On Thu, Sep 15, 2016 at 5:07 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
> On Thu, Sep 15, 2016 at 4:33 PM, Kyle Huey <me@xxxxxxxxxxxx> wrote:
>> +int get_cpuid_mode(unsigned long adr)
>> +{
>> + unsigned int val;
>> +
>> + if (test_thread_flag(TIF_NOCPUID))
>> + val = ARCH_CPUID_SIGSEGV;
>> + else
>> + val = ARCH_CPUID_ENABLE;
>> +
>> + return put_user(val, (unsigned int __user *)adr);
>> +}
>
> Can we just do:
>
> if (arg2 != 0)
> return -EINVAL;
> else
> return test_thread_flag(TIF_NOCPUID) ? ARCH_CPUID_SIGSEGBV : ARCH_CPUID_ENABLE;
We could. I copied the pattern of PR_GET_TSC here, but I don't feel
strongly about it.
>> diff --git a/tools/testing/selftests/x86/cpuid-fault.c b/tools/testing/selftests/x86/cpuid-fault.c
>> new file mode 100644
>> index 0000000..a9f3f68
>> --- /dev/null
>> +++ b/tools/testing/selftests/x86/cpuid-fault.c
>> @@ -0,0 +1,234 @@
>> +
>> +/*
>> + * Tests for arch_prctl(ARCH_GET_CPUID, ...) / prctl(ARCH_SET_CPUID, ...)
>> + *
>> + * Basic test to test behaviour of ARCH_GET_CPUID and ARCH_SET_CPUID
>> + */
>> +
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <unistd.h>
>> +#include <signal.h>
>> +#include <inttypes.h>
>> +#include <cpuid.h>
>> +#include <errno.h>
>> +#include <sys/wait.h>
>> +
>> +#include <sys/prctl.h>
>> +#include <linux/prctl.h>
>> +
>> +const char *cpuid_names[] = {
>> + [0] = "[not set]",
>
> Is 0 even possible?
Only if the call fails.
- Kyle
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