On 06/13/2018 05:45 PM, Ram Pai wrote:
> When a key is freed, the key is no more effective.
> Clear the bits corresponding to the pkey in the shadow
> register. Otherwise it will carry some spurious bits
> which can trigger false-positive asserts.
...--- a/tools/testing/selftests/vm/protection_keys.c
> +++ b/tools/testing/selftests/vm/protection_keys.c
> @@ -556,6 +556,9 @@ int alloc_pkey(void)
> int sys_pkey_free(unsigned long pkey)
> {
> int ret = syscall(SYS_pkey_free, pkey);
> +
> + if (!ret)
> + shadow_pkey_reg &= clear_pkey_flags(pkey, PKEY_DISABLE_ACCESS);
> dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret);
> return ret;
> }
This would be great code for an actual application. But, I'm not
immediately convinced we want sane, kind behavior in our selftest. x86
doesn't clear the hardware register at pkey_free, so wouldn't this cause
the shadow and the hardware register to diverge?
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