ksym_tracer: Extract trace entry from struct trace_ksym

struct trace_ksym is used as an entry in hbp list, and is also
used as trace_entry stored in ring buffer.

This is not necessary and is a waste of memory in ring buffer.

There is also a bug that dereferencing field->ksym_hbp in
ksym_trace_output() can be invalid.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: "K.Prasad" <prasad@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <4A52E2A4.4050007@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 7d5cc37b8fcaf9d57a516f8601f81a3d0e9a47de..ff1ef411a1767a0a2ea7b271cfa9b67fa94bf3da 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -215,17 +215,12 @@ struct syscall_trace_exit {
 #define KSYM_SELFTEST_ENTRY "ksym_selftest_dummy"
 extern int process_new_ksym_entry(char *ksymname, int op, unsigned long addr);
 
-struct trace_ksym {
+struct ksym_trace_entry {
        struct trace_entry      ent;
-       struct hw_breakpoint    *ksym_hbp;
-       unsigned long           ksym_addr;
        unsigned long           ip;
-#ifdef CONFIG_PROFILE_KSYM_TRACER
-       unsigned long           counter;
-#endif
-       struct hlist_node       ksym_hlist;
+       unsigned char           type;
        char                    ksym_name[KSYM_NAME_LEN];
-       char                    p_name[TASK_COMM_LEN];
+       char                    cmd[TASK_COMM_LEN];
 };
 
 /*
@@ -343,7 +338,7 @@ extern void __ftrace_bad_type(void);
                          TRACE_SYSCALL_ENTER);                         \
                IF_ASSIGN(var, ent, struct syscall_trace_exit,          \
                          TRACE_SYSCALL_EXIT);                          \
-               IF_ASSIGN(var, ent, struct trace_ksym, TRACE_KSYM);     \
+               IF_ASSIGN(var, ent, struct ksym_trace_entry, TRACE_KSYM);\
                __ftrace_bad_type();                                    \
        } while (0)
 

diff --git a/kernel/trace/trace_ksym.c b/kernel/trace/trace_ksym.c
index eef97e7c8db7ce3f0fdd2438f6bb14ddbb8d23ce..085ff055fdfad6852fa6641d437abeaf7242cd10 100644 (file)
--- a/kernel/trace/trace_ksym.c
+++ b/kernel/trace/trace_ksym.c
@@ -37,6 +37,15 @@
 #define KSYM_TRACER_OP_LEN 3 /* rw- */
 #define KSYM_FILTER_ENTRY_LEN (KSYM_NAME_LEN + KSYM_TRACER_OP_LEN + 1)
 
+struct trace_ksym {
+       struct hw_breakpoint    *ksym_hbp;
+       unsigned long           ksym_addr;
+#ifdef CONFIG_PROFILE_KSYM_TRACER
+       unsigned long           counter;
+#endif
+       struct hlist_node       ksym_hlist;
+};
+
 static struct trace_array *ksym_trace_array;
 
 static unsigned int ksym_filter_entry_count;
@@ -71,7 +80,7 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
 {
        struct ring_buffer_event *event;
        struct trace_array *tr;
-       struct trace_ksym *entry;
+       struct ksym_trace_entry *entry;
        int pc;
 
        if (!ksym_tracing_enabled)
@@ -85,11 +94,12 @@ void ksym_hbp_handler(struct hw_breakpoint *hbp, struct pt_regs *regs)
        if (!event)
                return;
 
-       entry = ring_buffer_event_data(event);
+       entry           = ring_buffer_event_data(event);
+       entry->ip       = instruction_pointer(regs);
+       entry->type     = hbp->info.type;
        strlcpy(entry->ksym_name, hbp->info.name, KSYM_SYMBOL_LEN);
-       entry->ksym_hbp = hbp;
-       entry->ip = instruction_pointer(regs);
-       strlcpy(entry->p_name, current->comm, TASK_COMM_LEN);
+       strlcpy(entry->cmd, current->comm, TASK_COMM_LEN);
+
 #ifdef CONFIG_PROFILE_KSYM_TRACER
        ksym_collect_stats(hbp->info.address);
 #endif /* CONFIG_PROFILE_KSYM_TRACER */
@@ -380,7 +390,7 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
 {
        struct trace_entry *entry = iter->ent;
        struct trace_seq *s = &iter->seq;
-       struct trace_ksym *field;
+       struct ksym_trace_entry *field;
        char str[KSYM_SYMBOL_LEN];
        int ret;
 
@@ -389,12 +399,12 @@ static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
 
        trace_assign_type(field, entry);
 
-       ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->p_name,
+       ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->cmd,
                                entry->pid, iter->cpu, field->ksym_name);
        if (!ret)
                return TRACE_TYPE_PARTIAL_LINE;
 
-       switch (field->ksym_hbp->info.type) {
+       switch (field->type) {
        case HW_BREAKPOINT_WRITE:
                ret = trace_seq_printf(s, " W  ");
                break;