[PATCH 09/15] powerpc/watchpoint: Convert thread_struct->hw_brk to an array

[Ravi Bangoria]

So far powerpc hw supported only one watchpoint. But Future Power
architecture is introducing 2nd DAWR. Convert thread_struct->hw_brk
into an array.

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
---
 arch/powerpc/include/asm/processor.h |  2 +-
 arch/powerpc/kernel/process.c        | 43 ++++++++++++++++++++--------
 arch/powerpc/kernel/ptrace.c         | 42 ++++++++++++++++++++-------
 arch/powerpc/kernel/ptrace32.c       |  4 +--
 arch/powerpc/kernel/signal.c         |  9 ++++--
 5 files changed, 72 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 666b2825278c..57a8fac2e72b 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -183,7 +183,7 @@ struct thread_struct {
 	 */
 	struct perf_event *last_hit_ubp;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-	struct arch_hw_breakpoint hw_brk; /* info on the hardware breakpoint */
+	struct arch_hw_breakpoint hw_brk[HBP_NUM_MAX]; /* hardware breakpoint info */
 	unsigned long	trap_nr;	/* last trap # on this thread */
 	u8 load_slb;			/* Ages out SLB preload cache entries */
 	u8 load_fp;
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f6bb2586fa5d..42ff62ef749c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -704,21 +704,25 @@ void switch_booke_debug_regs(struct debug_reg *new_debug)
 EXPORT_SYMBOL_GPL(switch_booke_debug_regs);
 #else	/* !CONFIG_PPC_ADV_DEBUG_REGS */
 #ifndef CONFIG_HAVE_HW_BREAKPOINT
-static void set_breakpoint(struct arch_hw_breakpoint *brk)
+static void set_breakpoint(struct arch_hw_breakpoint *brk, int i)
 {
 	preempt_disable();
-	__set_breakpoint(brk, 0);
+	__set_breakpoint(brk, i);
 	preempt_enable();
 }
 
 static void set_debug_reg_defaults(struct thread_struct *thread)
 {
-	thread->hw_brk.address = 0;
-	thread->hw_brk.type = 0;
-	thread->hw_brk.len = 0;
-	thread->hw_brk.hw_len = 0;
-	if (ppc_breakpoint_available())
-		set_breakpoint(&thread->hw_brk);
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		thread->hw_brk[i].address = 0;
+		thread->hw_brk[i].type = 0;
+		thread->hw_brk[i].len = 0;
+		thread->hw_brk[i].hw_len = 0;
+		if (ppc_breakpoint_available())
+			set_breakpoint(&thread->hw_brk[i], i);
+	}
 }
 #endif /* !CONFIG_HAVE_HW_BREAKPOINT */
 #endif	/* CONFIG_PPC_ADV_DEBUG_REGS */
@@ -1141,6 +1145,24 @@ static inline void restore_sprs(struct thread_struct *old_thread,
 	thread_pkey_regs_restore(new_thread, old_thread);
 }
 
+#ifndef CONFIG_HAVE_HW_BREAKPOINT
+static void switch_hw_breakpoint(struct task_struct *new)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk[i]),
+					   &new->thread.hw_brk[i]))) {
+			__set_breakpoint(&new->thread.hw_brk[i], i);
+		}
+	}
+}
+#else
+static void switch_hw_breakpoint(struct task_struct *new)
+{
+}
+#endif
+
 struct task_struct *__switch_to(struct task_struct *prev,
 	struct task_struct *new)
 {
@@ -1172,10 +1194,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
  * For PPC_BOOK3S_64, we use the hw-breakpoint interfaces that would
  * schedule DABR
  */
-#ifndef CONFIG_HAVE_HW_BREAKPOINT
-	if (unlikely(!hw_brk_match(this_cpu_ptr(&current_brk[0]), &new->thread.hw_brk)))
-		__set_breakpoint(&new->thread.hw_brk, 0);
-#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+	switch_hw_breakpoint(new);
 #endif
 
 	/*
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index dd46e174dbe7..f6d7955fc61e 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2382,6 +2382,11 @@ void ptrace_triggered(struct perf_event *bp,
 }
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
+/*
+ * ptrace_set_debugreg() fakes DABR and DABR is only one. So even if
+ * internal hw supports more than one watchpoint, we support only one
+ * watchpoint with this interface.
+ */
 static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 			       unsigned long data)
 {
@@ -2451,7 +2456,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 			return ret;
 		}
 		thread->ptrace_bps[0] = bp;
-		thread->hw_brk = hw_brk;
+		thread->hw_brk[0] = hw_brk;
 		return 0;
 	}
 
@@ -2473,7 +2478,7 @@ static int ptrace_set_debugreg(struct task_struct *task, unsigned long addr,
 	if (set_bp && (!ppc_breakpoint_available()))
 		return -ENODEV;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-	task->thread.hw_brk = hw_brk;
+	task->thread.hw_brk[0] = hw_brk;
 #else /* CONFIG_PPC_ADV_DEBUG_REGS */
 	/* As described above, it was assumed 3 bits were passed with the data
 	 *  address, but we will assume only the mode bits will be passed
@@ -2824,9 +2829,23 @@ static int set_dac_range(struct task_struct *child,
 }
 #endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */
 
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+static int empty_hw_brk(struct thread_struct *thread)
+{
+	int i;
+
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (!thread->hw_brk[i].address)
+			return i;
+	}
+	return -1;
+}
+#endif
+
 static long ppc_set_hwdebug(struct task_struct *child,
 		     struct ppc_hw_breakpoint *bp_info)
 {
+	int i;
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	int len = 0;
 	struct thread_struct *thread = &(child->thread);
@@ -2919,15 +2938,16 @@ static long ppc_set_hwdebug(struct task_struct *child,
 	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
 		return -EINVAL;
 
-	if (child->thread.hw_brk.address)
+	i = empty_hw_brk(&child->thread);
+	if (i < 0)
 		return -ENOSPC;
 
 	if (!ppc_breakpoint_available())
 		return -ENODEV;
 
-	child->thread.hw_brk = brk;
+	child->thread.hw_brk[i] = brk;
 
-	return 1;
+	return i + 1;
 #endif /* !CONFIG_PPC_ADV_DEBUG_DVCS */
 }
 
@@ -2955,7 +2975,7 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
 	}
 	return rc;
 #else
-	if (data != 1)
+	if (data < 1 || data > nr_wp_slots())
 		return -EINVAL;
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -2967,11 +2987,11 @@ static long ppc_del_hwdebug(struct task_struct *child, long data)
 		ret = -ENOENT;
 	return ret;
 #else /* CONFIG_HAVE_HW_BREAKPOINT */
-	if (child->thread.hw_brk.address == 0)
+	if (child->thread.hw_brk[data - 1].address == 0)
 		return -ENOENT;
 
-	child->thread.hw_brk.address = 0;
-	child->thread.hw_brk.type = 0;
+	child->thread.hw_brk[data - 1].address = 0;
+	child->thread.hw_brk[data - 1].type = 0;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
 	return 0;
@@ -3124,8 +3144,8 @@ long arch_ptrace(struct task_struct *child, long request,
 #ifdef CONFIG_PPC_ADV_DEBUG_REGS
 		ret = put_user(child->thread.debug.dac1, datalp);
 #else
-		dabr_fake = ((child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
-			     (child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
+		dabr_fake = ((child->thread.hw_brk[0].address & (~HW_BRK_TYPE_DABR)) |
+			     (child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
 		ret = put_user(dabr_fake, datalp);
 #endif
 		break;
diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index f37eb53de1a1..e227cd320b46 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -270,8 +270,8 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
 		ret = put_user(child->thread.debug.dac1, (u32 __user *)data);
 #else
 		dabr_fake = (
-			(child->thread.hw_brk.address & (~HW_BRK_TYPE_DABR)) |
-			(child->thread.hw_brk.type & HW_BRK_TYPE_DABR));
+			(child->thread.hw_brk[0].address & (~HW_BRK_TYPE_DABR)) |
+			(child->thread.hw_brk[0].type & HW_BRK_TYPE_DABR));
 		ret = put_user(dabr_fake, (u32 __user *)data);
 #endif
 		break;
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index 8bc6cc55420a..3116896e89a6 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -107,6 +107,9 @@ static void do_signal(struct task_struct *tsk)
 	struct ksignal ksig = { .sig = 0 };
 	int ret;
 	int is32 = is_32bit_task();
+#ifndef CONFIG_PPC_ADV_DEBUG_REGS
+	int i;
+#endif
 
 	BUG_ON(tsk != current);
 
@@ -128,8 +131,10 @@ static void do_signal(struct task_struct *tsk)
 	 * user space. The DABR will have been cleared if it
 	 * triggered inside the kernel.
 	 */
-	if (tsk->thread.hw_brk.address && tsk->thread.hw_brk.type)
-		__set_breakpoint(&tsk->thread.hw_brk, 0);
+	for (i = 0; i < nr_wp_slots(); i++) {
+		if (tsk->thread.hw_brk[i].address && tsk->thread.hw_brk[i].type)
+			__set_breakpoint(&tsk->thread.hw_brk[i], i);
+	}
 #endif
 	/* Re-enable the breakpoints for the signal stack */
 	thread_change_pc(tsk, tsk->thread.regs);
-- 
2.21.1