[tip:perf/core] tools lib traceevent: Fix string handling in heterogeneous arch environments

From: tip-bot for Kapileshwar Singh
Date: Wed Sep 23 2015 - 04:46:01 EST


Commit-ID: c2e4b24ff848bb180f9b9cd873a38327cd219ad2
Gitweb: http://git.kernel.org/tip/c2e4b24ff848bb180f9b9cd873a38327cd219ad2
Author: Kapileshwar Singh <kapileshwar.singh@xxxxxxx>
AuthorDate: Tue, 22 Sep 2015 14:22:03 +0100
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 22 Sep 2015 11:57:04 -0300

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@xxxxxxx>
Signed-off-by: Kapileshwar Singh <kapileshwar.singh@xxxxxxx>
Reviewed-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Javi Merino <javi.merino@xxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1442928123-13824-1-git-send-email-kapileshwar.singh@xxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/lib/traceevent/event-parse.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 4d88593..cf42b09 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);
--
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