Re: [PATCH v13 17/24] selftests/vm: powerpc implementation to check support for pkey

[Ram Pai]

On Wed, Jun 20, 2018 at 08:09:12AM -0700, Dave Hansen wrote:
> > -   if (cpu_has_pku()) {
> > -   dprintf1("SKIP: %s: no CPU support\n", __func__);
> > +   if (is_pkey_supported()) {
> > +   dprintf1("SKIP: %s: no CPU/kernel support\n", __func__);
> > return;
> > }
> 
> I actually kinda wanted a specific message for when the *CPU* doesn't
> support the feature.

is_pkey_supported() x86 implementation has specific messages. it will
print if the CPU doesn't support the feature.

RP

-- 
Ram Pai

Re: [PATCH v13 17/24] selftests/vm: powerpc implementation to check support for pkey

[Dave Hansen]

> - if (cpu_has_pku()) {
> - dprintf1("SKIP: %s: no CPU support\n", __func__);
> + if (is_pkey_supported()) {
> + dprintf1("SKIP: %s: no CPU/kernel support\n", __func__);
>   return;
>   }

I actually kinda wanted a specific message for when the *CPU* doesn't
support the feature.

[PATCH v13 17/24] selftests/vm: powerpc implementation to check support for pkey

[Ram Pai]

pkey subsystem is supported if the hardware and kernel has support.
We determine that by checking if allocation of a key succeeds or not.

cc: Dave Hansen 
cc: Florian Weimer 
Signed-off-by: Ram Pai 
---
 tools/testing/selftests/vm/pkey-helpers.h|2 ++
 tools/testing/selftests/vm/pkey-powerpc.h|   14 --
 tools/testing/selftests/vm/pkey-x86.h|8 
 tools/testing/selftests/vm/protection_keys.c |9 +
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/vm/pkey-helpers.h 
b/tools/testing/selftests/vm/pkey-helpers.h
index 321bbbd..288ccff 100644
--- a/tools/testing/selftests/vm/pkey-helpers.h
+++ b/tools/testing/selftests/vm/pkey-helpers.h
@@ -76,6 +76,8 @@ static inline void sigsafe_printf(const char *format, ...)
 
 __attribute__((noinline)) int read_ptr(int *ptr);
 void expected_pkey_fault(int pkey);
+int sys_pkey_alloc(unsigned long flags, u64 init_val);
+int sys_pkey_free(unsigned long pkey);
 
 #if defined(__i386__) || defined(__x86_64__) /* arch */
 #include "pkey-x86.h"
diff --git a/tools/testing/selftests/vm/pkey-powerpc.h 
b/tools/testing/selftests/vm/pkey-powerpc.h
index ec6f5d7..957f6f6 100644
--- a/tools/testing/selftests/vm/pkey-powerpc.h
+++ b/tools/testing/selftests/vm/pkey-powerpc.h
@@ -62,9 +62,19 @@ static inline void __write_pkey_reg(pkey_reg_t pkey_reg)
pkey_reg);
 }
 
-static inline int cpu_has_pku(void)
+static inline bool is_pkey_supported(void)
 {
-   return 1;
+   /*
+* No simple way to determine this.
+* Lets try allocating a key and see if it succeeds.
+*/
+   int ret = sys_pkey_alloc(0, 0);
+
+   if (ret > 0) {
+   sys_pkey_free(ret);
+   return true;
+   }
+   return false;
 }
 
 static inline int arch_reserved_keys(void)
diff --git a/tools/testing/selftests/vm/pkey-x86.h 
b/tools/testing/selftests/vm/pkey-x86.h
index 95ee952..6820c10 100644
--- a/tools/testing/selftests/vm/pkey-x86.h
+++ b/tools/testing/selftests/vm/pkey-x86.h
@@ -105,7 +105,7 @@ static inline void __cpuid(unsigned int *eax, unsigned int 
*ebx,
 #define X86_FEATURE_PKU(1<<3) /* Protection Keys for Userspace */
 #define X86_FEATURE_OSPKE  (1<<4) /* OS Protection Keys Enable */
 
-static inline int cpu_has_pku(void)
+static inline bool is_pkey_supported(void)
 {
unsigned int eax;
unsigned int ebx;
@@ -118,13 +118,13 @@ static inline int cpu_has_pku(void)
 
if (!(ecx & X86_FEATURE_PKU)) {
dprintf2("cpu does not have PKU\n");
-   return 0;
+   return false;
}
if (!(ecx & X86_FEATURE_OSPKE)) {
dprintf2("cpu does not have OSPKE\n");
-   return 0;
+   return false;
}
-   return 1;
+   return true;
 }
 
 #define XSTATE_PKEY_BIT(9)
diff --git a/tools/testing/selftests/vm/protection_keys.c 
b/tools/testing/selftests/vm/protection_keys.c
index ba184ca..cb81a47 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -1393,8 +1393,8 @@ void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 
pkey)
int size = PAGE_SIZE;
int sret;
 
-   if (cpu_has_pku()) {
-   dprintf1("SKIP: %s: no CPU support\n", __func__);
+   if (is_pkey_supported()) {
+   dprintf1("SKIP: %s: no CPU/kernel support\n", __func__);
return;
}
 
@@ -1458,12 +1458,13 @@ void run_tests_once(void)
 int main(void)
 {
int nr_iterations = 22;
+   int pkey_supported = is_pkey_supported();
 
setup_handlers();
 
-   printf("has pkey: %d\n", cpu_has_pku());
+   printf("has pkey: %s\n", pkey_supported ? "Yes" : "No");
 
-   if (!cpu_has_pku()) {
+   if (!pkey_supported) {
int size = PAGE_SIZE;
int *ptr;
 
-- 
1.7.1