On 2022-03-15 at 09:44:25 -0700, Reinette Chatre wrote:
Some selftests depend on information provided by the CPUID instruction. To support this dependency the selftests implement private wrappers for CPUID.
Duplication of the CPUID wrappers should be avoided.
Both gcc and clang/LLVM provide __cpuid_count() macros but neither the macro nor its header file are available in all the compiler versions that need to be supported by the selftests. __cpuid_count() as provided by gcc is available starting with gcc v4.4, so it is not available if the latest tests need to be run in all the environments required to support kernels v4.9 and v4.14 that have the minimal required gcc v3.2.
Provide a centrally defined macro for __cpuid_count() to help eliminate the duplicate CPUID wrappers while continuing to compile in older environments.
Suggested-by: Shuah Khan skhan@linuxfoundation.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com
Note to maintainers:
- Macro is identical to the one provided by gcc, but not liked by checkpatch.pl with message "Macros with complex values should be enclosed in parentheses". Similar style is used in kernel, for example in arch/x86/kernel/fpu/xstate.h.
tools/testing/selftests/kselftest.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h index f1180987492c..898d7b2fac6c 100644 --- a/tools/testing/selftests/kselftest.h +++ b/tools/testing/selftests/kselftest.h @@ -52,6 +52,21 @@
- have __cpuid_count().
- */
+#ifndef __cpuid_count +#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))+#endif
Linux C check tool "scripts/checkpatch.pl" shows an error: " ERROR: Macros with complex values should be enclosed in parentheses ... +#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)) " Googling: https://www.google.com/search?q=Macros+with+complex+values+should+be+enclose... -> https://stackoverflow.com/questions/8142280/why-do-we-need-parentheses-aroun...
Could we fix it as follow, shall we? " #ifndef __cpuid_count #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)) \ }) #endif " Thanks! --Pengfei