[AVR32] Enable debugging only when needed

Keep track of processes being debugged (including the kernel itself)
and turn the OCD system on and off as appropriate. Since enabling
debugging turns off some optimizations in the CPU core, this fixes the
issue that enabling KProbes support or simply running a program under
gdbserver will reduce system performance significantly until the next
reboot.

The CPU performance will still be reduced for all processes while a
process is being debugged, but this is a lot better than reducing the
performance forever.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/arch/avr32/kernel/ptrace.c b/arch/avr32/kernel/ptrace.c
index 002369e44093..1fed38fcf594 100644
--- a/arch/avr32/kernel/ptrace.c
+++ b/arch/avr32/kernel/ptrace.c
@@ -58,6 +58,7 @@ void ptrace_disable(struct task_struct *child)
 {
         clear_tsk_thread_flag(child, TIF_SINGLE_STEP);
         clear_tsk_thread_flag(child, TIF_BREAKPOINT);
+        ocd_disable(child);
 }
 
 /*
@@ -144,10 +145,6 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
 {
         int ret;
 
-        pr_debug("ptrace: Enabling monitor mode...\n");
-        ocd_write(DC, ocd_read(DC) | (1 << OCD_DC_MM_BIT)
-                        | (1 << OCD_DC_DBE_BIT));
-
         switch (request) {
         /* Read the word at location addr in the child process */
         case PTRACE_PEEKTEXT: