Em Mon, May 17, 2010 at 12:04:01PM +0200, Stephane Eranian escreveu:
> The -c option defines the user requested sampling period. It was implemented
> using an unsigned int variable but the type of the option was OPT_LONG.
> Thus,
> the option parser was overwriting memory belonging to other variables,
> namely
> the mmap_pages leading to a zero page sampling buffer. The bug was exposed
> only when compiling at -O0, probably because the compiler was padding
> variables at higher optimization levels.
Well spotted!
> This patch fixes this problem by declaring user_interval as u64. This also
> avoids wrap-around issues for large period on 32-bit systems.
>
> Signed-off-by: Stephane Eranian <eran...@google.com>
> --
> tools/perf/builtin-record.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 0f467cf..78f64cc 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -33,8 +33,8 @@ enum write_mode_t {
>
> static int *fd[MAX_NR_CPUS][MAX_COUNTERS];
>
> -static unsigned int user_interval = UINT_MAX;
> -static long default_interval = 0;
> +static u64 user_interval = ULLONG_MAX;
> +static u64 default_interval = 0;
The parsing code uses this for OPT_LONG:
case OPTION_LONG:
if (unset) {
*(long *)opt->value = 0;
return 0;
}
if (opt->flags & PARSE_OPT_OPTARG && !p->opt) {
*(long *)opt->value = opt->defval;
return 0;
}
if (get_arg(p, opt, flags, &arg))
return -1;
*(long *)opt->value = strtol(arg, (char **)&s, 10);
So I think we should augment the parsing code to have OPTION_ULONG, and,
for handling u64, OPTION_ULLONG.
I'll add that and then modify your patch to use it.
- Arnaldo
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