ARM: hw_breakpoint: check if monitor mode is enabled during validation

[firefly-linux-kernel-4.4.55.git] / arch / arm / kernel / hw_breakpoint.c

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 983558eb90234acef1df7d4b9bec208e9fc89c1e..8e9532152bd9bc046fe2560f8240e446639c07af 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -228,6 +228,13 @@ static int get_num_brps(void)
  * be put into halting debug mode at any time by an external debugger
  * but there is nothing we can do to prevent that.
  */
+static int monitor_mode_enabled(void)
+{
+       u32 dscr;
+       ARM_DBG_READ(c1, 0, dscr);
+       return !!(dscr & ARM_DSCR_MDBGEN);
+}
+
 static int enable_monitor_mode(void)
 {
        u32 dscr;
@@ -321,14 +328,9 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 {
        struct arch_hw_breakpoint *info = counter_arch_bp(bp);
        struct perf_event **slot, **slots;
-       int i, max_slots, ctrl_base, val_base, ret = 0;
+       int i, max_slots, ctrl_base, val_base;
        u32 addr, ctrl;
 
-       /* Ensure that we are in monitor mode and halting mode is disabled. */
-       ret = enable_monitor_mode();
-       if (ret)
-               goto out;
-
        addr = info->address;
        ctrl = encode_ctrl_reg(info->ctrl) | 0x1;
 
@@ -355,10 +357,8 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
                }
        }
 
-       if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n")) {
-               ret = -EBUSY;
-               goto out;
-       }
+       if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot\n"))
+               return -EBUSY;
 
        /* Override the breakpoint data with the step data. */
        if (info->step_ctrl.enabled) {
@@ -376,9 +376,7 @@ int arch_install_hw_breakpoint(struct perf_event *bp)
 
        /* Setup the control register. */
        write_wb_reg(ctrl_base + i, ctrl);
-
-out:
-       return ret;
+       return 0;
 }
 
 void arch_uninstall_hw_breakpoint(struct perf_event *bp)
@@ -589,6 +587,10 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp)
        int ret = 0;
        u32 offset, alignment_mask = 0x3;
 
+       /* Ensure that we are in monitor debug mode. */
+       if (!monitor_mode_enabled())
+               return -ENODEV;
+
        /* Build the arch_hw_breakpoint. */
        ret = arch_build_bp_info(bp);
        if (ret)