powerpc/booke: Add support for advanced debug registers

powerpc/booke: Add support for advanced debug registers

From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>

Based on patches originally written by Torez Smith.

This patch defines context switch and trap related functionality
for BookE specific Debug Registers. It adds support to ptrace()
for setting and getting BookE related Debug Registers

Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Torez Smith  <lnxtorez@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <dwg@au1.ibm.com>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Sergio Durigan Junior <sergiodj@br.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@br.ibm.com>
Cc: linuxppc-dev list <Linuxppc-dev@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index e4883ae36277..266610119f66 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -1092,8 +1092,12 @@ int sys_debug_setcontext(struct ucontext __user *ctx,
                                 new_msr |= MSR_DE;
                                 new_dbcr0 |= (DBCR0_IDM | DBCR0_IC);
                         } else {
-                                new_msr &= ~MSR_DE;
-                                new_dbcr0 &= ~(DBCR0_IDM | DBCR0_IC);
+                                new_dbcr0 &= ~DBCR0_IC;
+                                if (!DBCR_ACTIVE_EVENTS(new_dbcr0,
+                                                current->thread.dbcr1)) {
+                                        new_msr &= ~MSR_DE;
+                                        new_dbcr0 &= ~DBCR0_IDM;
+                                }
                         }
 #else
                         if (op.dbg_value)