sh: hw-breakpoints: Add preliminary support for SH-4A UBC.

This adds preliminary support for the SH-4A UBC to the hw-breakpoints API.
Presently only a single channel is implemented, and the ptrace interface
still needs to be converted. This is the first step to cleaning up the
long-standing UBC mess, making the UBC more generally accessible, and
finally making it SMP safe.

An additional abstraction will be layered on top of this as with the perf
events code to permit the various CPU families to wire up support for
their own specific UBCs, as many variations exist.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 0 insertions, 19 deletions

diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 9be35f348093..bdb10446cbac 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -65,31 +65,12 @@ static inline int put_stack_long(struct task_struct *task, int offset,
 
 void user_enable_single_step(struct task_struct *child)
 {
-	/* Next scheduling will set up UBC */
-	if (child->thread.ubc_pc == 0)
-		ubc_usercnt += 1;
-
-	child->thread.ubc_pc = get_stack_long(child,
-				offsetof(struct pt_regs, pc));
-
 	set_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 void user_disable_single_step(struct task_struct *child)
 {
 	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
-
-	/*
-	 * Ensure the UBC is not programmed at the next context switch.
-	 *
-	 * Normally this is not needed but there are sequences such as
-	 * singlestep, signal delivery, and continue that leave the
-	 * ubc_pc non-zero leading to spurious SIGTRAPs.
-	 */
-	if (child->thread.ubc_pc != 0) {
-		ubc_usercnt -= 1;
-		child->thread.ubc_pc = 0;
-	}
 }
 
 /*