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@xxxxxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
---
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)
--
2.39.2
