tracetool: fix log-stap format

[PATCH 2/2] tracetool: fix "PRI" macro decoding

Posted by Laurent Vivier 5 years, 1 month ago

macro is not reset after use, so the format decoded is always the
one of the first "PRI" in the format string.

For instance:

  vhost_vdpa_set_config(void *dev, uint32_t offset, uint32_t size, \
                        uint32_t flags) "dev: %p offset: %"PRIu32" \
                        size: %"PRIu32" flags: 0x%"PRIx32

generates:

  printf("%d@%d vhost_vdpa_set_config dev: %p offset: %u size: %u \
          flags: 0x%u\n", pid(), gettimeofday_ns(), dev, offset, \
          size, flags)

for the "flags" parameter, we can see a "0x%u" rather than a "0x%x"
because the first macro was "PRIu32" (for offset).

In the loop, macro becomes "PRIu32PRIu32PRIx32", and c_macro_to_format()
returns always macro[3] ('u' in this case). This patch resets macro after
the format has been decoded.

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
 scripts/tracetool/format/log_stap.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/tracetool/format/log_stap.py b/scripts/tracetool/format/log_stap.py
index b486beb67239..3e1186ae9cc2 100644
--- a/scripts/tracetool/format/log_stap.py
+++ b/scripts/tracetool/format/log_stap.py
@@ -54,6 +54,7 @@ def c_fmt_to_stap(fmt):
             else:
                 if state == STATE_MACRO:
                     bits.append(c_macro_to_format(macro))
+                    macro = ""
                 state = STATE_LITERAL
         elif fmt[i] == ' ' or fmt[i] == '\t':
             if state == STATE_MACRO:
-- 
2.29.2

Re: [PATCH 2/2] tracetool: fix "PRI" macro decoding

Posted by Philippe Mathieu-Daudé 5 years, 1 month ago

On 1/5/21 8:17 PM, Laurent Vivier wrote:
> macro is not reset after use, so the format decoded is always the
> one of the first "PRI" in the format string.
> 
> For instance:
> 
>   vhost_vdpa_set_config(void *dev, uint32_t offset, uint32_t size, \
>                         uint32_t flags) "dev: %p offset: %"PRIu32" \
>                         size: %"PRIu32" flags: 0x%"PRIx32
> 
> generates:
> 
>   printf("%d@%d vhost_vdpa_set_config dev: %p offset: %u size: %u \
>           flags: 0x%u\n", pid(), gettimeofday_ns(), dev, offset, \
>           size, flags)
> 
> for the "flags" parameter, we can see a "0x%u" rather than a "0x%x"
> because the first macro was "PRIu32" (for offset).
> 
> In the loop, macro becomes "PRIu32PRIu32PRIx32", and c_macro_to_format()
> returns always macro[3] ('u' in this case). This patch resets macro after
> the format has been decoded.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  scripts/tracetool/format/log_stap.py | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/scripts/tracetool/format/log_stap.py b/scripts/tracetool/format/log_stap.py
> index b486beb67239..3e1186ae9cc2 100644
> --- a/scripts/tracetool/format/log_stap.py
> +++ b/scripts/tracetool/format/log_stap.py
> @@ -54,6 +54,7 @@ def c_fmt_to_stap(fmt):
>              else:
>                  if state == STATE_MACRO:
>                      bits.append(c_macro_to_format(macro))
> +                    macro = ""
>                  state = STATE_LITERAL
>          elif fmt[i] == ' ' or fmt[i] == '\t':
>              if state == STATE_MACRO:

What about the 'else' case?

Re: [PATCH 2/2] tracetool: fix "PRI" macro decoding

Posted by Laurent Vivier 5 years, 1 month ago

On 05/01/2021 20:44, Philippe Mathieu-Daudé wrote:
> On 1/5/21 8:17 PM, Laurent Vivier wrote:
>> macro is not reset after use, so the format decoded is always the
>> one of the first "PRI" in the format string.
>>
>> For instance:
>>
>>   vhost_vdpa_set_config(void *dev, uint32_t offset, uint32_t size, \
>>                         uint32_t flags) "dev: %p offset: %"PRIu32" \
>>                         size: %"PRIu32" flags: 0x%"PRIx32
>>
>> generates:
>>
>>   printf("%d@%d vhost_vdpa_set_config dev: %p offset: %u size: %u \
>>           flags: 0x%u\n", pid(), gettimeofday_ns(), dev, offset, \
>>           size, flags)
>>
>> for the "flags" parameter, we can see a "0x%u" rather than a "0x%x"
>> because the first macro was "PRIu32" (for offset).
>>
>> In the loop, macro becomes "PRIu32PRIu32PRIx32", and c_macro_to_format()
>> returns always macro[3] ('u' in this case). This patch resets macro after
>> the format has been decoded.
>>
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> ---
>>  scripts/tracetool/format/log_stap.py | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/scripts/tracetool/format/log_stap.py b/scripts/tracetool/format/log_stap.py
>> index b486beb67239..3e1186ae9cc2 100644
>> --- a/scripts/tracetool/format/log_stap.py
>> +++ b/scripts/tracetool/format/log_stap.py
>> @@ -54,6 +54,7 @@ def c_fmt_to_stap(fmt):
>>              else:
>>                  if state == STATE_MACRO:
>>                      bits.append(c_macro_to_format(macro))
>> +                    macro = ""
>>                  state = STATE_LITERAL
>>          elif fmt[i] == ' ' or fmt[i] == '\t':
>>              if state == STATE_MACRO:
> 
> What about the 'else' case?
> 

It already has the 'macro = ""', so no need to fix it.

Thanks,
Laurent

Re: [PATCH 2/2] tracetool: fix "PRI" macro decoding

Posted by Daniel P. Berrangé 5 years, 1 month ago

On Tue, Jan 05, 2021 at 08:17:21PM +0100, Laurent Vivier wrote:
> macro is not reset after use, so the format decoded is always the
> one of the first "PRI" in the format string.
> 
> For instance:
> 
>   vhost_vdpa_set_config(void *dev, uint32_t offset, uint32_t size, \
>                         uint32_t flags) "dev: %p offset: %"PRIu32" \
>                         size: %"PRIu32" flags: 0x%"PRIx32
> 
> generates:
> 
>   printf("%d@%d vhost_vdpa_set_config dev: %p offset: %u size: %u \
>           flags: 0x%u\n", pid(), gettimeofday_ns(), dev, offset, \
>           size, flags)
> 
> for the "flags" parameter, we can see a "0x%u" rather than a "0x%x"
> because the first macro was "PRIu32" (for offset).
> 
> In the loop, macro becomes "PRIu32PRIu32PRIx32", and c_macro_to_format()
> returns always macro[3] ('u' in this case). This patch resets macro after
> the format has been decoded.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  scripts/tracetool/format/log_stap.py | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/scripts/tracetool/format/log_stap.py b/scripts/tracetool/format/log_stap.py
> index b486beb67239..3e1186ae9cc2 100644
> --- a/scripts/tracetool/format/log_stap.py
> +++ b/scripts/tracetool/format/log_stap.py
> @@ -54,6 +54,7 @@ def c_fmt_to_stap(fmt):
>              else:
>                  if state == STATE_MACRO:
>                      bits.append(c_macro_to_format(macro))
> +                    macro = ""
>                  state = STATE_LITERAL
>          elif fmt[i] == ' ' or fmt[i] == '\t':
>              if state == STATE_MACRO:

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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Re: [PATCH 2/2] tracetool: fix "PRI" macro decoding

Posted by Stefan Hajnoczi 5 years ago

On Tue, Jan 05, 2021 at 08:17:21PM +0100, Laurent Vivier wrote:
> macro is not reset after use, so the format decoded is always the
> one of the first "PRI" in the format string.
> 
> For instance:
> 
>   vhost_vdpa_set_config(void *dev, uint32_t offset, uint32_t size, \
>                         uint32_t flags) "dev: %p offset: %"PRIu32" \
>                         size: %"PRIu32" flags: 0x%"PRIx32
> 
> generates:
> 
>   printf("%d@%d vhost_vdpa_set_config dev: %p offset: %u size: %u \
>           flags: 0x%u\n", pid(), gettimeofday_ns(), dev, offset, \
>           size, flags)
> 
> for the "flags" parameter, we can see a "0x%u" rather than a "0x%x"
> because the first macro was "PRIu32" (for offset).
> 
> In the loop, macro becomes "PRIu32PRIu32PRIx32", and c_macro_to_format()
> returns always macro[3] ('u' in this case). This patch resets macro after
> the format has been decoded.
> 
> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
> ---
>  scripts/tracetool/format/log_stap.py | 1 +
>  1 file changed, 1 insertion(+)

Thanks, applied to my tracing tree:
https://gitlab.com/stefanha/qemu/commits/tracing

Stefan