Building resctrl selftest fails on ARM because it uses __cpuid_count() that fails the build with error:
CC resctrl_tests 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:323:6: ../kselftest.h:74:9: error: impossible constraint in 'asm' 74 | __asm__ __volatile__ ("cpuid\n\t" \ | ^~~~~~~ cat_test.c:301:17: note: in expansion of macro '__cpuid_count' 301 | __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:303:17: note: in expansion of macro '__cpuid_count' 303 | __cpuid_count(0x10, 2, eax, ebx, ecx, edx); | ^~~~~~~~~~~~~
The resctrl selftest would run that code only on Intel CPUs but as is, the code cannot be build at all.
Define HAVE_CPUID in lib.mk based on ARCH (x86 or x86_64). If ARCH is not set, acquire it using uname -m.
Provide a stub for __cpuid_count() if HAVE_CPUID is not present to allow build to succeed. The stub casts its arguments to void to avoid causing "unused variable" or "set but not used" warnings.
Fixes: ae638551ab64 ("selftests/resctrl: Add non-contiguous CBMs CAT test") Reported-by: Muhammad Usama Anjum usama.anjum@collabora.com Signed-off-by: Ilpo Järvinen ilpo.jarvinen@linux.intel.com --- v3: - Remove "empty" wording - Also cast input parameters to void - Initialize ARCH from uname -m if not set (this might allow cleaning up some other makefiles but that is left as future work) v2: - Removed RFC & added Fixes and Tested-by - Fixed the error message's line splits - Noted down the reason for void casts in the stub --- tools/testing/selftests/kselftest.h | 6 ++++++ tools/testing/selftests/lib.mk | 6 ++++++ 2 files changed, 12 insertions(+)
diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h index b8967b6e29d5..9c4bfbf107f1 100644 --- a/tools/testing/selftests/kselftest.h +++ b/tools/testing/selftests/kselftest.h @@ -70,10 +70,16 @@ * have __cpuid_count(). */ #ifndef __cpuid_count +#ifdef HAVE_CPUID #define __cpuid_count(level, count, a, b, c, d) \ __asm__ __volatile__ ("cpuid\n\t" \ : "=a" (a), "=b" (b), "=c" (c), "=d" (d) \ : "0" (level), "2" (count)) +#else +#define __cpuid_count(level, count, a, b, c, d) do { \ + (void)level; (void)count; (void)a; (void)b; (void)c; (void)d; \ +} while (0) +#endif #endif
/* define kselftest exit codes */ diff --git a/tools/testing/selftests/lib.mk b/tools/testing/selftests/lib.mk index d6edcfcb5be8..8e3069926153 100644 --- a/tools/testing/selftests/lib.mk +++ b/tools/testing/selftests/lib.mk @@ -23,6 +23,8 @@ CLANG_TARGET_FLAGS_x86_64 := x86_64-linux-gnu
# Default to host architecture if ARCH is not explicitly given. ifeq ($(ARCH),) +ARCH := $(shell uname -m 2>/dev/null || echo not) +ARCH := $(shell echo $(ARCH) | sed -e s/i.86/x86/) CLANG_TARGET_FLAGS := $(shell $(CLANG) -print-target-triple) else CLANG_TARGET_FLAGS := $(CLANG_TARGET_FLAGS_$(ARCH)) @@ -199,6 +201,10 @@ clean: $(if $(TEST_GEN_MODS_DIR),clean_mods_dir) # Build with _GNU_SOURCE by default CFLAGS += -D_GNU_SOURCE=
+ifeq ($(ARCH),$(filter $(ARCH),x86 x86_64)) +CFLAGS += -DHAVE_CPUID= +endif + # Enables to extend CFLAGS and LDFLAGS from command line, e.g. # make USERCFLAGS=-Werror USERLDFLAGS=-static CFLAGS += $(USERCFLAGS)