Re: [PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Madhavan Srinivasan]

Hi Arnaldo,

Any updates for this fix. Kindly let me know.

Maddy

On Tuesday 28 June 2016 02:24 PM, Jiri Olsa wrote:
> On Thu, Jun 23, 2016 at 11:19:27AM +0530, Madhavan Srinivasan wrote:
>
> SNIP
>
>> Changelog v1:
>> 1)updated commit message and patch subject
>> 2)Add the fix to print_sample_iregs() in builtin-script.c
>>
>>  tools/include/linux/bitmap.h |  2 ++
>>  tools/lib/bitmap.c   | 18 ++
>>  tools/perf/builtin-script.c  |  4 +++-
>>  tools/perf/util/session.c|  4 +++-
>>  4 files changed, 26 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
>> index 28f5493da491..5e98525387dc 100644
>> --- a/tools/include/linux/bitmap.h
>> +++ b/tools/include/linux/bitmap.h
>> @@ -2,6 +2,7 @@
>>  #define _PERF_BITOPS_H
>>  
>>  #include 
>> +#include 
> this could go in the bitmap.c file, but anyway:
>
> Acked-by: Jiri Olsa 
>
> thanks,
> jirka
>
>>  #include 
>>  
>>  #define DECLARE_BITMAP(name,bits) \
>> @@ -10,6 +11,7 @@
>>  int __bitmap_weight(const unsigned long *bitmap, int bits);
>>  void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
>>   const unsigned long *bitmap2, int bits);
>> +void bitmap_from_u64(unsigned long *dst, u64 mask);
>>  
>>  #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 
>> 1)))
>>  
> SNIP
>

Re: [PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Madhavan Srinivasan]

Hi Arnaldo,

Any updates for this fix. Kindly let me know.

Maddy

On Tuesday 28 June 2016 02:24 PM, Jiri Olsa wrote:
> On Thu, Jun 23, 2016 at 11:19:27AM +0530, Madhavan Srinivasan wrote:
>
> SNIP
>
>> Changelog v1:
>> 1)updated commit message and patch subject
>> 2)Add the fix to print_sample_iregs() in builtin-script.c
>>
>>  tools/include/linux/bitmap.h |  2 ++
>>  tools/lib/bitmap.c   | 18 ++
>>  tools/perf/builtin-script.c  |  4 +++-
>>  tools/perf/util/session.c|  4 +++-
>>  4 files changed, 26 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
>> index 28f5493da491..5e98525387dc 100644
>> --- a/tools/include/linux/bitmap.h
>> +++ b/tools/include/linux/bitmap.h
>> @@ -2,6 +2,7 @@
>>  #define _PERF_BITOPS_H
>>  
>>  #include 
>> +#include 
> this could go in the bitmap.c file, but anyway:
>
> Acked-by: Jiri Olsa 
>
> thanks,
> jirka
>
>>  #include 
>>  
>>  #define DECLARE_BITMAP(name,bits) \
>> @@ -10,6 +11,7 @@
>>  int __bitmap_weight(const unsigned long *bitmap, int bits);
>>  void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
>>   const unsigned long *bitmap2, int bits);
>> +void bitmap_from_u64(unsigned long *dst, u64 mask);
>>  
>>  #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 
>> 1)))
>>  
> SNIP
>

Re: [PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Jiri Olsa]

On Thu, Jun 23, 2016 at 11:19:27AM +0530, Madhavan Srinivasan wrote:

SNIP

> 
> Changelog v1:
> 1)updated commit message and patch subject
> 2)Add the fix to print_sample_iregs() in builtin-script.c
> 
>  tools/include/linux/bitmap.h |  2 ++
>  tools/lib/bitmap.c   | 18 ++
>  tools/perf/builtin-script.c  |  4 +++-
>  tools/perf/util/session.c|  4 +++-
>  4 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
> index 28f5493da491..5e98525387dc 100644
> --- a/tools/include/linux/bitmap.h
> +++ b/tools/include/linux/bitmap.h
> @@ -2,6 +2,7 @@
>  #define _PERF_BITOPS_H
>  
>  #include 
> +#include 

this could go in the bitmap.c file, but anyway:

Acked-by: Jiri Olsa 

thanks,
jirka

>  #include 
>  
>  #define DECLARE_BITMAP(name,bits) \
> @@ -10,6 +11,7 @@
>  int __bitmap_weight(const unsigned long *bitmap, int bits);
>  void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
>const unsigned long *bitmap2, int bits);
> +void bitmap_from_u64(unsigned long *dst, u64 mask);
>  
>  #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 
> 1)))
>  

SNIP

Re: [PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Jiri Olsa]

On Thu, Jun 23, 2016 at 11:19:27AM +0530, Madhavan Srinivasan wrote:

SNIP

> 
> Changelog v1:
> 1)updated commit message and patch subject
> 2)Add the fix to print_sample_iregs() in builtin-script.c
> 
>  tools/include/linux/bitmap.h |  2 ++
>  tools/lib/bitmap.c   | 18 ++
>  tools/perf/builtin-script.c  |  4 +++-
>  tools/perf/util/session.c|  4 +++-
>  4 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
> index 28f5493da491..5e98525387dc 100644
> --- a/tools/include/linux/bitmap.h
> +++ b/tools/include/linux/bitmap.h
> @@ -2,6 +2,7 @@
>  #define _PERF_BITOPS_H
>  
>  #include 
> +#include 

this could go in the bitmap.c file, but anyway:

Acked-by: Jiri Olsa 

thanks,
jirka

>  #include 
>  
>  #define DECLARE_BITMAP(name,bits) \
> @@ -10,6 +11,7 @@
>  int __bitmap_weight(const unsigned long *bitmap, int bits);
>  void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
>const unsigned long *bitmap2, int bits);
> +void bitmap_from_u64(unsigned long *dst, u64 mask);
>  
>  #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 
> 1)))
>  

SNIP

[PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Madhavan Srinivasan]

When decoding the perf_regs mask in regs_dump__printf(),
we loop through the mask using find_first_bit and find_next_bit functions.
"mask" is of type "u64", but sent as a "unsigned long *" to
lib functions along with sizeof().

While the exisitng code works fine in most of the case,
the logic is broken when using a 32bit perf on a 64bit kernel (Big Endian).
When reading u64 using (u32 *)()[0], perf (lib/find_*_bit()) assumes it gets
lower 32bits of u64 which is wrong. Proposed fix is to swap the words
of the u64 to handle this case. This is _not_ endianess swap.

Suggested-by: Yury Norov 
Cc: Yury Norov 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Adrian Hunter 
Cc: Kan Liang 
Cc: Wang Nan 
Cc: Michael Ellerman 
Signed-off-by: Madhavan Srinivasan 
---
Changelog v4:
1) Removed the new macro and resued the DECLARE_BITMAP

Changelog v3:
1)Moved the swap function to lib/bitmap.c
2)Added a macro for declaration
3)Added the comments

Changelog v2:
1)Moved the swap code to a common function
2)Added more comments in the code

Changelog v1:
1)updated commit message and patch subject
2)Add the fix to print_sample_iregs() in builtin-script.c

 tools/include/linux/bitmap.h |  2 ++
 tools/lib/bitmap.c   | 18 ++
 tools/perf/builtin-script.c  |  4 +++-
 tools/perf/util/session.c|  4 +++-
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index 28f5493da491..5e98525387dc 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -2,6 +2,7 @@
 #define _PERF_BITOPS_H
 
 #include 
+#include 
 #include 
 
 #define DECLARE_BITMAP(name,bits) \
@@ -10,6 +11,7 @@
 int __bitmap_weight(const unsigned long *bitmap, int bits);
 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 const unsigned long *bitmap2, int bits);
+void bitmap_from_u64(unsigned long *dst, u64 mask);
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 
diff --git a/tools/lib/bitmap.c b/tools/lib/bitmap.c
index 0a1adcfd..464a0cc63e6a 100644
--- a/tools/lib/bitmap.c
+++ b/tools/lib/bitmap.c
@@ -29,3 +29,21 @@ void __bitmap_or(unsigned long *dst, const unsigned long 
*bitmap1,
for (k = 0; k < nr; k++)
dst[k] = bitmap1[k] | bitmap2[k];
 }
+
+/*
+ * bitmap_from_u64 - Check and swap words within u64.
+ *  @mask: source bitmap
+ *  @dst:  destination bitmap
+ *
+ * In 32 bit big endian userspace on a 64bit kernel, 'unsigned long' is 32 
bits.
+ * When reading u64 using (u32 *)()[0] and (u32 *)()[1],
+ * we will get wrong value for the mask. That is "(u32 *)()[0]"
+ * gets upper 32 bits of u64, but perf may expect lower 32bits of u64.
+ */
+void bitmap_from_u64(unsigned long *dst, u64 mask)
+{
+   dst[0] = mask & ULONG_MAX;
+
+   if (sizeof(mask) > sizeof(unsigned long))
+   dst[1] = mask >> 32;
+}
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index e3ce2f34d3ad..132a4bb70c31 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -412,11 +412,13 @@ static void print_sample_iregs(struct perf_sample *sample,
struct regs_dump *regs = >intr_regs;
uint64_t mask = attr->sample_regs_intr;
unsigned i = 0, r;
+   DECLARE_BITMAP(_mask, 64);
 
if (!regs)
return;
 
-   for_each_set_bit(r, (unsigned long *) , sizeof(mask) * 8) {
+   bitmap_from_u64(_mask, mask);
+   for_each_set_bit(r, _mask, sizeof(mask) * 8) {
u64 val = regs->regs[i++];
printf("%5s:0x%"PRIx64" ", perf_reg_name(r), val);
}
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 5214974e841a..3576bf13 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -940,8 +940,10 @@ static void branch_stack__printf(struct perf_sample 
*sample)
 static void regs_dump__printf(u64 mask, u64 *regs)
 {
unsigned rid, i = 0;
+   DECLARE_BITMAP(_mask, 64);
 
-   for_each_set_bit(rid, (unsigned long *) , sizeof(mask) * 8) {
+   bitmap_from_u64(_mask, mask);
+   for_each_set_bit(rid, _mask, sizeof(mask) * 8) {
u64 val = regs[i++];
 
printf(" %-5s 0x%" PRIx64 "\n",
-- 
1.9.1

[PATCH v5] tools/perf: Fix the mask in regs_dump__printf and print_sample_iregs

[Madhavan Srinivasan]

When decoding the perf_regs mask in regs_dump__printf(),
we loop through the mask using find_first_bit and find_next_bit functions.
"mask" is of type "u64", but sent as a "unsigned long *" to
lib functions along with sizeof().

While the exisitng code works fine in most of the case,
the logic is broken when using a 32bit perf on a 64bit kernel (Big Endian).
When reading u64 using (u32 *)()[0], perf (lib/find_*_bit()) assumes it gets
lower 32bits of u64 which is wrong. Proposed fix is to swap the words
of the u64 to handle this case. This is _not_ endianess swap.

Suggested-by: Yury Norov 
Cc: Yury Norov 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Jiri Olsa 
Cc: Adrian Hunter 
Cc: Kan Liang 
Cc: Wang Nan 
Cc: Michael Ellerman 
Signed-off-by: Madhavan Srinivasan 
---
Changelog v4:
1) Removed the new macro and resued the DECLARE_BITMAP

Changelog v3:
1)Moved the swap function to lib/bitmap.c
2)Added a macro for declaration
3)Added the comments

Changelog v2:
1)Moved the swap code to a common function
2)Added more comments in the code

Changelog v1:
1)updated commit message and patch subject
2)Add the fix to print_sample_iregs() in builtin-script.c

 tools/include/linux/bitmap.h |  2 ++
 tools/lib/bitmap.c   | 18 ++
 tools/perf/builtin-script.c  |  4 +++-
 tools/perf/util/session.c|  4 +++-
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/include/linux/bitmap.h b/tools/include/linux/bitmap.h
index 28f5493da491..5e98525387dc 100644
--- a/tools/include/linux/bitmap.h
+++ b/tools/include/linux/bitmap.h
@@ -2,6 +2,7 @@
 #define _PERF_BITOPS_H
 
 #include 
+#include 
 #include 
 
 #define DECLARE_BITMAP(name,bits) \
@@ -10,6 +11,7 @@
 int __bitmap_weight(const unsigned long *bitmap, int bits);
 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
 const unsigned long *bitmap2, int bits);
+void bitmap_from_u64(unsigned long *dst, u64 mask);
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
 
diff --git a/tools/lib/bitmap.c b/tools/lib/bitmap.c
index 0a1adcfd..464a0cc63e6a 100644
--- a/tools/lib/bitmap.c
+++ b/tools/lib/bitmap.c
@@ -29,3 +29,21 @@ void __bitmap_or(unsigned long *dst, const unsigned long 
*bitmap1,
for (k = 0; k < nr; k++)
dst[k] = bitmap1[k] | bitmap2[k];
 }
+
+/*
+ * bitmap_from_u64 - Check and swap words within u64.
+ *  @mask: source bitmap
+ *  @dst:  destination bitmap
+ *
+ * In 32 bit big endian userspace on a 64bit kernel, 'unsigned long' is 32 
bits.
+ * When reading u64 using (u32 *)()[0] and (u32 *)()[1],
+ * we will get wrong value for the mask. That is "(u32 *)()[0]"
+ * gets upper 32 bits of u64, but perf may expect lower 32bits of u64.
+ */
+void bitmap_from_u64(unsigned long *dst, u64 mask)
+{
+   dst[0] = mask & ULONG_MAX;
+
+   if (sizeof(mask) > sizeof(unsigned long))
+   dst[1] = mask >> 32;
+}
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index e3ce2f34d3ad..132a4bb70c31 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -412,11 +412,13 @@ static void print_sample_iregs(struct perf_sample *sample,
struct regs_dump *regs = >intr_regs;
uint64_t mask = attr->sample_regs_intr;
unsigned i = 0, r;
+   DECLARE_BITMAP(_mask, 64);
 
if (!regs)
return;
 
-   for_each_set_bit(r, (unsigned long *) , sizeof(mask) * 8) {
+   bitmap_from_u64(_mask, mask);
+   for_each_set_bit(r, _mask, sizeof(mask) * 8) {
u64 val = regs->regs[i++];
printf("%5s:0x%"PRIx64" ", perf_reg_name(r), val);
}
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 5214974e841a..3576bf13 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -940,8 +940,10 @@ static void branch_stack__printf(struct perf_sample 
*sample)
 static void regs_dump__printf(u64 mask, u64 *regs)
 {
unsigned rid, i = 0;
+   DECLARE_BITMAP(_mask, 64);
 
-   for_each_set_bit(rid, (unsigned long *) , sizeof(mask) * 8) {
+   bitmap_from_u64(_mask, mask);
+   for_each_set_bit(rid, _mask, sizeof(mask) * 8) {
u64 val = regs[i++];
 
printf(" %-5s 0x%" PRIx64 "\n",
-- 
1.9.1