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[PATCH 5/5] perf/probe: Change MAX_CMDLEN

Started byRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
First post2017-02-02 12:20 +0100
Last post2017-02-07 06:50 +0100
Articles 3 — 2 participants

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  [PATCH 5/5] perf/probe: Change MAX_CMDLEN Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2017-02-02 12:20 +0100
    Re: [PATCH 5/5] perf/probe: Change MAX_CMDLEN Masami Hiramatsu <mhiramat@kernel.org> - 2017-02-07 02:50 +0100
      [PATCH v2] perf/probe: Change MAX_CMDLEN Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> - 2017-02-07 06:50 +0100

#1572282 — [PATCH 5/5] perf/probe: Change MAX_CMDLEN

FromRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Date2017-02-02 12:20 +0100
Subject[PATCH 5/5] perf/probe: Change MAX_CMDLEN
Message-ID<t6nAJ-3eT-9@gated-at.bofh.it>
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 beyond 256 characters, increase value of MAX_CMDLEN
to 512.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
---
 tools/perf/util/probe-event.c | 1 -
 tools/perf/util/probe-file.c  | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 2c1bca2..5f3256f 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..1580e26 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -29,7 +29,7 @@
 #include "session.h"
 #include "perf_regs.h"
 
-#define MAX_CMDLEN 256
+#define MAX_CMDLEN 512
 
 static void print_open_warning(int err, bool uprobe)
 {
-- 
2.9.3

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#1575320

FromMasami Hiramatsu <mhiramat@kernel.org>
Date2017-02-07 02:50 +0100
Message-ID<t834S-4uf-13@gated-at.bofh.it>
In reply to#1572282
On Thu,  2 Feb 2017 16:41:43 +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 beyond 256 characters, increase value of MAX_CMDLEN
> to 512.

OK, actually in the kernel side, it accepts up to 4094 (+"\n\0")
so it is a good time to expand it to 4094.
(I found another buggy message in kernel... will be fixed soon)

Thank you,

> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
> ---
>  tools/perf/util/probe-event.c | 1 -
>  tools/perf/util/probe-file.c  | 2 +-
>  2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 2c1bca2..5f3256f 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..1580e26 100644
> --- a/tools/perf/util/probe-file.c
> +++ b/tools/perf/util/probe-file.c
> @@ -29,7 +29,7 @@
>  #include "session.h"
>  #include "perf_regs.h"
>  
> -#define MAX_CMDLEN 256
> +#define MAX_CMDLEN 512
>  
>  static void print_open_warning(int err, bool uprobe)
>  {
> -- 
> 2.9.3
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

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#1575396 — [PATCH v2] perf/probe: Change MAX_CMDLEN

FromRavi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Date2017-02-07 06:50 +0100
Subject[PATCH v2] perf/probe: Change MAX_CMDLEN
Message-ID<t86P7-71B-5@gated-at.bofh.it>
In reply to#1575320
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.

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

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