1 files changed, 121 insertions, 13 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c75d7988902c..57d7e5397d56 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -287,20 +287,62 @@ struct tracer {
         struct tracer_flags     *flags;
         bool                    print_max;
         bool                    use_max_tr;
+        bool                    allocated_snapshot;
 };
 
 
 /* Only current can touch trace_recursion */
-#define trace_recursion_inc() do { (current)->trace_recursion++; } while (0)
-#define trace_recursion_dec() do { (current)->trace_recursion--; } while (0)
 
-/* Ring buffer has the 10 LSB bits to count */
-#define trace_recursion_buffer() ((current)->trace_recursion & 0x3ff)
-
-/* for function tracing recursion */
-#define TRACE_INTERNAL_BIT              (1<<11)
-#define TRACE_GLOBAL_BIT                (1<<12)
-#define TRACE_CONTROL_BIT               (1<<13)
+/*
+ * For function tracing recursion:
+ *  The order of these bits are important.
+ *
+ *  When function tracing occurs, the following steps are made:
+ *   If arch does not support a ftrace feature:
+ *    call internal function (uses INTERNAL bits) which calls...
+ *   If callback is registered to the "global" list, the list
+ *    function is called and recursion checks the GLOBAL bits.
+ *    then this function calls...
+ *   The function callback, which can use the FTRACE bits to
+ *    check for recursion.
+ *
+ * Now if the arch does not suppport a feature, and it calls
+ * the global list function which calls the ftrace callback
+ * all three of these steps will do a recursion protection.
+ * There's no reason to do one if the previous caller already
+ * did. The recursion that we are protecting against will
+ * go through the same steps again.
+ *
+ * To prevent the multiple recursion checks, if a recursion
+ * bit is set that is higher than the MAX bit of the current
+ * check, then we know that the check was made by the previous
+ * caller, and we can skip the current check.
+ */
+enum {
+        TRACE_BUFFER_BIT,
+        TRACE_BUFFER_NMI_BIT,
+        TRACE_BUFFER_IRQ_BIT,
+        TRACE_BUFFER_SIRQ_BIT,
+
+        /* Start of function recursion bits */
+        TRACE_FTRACE_BIT,
+        TRACE_FTRACE_NMI_BIT,
+        TRACE_FTRACE_IRQ_BIT,
+        TRACE_FTRACE_SIRQ_BIT,
+
+        /* GLOBAL_BITs must be greater than FTRACE_BITs */
+        TRACE_GLOBAL_BIT,
+        TRACE_GLOBAL_NMI_BIT,
+        TRACE_GLOBAL_IRQ_BIT,
+        TRACE_GLOBAL_SIRQ_BIT,
+
+        /* INTERNAL_BITs must be greater than GLOBAL_BITs */
+        TRACE_INTERNAL_BIT,
+        TRACE_INTERNAL_NMI_BIT,
+        TRACE_INTERNAL_IRQ_BIT,
+        TRACE_INTERNAL_SIRQ_BIT,
+
+        TRACE_CONTROL_BIT,
 
 /*
  * Abuse of the trace_recursion.
@@ -309,11 +351,77 @@ struct tracer {
  * was called in irq context but we have irq tracing off. Since this
  * can only be modified by current, we can reuse trace_recursion.
  */
-#define TRACE_IRQ_BIT                   (1<<13)
+        TRACE_IRQ_BIT,
+};
+
+#define trace_recursion_set(bit)        do { (current)->trace_recursion |= (1<<(bit)); } while (0)
+#define trace_recursion_clear(bit)      do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
+#define trace_recursion_test(bit)       ((current)->trace_recursion & (1<<(bit)))
+
+#define TRACE_CONTEXT_BITS      4
+
+#define TRACE_FTRACE_START      TRACE_FTRACE_BIT
+#define TRACE_FTRACE_MAX        ((1 << (TRACE_FTRACE_START + TRACE_CONTEXT_BITS)) - 1)
+
+#define TRACE_GLOBAL_START      TRACE_GLOBAL_BIT
+#define TRACE_GLOBAL_MAX        ((1 << (TRACE_GLOBAL_START + TRACE_CONTEXT_BITS)) - 1)
+
+#define TRACE_LIST_START        TRACE_INTERNAL_BIT
+#define TRACE_LIST_MAX          ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)
+
+#define TRACE_CONTEXT_MASK      TRACE_LIST_MAX
+
+static __always_inline int trace_get_context_bit(void)
+{
+        int bit;
 
-#define trace_recursion_set(bit)        do { (current)->trace_recursion |= (bit); } while (0)
-#define trace_recursion_clear(bit)      do { (current)->trace_recursion &= ~(bit); } while (0)
-#define trace_recursion_test(bit)       ((current)->trace_recursion & (bit))
+        if (in_interrupt()) {
+                if (in_nmi())
+                        bit = 0;
+
+                else if (in_irq())
+                        bit = 1;
+                else
+                        bit = 2;
+        } else
+                bit = 3;
+
+        return bit;
+}
+
+static __always_inline int trace_test_and_set_recursion(int start, int max)
+{
+        unsigned int val = current->trace_recursion;
+        int bit;
+
+        /* A previous recursion check was made */
+        if ((val & TRACE_CONTEXT_MASK) > max)
+                return 0;
+
+        bit = trace_get_context_bit() + start;
+        if (unlikely(val & (1 << bit)))
+                return -1;
+
+        val |= 1 << bit;
+        current->trace_recursion = val;
+        barrier();
+
+        return bit;
+}
+
+static __always_inline void trace_clear_recursion(int bit)
+{
+        unsigned int val = current->trace_recursion;
+
+        if (!bit)
+                return;
+
+        bit = 1 << bit;
+        val &= ~bit;
+
+        barrier();
+        current->trace_recursion = val;
+}
 
 #define TRACE_PIPE_ALL_CPU      -1