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SubjectRe: [PATCH v2] perf/probe: Change MAX_CMDLEN
On Tue,  7 Feb 2017 11:15:47 +0530
Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> wrote:

> There are many SDT markers in powerpc whose uprobe definition goes
> beyond current MAX_CMDLEN, especially when target filename is long
> and sdt marker has long list of arguments. For example, definition
> of sdt marker
>
> method__compile__end: 8@17 8@9 8@10 -4@8 8@7 -4@6 8@5 -4@4 1@37(28)
>
> from file
>
> /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.91-2.b14.fc22.ppc64/jre/lib/\
> ppc64/server/libjvm.so
>
> is
>
> p:sdt_hotspot/method__compile__end /usr/lib/jvm/java-1.8.0-openjdk-\
> 1.8.0.91-2.b14.fc22.ppc64/jre/lib/ppc64/server/libjvm.so:0x4c4e00\
> arg1=%gpr17:u64 arg2=%gpr9:u64 arg3=%gpr10:u64 arg4=%gpr8:s32\
> arg5=%gpr7:u64 arg6=%gpr6:s32 arg7=%gpr5:u64 arg8=%gpr4:s32\
> arg9=+37(%gpr28):u8
>
> Perf probe fails with seg fault for such markers. As uprobe_events file
> accepts definition upto 4094 characters(4096 - 2 (\n\0)), increase value
> of MAX_CMDLEN to 4094.

This looks good to me.

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

Thanks,

>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
> ---
> Changes in v2:
> - Set MAX_CMDLEN to 4094 instead of 512
>
> tools/perf/util/probe-event.c | 1 -
> tools/perf/util/probe-file.c | 3 ++-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6a6f44d..e6e3244 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -47,7 +47,6 @@
> #include "probe-file.h"
> #include "session.h"
>
> -#define MAX_CMDLEN 256
> #define PERFPROBE_GROUP "probe"
>
> bool probe_event_dry_run; /* Dry run flag */
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 38eca3c..fdabe7e 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -29,7 +29,8 @@
> #include "session.h"
> #include "perf_regs.h"
>
> -#define MAX_CMDLEN 256
> +/* 4096 - 2 ('\n' + '\0') */
> +#define MAX_CMDLEN 4094
>
> static void print_open_warning(int err, bool uprobe)
> {
> --
> 2.9.3
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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