[PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Leo Yan]

On Hikey arm64 octa A53 platform, when use command './perf report -v
-k vmlinux --stdio' it outputs below error info, and it skips to load
kernel symbol and doesn't print symbol for event:
Failed to open [kernel.kallsyms]_text, continuing without symbols.

The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
kernel mmap name into struct machine"), which changes the logic for
machine mmap_name by removing function machine__mmap_name() and always
use 'machine->mmap_name'.  Comparing difference between
machine__mmap_name() and 'machine->mmap_name', the later one includes
the string for specified kernel vmlinux string with option '-k' in
command, but the old function machine__mmap_name() ignores vmlinux
path string.  As result, event's mmap file name doesn't match with
machine mmap file name anymore and it skips to load kernel symbol from
vmlinux file.

To resolve this issue, this patch adds extra checking for
'symbol_conf.vmlinux_name', when it has been set string so we can know
it includes vmlinux path string specified for option '-k'. For this
case it sets 'is_kernel_mmap' to true and run into flow to load kernel
symbol from vmlinux.

This patch has been verified with two commands: './perf report -v
-k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
-k vmlinux'.

Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
 tools/perf/util/machine.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 12b7427..3125871 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
 	else
 		kernel_type = DSO_TYPE_GUEST_KERNEL;
 
-	is_kernel_mmap = memcmp(event->mmap.filename,
-				machine->mmap_name,
-				strlen(machine->mmap_name) - 1) == 0;
+	/*
+	 * When symbol_conf.vmlinux_name is not NULL, it includes the specified
+	 * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
+	 * true for creating machine symbol map.
+	 */
+	if (symbol_conf.vmlinux_name)
+		is_kernel_mmap = true;
+	else
+		is_kernel_mmap = memcmp(event->mmap.filename,
+					machine->mmap_name,
+					strlen(machine->mmap_name) - 1) == 0;
+
 	if (event->mmap.filename[0] == '/' ||
 	    (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
 		map = machine__findnew_module_map(machine, event->mmap.start,
-- 
2.7.4

Re: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Mathieu Poirier]

On 8 March 2018 at 23:05, Leo Yan <leo.yan@linaro.org> wrote:
> On Hikey arm64 octa A53 platform, when use command './perf report -v
> -k vmlinux --stdio' it outputs below error info, and it skips to load
> kernel symbol and doesn't print symbol for event:
> Failed to open [kernel.kallsyms]_text, continuing without symbols.
>
> The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
> kernel mmap name into struct machine"), which changes the logic for
> machine mmap_name by removing function machine__mmap_name() and always
> use 'machine->mmap_name'.  Comparing difference between
> machine__mmap_name() and 'machine->mmap_name', the later one includes
> the string for specified kernel vmlinux string with option '-k' in
> command, but the old function machine__mmap_name() ignores vmlinux
> path string.  As result, event's mmap file name doesn't match with
> machine mmap file name anymore and it skips to load kernel symbol from
> vmlinux file.
>
> To resolve this issue, this patch adds extra checking for
> 'symbol_conf.vmlinux_name', when it has been set string so we can know
> it includes vmlinux path string specified for option '-k'. For this
> case it sets 'is_kernel_mmap' to true and run into flow to load kernel
> symbol from vmlinux.
>
> This patch has been verified with two commands: './perf report -v
> -k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
> -k vmlinux'.
>
> Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  tools/perf/util/machine.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 12b7427..3125871 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
>         else
>                 kernel_type = DSO_TYPE_GUEST_KERNEL;
>
> -       is_kernel_mmap = memcmp(event->mmap.filename,
> -                               machine->mmap_name,
> -                               strlen(machine->mmap_name) - 1) == 0;
> +       /*
> +        * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> +        * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
> +        * true for creating machine symbol map.
> +        */
> +       if (symbol_conf.vmlinux_name)
> +               is_kernel_mmap = true;
> +       else
> +               is_kernel_mmap = memcmp(event->mmap.filename,
> +                                       machine->mmap_name,
> +                                       strlen(machine->mmap_name) - 1) == 0;
> +

I have tested this on my side and things work properly.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>


>         if (event->mmap.filename[0] == '/' ||
>             (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
>                 map = machine__findnew_module_map(machine, event->mmap.start,
> --
> 2.7.4
>

Re: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Arnaldo Carvalho de Melo]

Em Fri, Mar 09, 2018 at 02:05:23PM +0800, Leo Yan escreveu:
> On Hikey arm64 octa A53 platform, when use command './perf report -v
> -k vmlinux --stdio' it outputs below error info, and it skips to load
> kernel symbol and doesn't print symbol for event:
> Failed to open [kernel.kallsyms]_text, continuing without symbols.
> 
> The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
> kernel mmap name into struct machine"), which changes the logic for

commit 8c7f1bb37b29f140e08175132f3abb4d5ad229fc
Author: Jiri Olsa <jolsa@kernel.org>
Date:   Thu Feb 15 13:26:30 2018 +0100

    perf machine: Move kernel mmap name into struct machine

Jiri, can you please check this and Ack?

- Arnaldo

> machine mmap_name by removing function machine__mmap_name() and always
> use 'machine->mmap_name'.  Comparing difference between
> machine__mmap_name() and 'machine->mmap_name', the later one includes
> the string for specified kernel vmlinux string with option '-k' in
> command, but the old function machine__mmap_name() ignores vmlinux
> path string.  As result, event's mmap file name doesn't match with
> machine mmap file name anymore and it skips to load kernel symbol from
> vmlinux file.
> 
> To resolve this issue, this patch adds extra checking for
> 'symbol_conf.vmlinux_name', when it has been set string so we can know
> it includes vmlinux path string specified for option '-k'. For this
> case it sets 'is_kernel_mmap' to true and run into flow to load kernel
> symbol from vmlinux.
> 
> This patch has been verified with two commands: './perf report -v
> -k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
> -k vmlinux'.
> 
> Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  tools/perf/util/machine.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 12b7427..3125871 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
>  	else
>  		kernel_type = DSO_TYPE_GUEST_KERNEL;
>  
> -	is_kernel_mmap = memcmp(event->mmap.filename,
> -				machine->mmap_name,
> -				strlen(machine->mmap_name) - 1) == 0;
> +	/*
> +	 * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> +	 * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
> +	 * true for creating machine symbol map.
> +	 */
> +	if (symbol_conf.vmlinux_name)
> +		is_kernel_mmap = true;
> +	else
> +		is_kernel_mmap = memcmp(event->mmap.filename,
> +					machine->mmap_name,
> +					strlen(machine->mmap_name) - 1) == 0;
> +
>  	if (event->mmap.filename[0] == '/' ||
>  	    (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
>  		map = machine__findnew_module_map(machine, event->mmap.start,
> -- 
> 2.7.4

Re: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Jiri Olsa]

On Fri, Mar 09, 2018 at 02:05:23PM +0800, Leo Yan wrote:
> On Hikey arm64 octa A53 platform, when use command './perf report -v
> -k vmlinux --stdio' it outputs below error info, and it skips to load
> kernel symbol and doesn't print symbol for event:
> Failed to open [kernel.kallsyms]_text, continuing without symbols.
> 
> The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
> kernel mmap name into struct machine"), which changes the logic for
> machine mmap_name by removing function machine__mmap_name() and always
> use 'machine->mmap_name'.  Comparing difference between
> machine__mmap_name() and 'machine->mmap_name', the later one includes
> the string for specified kernel vmlinux string with option '-k' in
> command, but the old function machine__mmap_name() ignores vmlinux
> path string.  As result, event's mmap file name doesn't match with
> machine mmap file name anymore and it skips to load kernel symbol from
> vmlinux file.
> 
> To resolve this issue, this patch adds extra checking for
> 'symbol_conf.vmlinux_name', when it has been set string so we can know
> it includes vmlinux path string specified for option '-k'. For this
> case it sets 'is_kernel_mmap' to true and run into flow to load kernel
> symbol from vmlinux.
> 
> This patch has been verified with two commands: './perf report -v
> -k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
> -k vmlinux'.
> 
> Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> ---
>  tools/perf/util/machine.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 12b7427..3125871 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
>  	else
>  		kernel_type = DSO_TYPE_GUEST_KERNEL;
>  
> -	is_kernel_mmap = memcmp(event->mmap.filename,
> -				machine->mmap_name,
> -				strlen(machine->mmap_name) - 1) == 0;
> +	/*
> +	 * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> +	 * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
> +	 * true for creating machine symbol map.
> +	 */
> +	if (symbol_conf.vmlinux_name)
> +		is_kernel_mmap = true;
> +	else
> +		is_kernel_mmap = memcmp(event->mmap.filename,
> +					machine->mmap_name,
> +					strlen(machine->mmap_name) - 1) == 0;
> +
>  	if (event->mmap.filename[0] == '/' ||
>  	    (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
>  		map = machine__findnew_module_map(machine, event->mmap.start,

right, the mmap gets confused with the vmlinux path, but I wonder
the fix should be not to include symbol_conf.vmlinux_name in the
mmap_name like below.. untested

thanks,
jirka


---
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 43fbbee409ec..f0cb72022177 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -51,15 +51,9 @@ static void machine__threads_init(struct machine *machine)
 static int machine__set_mmap_name(struct machine *machine)
 {
 	if (machine__is_host(machine)) {
-		if (symbol_conf.vmlinux_name)
-			machine->mmap_name = strdup(symbol_conf.vmlinux_name);
-		else
-			machine->mmap_name = strdup("[kernel.kallsyms]");
+		machine->mmap_name = strdup("[kernel.kallsyms]");
 	} else if (machine__is_default_guest(machine)) {
-		if (symbol_conf.default_guest_vmlinux_name)
-			machine->mmap_name = strdup(symbol_conf.default_guest_vmlinux_name);
-		else
-			machine->mmap_name = strdup("[guest.kernel.kallsyms]");
+		machine->mmap_name = strdup("[guest.kernel.kallsyms]");
 	} else {
 		if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
 			 machine->pid) < 0)
@@ -794,9 +788,15 @@ static struct dso *machine__get_kernel(struct machine *machine)
 	struct dso *kernel;
 
 	if (machine__is_host(machine)) {
+		if (symbol_conf.vmlinux_name)
+			vmlinux_name = symbol_conf.vmlinux_name;
+
 		kernel = machine__findnew_kernel(machine, vmlinux_name,
 						 "[kernel]", DSO_TYPE_KERNEL);
 	} else {
+		if (symbol_conf.default_guest_vmlinux_name)
+			vmlinux_name = symbol_conf.default_guest_vmlinux_name;
+
 		kernel = machine__findnew_kernel(machine, vmlinux_name,
 						 "[guest.kernel]",
 						 DSO_TYPE_GUEST_KERNEL);

Re: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Leo Yan]

Hi Jiri,

On Fri, Mar 09, 2018 at 09:56:00PM +0100, Jiri Olsa wrote:
> On Fri, Mar 09, 2018 at 02:05:23PM +0800, Leo Yan wrote:
> > On Hikey arm64 octa A53 platform, when use command './perf report -v
> > -k vmlinux --stdio' it outputs below error info, and it skips to load
> > kernel symbol and doesn't print symbol for event:
> > Failed to open [kernel.kallsyms]_text, continuing without symbols.
> > 
> > The regression is introduced by commit ("8c7f1bb37b29 perf machine: Move
> > kernel mmap name into struct machine"), which changes the logic for
> > machine mmap_name by removing function machine__mmap_name() and always
> > use 'machine->mmap_name'.  Comparing difference between
> > machine__mmap_name() and 'machine->mmap_name', the later one includes
> > the string for specified kernel vmlinux string with option '-k' in
> > command, but the old function machine__mmap_name() ignores vmlinux
> > path string.  As result, event's mmap file name doesn't match with
> > machine mmap file name anymore and it skips to load kernel symbol from
> > vmlinux file.
> > 
> > To resolve this issue, this patch adds extra checking for
> > 'symbol_conf.vmlinux_name', when it has been set string so we can know
> > it includes vmlinux path string specified for option '-k'. For this
> > case it sets 'is_kernel_mmap' to true and run into flow to load kernel
> > symbol from vmlinux.
> > 
> > This patch has been verified with two commands: './perf report -v
> > -k vmlinux --stdio' and './perf script -v -F cpu,event,ip,sym,symoff
> > -k vmlinux'.
> > 
> > Suggested-by: Mathieu Poirier <mathieu.poirier@linaro.org>
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> >  tools/perf/util/machine.c | 15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> > 
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index 12b7427..3125871 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> >  	else
> >  		kernel_type = DSO_TYPE_GUEST_KERNEL;
> >  
> > -	is_kernel_mmap = memcmp(event->mmap.filename,
> > -				machine->mmap_name,
> > -				strlen(machine->mmap_name) - 1) == 0;
> > +	/*
> > +	 * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> > +	 * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
> > +	 * true for creating machine symbol map.
> > +	 */
> > +	if (symbol_conf.vmlinux_name)
> > +		is_kernel_mmap = true;
> > +	else
> > +		is_kernel_mmap = memcmp(event->mmap.filename,
> > +					machine->mmap_name,
> > +					strlen(machine->mmap_name) - 1) == 0;
> > +
> >  	if (event->mmap.filename[0] == '/' ||
> >  	    (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
> >  		map = machine__findnew_module_map(machine, event->mmap.start,
> 
> right, the mmap gets confused with the vmlinux path, but I wonder
> the fix should be not to include symbol_conf.vmlinux_name in the
> mmap_name like below.. untested

I tested below fixing at my side, and confirm your fixing also can
resolve this issue.  After reviewing the change, it's more neat than my
own change .  So you could add my test tag :)

Tested-by: Leo Yan <leo.yan@linaro.org>

BTW, I have a minor comment for code refactoring, it's up to you if
need or not and if need use a new patch for refactoring, please see below
inline comment.

Thanks,
Leo Yan

> ---
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 43fbbee409ec..f0cb72022177 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -51,15 +51,9 @@ static void machine__threads_init(struct machine *machine)
>  static int machine__set_mmap_name(struct machine *machine)
>  {
>  	if (machine__is_host(machine)) {
> -		if (symbol_conf.vmlinux_name)
> -			machine->mmap_name = strdup(symbol_conf.vmlinux_name);
> -		else
> -			machine->mmap_name = strdup("[kernel.kallsyms]");
> +		machine->mmap_name = strdup("[kernel.kallsyms]");
>  	} else if (machine__is_default_guest(machine)) {
> -		if (symbol_conf.default_guest_vmlinux_name)
> -			machine->mmap_name = strdup(symbol_conf.default_guest_vmlinux_name);
> -		else
> -			machine->mmap_name = strdup("[guest.kernel.kallsyms]");
> +		machine->mmap_name = strdup("[guest.kernel.kallsyms]");
>  	} else {
>  		if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
>  			 machine->pid) < 0)

Do you think below format is better or not?

 static int machine__set_mmap_name(struct machine *machine)
 {
-       if (machine__is_host(machine)) {
-               if (symbol_conf.vmlinux_name)
-                       machine->mmap_name = strdup(symbol_conf.vmlinux_name);
-               else
-                       machine->mmap_name = strdup("[kernel.kallsyms]");
-       } else if (machine__is_default_guest(machine)) {
-               if (symbol_conf.default_guest_vmlinux_name)
-                       machine->mmap_name = strdup(symbol_conf.default_guest_vmlinux_name);
-               else
-                       machine->mmap_name = strdup("[guest.kernel.kallsyms]");
-       } else {
-               if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
-                        machine->pid) < 0)
-                       machine->mmap_name = NULL;
-       }
+       if (machine__is_host(machine))
+               machine->mmap_name = strdup("[kernel.kallsyms]");
+       else if (machine__is_default_guest(machine))
+               machine->mmap_name = strdup("[guest.kernel.kallsyms]");
+       else if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
+                machine->pid) < 0)
+               machine->mmap_name = NULL;
 
        return machine->mmap_name ? 0 : -ENOMEM;
 }

> @@ -794,9 +788,15 @@ static struct dso *machine__get_kernel(struct machine *machine)
>  	struct dso *kernel;
>  
>  	if (machine__is_host(machine)) {
> +		if (symbol_conf.vmlinux_name)
> +			vmlinux_name = symbol_conf.vmlinux_name;
> +
>  		kernel = machine__findnew_kernel(machine, vmlinux_name,
>  						 "[kernel]", DSO_TYPE_KERNEL);
>  	} else {
> +		if (symbol_conf.default_guest_vmlinux_name)
> +			vmlinux_name = symbol_conf.default_guest_vmlinux_name;
> +
>  		kernel = machine__findnew_kernel(machine, vmlinux_name,
>  						 "[guest.kernel]",
>  						 DSO_TYPE_GUEST_KERNEL);

Re: [PATCH v2] perf machine: Fix load kernel symbol with '-k' option

[Jiri Olsa]

On Sat, Mar 10, 2018 at 05:50:56PM +0800, Leo Yan wrote:

SNIP

> > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > > index 12b7427..3125871 100644
> > > --- a/tools/perf/util/machine.c
> > > +++ b/tools/perf/util/machine.c
> > > @@ -1299,9 +1299,18 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
> > >  	else
> > >  		kernel_type = DSO_TYPE_GUEST_KERNEL;
> > >  
> > > -	is_kernel_mmap = memcmp(event->mmap.filename,
> > > -				machine->mmap_name,
> > > -				strlen(machine->mmap_name) - 1) == 0;
> > > +	/*
> > > +	 * When symbol_conf.vmlinux_name is not NULL, it includes the specified
> > > +	 * kernel vmlinux path with option '-k'.  So set 'is_kernel_mmap' to
> > > +	 * true for creating machine symbol map.
> > > +	 */
> > > +	if (symbol_conf.vmlinux_name)
> > > +		is_kernel_mmap = true;
> > > +	else
> > > +		is_kernel_mmap = memcmp(event->mmap.filename,
> > > +					machine->mmap_name,
> > > +					strlen(machine->mmap_name) - 1) == 0;
> > > +
> > >  	if (event->mmap.filename[0] == '/' ||
> > >  	    (!is_kernel_mmap && event->mmap.filename[0] == '[')) {
> > >  		map = machine__findnew_module_map(machine, event->mmap.start,
> > 
> > right, the mmap gets confused with the vmlinux path, but I wonder
> > the fix should be not to include symbol_conf.vmlinux_name in the
> > mmap_name like below.. untested
> 
> I tested below fixing at my side, and confirm your fixing also can
> resolve this issue.  After reviewing the change, it's more neat than my
> own change .  So you could add my test tag :)
> 
> Tested-by: Leo Yan <leo.yan@linaro.org>

thanks

SNIP

>  static int machine__set_mmap_name(struct machine *machine)
>  {
> -       if (machine__is_host(machine)) {
> -               if (symbol_conf.vmlinux_name)
> -                       machine->mmap_name = strdup(symbol_conf.vmlinux_name);
> -               else
> -                       machine->mmap_name = strdup("[kernel.kallsyms]");
> -       } else if (machine__is_default_guest(machine)) {
> -               if (symbol_conf.default_guest_vmlinux_name)
> -                       machine->mmap_name = strdup(symbol_conf.default_guest_vmlinux_name);
> -               else
> -                       machine->mmap_name = strdup("[guest.kernel.kallsyms]");
> -       } else {
> -               if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
> -                        machine->pid) < 0)
> -                       machine->mmap_name = NULL;
> -       }
> +       if (machine__is_host(machine))
> +               machine->mmap_name = strdup("[kernel.kallsyms]");
> +       else if (machine__is_default_guest(machine))
> +               machine->mmap_name = strdup("[guest.kernel.kallsyms]");
> +       else if (asprintf(&machine->mmap_name, "[guest.kernel.kallsyms.%d]",
> +                machine->pid) < 0)
> +               machine->mmap_name = NULL;

yea, that looks better.. will change

jirka