ftrace: mmiotrace, updates

here is a patch that makes mmiotrace work almost well within the tracing
framework. The patch applies on top of my previous patch. I have my own
output formatting in place now.

Summary of changes:
- fix the NULL dereference that was due to not calling tracing_reset()
- add print_line() callback into struct tracer
- implement print_line() for mmiotrace, producing up-to-spec text
- add my output header, but that is not really called in the right place
- rewrote the main structs in mmiotrace
- added two new trace entry types: TRACE_MMIO_RW and TRACE_MMIO_MAP
- made some functions in trace.c non-static
- check current==NULL in tracing_generic_entry_update()
- fix(?) comparison in trace_seq_printf()

Things seem to work fine except a few issues. Markers (text lines injected
into mmiotrace log) are missing, I did not feel hacking them in before we
have variable length entries. My output header is printed only for 'trace'
file, but not 'trace_pipe'. For some reason, despite my quick fix,
iter->trace is NULL in print_trace_line() when called from 'trace_pipe'
file, which means I don't get proper output formatting.

I only tried by loading nouveau.ko, which just detects the card, and that
is traced fine. I didn't try further. Map, two reads and unmap. Works
perfectly.

I am missing the information about overflows, I'd prefer to have a
counter for lost events. I didn't try, but I guess currently there is no
way of knowning when it overflows?

So, not too far from being fully operational, it seems :-)
And looking at the diffstat, there also is some 700-900 lines of user space
code that just became obsolete.

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

3 files changed, 171 insertions, 28 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3271916ff033..d14fe49e9638 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -831,6 +831,40 @@ ftrace(struct trace_array *tr, struct trace_array_cpu *data,
                 trace_function(tr, data, ip, parent_ip, flags);
 }
 
+#ifdef CONFIG_MMIOTRACE
+void __trace_mmiotrace_rw(struct trace_array *tr, struct trace_array_cpu *data,
+                                                struct mmiotrace_rw *rw)
+{
+        struct trace_entry *entry;
+        unsigned long irq_flags;
+
+        spin_lock_irqsave(&data->lock, irq_flags);
+        entry                   = tracing_get_trace_entry(tr, data);
+        tracing_generic_entry_update(entry, 0);
+        entry->type             = TRACE_MMIO_RW;
+        entry->mmiorw           = *rw;
+        spin_unlock_irqrestore(&data->lock, irq_flags);
+
+        trace_wake_up();
+}
+
+void __trace_mmiotrace_map(struct trace_array *tr, struct trace_array_cpu *data,
+                                                struct mmiotrace_map *map)
+{
+        struct trace_entry *entry;
+        unsigned long irq_flags;
+
+        spin_lock_irqsave(&data->lock, irq_flags);
+        entry                   = tracing_get_trace_entry(tr, data);
+        tracing_generic_entry_update(entry, 0);
+        entry->type             = TRACE_MMIO_MAP;
+        entry->mmiomap          = *map;
+        spin_unlock_irqrestore(&data->lock, irq_flags);
+
+        trace_wake_up();
+}
+#endif
+
 void __trace_stack(struct trace_array *tr,
                    struct trace_array_cpu *data,
                    unsigned long flags,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index c460e85e94ed..0ef9ef74c806 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -5,6 +5,7 @@
 #include <asm/atomic.h>
 #include <linux/sched.h>
 #include <linux/clocksource.h>
+#include <linux/mmiotrace.h>
 
 enum trace_type {
         __TRACE_FIRST_TYPE = 0,
@@ -14,6 +15,8 @@ enum trace_type {
         TRACE_WAKE,
         TRACE_STACK,
         TRACE_SPECIAL,
+        TRACE_MMIO_RW,
+        TRACE_MMIO_MAP,
 
         __TRACE_LAST_TYPE
 };
@@ -75,6 +78,8 @@ struct trace_entry {
                 struct ctx_switch_entry         ctx;
                 struct special_entry            special;
                 struct stack_entry              stack;
+                struct mmiotrace_rw             mmiorw;
+                struct mmiotrace_map            mmiomap;
         };
 };
 
@@ -255,6 +260,15 @@ extern unsigned long ftrace_update_tot_cnt;
 extern int DYN_FTRACE_TEST_NAME(void);
 #endif
 
+#ifdef CONFIG_MMIOTRACE
+extern void __trace_mmiotrace_rw(struct trace_array *tr,
+                                struct trace_array_cpu *data,
+                                struct mmiotrace_rw *rw);
+extern void __trace_mmiotrace_map(struct trace_array *tr,
+                                struct trace_array_cpu *data,
+                                struct mmiotrace_map *map);
+#endif
+
 #ifdef CONFIG_FTRACE_STARTUP_TEST
 #ifdef CONFIG_FTRACE
 extern int trace_selftest_startup_function(struct tracer *trace,
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index e4dd03cc5aa6..3a12b1ad0c63 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -11,19 +11,26 @@
 
 #include "trace.h"
 
-extern void
-__trace_special(void *__tr, void *__data,
-                unsigned long arg1, unsigned long arg2, unsigned long arg3);
-
 static struct trace_array *mmio_trace_array;
 
+static void mmio_reset_data(struct trace_array *tr)
+{
+        int cpu;
+
+        tr->time_start = ftrace_now(tr->cpu);
+
+        for_each_online_cpu(cpu)
+                tracing_reset(tr->data[cpu]);
+}
 
 static void mmio_trace_init(struct trace_array *tr)
 {
         pr_debug("in %s\n", __func__);
         mmio_trace_array = tr;
-        if (tr->ctrl)
+        if (tr->ctrl) {
+                mmio_reset_data(tr);
                 enable_mmiotrace();
+        }
 }
 
 static void mmio_trace_reset(struct trace_array *tr)
@@ -31,15 +38,110 @@ static void mmio_trace_reset(struct trace_array *tr)
         pr_debug("in %s\n", __func__);
         if (tr->ctrl)
                 disable_mmiotrace();
+        mmio_reset_data(tr);
+        mmio_trace_array = NULL;
 }
 
 static void mmio_trace_ctrl_update(struct trace_array *tr)
 {
         pr_debug("in %s\n", __func__);
-        if (tr->ctrl)
+        if (tr->ctrl) {
+                mmio_reset_data(tr);
                 enable_mmiotrace();
-        else
+        } else {
                 disable_mmiotrace();
+        }
+}
+
+/* XXX: This is not called for trace_pipe file! */
+void mmio_print_header(struct trace_iterator *iter)
+{
+        struct trace_seq *s = &iter->seq;
+        trace_seq_printf(s, "VERSION broken 20070824\n");
+        /* TODO: print /proc/bus/pci/devices contents as PCIDEV lines */
+}
+
+static int mmio_print_rw(struct trace_iterator *iter)
+{
+        struct trace_entry *entry = iter->ent;
+        struct mmiotrace_rw *rw = &entry->mmiorw;
+        struct trace_seq *s     = &iter->seq;
+        unsigned long long t    = ns2usecs(entry->t);
+        unsigned long usec_rem  = do_div(t, 1000000ULL);
+        unsigned secs           = (unsigned long)t;
+        int ret = 1;
+
+        switch (entry->mmiorw.opcode) {
+        case MMIO_READ:
+                ret = trace_seq_printf(s,
+                        "R %d %lu.%06lu %d 0x%lx 0x%lx 0x%lx %d\n",
+                        rw->width, secs, usec_rem, rw->map_id, rw->phys,
+                        rw->value, rw->pc, entry->pid);
+                break;
+        case MMIO_WRITE:
+                ret = trace_seq_printf(s,
+                        "W %d %lu.%06lu %d 0x%lx 0x%lx 0x%lx %d\n",
+                        rw->width, secs, usec_rem, rw->map_id, rw->phys,
+                        rw->value, rw->pc, entry->pid);
+                break;
+        case MMIO_UNKNOWN_OP:
+                ret = trace_seq_printf(s,
+                        "UNKNOWN %lu.%06lu %d 0x%lx %02x,%02x,%02x 0x%lx %d\n",
+                        secs, usec_rem, rw->map_id, rw->phys,
+                        (rw->value >> 16) & 0xff, (rw->value >> 8) & 0xff,
+                        (rw->value >> 0) & 0xff, rw->pc, entry->pid);
+                break;
+        default:
+                ret = trace_seq_printf(s, "rw what?\n");
+                break;
+        }
+        if (ret)
+                return 1;
+        return 0;
+}
+
+static int mmio_print_map(struct trace_iterator *iter)
+{
+        struct trace_entry *entry = iter->ent;
+        struct mmiotrace_map *m = &entry->mmiomap;
+        struct trace_seq *s     = &iter->seq;
+        unsigned long long t    = ns2usecs(entry->t);
+        unsigned long usec_rem  = do_div(t, 1000000ULL);
+        unsigned secs           = (unsigned long)t;
+        int ret = 1;
+
+        switch (entry->mmiorw.opcode) {
+        case MMIO_PROBE:
+                ret = trace_seq_printf(s,
+                        "MAP %lu.%06lu %d 0x%lx 0x%lx 0x%lx 0x%lx %d\n",
+                        secs, usec_rem, m->map_id, m->phys, m->virt, m->len,
+                        0UL, entry->pid);
+                break;
+        case MMIO_UNPROBE:
+                ret = trace_seq_printf(s,
+                        "UNMAP %lu.%06lu %d 0x%lx %d\n",
+                        secs, usec_rem, m->map_id, 0UL, entry->pid);
+                break;
+        default:
+                ret = trace_seq_printf(s, "map what?\n");
+                break;
+        }
+        if (ret)
+                return 1;
+        return 0;
+}
+
+/* return 0 to abort printing without consuming current entry in pipe mode */
+static int mmio_print_line(struct trace_iterator *iter)
+{
+        switch (iter->ent->type) {
+        case TRACE_MMIO_RW:
+                return mmio_print_rw(iter);
+        case TRACE_MMIO_MAP:
+                return mmio_print_map(iter);
+        default:
+                return 1; /* ignore unknown entries */
+        }
 }
 
 static struct tracer mmio_tracer __read_mostly =
@@ -47,38 +149,31 @@ static struct tracer mmio_tracer __read_mostly =
         .name           = "mmiotrace",
         .init           = mmio_trace_init,
         .reset          = mmio_trace_reset,
+        .open           = mmio_print_header,
         .ctrl_update    = mmio_trace_ctrl_update,
+        .print_line     = mmio_print_line,
 };
 
 __init static int init_mmio_trace(void)
 {
-        int ret = init_mmiotrace();
-        if (ret)
-                return ret;
         return register_tracer(&mmio_tracer);
 }
 device_initcall(init_mmio_trace);
 
-void mmio_trace_record(u32 type, unsigned long addr, unsigned long arg)
+void mmio_trace_rw(struct mmiotrace_rw *rw)
 {
         struct trace_array *tr = mmio_trace_array;
         struct trace_array_cpu *data = tr->data[smp_processor_id()];
+        __trace_mmiotrace_rw(tr, data, rw);
+}
 
-        if (!current || current->pid == 0) {
-                /*
-                 * XXX: This is a problem. We need to able to record, no
-                 * matter what. tracing_generic_entry_update() would crash.
-                 */
-                static unsigned limit;
-                if (limit++ < 12)
-                        pr_err("Error in %s: no current.\n", __func__);
-                return;
-        }
-        if (!tr || !data) {
-                static unsigned limit;
-                if (limit++ < 12)
-                        pr_err("%s: no tr or data\n", __func__);
-                return;
-        }
-        __trace_special(tr, data, type, addr, arg);
+void mmio_trace_mapping(struct mmiotrace_map *map)
+{
+        struct trace_array *tr = mmio_trace_array;
+        struct trace_array_cpu *data;
+
+        preempt_disable();
+        data = tr->data[smp_processor_id()];
+        __trace_mmiotrace_map(tr, data, map);
+        preempt_enable();
 }