[PATCH 10/15] powerpc/watchpoint: Use loop for thread_struct->ptrace_bps

[Ravi Bangoria]

ptrace_bps is already an array of size HBP_NUM_MAX. But we use
hardcoded index 0 while fetching/updating it. Convert such code
to loop over array.

Signed-off-by: Ravi Bangoria <ravi.bango...@linux.ibm.com>
---
 arch/powerpc/kernel/hw_breakpoint.c |  7 +++++--
 arch/powerpc/kernel/process.c       |  6 +++++-
 arch/powerpc/kernel/ptrace.c        | 28 +++++++++++++++++++++-------
 3 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/hw_breakpoint.c 
b/arch/powerpc/kernel/hw_breakpoint.c
index f4d48f87dcb8..b27aca623267 100644
--- a/arch/powerpc/kernel/hw_breakpoint.c
+++ b/arch/powerpc/kernel/hw_breakpoint.c
@@ -419,10 +419,13 @@ NOKPROBE_SYMBOL(hw_breakpoint_exceptions_notify);
  */
 void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
 {
+       int i;
        struct thread_struct *t = &tsk->thread;
 
-       unregister_hw_breakpoint(t->ptrace_bps[0]);
-       t->ptrace_bps[0] = NULL;
+       for (i = 0; i < nr_wp_slots(); i++) {
+               unregister_hw_breakpoint(t->ptrace_bps[i]);
+               t->ptrace_bps[i] = NULL;
+       }
 }
 
 void hw_breakpoint_pmu_read(struct perf_event *bp)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 42ff62ef749c..b9ab740fcacf 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1628,6 +1628,9 @@ int copy_thread_tls(unsigned long clone_flags, unsigned 
long usp,
        void (*f)(void);
        unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
        struct thread_info *ti = task_thread_info(p);
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+       int i;
+#endif
 
        klp_init_thread_info(p);
 
@@ -1687,7 +1690,8 @@ int copy_thread_tls(unsigned long clone_flags, unsigned 
long usp,
        p->thread.ksp_limit = (unsigned long)end_of_stack(p);
 #endif
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-       p->thread.ptrace_bps[0] = NULL;
+       for (i = 0; i < nr_wp_slots(); i++)
+               p->thread.ptrace_bps[i] = NULL;
 #endif
 
        p->thread.fp_save_area = NULL;
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index f6d7955fc61e..e2651f86d56f 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -2829,6 +2829,19 @@ static int set_dac_range(struct task_struct *child,
 }
 #endif /* CONFIG_PPC_ADV_DEBUG_DAC_RANGE */
 
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static int empty_ptrace_bp(struct thread_struct *thread)
+{
+       int i;
+
+       for (i = 0; i < nr_wp_slots(); i++) {
+               if (!thread->ptrace_bps[i])
+                       return i;
+       }
+       return -1;
+}
+#endif
+
 #ifndef CONFIG_PPC_ADV_DEBUG_REGS
 static int empty_hw_brk(struct thread_struct *thread)
 {
@@ -2915,8 +2928,9 @@ static long ppc_set_hwdebug(struct task_struct *child,
                len = 1;
        else
                return -EINVAL;
-       bp = thread->ptrace_bps[0];
-       if (bp)
+
+       i = empty_ptrace_bp(thread);
+       if (i < 0)
                return -ENOSPC;
 
        /* Create a new breakpoint request if one doesn't exist already */
@@ -2925,14 +2939,14 @@ static long ppc_set_hwdebug(struct task_struct *child,
        attr.bp_len = len;
        arch_bp_generic_fields(brk.type, &attr.bp_type);
 
-       thread->ptrace_bps[0] = bp = register_user_hw_breakpoint(&attr,
+       thread->ptrace_bps[i] = bp = register_user_hw_breakpoint(&attr,
                                               ptrace_triggered, NULL, child);
        if (IS_ERR(bp)) {
-               thread->ptrace_bps[0] = NULL;
+               thread->ptrace_bps[i] = NULL;
                return PTR_ERR(bp);
        }
 
-       return 1;
+       return i + 1;
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
 
        if (bp_info->addr_mode != PPC_BREAKPOINT_MODE_EXACT)
@@ -2979,10 +2993,10 @@ static long ppc_del_hwdebug(struct task_struct *child, 
long data)
                return -EINVAL;
 
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-       bp = thread->ptrace_bps[0];
+       bp = thread->ptrace_bps[data - 1];
        if (bp) {
                unregister_hw_breakpoint(bp);
-               thread->ptrace_bps[0] = NULL;
+               thread->ptrace_bps[data - 1] = NULL;
        } else
                ret = -ENOENT;
        return ret;
-- 
2.21.1