ftrace: add stack tracing

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 08fbef1..0d3714e 100644 (file)
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -93,6 +93,7 @@ static inline void tracer_disable(void)
 # define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))
 # define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))
 # define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))
+# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))
 #else
 # define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))
 # define CALLER_ADDR1 0UL
@@ -100,6 +101,7 @@ static inline void tracer_disable(void)
 # define CALLER_ADDR3 0UL
 # define CALLER_ADDR4 0UL
 # define CALLER_ADDR5 0UL
+# define CALLER_ADDR6 0UL
 #endif
 
 #ifdef CONFIG_IRQSOFF_TRACER

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 3f73a17..eb1988e 100644 (file)
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -10,6 +10,7 @@ config TRACER_MAX_TRACE
 config TRACING
        bool
        select DEBUG_FS
+       select STACKTRACE
 
 config FTRACE
        bool "Kernel Function Tracer"

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 192c135..b4b1b4f 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -28,6 +28,8 @@
 #include <linux/gfp.h>
 #include <linux/fs.h>
 
+#include <linux/stacktrace.h>
+
 #include "trace.h"
 
 unsigned long __read_mostly    tracing_max_latency = (cycle_t)ULONG_MAX;
@@ -88,6 +90,7 @@ enum trace_type {
        TRACE_FN,
        TRACE_CTX,
        TRACE_WAKE,
+       TRACE_STACK,
        TRACE_SPECIAL,
 
        __TRACE_LAST_TYPE
@@ -109,6 +112,7 @@ enum trace_iterator_flags {
        TRACE_ITER_HEX                  = 0x20,
        TRACE_ITER_BIN                  = 0x40,
        TRACE_ITER_BLOCK                = 0x80,
+       TRACE_ITER_STACKTRACE           = 0x100,
 };
 
 #define TRACE_ITER_SYM_MASK \
@@ -124,10 +128,11 @@ static const char *trace_options[] = {
        "hex",
        "bin",
        "block",
+       "stacktrace",
        NULL
 };
 
-static unsigned trace_flags;
+static unsigned trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_STACKTRACE;
 
 static DEFINE_SPINLOCK(ftrace_max_lock);
 
@@ -657,7 +662,7 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data,
        spin_unlock_irqrestore(&data->lock, irq_flags);
 
        if (!(trace_flags & TRACE_ITER_BLOCK))
-               wake_up (&trace_wait);
+               wake_up(&trace_wait);
 }
 
 void
@@ -685,13 +690,39 @@ trace_special(struct trace_array *tr, struct trace_array_cpu *data,
        spin_unlock_irqrestore(&data->lock, irq_flags);
 
        if (!(trace_flags & TRACE_ITER_BLOCK))
-               wake_up (&trace_wait);
+               wake_up(&trace_wait);
+}
+
+void __trace_stack(struct trace_array *tr,
+                  struct trace_array_cpu *data,
+                  unsigned long flags,
+                  int skip)
+{
+       struct trace_entry *entry;
+       struct stack_trace trace;
+
+       if (!(trace_flags & TRACE_ITER_STACKTRACE))
+               return;
+
+       entry                   = tracing_get_trace_entry(tr, data);
+       tracing_generic_entry_update(entry, flags);
+       entry->type             = TRACE_STACK;
+
+       memset(&entry->stack, 0, sizeof(entry->stack));
+
+       trace.nr_entries        = 0;
+       trace.max_entries       = FTRACE_STACK_ENTRIES;
+       trace.skip              = skip;
+       trace.entries           = entry->stack.caller;
+
+       save_stack_trace(&trace);
 }
 
 void
 tracing_sched_switch_trace(struct trace_array *tr,
                           struct trace_array_cpu *data,
-                          struct task_struct *prev, struct task_struct *next,
+                          struct task_struct *prev,
+                          struct task_struct *next,
                           unsigned long flags)
 {
        struct trace_entry *entry;
@@ -706,16 +737,18 @@ tracing_sched_switch_trace(struct trace_array *tr,
        entry->ctx.prev_state   = prev->state;
        entry->ctx.next_pid     = next->pid;
        entry->ctx.next_prio    = next->prio;
+       __trace_stack(tr, data, flags, 4);
        spin_unlock_irqrestore(&data->lock, irq_flags);
 
        if (!(trace_flags & TRACE_ITER_BLOCK))
-               wake_up (&trace_wait);
+               wake_up(&trace_wait);
 }
 
 void
 tracing_sched_wakeup_trace(struct trace_array *tr,
                           struct trace_array_cpu *data,
-                          struct task_struct *wakee, struct task_struct *curr,
+                          struct task_struct *wakee,
+                          struct task_struct *curr,
                           unsigned long flags)
 {
        struct trace_entry *entry;
@@ -730,6 +763,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr,
        entry->ctx.prev_state   = curr->state;
        entry->ctx.next_pid     = wakee->pid;
        entry->ctx.next_prio    = wakee->prio;
+       __trace_stack(tr, data, flags, 5);
        spin_unlock_irqrestore(&data->lock, irq_flags);
 
        if (!(trace_flags & TRACE_ITER_BLOCK))
@@ -1179,6 +1213,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
        unsigned long rel_usecs;
        char *comm;
        int S;
+       int i;
 
        if (!next_entry)
                next_entry = entry;
@@ -1197,8 +1232,10 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
                                 abs_usecs % 1000, rel_usecs/1000,
                                 rel_usecs % 1000);
        } else {
-               lat_print_generic(s, entry, cpu);
-               lat_print_timestamp(s, abs_usecs, rel_usecs);
+               if (entry->type != TRACE_STACK) {
+                       lat_print_generic(s, entry, cpu);
+                       lat_print_timestamp(s, abs_usecs, rel_usecs);
+               }
        }
        switch (entry->type) {
        case TRACE_FN:
@@ -1226,6 +1263,14 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu)
                                 entry->special.arg2,
                                 entry->special.arg3);
                break;
+       case TRACE_STACK:
+               for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+                       if (i)
+                               trace_seq_puts(s, " <= ");
+                       seq_print_ip_sym(s, entry->stack.caller[i], sym_flags);
+               }
+               trace_seq_puts(s, "\n");
+               break;
        default:
                trace_seq_printf(s, "Unknown type %d\n", entry->type);
        }
@@ -1241,8 +1286,9 @@ static int print_trace_fmt(struct trace_iterator *iter)
        unsigned long long t;
        unsigned long secs;
        char *comm;
-       int S;
        int ret;
+       int S;
+       int i;
 
        entry = iter->ent;
 
@@ -1252,15 +1298,17 @@ static int print_trace_fmt(struct trace_iterator *iter)
        usec_rem = do_div(t, 1000000ULL);
        secs = (unsigned long)t;
 
-       ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
-       if (!ret)
-               return 0;
-       ret = trace_seq_printf(s, "[%02d] ", iter->cpu);
-       if (!ret)
-               return 0;
-       ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
-       if (!ret)
-               return 0;
+       if (entry->type != TRACE_STACK) {
+               ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);
+               if (!ret)
+                       return 0;
+               ret = trace_seq_printf(s, "[%02d] ", iter->cpu);
+               if (!ret)
+                       return 0;
+               ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);
+               if (!ret)
+                       return 0;
+       }
 
        switch (entry->type) {
        case TRACE_FN:
@@ -1303,6 +1351,22 @@ static int print_trace_fmt(struct trace_iterator *iter)
                if (!ret)
                        return 0;
                break;
+       case TRACE_STACK:
+               for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {
+                       if (i) {
+                               ret = trace_seq_puts(s, " <= ");
+                               if (!ret)
+                                       return 0;
+                       }
+                       ret = seq_print_ip_sym(s, entry->stack.caller[i],
+                                              sym_flags);
+                       if (!ret)
+                               return 0;
+               }
+               ret = trace_seq_puts(s, "\n");
+               if (!ret)
+                       return 0;
+               break;
        }
        return 1;
 }
@@ -1344,6 +1408,7 @@ static int print_raw_fmt(struct trace_iterator *iter)
                        return 0;
                break;
        case TRACE_SPECIAL:
+       case TRACE_STACK:
                ret = trace_seq_printf(s, " %lx %lx %lx\n",
                                 entry->special.arg1,
                                 entry->special.arg2,
@@ -1399,6 +1464,7 @@ static int print_hex_fmt(struct trace_iterator *iter)
                SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);
                break;
        case TRACE_SPECIAL:
+       case TRACE_STACK:
                SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg1);
                SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg2);
                SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg3);
@@ -1433,6 +1499,7 @@ static int print_bin_fmt(struct trace_iterator *iter)
                SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);
                break;
        case TRACE_SPECIAL:
+       case TRACE_STACK:
                SEQ_PUT_FIELD_RET(s, entry->special.arg1);
                SEQ_PUT_FIELD_RET(s, entry->special.arg2);
                SEQ_PUT_FIELD_RET(s, entry->special.arg3);

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 90e0ba0..387bdcf 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -34,6 +34,16 @@ struct special_entry {
        unsigned long           arg3;
 };
 
+/*
+ * Stack-trace entry:
+ */
+
+#define FTRACE_STACK_ENTRIES   5
+
+struct stack_entry {
+       unsigned long           caller[FTRACE_STACK_ENTRIES];
+};
+
 /*
  * The trace entry - the most basic unit of tracing. This is what
  * is printed in the end as a single line in the trace output, such as:
@@ -51,6 +61,7 @@ struct trace_entry {
                struct ftrace_entry             fn;
                struct ctx_switch_entry         ctx;
                struct special_entry            special;
+               struct stack_entry              stack;
        };
 };