selftests:resctrl: Fix build failure on archs without __cpuid_count()

When resctrl is built on architectures without __cpuid_count()
support, build fails. resctrl uses __cpuid_count() defined in
kselftest.h.

Even though the problem is seen while building resctrl on aarch64,
this error can be seen on any platform that doesn't support CPUID.

CPUID is a x86/x86-64 feature and code paths with CPUID asm commands
will fail to build on all other architectures.

All others tests call __cpuid_count() do so from x86/x86_64 code paths
when _i386__ or __x86_64__ are defined. resctrl is an exception.

Fix the problem by defining __cpuid_count() only when __i386__ or
__x86_64__ are defined in kselftest.h and changing resctrl to call
__cpuid_count() only when __i386__ or __x86_64__ are defined.

In file included from resctrl.h:24,
                 from cat_test.c:11:
In function ‘arch_supports_noncont_cat’,
    inlined from ‘noncont_cat_run_test’ at cat_test.c:326:6:
../kselftest.h:74:9: error: impossible constraint in ‘asm’
   74 |         __asm__ __volatile__ ("cpuid\n\t"                               \
      |         ^~~~~~~
cat_test.c:304:17: note: in expansion of macro ‘__cpuid_count’
  304 |                 __cpuid_count(0x10, 1, eax, ebx, ecx, edx);
      |                 ^~~~~~~~~~~~~
../kselftest.h:74:9: error: impossible constraint in ‘asm’
   74 |         __asm__ __volatile__ ("cpuid\n\t"                               \
      |         ^~~~~~~
cat_test.c:306:17: note: in expansion of macro ‘__cpuid_count’
  306 |                 __cpuid_count(0x10, 2, eax, ebx, ecx, edx);

Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test")
Reported-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Closes: https://lore.kernel.org/lkml/20240809071059.265914-1-usama.anjum@collabora.com/
Reported-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
index b8967b6e29d5037f29276dfb6a798bcee3e5f543..e195ec1568599a721b8fe166059603fc082a4425 100644 (file)
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -61,6 +61,7 @@
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 #endif
 
+#if defined(__i386__) || defined(__x86_64__) /* arch */
 /*
  * gcc cpuid.h provides __cpuid_count() since v4.4.
  * Clang/LLVM cpuid.h provides  __cpuid_count() since v3.4.0.
@@ -75,6 +76,7 @@
                              : "=a" (a), "=b" (b), "=c" (c), "=d" (d)  \
                              : "0" (level), "2" (count))
 #endif
+#endif /* end arch */
 
 /* define kselftest exit codes */
 #define KSFT_PASS  0

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 742782438ca3b0d59c1ce786648c361c4572083a..94cfdba5308d8c874054a91c792c2657e52f0973 100644 (file)
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -290,12 +290,12 @@ static int cat_run_test(const struct resctrl_test *test, const struct user_param
 
 static bool arch_supports_noncont_cat(const struct resctrl_test *test)
 {
-       unsigned int eax, ebx, ecx, edx;
-
        /* AMD always supports non-contiguous CBM. */
        if (get_vendor() == ARCH_AMD)
                return true;
 
+#if defined(__i386__) || defined(__x86_64__) /* arch */
+       unsigned int eax, ebx, ecx, edx;
        /* Intel support for non-contiguous CBM needs to be discovered. */
        if (!strcmp(test->resource, "L3"))
                __cpuid_count(0x10, 1, eax, ebx, ecx, edx);
@@ -305,6 +305,9 @@ static bool arch_supports_noncont_cat(const struct resctrl_test *test)
                return false;
 
        return ((ecx >> 3) & 1);
+#endif /* end arch */
+
+       return false;
 }
 
 static int noncont_cat_run_test(const struct resctrl_test *test,