP);
+}
+
 void user_disable_single_step(struct task_struct *task)
 {
         struct pt_regs *regs = task->thread.regs;
@@ -726,10 +745,10 @@ void user_disable_single_step(struct task_struct *task)
 
         if (regs != NULL) {
 #if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
-                task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_IDM);
+                task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT | DBCR0_IDM);
                 regs->msr &= ~MSR_DE;
 #else
-                regs->msr &= ~MSR_SE;
+                regs->msr &= ~(MSR_SE | MSR_BE);
 #endif
         }
         clear_tsk_thread_flag(task, TIF_SINGLESTEP);