tools lib traceevent: Fix string handling in heterogeneous arch environments

When a trace recorded on a 32-bit device is processed with a 64-bit
binary, the higher 32-bits of the address need to ignored.

The lack of this results in the output of the 64-bit pointer
value to the trace as the 32-bit address lookup fails in find_printk().

Before:

  burn-1778  [003]   548.600305: bputs:   0xc0046db2s: 2cec5c058d98c

After:

  burn-1778  [003]   548.600305: bputs:   0xc0046db2s: RT throttling activated

The problem occurs in PRINT_FIELD when the field is recognized as a
pointer to a string (of the type const char *)

Heterogeneous architectures cases below can arise and should be handled:

* Traces recorded using 32-bit addresses processed on a 64-bit machine
* Traces recorded using 64-bit addresses processed on a 32-bit machine

Reported-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Kapileshwar Singh <kapileshwar.singh@arm.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Javi Merino <javi.merino@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1442928123-13824-1-git-send-email-kapileshwar.singh@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 20 insertions, 3 deletions

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 4d885934b919..cf42b090477b 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -3795,7 +3795,7 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
         struct format_field *field;
         struct printk_map *printk;
         long long val, fval;
-        unsigned long addr;
+        unsigned long long addr;
         char *str;
         unsigned char *hex;
         int print;
@@ -3828,13 +3828,30 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
                  */
                 if (!(field->flags & FIELD_IS_ARRAY) &&
                     field->size == pevent->long_size) {
-                        addr = *(unsigned long *)(data + field->offset);
+
+                        /* Handle heterogeneous recording and processing
+                         * architectures
+                         *
+                         * CASE I:
+                         * Traces recorded on 32-bit devices (32-bit
+                         * addressing) and processed on 64-bit devices:
+                         * In this case, only 32 bits should be read.
+                         *
+                         * CASE II:
+                         * Traces recorded on 64 bit devices and processed
+                         * on 32-bit devices:
+                         * In this case, 64 bits must be read.
+                         */
+                        addr = (pevent->long_size == 8) ?
+                                *(unsigned long long *)(data + field->offset) :
+                                (unsigned long long)*(unsigned int *)(data + field->offset);
+
                         /* Check if it matches a print format */
                         printk = find_printk(pevent, addr);
                         if (printk)
                                 trace_seq_puts(s, printk->printk);
                         else
-                                trace_seq_printf(s, "%lx", addr);
+                                trace_seq_printf(s, "%llx", addr);
                         break;
                 }
                 str = malloc(len + 1);