gcc as well as clang makes the __cpuid_count() macro available via cpuid.h to conveniently call the CPUID instruction.
Below is a copy of the macro as found in cpuid.h:
#define __cpuid_count(level, count, a, b, c, d) \ __asm__ ("cpuid\n\t" \ : "=a" (a), "=b" (b), "=c" (c), "=d" (d) \ : "0" (level), "2" (count))
The pkeys test contains a local function used as wrapper of the CPUID instruction. One difference between the pkeys implementation and the macro from cpuid.h is that the pkeys implementation provides the "volatile" qualifier to the asm() call. The "volatile" qualifier is necessary if CPUID has side effects and thus specifies that any optimizations should be avoided. The pkeys test uses CPUID to query the system for its protection keys status and save area properties, queries without side effect, the "volatile" qualifier is not required and the macro from cpuid.h can be used instead.
Remove the duplicated wrapper to CPUID and use __cpuid_count() from cpuid.h instead.
Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Ram Pai linuxram@us.ibm.com Cc: Sandipan Das sandipan@linux.ibm.com Cc: Florian Weimer fweimer@redhat.com Cc: "Desnes A. Nunes do Rosario" desnesn@linux.vnet.ibm.com Cc: Ingo Molnar mingo@kernel.org Cc: Thiago Jung Bauermann bauerman@linux.ibm.com Cc: Michael Ellerman mpe@ellerman.id.au Cc: Michal Suchanek msuchanek@suse.de Cc: linux-mm@kvack.org Signed-off-by: Reinette Chatre reinette.chatre@intel.com --- tools/testing/selftests/vm/pkey-x86.h | 22 +++------------------- 1 file changed, 3 insertions(+), 19 deletions(-)
diff --git a/tools/testing/selftests/vm/pkey-x86.h b/tools/testing/selftests/vm/pkey-x86.h index e4a4ce2b826d..17b20af8d8f8 100644 --- a/tools/testing/selftests/vm/pkey-x86.h +++ b/tools/testing/selftests/vm/pkey-x86.h @@ -2,6 +2,7 @@
#ifndef _PKEYS_X86_H #define _PKEYS_X86_H +#include <cpuid.h>
#ifdef __i386__
@@ -80,19 +81,6 @@ static inline void __write_pkey_reg(u64 pkey_reg) assert(pkey_reg == __read_pkey_reg()); }
-static inline void __cpuid(unsigned int *eax, unsigned int *ebx, - unsigned int *ecx, unsigned int *edx) -{ - /* ecx is often an input as well as an output. */ - asm volatile( - "cpuid;" - : "=a" (*eax), - "=b" (*ebx), - "=c" (*ecx), - "=d" (*edx) - : "0" (*eax), "2" (*ecx)); -} - /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */ #define X86_FEATURE_PKU (1<<3) /* Protection Keys for Userspace */ #define X86_FEATURE_OSPKE (1<<4) /* OS Protection Keys Enable */ @@ -104,9 +92,7 @@ static inline int cpu_has_pkeys(void) unsigned int ecx; unsigned int edx;
- eax = 0x7; - ecx = 0x0; - __cpuid(&eax, &ebx, &ecx, &edx); + __cpuid_count(0x7, 0x0, eax, ebx, ecx, edx);
if (!(ecx & X86_FEATURE_PKU)) { dprintf2("cpu does not have PKU\n"); @@ -142,9 +128,7 @@ int pkey_reg_xstate_offset(void) /* assume that XSTATE_PKEY is set in XCR0 */ leaf = XSTATE_PKEY_BIT; { - eax = XSTATE_CPUID; - ecx = leaf; - __cpuid(&eax, &ebx, &ecx, &edx); + __cpuid_count(XSTATE_CPUID, leaf, eax, ebx, ecx, edx);
if (leaf == XSTATE_PKEY_BIT) { xstate_offset = ebx;