Re: [PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-15 Thread Jiri Olsa
On Tue, Dec 15, 2015 at 04:18:44AM +, Wang Nan wrote:
> Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
> testcases when kptr_restrict is on') solves a double free problem when
> 'perf test hist' calling setup_fake_machine(). However, the result is
> still incorrect. For example:
> 
>  $ ./perf test -v 'filtering hist entries'
>  25: Test filtering hist entries  :
>  --- start ---
>  test child forked, pid 4186
>  Cannot create kernel maps
>  test child finished with 0
>   end 
>  Test filtering hist entries: Ok
> 
> In this case the body of this test is not get executed at all, but the
> result is 'Ok'. I think 'Skip' should be better.
> 
> The reason is that *ALL* hists test cases forget to reset err after
> using it to hold an error code.
> 
> This patch ensure err is reset.
> 
> In case when kptr_restrict prevent normal user get kernel address, this
> test should be skipped, not fail. This patch uses linux/err.h to store
> error code in return value of setup_fake_machine(), and let 'EACCES' to
> indicate this problem.
> 
> Signed-off-by: Wang Nan 
> Cc: Arnaldo Carvalho de Melo 
> Cc: Jiri Olsa 
> Cc: Masami Hiramatsu 
> Cc: Namhyung Kim 

Acked-by: Jiri Olsa 

thanks,
jirka
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Re: [PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-15 Thread Jiri Olsa
On Tue, Dec 15, 2015 at 04:18:44AM +, Wang Nan wrote:
> Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
> testcases when kptr_restrict is on') solves a double free problem when
> 'perf test hist' calling setup_fake_machine(). However, the result is
> still incorrect. For example:
> 
>  $ ./perf test -v 'filtering hist entries'
>  25: Test filtering hist entries  :
>  --- start ---
>  test child forked, pid 4186
>  Cannot create kernel maps
>  test child finished with 0
>   end 
>  Test filtering hist entries: Ok
> 
> In this case the body of this test is not get executed at all, but the
> result is 'Ok'. I think 'Skip' should be better.
> 
> The reason is that *ALL* hists test cases forget to reset err after
> using it to hold an error code.
> 
> This patch ensure err is reset.
> 
> In case when kptr_restrict prevent normal user get kernel address, this
> test should be skipped, not fail. This patch uses linux/err.h to store
> error code in return value of setup_fake_machine(), and let 'EACCES' to
> indicate this problem.
> 
> Signed-off-by: Wang Nan 
> Cc: Arnaldo Carvalho de Melo 
> Cc: Jiri Olsa 
> Cc: Masami Hiramatsu 
> Cc: Namhyung Kim 

Acked-by: Jiri Olsa 

thanks,
jirka
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/


Re: [PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-14 Thread Namhyung Kim
Hi,

On Tue, Dec 15, 2015 at 04:18:44AM +, Wang Nan wrote:
> Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
> testcases when kptr_restrict is on') solves a double free problem when
> 'perf test hist' calling setup_fake_machine(). However, the result is
> still incorrect. For example:
> 
>  $ ./perf test -v 'filtering hist entries'
>  25: Test filtering hist entries  :
>  --- start ---
>  test child forked, pid 4186
>  Cannot create kernel maps
>  test child finished with 0
>   end 
>  Test filtering hist entries: Ok
> 
> In this case the body of this test is not get executed at all, but the
> result is 'Ok'. I think 'Skip' should be better.

Right, I missed this part.

But on second thought, I think it should not create real kernel maps.
What setup_fake_machine() does is to create/insert fake
dso/mmap/symbols for testing hist functions.  So it has to use the
predefined info not real ones.


> 
> The reason is that *ALL* hists test cases forget to reset err after
> using it to hold an error code.
> 
> This patch ensure err is reset.
> 
> In case when kptr_restrict prevent normal user get kernel address, this
> test should be skipped, not fail. This patch uses linux/err.h to store
> error code in return value of setup_fake_machine(), and let 'EACCES' to
> indicate this problem.

Please just remove the machine__create_kernel_maps() in
setup_fake_machine() and simply return TEST_FAIL if there's an error.

Thanks,
Namhyung


> 
> Signed-off-by: Wang Nan 
> Cc: Arnaldo Carvalho de Melo 
> Cc: Jiri Olsa 
> Cc: Masami Hiramatsu 
> Cc: Namhyung Kim 
> ---
>  tools/perf/tests/hists_common.c   | 12 +---
>  tools/perf/tests/hists_common.h   |  1 +
>  tools/perf/tests/hists_cumulate.c |  6 +-
>  tools/perf/tests/hists_filter.c   |  6 +-
>  tools/perf/tests/hists_link.c |  6 +-
>  tools/perf/tests/hists_output.c   |  6 +-
>  6 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
> index bcfd081..2eca1b2 100644
> --- a/tools/perf/tests/hists_common.c
> +++ b/tools/perf/tests/hists_common.c
> @@ -81,15 +81,20 @@ struct machine *setup_fake_machine(struct machines 
> *machines)
>  {
>   struct machine *machine = machines__find(machines, HOST_KERNEL_ID);
>   size_t i;
> + int err = -ENOMEM;
>  
>   if (machine == NULL) {
>   pr_debug("Not enough memory for machine setup\n");
> - return NULL;
> + return ERR_PTR(-ENOMEM);
>   }
>  
>   if (machine__create_kernel_maps(machine)) {
>   pr_debug("Cannot create kernel maps\n");
> - return NULL;
> + if (symbol_conf.kptr_restrict) {
> + pr_debug("Hint: Check 
> /proc/sys/kernel/kptr_restrict.\n");
> + err = -EACCES;
> + }
> + return ERR_PTR(err);
>   }
>  
>   for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
> @@ -155,7 +160,8 @@ struct machine *setup_fake_machine(struct machines 
> *machines)
>  out:
>   pr_debug("Not enough memory for machine setup\n");
>   machine__delete_threads(machine);
> - return NULL;
> + machine__exit(machine);
> + return ERR_PTR(err);
>  }
>  
>  void print_hists_in(struct hists *hists)
> diff --git a/tools/perf/tests/hists_common.h b/tools/perf/tests/hists_common.h
> index 888254e..0252eae 100644
> --- a/tools/perf/tests/hists_common.h
> +++ b/tools/perf/tests/hists_common.h
> @@ -1,5 +1,6 @@
>  #ifndef __PERF_TESTS__HISTS_COMMON_H__
>  #define __PERF_TESTS__HISTS_COMMON_H__
> +#include 
>  
>  struct machine;
>  struct machines;
> diff --git a/tools/perf/tests/hists_cumulate.c 
> b/tools/perf/tests/hists_cumulate.c
> index 8292948..c211075 100644
> --- a/tools/perf/tests/hists_cumulate.c
> +++ b/tools/perf/tests/hists_cumulate.c
> @@ -706,13 +706,17 @@ int test__hists_cumulate(int subtest __maybe_unused)
>   err = parse_events(evlist, "cpu-clock", NULL);
>   if (err)
>   goto out;
> + err = TEST_FAIL;
>  
>   machines__init();
>  
>   /* setup threads/dso/map/symbols also */
>   machine = setup_fake_machine();
> - if (!machine)
> + if (IS_ERR(machine)) {
> + if (PTR_ERR(machine) == -EACCES)
> + err = TEST_SKIP;
>   goto out;
> + }
>  
>   if (verbose > 1)
>   machine__fprintf(machine, stderr);
> diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
> index ccb5b49..795a04d 100644
> --- a/tools/perf/tests/hists_filter.c
> +++ b/tools/perf/tests/hists_filter.c
> @@ -120,6 +120,7 @@ int test__hists_filter(int subtest __maybe_unused)
>   err = parse_events(evlist, "task-clock", NULL);
>   if (err)
>   goto out;
> + err = TEST_FAIL;
>  
>   /* default sort order (comm,dso,sym) will be used */
>   if (setup_sorting() < 0)
> @@ -129,8 +130,11 @@ 

[PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-14 Thread Wang Nan
Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
testcases when kptr_restrict is on') solves a double free problem when
'perf test hist' calling setup_fake_machine(). However, the result is
still incorrect. For example:

 $ ./perf test -v 'filtering hist entries'
 25: Test filtering hist entries  :
 --- start ---
 test child forked, pid 4186
 Cannot create kernel maps
 test child finished with 0
  end 
 Test filtering hist entries: Ok

In this case the body of this test is not get executed at all, but the
result is 'Ok'. I think 'Skip' should be better.

The reason is that *ALL* hists test cases forget to reset err after
using it to hold an error code.

This patch ensure err is reset.

In case when kptr_restrict prevent normal user get kernel address, this
test should be skipped, not fail. This patch uses linux/err.h to store
error code in return value of setup_fake_machine(), and let 'EACCES' to
indicate this problem.

Signed-off-by: Wang Nan 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
---
 tools/perf/tests/hists_common.c   | 12 +---
 tools/perf/tests/hists_common.h   |  1 +
 tools/perf/tests/hists_cumulate.c |  6 +-
 tools/perf/tests/hists_filter.c   |  6 +-
 tools/perf/tests/hists_link.c |  6 +-
 tools/perf/tests/hists_output.c   |  6 +-
 6 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
index bcfd081..2eca1b2 100644
--- a/tools/perf/tests/hists_common.c
+++ b/tools/perf/tests/hists_common.c
@@ -81,15 +81,20 @@ struct machine *setup_fake_machine(struct machines 
*machines)
 {
struct machine *machine = machines__find(machines, HOST_KERNEL_ID);
size_t i;
+   int err = -ENOMEM;
 
if (machine == NULL) {
pr_debug("Not enough memory for machine setup\n");
-   return NULL;
+   return ERR_PTR(-ENOMEM);
}
 
if (machine__create_kernel_maps(machine)) {
pr_debug("Cannot create kernel maps\n");
-   return NULL;
+   if (symbol_conf.kptr_restrict) {
+   pr_debug("Hint: Check 
/proc/sys/kernel/kptr_restrict.\n");
+   err = -EACCES;
+   }
+   return ERR_PTR(err);
}
 
for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
@@ -155,7 +160,8 @@ struct machine *setup_fake_machine(struct machines 
*machines)
 out:
pr_debug("Not enough memory for machine setup\n");
machine__delete_threads(machine);
-   return NULL;
+   machine__exit(machine);
+   return ERR_PTR(err);
 }
 
 void print_hists_in(struct hists *hists)
diff --git a/tools/perf/tests/hists_common.h b/tools/perf/tests/hists_common.h
index 888254e..0252eae 100644
--- a/tools/perf/tests/hists_common.h
+++ b/tools/perf/tests/hists_common.h
@@ -1,5 +1,6 @@
 #ifndef __PERF_TESTS__HISTS_COMMON_H__
 #define __PERF_TESTS__HISTS_COMMON_H__
+#include 
 
 struct machine;
 struct machines;
diff --git a/tools/perf/tests/hists_cumulate.c 
b/tools/perf/tests/hists_cumulate.c
index 8292948..c211075 100644
--- a/tools/perf/tests/hists_cumulate.c
+++ b/tools/perf/tests/hists_cumulate.c
@@ -706,13 +706,17 @@ int test__hists_cumulate(int subtest __maybe_unused)
err = parse_events(evlist, "cpu-clock", NULL);
if (err)
goto out;
+   err = TEST_FAIL;
 
machines__init();
 
/* setup threads/dso/map/symbols also */
machine = setup_fake_machine();
-   if (!machine)
+   if (IS_ERR(machine)) {
+   if (PTR_ERR(machine) == -EACCES)
+   err = TEST_SKIP;
goto out;
+   }
 
if (verbose > 1)
machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
index ccb5b49..795a04d 100644
--- a/tools/perf/tests/hists_filter.c
+++ b/tools/perf/tests/hists_filter.c
@@ -120,6 +120,7 @@ int test__hists_filter(int subtest __maybe_unused)
err = parse_events(evlist, "task-clock", NULL);
if (err)
goto out;
+   err = TEST_FAIL;
 
/* default sort order (comm,dso,sym) will be used */
if (setup_sorting() < 0)
@@ -129,8 +130,11 @@ int test__hists_filter(int subtest __maybe_unused)
 
/* setup threads/dso/map/symbols also */
machine = setup_fake_machine();
-   if (!machine)
+   if (IS_ERR(machine)) {
+   if (PTR_ERR(machine) == -EACCES)
+   err = TEST_SKIP;
goto out;
+   }
 
if (verbose > 1)
machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_link.c b/tools/perf/tests/hists_link.c
index 6243e2b..f5f37ef9 100644
--- a/tools/perf/tests/hists_link.c
+++ b/tools/perf/tests/hists_link.c
@@ -293,6 +293,7 @@ int test__hists_link(int subtest 

Re: [PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-14 Thread Namhyung Kim
Hi,

On Tue, Dec 15, 2015 at 04:18:44AM +, Wang Nan wrote:
> Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
> testcases when kptr_restrict is on') solves a double free problem when
> 'perf test hist' calling setup_fake_machine(). However, the result is
> still incorrect. For example:
> 
>  $ ./perf test -v 'filtering hist entries'
>  25: Test filtering hist entries  :
>  --- start ---
>  test child forked, pid 4186
>  Cannot create kernel maps
>  test child finished with 0
>   end 
>  Test filtering hist entries: Ok
> 
> In this case the body of this test is not get executed at all, but the
> result is 'Ok'. I think 'Skip' should be better.

Right, I missed this part.

But on second thought, I think it should not create real kernel maps.
What setup_fake_machine() does is to create/insert fake
dso/mmap/symbols for testing hist functions.  So it has to use the
predefined info not real ones.


> 
> The reason is that *ALL* hists test cases forget to reset err after
> using it to hold an error code.
> 
> This patch ensure err is reset.
> 
> In case when kptr_restrict prevent normal user get kernel address, this
> test should be skipped, not fail. This patch uses linux/err.h to store
> error code in return value of setup_fake_machine(), and let 'EACCES' to
> indicate this problem.

Please just remove the machine__create_kernel_maps() in
setup_fake_machine() and simply return TEST_FAIL if there's an error.

Thanks,
Namhyung


> 
> Signed-off-by: Wang Nan 
> Cc: Arnaldo Carvalho de Melo 
> Cc: Jiri Olsa 
> Cc: Masami Hiramatsu 
> Cc: Namhyung Kim 
> ---
>  tools/perf/tests/hists_common.c   | 12 +---
>  tools/perf/tests/hists_common.h   |  1 +
>  tools/perf/tests/hists_cumulate.c |  6 +-
>  tools/perf/tests/hists_filter.c   |  6 +-
>  tools/perf/tests/hists_link.c |  6 +-
>  tools/perf/tests/hists_output.c   |  6 +-
>  6 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
> index bcfd081..2eca1b2 100644
> --- a/tools/perf/tests/hists_common.c
> +++ b/tools/perf/tests/hists_common.c
> @@ -81,15 +81,20 @@ struct machine *setup_fake_machine(struct machines 
> *machines)
>  {
>   struct machine *machine = machines__find(machines, HOST_KERNEL_ID);
>   size_t i;
> + int err = -ENOMEM;
>  
>   if (machine == NULL) {
>   pr_debug("Not enough memory for machine setup\n");
> - return NULL;
> + return ERR_PTR(-ENOMEM);
>   }
>  
>   if (machine__create_kernel_maps(machine)) {
>   pr_debug("Cannot create kernel maps\n");
> - return NULL;
> + if (symbol_conf.kptr_restrict) {
> + pr_debug("Hint: Check 
> /proc/sys/kernel/kptr_restrict.\n");
> + err = -EACCES;
> + }
> + return ERR_PTR(err);
>   }
>  
>   for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
> @@ -155,7 +160,8 @@ struct machine *setup_fake_machine(struct machines 
> *machines)
>  out:
>   pr_debug("Not enough memory for machine setup\n");
>   machine__delete_threads(machine);
> - return NULL;
> + machine__exit(machine);
> + return ERR_PTR(err);
>  }
>  
>  void print_hists_in(struct hists *hists)
> diff --git a/tools/perf/tests/hists_common.h b/tools/perf/tests/hists_common.h
> index 888254e..0252eae 100644
> --- a/tools/perf/tests/hists_common.h
> +++ b/tools/perf/tests/hists_common.h
> @@ -1,5 +1,6 @@
>  #ifndef __PERF_TESTS__HISTS_COMMON_H__
>  #define __PERF_TESTS__HISTS_COMMON_H__
> +#include 
>  
>  struct machine;
>  struct machines;
> diff --git a/tools/perf/tests/hists_cumulate.c 
> b/tools/perf/tests/hists_cumulate.c
> index 8292948..c211075 100644
> --- a/tools/perf/tests/hists_cumulate.c
> +++ b/tools/perf/tests/hists_cumulate.c
> @@ -706,13 +706,17 @@ int test__hists_cumulate(int subtest __maybe_unused)
>   err = parse_events(evlist, "cpu-clock", NULL);
>   if (err)
>   goto out;
> + err = TEST_FAIL;
>  
>   machines__init();
>  
>   /* setup threads/dso/map/symbols also */
>   machine = setup_fake_machine();
> - if (!machine)
> + if (IS_ERR(machine)) {
> + if (PTR_ERR(machine) == -EACCES)
> + err = TEST_SKIP;
>   goto out;
> + }
>  
>   if (verbose > 1)
>   machine__fprintf(machine, stderr);
> diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
> index ccb5b49..795a04d 100644
> --- a/tools/perf/tests/hists_filter.c
> +++ b/tools/perf/tests/hists_filter.c
> @@ -120,6 +120,7 @@ int test__hists_filter(int subtest __maybe_unused)
>   err = parse_events(evlist, "task-clock", NULL);
>   if (err)
>   goto out;
> + err = TEST_FAIL;
>  
>   

[PATCH] perf tests: Fix false TEST_OK result for 'perf test hist'

2015-12-14 Thread Wang Nan
Commit 71d6de64feddd4b45326fba2111b3006d9e0 ('perf test: Fix hist
testcases when kptr_restrict is on') solves a double free problem when
'perf test hist' calling setup_fake_machine(). However, the result is
still incorrect. For example:

 $ ./perf test -v 'filtering hist entries'
 25: Test filtering hist entries  :
 --- start ---
 test child forked, pid 4186
 Cannot create kernel maps
 test child finished with 0
  end 
 Test filtering hist entries: Ok

In this case the body of this test is not get executed at all, but the
result is 'Ok'. I think 'Skip' should be better.

The reason is that *ALL* hists test cases forget to reset err after
using it to hold an error code.

This patch ensure err is reset.

In case when kptr_restrict prevent normal user get kernel address, this
test should be skipped, not fail. This patch uses linux/err.h to store
error code in return value of setup_fake_machine(), and let 'EACCES' to
indicate this problem.

Signed-off-by: Wang Nan 
Cc: Arnaldo Carvalho de Melo 
Cc: Jiri Olsa 
Cc: Masami Hiramatsu 
Cc: Namhyung Kim 
---
 tools/perf/tests/hists_common.c   | 12 +---
 tools/perf/tests/hists_common.h   |  1 +
 tools/perf/tests/hists_cumulate.c |  6 +-
 tools/perf/tests/hists_filter.c   |  6 +-
 tools/perf/tests/hists_link.c |  6 +-
 tools/perf/tests/hists_output.c   |  6 +-
 6 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/tools/perf/tests/hists_common.c b/tools/perf/tests/hists_common.c
index bcfd081..2eca1b2 100644
--- a/tools/perf/tests/hists_common.c
+++ b/tools/perf/tests/hists_common.c
@@ -81,15 +81,20 @@ struct machine *setup_fake_machine(struct machines 
*machines)
 {
struct machine *machine = machines__find(machines, HOST_KERNEL_ID);
size_t i;
+   int err = -ENOMEM;
 
if (machine == NULL) {
pr_debug("Not enough memory for machine setup\n");
-   return NULL;
+   return ERR_PTR(-ENOMEM);
}
 
if (machine__create_kernel_maps(machine)) {
pr_debug("Cannot create kernel maps\n");
-   return NULL;
+   if (symbol_conf.kptr_restrict) {
+   pr_debug("Hint: Check 
/proc/sys/kernel/kptr_restrict.\n");
+   err = -EACCES;
+   }
+   return ERR_PTR(err);
}
 
for (i = 0; i < ARRAY_SIZE(fake_threads); i++) {
@@ -155,7 +160,8 @@ struct machine *setup_fake_machine(struct machines 
*machines)
 out:
pr_debug("Not enough memory for machine setup\n");
machine__delete_threads(machine);
-   return NULL;
+   machine__exit(machine);
+   return ERR_PTR(err);
 }
 
 void print_hists_in(struct hists *hists)
diff --git a/tools/perf/tests/hists_common.h b/tools/perf/tests/hists_common.h
index 888254e..0252eae 100644
--- a/tools/perf/tests/hists_common.h
+++ b/tools/perf/tests/hists_common.h
@@ -1,5 +1,6 @@
 #ifndef __PERF_TESTS__HISTS_COMMON_H__
 #define __PERF_TESTS__HISTS_COMMON_H__
+#include 
 
 struct machine;
 struct machines;
diff --git a/tools/perf/tests/hists_cumulate.c 
b/tools/perf/tests/hists_cumulate.c
index 8292948..c211075 100644
--- a/tools/perf/tests/hists_cumulate.c
+++ b/tools/perf/tests/hists_cumulate.c
@@ -706,13 +706,17 @@ int test__hists_cumulate(int subtest __maybe_unused)
err = parse_events(evlist, "cpu-clock", NULL);
if (err)
goto out;
+   err = TEST_FAIL;
 
machines__init();
 
/* setup threads/dso/map/symbols also */
machine = setup_fake_machine();
-   if (!machine)
+   if (IS_ERR(machine)) {
+   if (PTR_ERR(machine) == -EACCES)
+   err = TEST_SKIP;
goto out;
+   }
 
if (verbose > 1)
machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_filter.c b/tools/perf/tests/hists_filter.c
index ccb5b49..795a04d 100644
--- a/tools/perf/tests/hists_filter.c
+++ b/tools/perf/tests/hists_filter.c
@@ -120,6 +120,7 @@ int test__hists_filter(int subtest __maybe_unused)
err = parse_events(evlist, "task-clock", NULL);
if (err)
goto out;
+   err = TEST_FAIL;
 
/* default sort order (comm,dso,sym) will be used */
if (setup_sorting() < 0)
@@ -129,8 +130,11 @@ int test__hists_filter(int subtest __maybe_unused)
 
/* setup threads/dso/map/symbols also */
machine = setup_fake_machine();
-   if (!machine)
+   if (IS_ERR(machine)) {
+   if (PTR_ERR(machine) == -EACCES)
+   err = TEST_SKIP;
goto out;
+   }
 
if (verbose > 1)
machine__fprintf(machine, stderr);
diff --git a/tools/perf/tests/hists_link.c b/tools/perf/tests/hists_link.c
index 6243e2b..f5f37ef9 100644
---