Hexagon: add support for single-stepping (v4+)

Hardware single-step is only available on v4 and later
architectures.

Signed-off-by: Richard Kuo <rkuo@codeaurora.org>

4 files changed, 30 insertions, 1 deletions

diff --git a/arch/hexagon/kernel/ptrace.c b/arch/hexagon/kernel/ptrace.c
index 3982d9c9ec2b..70df50d797d8 100644
--- a/arch/hexagon/kernel/ptrace.c
+++ b/arch/hexagon/kernel/ptrace.c
@@ -32,6 +32,21 @@
 
 #include <asm/user.h>
 
+#if arch_has_single_step()
+/*  Both called from ptrace_resume  */
+void user_enable_single_step(struct task_struct *child)
+{
+        pt_set_singlestep(task_pt_regs(child));
+        set_tsk_thread_flag(child, TIF_SINGLESTEP);
+}
+
+void user_disable_single_step(struct task_struct *child)
+{
+        pt_clr_singlestep(task_pt_regs(child));
+        clear_tsk_thread_flag(child, TIF_SINGLESTEP);
+}
+#endif
+
 static int genregs_get(struct task_struct *target,
                    const struct user_regset *regset,
                    unsigned int pos, unsigned int count,
diff --git a/arch/hexagon/kernel/traps.c b/arch/hexagon/kernel/traps.c
index 12164a30e8ff..c2eeeef55335 100644
--- a/arch/hexagon/kernel/traps.c
+++ b/arch/hexagon/kernel/traps.c
@@ -451,3 +451,14 @@ void do_machcheck(struct pt_regs *regs)
         /* Halt and catch fire */
         __vmstop();
 }
+
+/*
+ * Treat this like the old 0xdb trap.
+ */
+
+void do_debug_exception(struct pt_regs *regs)
+{
+        regs->hvmer.vmest &= ~HVM_VMEST_CAUSE_MSK;
+        regs->hvmer.vmest |= (TRAP_DEBUG << HVM_VMEST_CAUSE_SFT);
+        do_trap0(regs);
+}
diff --git a/arch/hexagon/kernel/vm_entry.S b/arch/hexagon/kernel/vm_entry.S
index 053551ee7114..9add73ab57d8 100644
--- a/arch/hexagon/kernel/vm_entry.S
+++ b/arch/hexagon/kernel/vm_entry.S
@@ -367,6 +367,9 @@ _K_enter_trap0:
 _K_enter_machcheck:
         vm_event_entry(do_machcheck)
 
+        .globl _K_enter_debug
+_K_enter_debug:
+        vm_event_entry(do_debug_exception)
 
         .globl ret_from_fork
 ret_from_fork:
diff --git a/arch/hexagon/kernel/vm_vectors.S b/arch/hexagon/kernel/vm_vectors.S
index 620f42cc582a..aff4054a2cff 100644
--- a/arch/hexagon/kernel/vm_vectors.S
+++ b/arch/hexagon/kernel/vm_vectors.S
@@ -41,7 +41,7 @@ _K_VM_event_vector:
         jump 1b;  /*  Reset  */
         jump _K_enter_machcheck;
         jump _K_enter_genex;
-        jump 1b;  /*  3 Rsvd  */
+        jump _K_enter_debug;
         jump 1b;  /*  4 Rsvd  */
         jump _K_enter_trap0;
         jump 1b;  /*  6 Rsvd  */