powerpc/watchpoint: Convert thread_struct->hw_brk to an array

So far powerpc hw supported only one watchpoint. But Power10 is
introducing 2nd DAWR. Convert thread_struct->hw_brk into an array.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-10-ravi.bangoria@linux.ibm.com

1 files changed, 29 insertions, 11 deletions

diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
index 12962302d6a4..0dbb35392dd2 100644
--- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c
+++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c
@@ -67,11 +67,16 @@ int ptrace_get_debugreg(struct task_struct *child, unsigned long addr,
 	/* We only support one DABR and no IABRS at the moment */
 	if (addr > 0)
 		return -EINVAL;
-	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));
 	return put_user(dabr_fake, datalp);
 }
 
+/*
+ * 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.
+ */
 int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned long data)
 {
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -137,7 +142,7 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
 			return ret;
 
 		thread->ptrace_bps[0] = bp;
-		thread->hw_brk = hw_brk;
+		thread->hw_brk[0] = hw_brk;
 		return 0;
 	}
 
@@ -159,12 +164,24 @@ int ptrace_set_debugreg(struct task_struct *task, unsigned long addr, unsigned l
 	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;
 	return 0;
 }
 
+static int find_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;
+}
+
 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;
@@ -223,15 +240,16 @@ long ppc_set_hwdebug(struct task_struct *child, struct ppc_hw_breakpoint *bp_inf
 	if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
 		return -EINVAL;
 
-	if (child->thread.hw_brk.address)
+	i = find_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;
 }
 
 long ppc_del_hwdebug(struct task_struct *child, long data)
@@ -241,7 +259,7 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
 	struct thread_struct *thread = &child->thread;
 	struct perf_event *bp;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
-	if (data != 1)
+	if (data < 1 || data > nr_wp_slots())
 		return -EINVAL;
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
@@ -254,11 +272,11 @@ long ppc_del_hwdebug(struct task_struct *child, long data)
 	}
 	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;