parse-events: Handle '*' in TP_printk format

When the "*" (next arg is length) is used in the TP_printk format,
it is currently not handled. This will cause a shift in the arguments
that are passed in causing all arguments after to be corrupted.

Reported-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 53 insertions, 13 deletions

diff --git a/parse-events.c b/parse-events.c
index 13c41aa..c0118aa 100644
--- a/parse-events.c
+++ b/parse-events.c
@@ -3042,12 +3042,14 @@ static unsigned long long eval_flag(const char *flag)
 }
 
 static void print_str_arg(struct trace_seq *s, void *data, int size,
-                          struct event_format *event, struct print_arg *arg)
+                          struct event_format *event,
+                          int len_arg, struct print_arg *arg)
 {
         struct pevent *pevent = event->pevent;
         struct print_flag_sym *flag;
         unsigned long long val, fval;
         unsigned long addr;
+        int len_as_arg = len_arg >= 0;
         char *str;
         int print;
         int len;
@@ -3082,7 +3084,10 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                 str = malloc_or_die(len + 1);
                 memcpy(str, data + arg->field.field->offset, len);
                 str[len] = 0;
-                trace_seq_puts(s, str);
+                if (len_as_arg)
+                        trace_seq_printf(s, "%.*s", len_arg, str);
+                else
+                        trace_seq_puts(s, str);
                 free(str);
                 break;
         case PRINT_FLAGS:
@@ -3091,13 +3096,19 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                 for (flag = arg->flags.flags; flag; flag = flag->next) {
                         fval = eval_flag(flag->value);
                         if (!val && !fval) {
-                                trace_seq_puts(s, flag->str);
+                                if (len_as_arg)
+                                        trace_seq_printf(s, "%.*s", len_arg, flag->str);
+                                else
+                                        trace_seq_puts(s, flag->str);
                                 break;
                         }
                         if (fval && (val & fval) == fval) {
                                 if (print && arg->flags.delim)
                                         trace_seq_puts(s, arg->flags.delim);
-                                trace_seq_puts(s, flag->str);
+                                if (len_as_arg)
+                                        trace_seq_printf(s, "%.*s", len_arg, flag->str);
+                                else
+                                        trace_seq_puts(s, flag->str);
                                 print = 1;
                                 val &= ~fval;
                         }
@@ -3108,7 +3119,10 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                 for (flag = arg->symbol.symbols; flag; flag = flag->next) {
                         fval = eval_flag(flag->value);
                         if (val == fval) {
-                                trace_seq_puts(s, flag->str);
+                                if (len_as_arg)
+                                        trace_seq_printf(s, "%.*s", len_arg, flag->str);
+                                else
+                                        trace_seq_puts(s, flag->str);
                                 break;
                         }
                 }
@@ -3127,7 +3141,10 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                 }
                 str_offset = data2host4(pevent, data + arg->string.offset);
                 str_offset &= 0xffff;
-                trace_seq_puts(s, ((char *)data) + str_offset);
+                if (len_as_arg)
+                        trace_seq_printf(s, "%.*s", len_arg, ((char *)data) + str_offset);
+                else
+                        trace_seq_puts(s, ((char *)data) + str_offset);
                 break;
         }
         case PRINT_OP:
@@ -3138,9 +3155,9 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                         return;
                 val = eval_num_arg(data, size, event, arg->op.left);
                 if (val)
-                        print_str_arg(s, data, size, event, arg->op.right->op.left);
+                        print_str_arg(s, data, size, event, len_arg, arg->op.right->op.left);
                 else
-                        print_str_arg(s, data, size, event, arg->op.right->op.right);
+                        print_str_arg(s, data, size, event, len_arg, arg->op.right->op.right);
                 break;
         case PRINT_FUNC:
                 process_defined_func(s, data, size, event, arg);
@@ -3185,7 +3202,7 @@ process_defined_func(struct trace_seq *s, void *data, int size,
                         break;
                 case PEVENT_FUNC_ARG_STRING:
                         trace_seq_init(&str);
-                        print_str_arg(&str, data, size, event, farg);
+                        print_str_arg(&str, data, size, event, -1, farg);
                         trace_seq_terminate(&str);
                         string = malloc_or_die(sizeof(*string));
                         string->next = strings;
@@ -3494,6 +3511,8 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
         char *bprint_fmt = NULL;
         char format[32];
         int show_func;
+        int len_as_arg;
+        int len_arg;
         int len;
         int ls;
 
@@ -3535,6 +3554,7 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
                 } else if (*ptr == '%') {
                         saveptr = ptr;
                         show_func = 0;
+                        len_as_arg = 0;
  cont_process:
                         ptr++;
                         switch (*ptr) {
@@ -3550,6 +3570,14 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
                         case 'L':
                                 ls = 2;
                                 goto cont_process;
+                        case '*':
+                                /* The argument is the length. */
+                                if (!arg)
+                                        die("no argument match");
+                                len_arg = eval_num_arg(data, size, event, arg);
+                                len_as_arg = 1;
+                                arg = arg->next;
+                                goto cont_process;
                         case '.':
                         case 'z':
                         case 'Z':
@@ -3617,13 +3645,23 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
                                 }
                                 switch (ls) {
                                 case 0:
-                                        trace_seq_printf(s, format, (int)val);
+                                        if (len_as_arg)
+                                                trace_seq_printf(s, format, len_arg, (int)val);
+                                        else
+                                                trace_seq_printf(s, format, (int)val);
                                         break;
                                 case 1:
-                                        trace_seq_printf(s, format, (long)val);
+                                        if (len_as_arg)
+                                                trace_seq_printf(s, format, len_arg, (long)val);
+                                        else
+                                                trace_seq_printf(s, format, (long)val);
                                         break;
                                 case 2:
-                                        trace_seq_printf(s, format, (long long)val);
+                                        if (len_as_arg)
+                                                trace_seq_printf(s, format, len_arg,
+                                                                 (long long)val);
+                                        else
+                                                trace_seq_printf(s, format, (long long)val);
                                         break;
                                 default:
                                         die("bad count (%d)", ls);
@@ -3633,7 +3671,9 @@ static void pretty_print(struct trace_seq *s, void *data, int size, struct event
                                 if (!arg)
                                         die("no matching argument");
 
-                                print_str_arg(s, data, size, event, arg);
+                                if (!len_as_arg)
+                                        len_arg = -1;
+                                print_str_arg(s, data, size, event, len_arg, arg);
                                 arg = arg->next;
                                 break;
                         default: